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Journal of Geographical Sciences >

2016 , Vol. 26 >Issue 4: 484 - 500

DOI: https://doi.org/10.1007/s11442-016-1281-4

Orginal Article

An explanation of labor migration and grain
output growth:
Findings of a case study in eastern Tibetan Plateau

  • YAN Jianzhong , 1 ,
  • ZHANG Yili 2, 3 ,
  • HUA Xiaobo 1 ,
  • YANG Liang 4
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  • 1. College of Resources and Environment, Southwest University, Chongqing 400716, China
  • 2. Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
  • 3. University of Chinese Academy of Sciences, Beijing 10049, China
  • 4. Institute of Geography, University of Hamburg, 20144 Hamburg, Germany

Author: Yan Jianzhong (1972-), PhD and Professor, specialized in land use/cover change, climate change and regional adaptation. E-mail:

Received date: 2015-07-01

  Accepted date: 2015-09-24

  Online published: 2016-04-25

Supported by

National Natural Science Foundation of China, No.41071066, No.41571093 Strategic Priority Research Program of the Chinese Academy of Sciences, No XDB03030500

Copyright

Journal of Geographical Sciences, All Rights Reserved
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Abstract

Although there has been rapid rural-urban migration in rural China since the 1980s, the total grain production of China saw a continuous increase. As of today, the relationship between labor migration and grain output growth remains partial and contradictory. The main aim of this empirical study is to examine some specific measures adopted by peasants to deal with labor shortage and maintain grain output growth. Using tracking survey, participatory rural appraisal methods, and land plot investigation, we investigate 274 households and 1405 arable land plots in four villages in two stages in Jinchuan county, southwestern China. The results show that continuous emigration of labor from the four villages caused the abandonment of a small amount of land, decreased labor intensity, and reduced multiple cropping index, shifting from “corn-wheat” multiple cropping pattern to the “corn” cropping pattern, which means labor shortage in some households. At the same time, owing to surplus labor in the villages, the peasants utilize a series of means to offset the negative impacts of labor migration on grain output, such as cropland transfer, labor exchange in the busy seasons, and the substitution of capital and technology for labor. The econometric analysis also shows that labor migration boosts grain production. This study provides a reasonable explanation of grain output growth under rural-urban migration.

Key words： labor migration; land use change; labor intensity; capital intensity; grain output

Cite this article

YAN Jianzhong , ZHANG Yili , HUA Xiaobo , YANG Liang . An explanation of labor migration and grain
output growth:
Findings of a case study in eastern Tibetan Plateau[J]. Journal of Geographical Sciences, 2016 , 26(4) : 484 -500 . DOI: 10.1007/s11442-016-1281-4

1 Introduction

Since the 1980s, China has been undergoing a process of rapid out migration of rural labor to urban areas. According to the China Statistical Yearbook (1982-2011), the country’s urbanization rate increased from 20.91% in 1982 to 51.27% in 2012, showing 1.01% annual growth. Meanwhile, the rural population has a negative growth rate of 1.5% from 2001 to 2007. However, the total grain output has been constantly increasing since the 1980s.
An explanation of labor migration and grain output growth in China is critical to formulate appropriate policies that would maintain the increase of grain production capacity. For example, a question that needs to be addressed is, will the trend of grain output growth stop in the near future, or decades later? If the former is true, the government must actively enact policies that boost grain output accordingly. Moreover, these policies should be based on a comprehensive understanding of the measures adopted by the peasants to mitigate labor shortage and promote grain output.
Case studies from other countries show that depending on the presence of surplus labor and the extent of labor market perfection, the withdrawal of labor from agricultural to non-agricultural activities may or may not negatively affect agricultural output (Bardhan and Udry, 1999). These studies have shown three scenarios in the linkages between labor migration and agricultural output: (1) If there is sufficient surplus labor, remittances from family members working in cities allow rural residents to purchase high-quality seeds, fertilizers, pesticides, herbicides, and other new technology and infrastructure to boost crop yields (Stark and Bloom, 1985; Lucas, 1987; Rozelle et al., 1999; Dustmann and Kirchkamp, 2001; Woodruff and Zenteno, 2001; Brière et al., 2002; Black et al., 2003; Taylor et al., 2003;Taylor and López-Feldman, 2010). (2) In the case of a thin labor market and in the absence of surplus labor, labor withdrawal can reduce the on-farm labor as well as the agricultural output (Lipton, 1980; Clay et al., 1998; Macdonald et al., 2000; Mochebelele and Winter-Nelson, 2000; Holden et al., 2004; Strijker, 2005; Tzanopoulos et al., 2007; Yamada et al., 2007; Beyene, 2008; Brosig et al., 2009; Gray, 2009). (3) In the situation of a well-functioning labor market, hired labor can substitute for lost family labor with compromising output (Oseni and Winters, 2009).
While the relationship between labor migration and the continuous grain output growth in China seems to fit in the first scenario, we must note that the case studies on such a relationship remain partial and sometimes in contradictory. Several empirical analyses in China find that participation in labor migration fosters household ability to invest on the farm (Rozelle et al., 1999; Taylor et al., 1999, 2003; De Janvry et al., 2005), and case studies on the plain provinces of China show continuous increase of grain output as well as rapid increase of labor productivity (Hao et al., 2013). However, other case studies find that emigration of agricultural laborers has caused the marginalization of agricultural land, which has resulted in arable land abandonment and decrease in labor intensity, thus posing the additional challenge of ensuring food security (Liu and Li, 2006; Chen et al., 2009a; Tian et al., 2009; Xin and Li, 2009; Tian et al., 2010). A few studies have reported measures adopted to deal with labor shortage, such as substituting capital and technology for labor (Zhang et al., 2008; Chen et al., 2009a; Hao et al., 2013) and land transfer between households to mitigate land abandonment (Yao, 2000; Kung, 2002; Jin and Deininger, 2007). However, as of date, there remains a lack of comprehensive research which quantitatively examines the relationship between labor migration and grain output growth on household scale. The previous studies are not sufficient to explain the fact of labor migration and grain output growth in China, at either village scale or country scale. Furthermore, the existing studies on this issue focus mostly on plain areas, with little information about the mountainous regions, especially the Tibetan Plateau.
In this study, we aim to investigate some specific measures adopted by the peasants to deal with labor shortage and maintain grain output growth. We conduct rural household surveys to compare land transfers, labor exchange, changes in labor intensity, and the substitution of capital and technology for labor between 2005 and 2010 in four villages of Jinchuan county in the upper reaches of the Dadu River watershed in Sichuan province, southwestern China. An econometric analysis was also conducted to test how labor migration affects grain output growth.

2 Study area

The study chose Jinchuan county as the case area, where it is located at the upper Dadu River watershed at the eastern edge of the Tibetan Plateau (Figure 1, Zhang et al., 2002). The county is at a typical eco-fragile region and lies in the transitional zone between the Sichuan Basin and the Tibetan Plateau (Yan et al., 2005). Specifically, our field investigation and data collections cover four villages at the Sha’er Township in Jinchuan county. The main reason for choosing the upper Dadu River watershed as the study area is that we have conducted land use studies here for many years and on different scales, thus accumulating a wealth of data. At the regional scale, we have studied the area’s land cover changes (Yan et al., 2005a), the driving mechanisms and spatial simulation of land-use changes (Bai et al., 2004; Bai et al., 2005; Yan et al., 2005b), and the farmer and nomad livelihood diversification scenarios (Yan et al., 2010a). At the village scale, we have studied farmer livelihoods and the land use of two out of the four villages in 2005/2005: Keerma village (Zhang et al., 2008) and Danzhamu village (Yan et al., 2009). In the Danzhamu case, we investigated livelihood strategy and land use between the collective system and the household responsibility system, and found crop structure adjustment, decrease of labor input, increase of chemical fertilizer input since the 1980s. In the Keerma case, Zhang et al. (2008) reported that livelihood strategy affecting land use type and land use intensification level.
Figure 1 Location of the four villages at Sha’er Township, Jinchuan county
Jinchuan county is located in the eastern edge of the Tibetan Plateau between 31°04′ to 31°58′N and 101°13′ to 102°19′E, covering an area of 5524 km2. The landform in Jinchuan county tilts gradually from northwest to southeast with a few mountains of above 4000 m height. The Dadu River drains the area, forming a deep river valley with steep slope and dividing it into two types of morphologic regions - the southeast mountain canyon area and the northwest mountain plains. Due to the influence of latitude, altitude, surface variations, and the redistribution of water, heat and light, the climate there is complex and varies with long sunny days, temperature differences, clearly wet and dry seasons, and distinct vertical and seasonal differences (ECCJC, 2011). Sha’er township, located in the northeastern part of Jinchuan county, comprises valley and middle-mountain landform. The chosen Danzhamu and Sha’erni villages represent the agricultural area and Shidaan and Keerma villages represent agro-pastoral areas.
The Danzhamu and Sha’erni villages are located 4.0 km and 5.8 km away from the county town, respectively. The two villages have notable regional advantages because they are located in the flat areas of the river valley with low altitude and gentle terrain. They have complete irrigation canal systems for farmland and gardens, convenient transportation, and other necessary infrastructure. With increasing opportunities in the industry and service sectors, non-agricultural employment has gradually become the main income source in the villages. In 2010, there were 1835 residents occupying 438 households in Danzhamu village, and Sha’erni village had 1064 residents in 284 households.
The Shidaan and Keerma villages are located in the central and western parts of Sha’er township, 6 km and 10 km from the Jinchuan county town, respectively. They both have typical mountain canyon landform with large differences in elevation (2430 m to 4170 m), resulting in an agro-pastoral mode of land use with a farmland-based and imbalanced distribution of grassland resource. While Shidaan village has relatively few grassland resources, causing a large conflict between livestock feeding demand and pasture resource supply, Keerma village is located on the hillside with relatively abundant pasture resources. The two villages have the necessary infrastructure and adequate transportation systems. In 2010, there were 357 households and a population of 1490 in Shidaan village, and Keerma village had 110 households with 421 residents.

3 Methodology

3.1 Tracking study and semi-structured interview

In order to understand the transitional track and explore the relationship between labor migration and grain output growth, we use the qualitative approaches which mainly contain a tracking survey and semi-structured interview, to gain an understanding of the changes of labor and production at first. This method, tracking study, is particularly suited for our study since we have mastered the knowledge based on the field surveys taken in 2005 and 2006 (Zhang et al., 2008; Yan et al., 2009). We conducted detailed sample surveys on the differences in rural household conditions in the four typical villages.
Our study adopted participatory rural appraisal (PRA) tools and the results presented in this paper are based on in-depth semi-structured interviews. The designed questions related to family-member employment situation, changes in farmer livelihood strategies since the implementation of the land contract system, changes in land assets and land use (such as number and size of plots, nature of crops, fertilizers, and labor input) following land allotment to households, the number and type of livestock, livelihood assets such as shops and workshops, household income and expenditure, farmers’ evaluation of living standards, awareness of livelihood vulnerability, and their future plans of livelihood. The first survey was conducted in two stages, the first in August 2005 and then from June to August 2006, and the second survey was also done in two stages, the first from May to August 2011 and then in September 2012. While the first survey involves livelihood and land use of 2005, the second survey covers that for 2010. The first survey received responses from 272 households, and the second one, from 274 households, with 216 households having been covered by both surveys.
We obtained the information on rural households-contracted cropland plots in the four villages through field survey. In our field survey, we selected sample plots, inspected plot archives, and numbered sample plots and recorded each sample’s acreage, type of land use, situation of crop cultivation, and fertilizer input at the start of the land contract. Under the guidance of local peasants, we then conducted field surveys of individual plots and recorded their attributes. Information on households and plots are linked together later.

3.2 Econometric modeling

For better understanding of the driving forces of grain production, a conventional quantitative approach, multiple linear regression model, is utilized to address the factors affecting grain production by the peasants. The dependent variable is the change in grain production between 2005 and 2010 of a sample household (in kg). The multiple linear regression equation is as below:
where yi is the dependent variable, x0 the constant term, xi the explanatory variable, βi the regression coefficient, and ε the random error term.
Following similar studies on factors affecting grain production (Qin et al., 2011; Gu, 2013; Liu et al., 2014), this paper includes explanatory variables on household characteristics, livelihood assets, input factors, and regional differences, as detailed below (Table 1).
Table 1 Variables and description of the econometric model
Variable Description Unit Mean Standard deviation
1. Household characteristics
Age of household head (2005) Age of household head in 2005 _ 52.06 11.48
Education level of household head (2005) Illiterate, elementary, middle, high school, college and above, assigned 1, 2, 3, 4 and 5, separately _ 2.23 0.79
2. Changes in livelihood assets
Change of labor migration Labor migration number of 2010-labor migration number of 2005 Individual 0.22 1.05
Change of total income Total income of 2010-total income of 2005 10
thousand		 2.16 2.79
Change of income from animal husbandry Income from animal husbandry of 2010-income from animal husbandry of 2005 10 thousand 0.18 0.46
Change of seeded area Seeded area of 2010-seeded area of 2005 1/15 ha -0.14 3.27
3. Change in production materials
Change of fertilizer input Fertilizer input of 2010-fertilizer input of 2005 kg 223.88 220.5
Number of plot in 2005 Number of plots in 2005 _ 3.50 1.88
4. Regional variables
Sha’erni Assigned 1, others 0 _ 0.19 0.40
Kerma Assigned 1, others 0 _ 0.20 0.40
Shidaan Assigned 1, others 0 _ 0.27 0.44
(1) Household characteristics: The household head is the main decision maker on crop plantation of a household, and thus, the age and education level of the household head have an effect on grain production. In this paper, the age and education level of the household head in 2005 are chosen as explanatory variables.
(2) Change in livelihood assets: Income, cropland areas and labor arrangement are the three factors that were used in this study to represent livelihood assets of a household. Household income is composed of agricultural income, animal husbandry income, and off-farm income, as local people seek livelihood diversification. Change of income from animal husbandry between 2005 and 2010 is chosen as an explanatory variable. However, the change in off-farm income is not considered as an explanatory variable, as it is correlated with the change in total income (the correlation coefficient being 0.975) and the change in labor migration. Agricultural income is also not considered as an explanatory variable, as it is correlated with grain production. The change in seeded area is chosen as an explanatory variable, as it reflects the changes in cropland area and cropping system. Labor arrangement between grain production and off-farm employment, e.g. the change in labor migration number between 2005 and 2010 is chosen as an explanatory variable.
(3) Change in production materials: Given the availability of data, the change in fertilizer inputs was selected as an explanatory variable to represent changes in agricultural capital investment. The number of plots (2005) to represent the degree of land fragmentation, as higher land fragmentation causes farmers to increase labor input but reduce the efficiency of grain production.
(4) Regional variables: There are large differences in the agricultural conditions between the valley and the middle-mountain areas, such as climate, soil, traffic conditions, and irrigation, and therefore, regional variables are introduced.

4 Results

4.1 Characteristics of sample households

Although population size of the sample households remained constant in the study period, there is a slight reduction in the labor force (Table 2). Due to labor migration in this period, the households have a decrease of 0.4 units of agricultural labor force on average. As an increasing number of people received education, the education level of the sample households had a slight increase and the illiteracy rate had a slight decrease. Simultaneously, there is an obvious trend of population aging. Compared to 2005, the proportion of people aged over 60 years increased by 4.52% in 2010, while the proportion of people aged less than 20 years had a 5.82% decrease.
From 2005 to 2010, the incomes of the sample households increased quickly and the income structure changed substantially. In 2005, income from non-agricultural employment, animal husbandry, and agriculture account for 74.88%, 14.86%, and 9.08% of total income, respectively. In 2010, the proportion changed to 81.41%, 10.50%, and 5.93%, respectively, showing a livelihood strategy relying more on non-agricultural employment.
Table 2 Family characteristics of the sample households of the four villages in 2005 and 2010
2010 2005
Average population per household 4.40 4.43
Average labor per household 2.84 3.04
Average non-agricultural labor per household 1.39 1.18
Average agricultural labor per household 1.45 1.86
Education
level (%)		 Preschool 5.16 5.12
Illiteracy 14.10 14.64
Primary school 35.79 39.85
Junior high school 28.84 27.93
High school 9.58 9.52
College 6.53 2.93
Income
(CNY)		 Total income 33338.43 11751.55
Non-agricultural income 27140.09 8800.05
Animal husbandry income 3500.93 1746.48
Farming income 1976.2 1067.16
Other income 721.21 137.86
Per capita income 7487.42 2791.45

4.2 Labor migration and labor exchange

The surveys of 2005/2006 have shown labor migration in Keerma and Danzamu villages during 1982-2006 (Zhang et al., 2008; Yan et al., 2009). There was notable labor migration between 2005 and 2010, and agricultural laborers have reduced by 22%. In 2005, there were 656 laborers in the four sample villages, with 255 non-agricultural laborers and 401 agricultural laborers, accounting for 26.67% and 41.95% of the total population, respectively. Of the 351 male laborers, 193 were non-agricultural, whereas of the 305 female laborers, only 62 were non-agricultural. In 2010, there were 613 laborers, with 300 in the non-agricultural and 313 in the agricultural sector. Of the 333 male laborers, 223 worked in non-agricultural sectors. Of the 280 female laborers, 77 worked were non-agricultural.
Not only the reduction but also the aging of the agricultural labor forces has affected labor force input in grain production. Figure 2 shows the age structures of the laborers in the study period. In 2005, 63 male agricultural laborers were less than 50 years old, while the number was reduced to 21 in 2010. The number of female agricultural laborers aged less than 50 years also decreased from 143 in 2005 to 99 in 2010.
Figure 2 Age structure of labors of the sample households of the four villages in 2005 and 2010
With the trend of labor migration, labor exchange has become a common phenomenon in grain production to respond to labor shortage in busy seasons, as agricultural labor hiring seldom occurs in the study area. Labor exchange refers to farmers casually seeking help from their relatives and neighbors for the agricultural production activities; while there is no monetary payment involved, the hosts usually treat them with dishes. As there is a significant difference in households’ land area between the valley area and the middle-mountain area, the average labor exchange days between the two areas differ greatly. The average labor exchange days in Keerma and Shidaan were 36.89 annually, four times as much as that in Sha’erni and Danzhamu (where the average is 9.00). The correlative analysis of the 216 sample households shows that the correlation coefficient between the number of agricultural laborers in a household and the number of labor exchange days in 2010 is 0.282 and is significant. A reasonable explanation is that more agricultural laborers in a household may imply more cropland area and sharp labor shortage in busy seasons, as mainly women and aged laborers stay at home during such seasons.

4.3 Land transfer

Table 3 shows land transfer, land abandonment, and land reclamation of the sample households. Among the 216 sample households, 212 households cultivated cropland in 2005 and 201 households cultivated cropland in 2010. The number of households who never cultivated croplands increased slightly in the five years, as laborers in those households are mostly indulged in off-farm employments. Compared with 2005, the area of cropland transferring increased in 2010. Of the total arable land, in 2005, 1.712 ha were rented out, while 2.558 ha rented in, and in 2010, 4.055 ha were rented out, while 7.725 ha rented in. Thus, the size of the rent-in land is more than that of the rent-out land. This is mainly because of emigration of a few households to the countryside, and thus, while we were unable to investigate the situation of land rent-out of those households, land rent-in data was available as their lands were rent in by some sample households. Because of labor emigration and the presence of greater rent-in land than rent-out land, land transfers could avoid the marginalization of arable land and land abandonment, and sown areas may therefore not be reduced. Cropland is mainly rented out by the households with labor migration because of the lack of an adequate agricultural labor force and poor benefits from farming. However, those households without labor migration have to rely on farming and want to expand the farming area. This is in line with the empirical studies conducted in Zhejiang, Hubei, Jiangsu, Shandong, Tianjin, and Guangxi provincial units in China (Zhong and Wang, 2003; Du and Huang, 2005; Chen et al., 2008; Chen et al., 2009b; Zou, 2008). However, according to a study on Taipusi county on the ecotone of northern China, migrant workers are more willing to expand the scale of farming because of the easy substitution of capital and technology for labor force (Hao et al., 2010). The difference lies in the average cropland area per household. In the study area of Taipusi county in Hao et al. (2010), the average cropland area per household ranges from 1.85 to 2.26 ha, implying the potential for small-scale farming. For example, if a farmer can rent-in 2 ha of cropland, he/she may have about 4 ha of cropland and the possible net profit from farming may reach 40,000 CNY annually, more than the current average of off-farm income. Therefore, the farmers are more willing to expand the scale of farming. However, in the Dadu River watershed, average cropland area per household ranges from 0.03 to 1.13 ha, without any potential to expand to a small-scale farm.
Table 3 Land transfer and land abandonment of the sample households of the four villages in 2005 and 2010
2005 2010
Households Percentage
(%)		 Area
(ha)		 Area per household (ha) Households Percentage
(%)		 Area
(ha)		 Area per household (ha)
Farming 212 98.15 58.65 0.28 201 93.06 63.02 0.31
Rent out 16 7.41 1.71 0.11 41 18.98 4.06 0.10
Rent in 18 8.33 2.56 0.14 53 24.54 7.73 0.15
Abandonment 11 5.09 0.60 0.05 31 14.35 2.36 0.08
Reclamation 7 3.24 0.88 0.13 15 6.94 2.68 0.18
Land reclamation also existed in 2005 and 2010, mainly in Keerma and Shidaan. In 2005, there were seven households undertaking land reclamation, a total of about 0.88 ha. In 2010, there were 15 households that reclaimed 1.80ha land. The reasons of land reclamation are linked with the specific livelihood strategy of some households. Although all households sought off-farm income, some households with barriers to do so had to resort to land reclamation and land use intensification. Also, those households also raised more animals, as land reclamation may provide more corn for feed.

4.4 Crop arrangements

Farmers’ crop arrangements reflect changes in the crop type and labor intensity of land use (Yan et al., 2010b). On the basis of discussions with farmers about assessing their labor-intensive level of crops, the crop arrangements are classified into three labor-intensive forms: zero-intensive (abandoned farmland), extensive(single crop), and intensive(double crop).
From 2005 to 2010, extensive land use increased dramatically, which is manifested by the shift from “corn-wheat” double cropping mode to single cropping mode, mainly corn (Table 4). This phenomenon is widespread in southern China, and is especially noticeable in the rice belt where “double cropping of rice has changed to single cropping of rice” (Xin and Li, 2009). In 2005, the proportions of extensive and intensive land uses in the sample plots are 64.53% and 35.46%, respectively. Due to the low level of productivity and technology, crop arrangements often focused on labor-intensive cropping patterns to meet domestic consumption. In 2010, the proportions of extensive and intensive land uses in the sample plots are 81.35% and 15.04%, respectively. The acreages of intensive use land have decreased 11.17 ha, that is, a proportion of 20.42%, and those of the extensive-use land and zero-intensive land have risen 17.82% and 2.60%, respectively.
Table 4 Land-use intensity of the sample plots of the four villages in 2005 and 2010 (ha, %)
Intensity of land use Crop arrangement 2005 2010
Area Percentage Area Percentage
Zero intensity Land abandonment 0.6 1.01 2.36 3.61
Extensive use Corn 29.49 49.78 36.8 56.29
Potato 0.38 0.64 0.75 1.15
wheat 0.45 0.76 0.01 0.02
Beans 0.35 0.59 1.86 2.85
Pepper 0.19 0.32 0.59 0.90
Fruit tree 0.78 1.32 1.59 2.43
Grass 0.27 0.46 0.30 0.46
Corn intercrop potato 1.92 3.24 7.22 11.04
Corn intercrop potato and beans 0.49 0.83 0.90 1.38
Corn intercrop beans 2.55 4.30 1.53 2.34
Potato intercrop beans 0.19 0.32 0.71 1.09
Others 0.57 0.96 0.92 1.41
Intensive Vegetable (two harvests a year) 0.58 0.98 0.37 0.57
Corn + wheat + potato (beans) 0.18 0.30 0.46 0.70
Corn + wheat 20.25 34.18 9.00 13.77
In total 59.24 100 65.37 100

4.5 Considerable increase in capital intensity

Agricultural capital inputs comprise of inputs for increasing production and saving labor (Chen et al., 2009b). Seeds, fertilizers, pesticides, and plastic films are major production-increasing investments, of which the first two are generally essential. Agricultural machinery and herbicides are major labor-saving inputs.
From the 1980s to the 2010s, capital intensity of the study area has significantly increased, which is consistent with the situation of the whole country. At the start of the land contracted in the 1980s, farmers had few choices in their selection of fine seeds. They reserved wheat seeds in advance, and purchased the Jindan No. 4 corn seed because of its good quality and high yield. Currently, the farmers have more choices in selecting fine corn weeds, including varieties such as Zhenghong No.2, Zhenghong 311, Adan No. 9, Yuhong No. 22, Chendan No. 9, and Chuandan No. 15.
According to the 2005/2006 land plot survey, generally used fertilizers were poudrette, manure, plant ash and urea. Some farmers mainly used farmyard manure and a small amount of urea. In 2010, different types of fertilizers are used, for example, farmyard manures including poudrette, manure and plant ash, and chemical fertilizers including not only urea but also phosphate, ammonium bicarbonate, and compound fertilizer. The input of urea is also higher than that in the past. Compared to 2005, there are more fertilizer inputs and manure inputs in 2010, shifting from 631.02 kg/ha of fertilizer in 2005 to 1436.82 kg/ha in 2010, that is, nearly 1.7 times. The correlation coefficient between fertilizer input and agricultural labor input is 0.292 and significant, which implies that when a household inputs more agricultural laborers, they are sure to input more fertilizers. However, the correlation coefficient between fertilizer input and non-agricultural labor input is not significant.
Labor-saving input increased significantly since the beginning of the land contract in the 1980s. In 1982, farmers in this area used few herbicides or other labor-saving pharmaceutical products and mechanical products. Nowadays, the farmers generally adopt herbicides or other labor-saving pharmaceutical products. Apart from dzos, farmers also use mini-tillers, tractors, and threshers. The proportion of input of farm cattle, mini-tillers, tractors, and threshers is 63.43%, 16.20%, 8.33%, and 31.48%, respectively. As the price of mini-tiller is expensive, 91.43% of sample households always rent a mini-tiller during busy seasons at the rate of 900-1500 CNY/ha. Herbicides are commonly used by all farmers to save weeding time. In 2010, nearly 66% of sample household use herbicides.

4.6 Econometric analysis results

Total grain production of the 216 sample households is 514,383 kg in 2010, which is 32,165 kg more than that of 2005. Table 6 shows the regression results that help determine the causes for the continuous grain output growth despite the impact of agricultural labor migration. An analysis of the factors considered in this study, based on the regression results, is presented below (Table 5):
Table 5 Estimated results of influencing factors on grain production of the sample households of the four villages
Variable B Standard errors t Sig.
1. Household characteristics
Age of household head (2005) -8.021 5.209 -1.540 0.125
Education level of household head (2005) 177.571** 78.646 2.258 0.025
2. Changes in livelihood assets
Change of labor migration 101.559* 55.502 1.830 0.069
Change of income -7.981 20.930 -0.381 0.703
Change of income from animal husbandry 242.039** 125.014 1.936 0.054
Change of seeded area 324.905*** 18.837 17.248 0.000
3. Change in production materials
Change of fertilizer input 1.110*** 0.329 3.376 0.001
Number of plot in 2005 -69.936** 35.091 -1.993 0.048
4. Regional variables
Sha’erni 97.211 156.235 0.622 0.535
Kerma 118.992 177.006 0.672 0.502
Shidaan 706.751*** 172.829 4.089 0.000
Intercept -68.296 403.663 -0.169 0.866
R2 0.877
Adjust R2 0.769

Note: ***, ** and * represent significant level at 1%, 5% and 10%, respectively.

Education level of household head (2005). The education level of the household head has a positive effect on grain production and the estimated coefficient is statistically significant. A household head with a higher educational qualification may be more capable of processing information and applying it, and more inclined to use the mini-tiller, fertilizers, improved varieties, and herbicides to improve grain production.
Change of labor migration. The change of labor migration has a positive effect on grain production and the estimated coefficient is statistically significant. Although labor migration results in labor shortage, income from labor migration is transferred to other inputs for grain production. The substitution of capital for labor plays a great role and results in the increase of grain production.
Change of income from animal husbandry. The change in income from animal husbandry has a positive effect on grain production and the estimated coefficient is statistically significant. In the study area, agriculture and livestock husbandry are closely linked, by which agricultural products are used as feed for livestock, and the manure from livestock are used in the fields. In 2010, an average of 84.5% corn, 8.49% meat, and 35.6% tomato are used as feed. At the same time, the manure input was very high, averaging 10 748.98 kg/ha. Therefore, more livestock implies a greater need of feed from agriculture.
Change of fertilizer input. The change in fertilizer input has a positive effect on grain production and the estimated coefficient is statistically significant. Our explanation is that income from labor migration is used to buy fertilizer and other input factors which benefit grain production.
Change of seeded area. The change in seeded area has a significant positive effect on grain production and the estimated coefficient is statistically significant. Of the 216 sample households, 75 increased their seeded area, while 103 households reduced it, and the rest households maintained it. The main reason for seeded area change lies in the change of cropping system, primarily from “corn-wheat” to “corn”. Simultaneously, the introduction of improved variety induces a substantial increase of yield. For example, the yield of corn increases from 6790 kg/ha in 2005 to 7500 ka/ha in 2010, which can offset the slight reduction of seeded area.
Number of plots in 2005. The number of plots in 2005 has a negative effect on grain production and the estimated coefficient is statistically significant, which means that land fragmentation improves the traveling time between the plots, which reduce the efficiency of grain production.
Regional variables. Compared with the other three villages, Shidaan is located at higher elevation and the peasants raised more livestock, and therefore, more feeding is needed and the peasants have to cultivate more cropland to improve grain production.

5 Discussion

The nexus of labor migration and agricultural output growth of China are complex, while the case studies on such a relationship remains partial and sometimes in contradictory. On one hand, this study is consistent with previous case studies that peasants substitute capital and technology for labor (Taylor et al., 1999; Zhang et al., 2008; Chen et al., 2009a; Hao et al., 2013; Li et al., 2013). Apart from the substituting of capital and technology for labor, we find more measures adopted by the peasants to offset labor shortage, including labor exchange in busy seasons, flexible crop arrangement and land transfer between households. On the other hand, this study confirms that labor migration results in arable land abandonment and decrease in labor intensity (Liu and Li, 2006; Chen et al., 2009a; Tian et al., 2009; Xin and Li, 2009; Tian et al., 2010). As both phenomena appears in this case, an reasonable explanation is that labor shortage in some households and surplus labors in the villages coexist.
In this case, if we count cropland area per labor, there is still surplus labor in the four villages. By Huang’s view (2014), one agricultural labor can manage 15 mu (1 ha=15 mu) of cropland. However, in this case, the number is only 2.23 mu in 2005 and 3.12 mu in 2010, as one household has only 4.71 mu on an average. If one laborer wants to perform its full cultivating capacity of managing 1 ha of croplands, he/she must rent-in croplands of more than two households, implying that nearly 2/3 of the households must migrate into cities or towns. However, until 2010, only 53 households rented in 7.725 ha of cropland. The strong man-land relationship in the mountainous region restricts the agricultural laborers from expanding the cropland area, and they have to resort to animal husbandry and other vocations. High levels of hidden unemployment in agriculture are frequently found. However, some aspects of the study area, such as abandonment of a small amount of land, labor aging, decreased labor intensity, and reduced multiple cropping index, imply that the labor migration results in labor shortage of some households. Owing to the surplus labors in the villages, labor exchange in busy seasons and cropland transfer between households can effectively offset labor shortage of these households.
Nowadays, there are heated discussions on whether China has passed the Lewis turning point and entered a new era of labor shortage from a period of unlimited labor supply. John et al. (2011) reported a puzzle of migrant labor shortage and rural labor surplus in China. On one hand, there are reports of migrant labor scarcity and rising migrant wages; on the other hand, estimates suggest that a considerable pool of relatively unskilled labor is still available in the rural sector. They conclude that for institutional reasons both phenomena are likely to coexist at present and for some time in the future. However, Zhang et al. (2011) holds that the acceleration of real wages even in slack seasons indicates that the era of surplus labor is over.
In the near future, the trend of labor shortage will get severe. During 2005-2014, the wages in manufacturing and service industries in the urban areas have rapidly increased, which have attracted the women and less-educated men who have been engaged in agriculture earlier to seek off-farm employment. Moreover, while migrating to the urban areas, the whole household typically prefers to move at once (Anwaer et al., 2013). In the four villages, 15 out of 216 sample households are fully indulged in off-farm employment during 2005 and 2010. While this trend may accelerate in the future, the real number of household migration is hard to forecast. In addition, the elderly people currently managing the croplands may be too old to work in the next 10 years (Fan, 2003, 2004). If there is no surplus labor in the villages and the substitution of capital and technology for labor may not work in the near future, grain production is sure to decrease. Therefore, follow-up studies are needed to explore the capacity of labor-substitution measures and investigate the possible the turning point of surplus labor.
Previous studies have shown three scenarios in the linkages between labor migration and agricultural output in the world. As labor migration brings in labor shortage, this case does not correspond to the first scenario of the relationship between labor migration and agricultural output. It does not correspond to the second scenario either, as there is continuous grain production increase. Finally, it does not fit in the third scenario too, as there is no labor market. As labor shortage in some households and surplus labors in the villages coexist, this case shows another scenario of labor migration and grain output growth. To understand the nexus of labor migration and grain output of China, future case studies should focus on the significant flexibility of rural households in responding to demographic change and the important ways in which these household strategies mediate population-environment relationships.

6 Conclusions

Although there has been rapid rural-urban migration in rural China since the 1980s, the total grain production of China saw a continuous increase. As of today, the relationship between labor migration and grain production growth remains partial and contradictory. This study considers four villages in the eastern Tibetan Plateau to investigate the measures adopted by the local peasants to respond to labor shortage and boost grain production. The preliminary conclusions come to the following:
(1) This study provides a reasonable explanation of grain output growth under rural-urban migration in China. The continuous emigration of labor in the four villages has resulted in the abandonment of a small amount of land, decreased labor intensity, and reduced multiple cropping index. This may means that labor migration has brought in labor shortage in some households. However, as all households have relatively small cropland areas, the elderly and female, being largely home bound, can almost handle the farming work. At the same time, owing to surplus labors in the villages, the peasants utilize a series of means to offset the negative impacts of labor migration, including flexible crop arrangement, cropland transfer between households, labor exchange in busy season, and the substitution of capital and technology for labor.
(2) The econometric analysis confirmed that labor migration could boost grain production. Furthermore, the variables Education level of household head (2005), Change of income from animal husbandry, Change of fertilizer input and Change of seeded area have positive effects on grain production and the estimated coefficients are statistically significant, while the variable Number of plots in 2005 has a negative effect and the estimated coefficient is statistically significant.

The authors have declared that no competing interests exist.

References

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1
Anwaer M, Zhang X L, Cao H H, 2013. Urbanization in western China.Chinese Journal of Population Resources and Environment, 11(1): 79-86.

2
Bai W Q, Yan J Z, Zhang Y L, 2004. Land use/land cover change and driving forces in the region of upper reaches of the Dadu River.Progress in Geography, 23(1): 71-78. (in Chinese)<p>Based on remote sensing imageries of 1967，1987 and 2000， and a digital elevation model with a scale of 1∶250000， the land use/ land cover change and driving forces in an area of 18665 km<sup>2</sup> in the region of upper reaches of the Dadu river are examined. The results show that the dominant land type in research area changed from forest land to grassland between 1967 and 2000. This was mainly decrease of 319774 hm<sup>2</sup> and its proportion to total area dropped from 30.92% to 13.78%. Landscape pattern analysis finds out that forest patches had an increasing regularity with fragmentation process，which indicates that the decreased forest was an outcome of a planed cutting by state-owned forestry enterprises， rather than of blind cutting by local people. This point has been approved by historical documents. Therefore， it is concluded that governmental policies played a dominant role in land use/land cover change of this region. For analyzing various bio-physical and socio-economic driving forces， the method of Logistic stepwise regression is applied in our study. Through spatial analysis， the most significant drivers and their relative importance for cultivated land， forest land， grassland， water area， built-up land and unused land are founded out from such factors as terrain， elevation， roads， water system， urban and rural residential areas.</p>

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3
Bai W Q, Zhang Y M, Yan J Zet al., 2005. Simulation of land use dynamics in the upper reaches of the Dadu River.Geographical Research, 24(2): 206-212. (in Chinese)Based on remote sensing imageries of 1967,1987 and 2000, and a digital elevation model with a scale of 1:250000, the key forces driving land use change and controlling land use pattern in the upper reaches of the Dadu river are found out from such biophysical and socioeconomic factors as terrain, elevation, roads, water system, urban and rural residential areas, and then the probability maps for each land use type are created by using Logistic stepwise regression, of which the goodness of fit is evaluated for all equations with the ROC (Relative Operating Characteristics) method. In this study, CLUE-S model which has the capability of modeling changes in quantity and location simultaneously, is applied to simulate temporal and spatial changes in land use from 1967 to 1987 and from 1987 to 2000 for an area of 18665 km2 which covers the counties of Rangtang, Jinchuan and Barkam. Comparisons for validation between simulated land use maps and actual land use maps of 1987 and 2000 find that Kappa index reaches to 0. 86 and 0. 89 respectively, indicating a successful simulation. For a better understanding of the future land use changes in the region, the same model is further put into application to predict spatial distribution of land use changes in 2010 for three scenarios associating with current governmental policy of "grain to green". The results of scenario analysis demonstrate that CLUE-S model can play key roles in land use planning and ecological construction, and is also a key part of decision-support system. In the scenario analysis, the changes in quantity are specified on purpose, and thus the simulation is focused on land use changes in location. This is because land use and cover changes in the upper reaches of the Dadu river are mainly driven by policies, especially for forest land and cultivated land, and changes in area are usually determined by government. Therefore, such an application of CLUE-S model is more suitable to regions characterized by policy-driven land use change, in which once the changes in quantity, such as areas of forest cutting, afforestation, grazing-forbidden, or planned reserves, are specified, then their changes in locations can be predicted with the same model. Furthermore, the spatial resolution of modeling can reach to a level of single grid cell.

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Bardhan P, Udry C, 1999. Development Microeconomics. USA: Oxford University Press.

5
Beyene A D, 2008. Determinants of off-farm participation decision of farm households in Ethiopia.Agrekon Agricultural Economics Research Policy & Practice in Southern Africa, 47(1): 140-161.This study analyses the determinants of off-farm work participation decisions of farm households in Ethiopia. A bivariate probit model is applied to account for the simultaneity of participation decisions of both male and female members of farm households. The results of the analysis show that human capital variables such as health and training on non-farm activities have a positive effect on the off-farm participation decisions of male members of farm households. The education status of the head has no significant impact on the participation decisions of the members of the family as most of the off-farm activities do not require formal education. The availability of credit and transfer income is the other factors that have a positive impact on the decisions of male members to participate in off-farm activities. The effects of family and farm characteristics are also analysed. Finally, policies that aim to increase the off-farm work participation decisions of family members should take into consideration the difference in responses to the various factors that affect the off-farm work decisions of male and female members of farm households.

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6
Black R, King R, Tiemoko R.2003. Migration, return and small enterprise development in Ghana: A route out of poverty? In: International Workshop on Migration and Poverty in West Africa, University of Sussex, United Kingdom: Citeseer.

7
Brière B D L, Sadoulet E, Janvry A Det al., 2002. The roles of destination, gender, and household composition in explaining remittances: An analysis for the Dominican Sierra.Journal of Development Economics, 68(2): 309-328.Two non-exclusive hypotheses about what motivates remittances sent by Dominican migrants to their rural parents in the Sierra are tested: (a) an insurance contract taken by parents with their migrant children and (b) an investment by migrants in potential bequests. Results show that the relative importance of these two motives to remit is affected by destination (US vs. cities in the Dominican Republic), gender, and household composition. The insurance function is mainly fulfilled by female migrants to the US. Only when a male is the sole migrant in his household does he play the role of insurer. Investment, by contrast, is pursued by both males and females, but only among those migrating to the US.

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8
Brosig S, Glauben T, Herzfeld Tet al., 2009. Persistence of full- and part-time farming in Southern China.China Economic Review, 20(2): 360-371.<h2 class="secHeading" id="section_abstract">Abstract</h2><p id="">The goal of this study is to assess the dynamics of rural households' labor market participation in the wake of China's efforts to develop rural labor markets in a manner that is conducive to its transition to a market economy. Based on a theoretical model that emphasizes the impact of duration, i.e. of the number of years households spent part-time farming or full-time farming, respectively, we investigate the shifts between these two states. We also identify socioeconomic factors that determine these shifts. The empirical study is based on discrete time hazard approaches, using micro-level panel data from Zhejiang, Hubei, and Yunnan provinces from 1995 to 2002.</p><p id="">Estimation results suggest relatively high chances of shifts from full-time to part-time farming and a considerable lower risk for the shift in the opposite direction. Significant negative duration dependence is found for the move from full-time to part-time farming suggesting lock-in effects. In addition, we find that labor market participation decisions are significantly related to several household, farm and village characteristics. In particular, the likelihood of shifts from full-time farming to part-time farming is positively related to the educational level of households' workforce.</p>

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9
Chen M Q, Xiao H L, He W Jet al., 2008. An empirical study on factors affecting the households’ behavior in cultivated land transfer.Journal of Natural Resources, 23(3): 369-374. (in Chinese)Cultivated land transfer is an essential means for resolving the harmonies between the flaw of household contract responsibility system and the demands of agricultural modernization.In this paper,basing on the survey of 1396 households in 74 villages of 38 counties in Jiangxi province,the Logistic regressive model was set up to analyze factors affecting the households' behavior in cultivated land transfer out and in.And the affecting factors were divided into 3 groups: family characteristic factors,household economic factors and cultivated land resource gift.The family characteristic factors include total population,total labor forces,proportion of employees at non-agriculture to total labor forces;the household economic factors include income per person,the proportion of income from farmland to total income;and resource gift factors include physiognomy,cultivated land area per person,and spatial distribution of cultivated land.The results showed that non-agriculture employment opportunity plays a most important role in the cultivated land transfer out;the household income level and cultivated land transfer are mutually affected,the household income of transfer out is generally higher than that of transfer in;physiognomy is another important factor affecting the households' behavior in cultivated land transfer,the more flat physiognomy is,the more easy the cultivated land transfer out.So,in order to promote cultivated land transfer,some actions should be taken such as accelerating rural labor forces transfer into non-agriculture,increasing support for agriculture,and improving the spatial distribution of cultivated land.

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10
Chen Y F, Liu Y S, Zhai R X, 2009b. Households’ willingness and its determinants on the scale operation of farmland in the coastal areas of east China based on household survey.Resources Science, 31(7): 1102-1108. (in Chinese)With the implementation of reform and opening up policies, rapid industrialization and urbanization have brought unprecedented opportunities and challenges to the sustainable agriculture in China. Also, peasants’ income has increased, accompanied with the great amount of agricultural labor transfer, agricultural decline, arable land loss, etc.. Scale operation of farmland becomes one of the most important methods for increasing farmer’s income and grain yield, especially in the coastal areas of east China. In order to promote scale land use, it is meaningful to understand farmer’s willingness and its formation mechanism at first. Based on the data from 323 households in 3 provinces and 1 municipal city in the coastal areas of east China, interesting insights are obtained into farmer’s willingness to accept the scale operation of farmland and its determinants. A logistic regressive model, which includes variables divided into personal characteristics of the householder, family condition, economic feature, and external factors, is set up. Results are as follows: The general willingness to promote scale operation of farmland in the coastal areas of east China is strong with an average of 61.0% households looking forward to scale land use, but the percentages of willingness in different places vary. There is a decreasing trend in the percentages of willingness from Zhejiang (81.4%), Jiangsu (61.0%), Tianjin (53.1%) to Shandong (52.4%). Of all the factors that influence households’ willingness, householder’s employment pattern, land lease behavior, agro-technical training, commuting conditions, and farmland resource endowment are the main determinants, while the householder’s educational level, family population, per capital income, and the source of family income are less relevant. To specify, the more the household takes part in non-agriculture industries, and the richer the farmland resource is, the weaker the household’s intentions are to increase the operational scale. Efficient agro-technical trainings and good commuting conditions can facilitate the promotion of scale operation of farmland. Furthermore, households who have already involved in land lease behavior are more willing to support scale operation of farmland. The results are quite different from those in other regions in China, not only in the character of farmer s’ willingness on scale land use, but also in its formation mechanism. Taking the great regional and personal disparities in households’ willingness on the scale operation of farmland into consideration, it’s necessary to adopt classified and regional policies. For the coastal areas of east China, in order to further promote the scale operation of farmland, actions should be taken to accelerate the transfer of rural labor, conduct agro-technical training, improve agriculture production environment, and innovate the form of agricultural land lease. Finally, policies for each province (municipal city) are suggested respectively.

11
Chen Y Q, Li X B, Tian Y Jet al., 2009a. Structural change of agricultural land use intensity and its regional disparity in China.Journal of Geographical Sciences, 19(5): 545-556.<a name="Abs1"></a>Based on the data from the Cost-benefit Data of Farm Produce and the China Agricultural Yearbook, this paper divided the intensity of cultivated land use into labor intensity and capital intensity, and then analyzed their temporal and spatial change at both national and provincial levels between 1980 and 2006. The results showed that: (1) At the national level, labor intensity on food produce decreased from 398.5 day/ha in 1980 to 130.25 day/ha in 2006; and a continuous decrease with a steep decline between 1980 and 1986, a slower decline from 1987 to 1996, and another steep decline from 1997 to 2006. On the contrary, capital intensity shows an increasing trend since 1980. As to the internal composition of capital intensity, the proportion of seed, chemical fertilizer and pesticide input decreased from 90.36% to 73.44% and the proportion of machinery increased from 9.64% to 26.56%. The less emphasis on yield-increasing input and more emphasis on labor-saving input are the main reasons for a slow increase of yield per unit area after 1996. (2) At the provincial level, the developed areas have lower labor intensity and higher capital intensity. The less developed ones have higher labor intensity but lower capital intensity. From the viewpoint of the internal composition of capital intensity, labor-saving input accounts for more proportion in the developed areas than that of other areas. The main reason is that in these developed areas, labor input has become a constraint factor in food production as more and more labors engaged in off-farm work. Farmers increase the labor-saving input for higher labor productivity. However, in the less developed areas, the major constraint is the shortage of capital; food production is still depending on labor and yield-increasing inputs.

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12
Clay D, Reardon T, Kangasniemi J, 1998. Sustainable intensification in the highland tropics: Rwandan farmers' investments in land conservation and soil fertility.Economic Development and Cultural Change, 46(2): 351-377.

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14
Du W X, Huang X J, 2005. Regional difference and influencing factors of farm households’ willingness of rural land transmission: A case study of Shanghai, Nanjing, Taizhou and Yangzhou cities in Yangtze-Delta Region.Resources Science, 26(6): 90-94. (in Chinese)The development of rural land market has greatly influenced the macroeconomy of China.It is necessary to give some rational and feasible suggestions for the local governments along with the commencement of another round of innovation of land use system,so that they can perfect the rural land transfer market.The author makes a typical analysis of the operation of the land market at farm household level in Yangtze-delta region based on the questionnaire in the Shanghai,Nanjing,Taizhou and Yangzhou to understand the regional differentia and the influencing factors of farm households' will to transfer rural land more scientifically.The fieldwork of questionnaires of 319 farm households' will has been held in seven administrative villages distributed in four cities.A model was established to analyze the regional differentia and the influencing factors of farm households' will during rural land transfer based on the feedbacks of the questionnaires.It shows that there are seven factors including the ratio of nonagriculture population to total population in a family,the highest education level in the family,agricultural pure income per square,the distance from home to main road,family's Engel coefficient,regional economic development level,and registered permanent residence locus.The most important factor influencing the farm households' will to transfer rural land is different in different cities: it is the ratio of non-agriculture population to total population in a family in Shanghai and Yangzhou,family's Engel coefficient in Nanjing,and agricultural pure income per area in Taizhou.A single microeconomic factor will have multiplier effect on macro-economy.The author considers that the will of farm households' rural land transfer will be activated and the rural land transfer market led by market economy in Yangtze-delta region will be perfected gradually,only when the rational and feasible measures based on the local rural land transfer market are carried out.

15
Dustmann C, Kirchkamp O, 2001. The optimal migration duration and activity choice after re-migration.Journal of Development Economics, 67(1): 351-372.If migrants return to their origin countries, two questions arise which are of immediate economic interest for both immigration and emigration country: what determines their optimal migration duration, and what are the activities migrants choose after a return. Little research has been devoted to these two issues. This paper utilises a unique survey data set which records activities of returned migrants. We first illustrate the activities of immigrants after returning. We show that more than half of the returning migrants are economically active after return, and most of them engage in entrepreneurial activities. We then develop a model where migrants decide simultaneously about the optimal migration duration, and their after-return activities. Guided by this model, we specify and estimate an empirical model, where the after-return activity, and the optimal migration duration are simultaneously chosen.

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16
Editorial Committee of Chorography of Jinchuan County (ECCJC), 2011. Jinchuan Yearbook. Beijing: China Minzu University Press. (in Chinese)

17
Fan C C, 2003. Rural-urban migration and gender division of labor in transitional China.International Journal of Urban and Regional Research, 27(1): 24-47.Over the last two decades, social and economic changes in transitional economies have produced many new outcomes. In this article, I examine some of the ways in which China's transition has produced gendered outcomes and highlight evidence of these outcomes. I argue that during transition the state has shifted its goals to economic ones, but unlike capitalist economies it still has at its disposal instruments of social control. Peasants are made more vulnerable and must rely on migrant work for survival, but their low institutional status relegates them to outsider status in urban areas. These circumstances, together with socio-cultural traditions that constrain women's mobility and endorse stratifications, have enabled the development of a labor regime that fosters segmentation and division of labor. Peasant migrants' reliance on social network further reinforces segregation in the urban labor market. Using multiple sources of macro-level and field surveys, I examine both quantitative and qualitative evidence of gender segregation and division of labor. The findings show that a high degree of gender segregation among rural-urban migrants exists in the urban labor market, that peasant women's urban work opportunities are short-lived, and that upon marriage women migrants are relegated back to the village and to the 'inside', in part to sustain gender division of labor as a household strategy. Copyright Joint Editors and Blackwell Publishing Ltd 2003.

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Fan C C, 2004. The state, the migrant labor regime and maiden workers in China.Political Geography, 23(3): 283-305.<h2 class="secHeading" id="section_abstract">Abstract</h2><p id="">Recent research (re)emphasizing the role of the state and the institutional perspective generally neglects socialist economies. At the same time, feminist studies on migration rarely focus on mobility in transitional contexts. Informed by these two bodies of literature, this paper examines how the post-Mao state in China has fostered a migrant labor regime and the incorporation of young, single rural women, dubbed &ldquo;maiden workers,&rdquo; into urban work. I argue that the Chinese state has taken on a developmentalist mandate and by doing so has also transformed gender relations in the peasant household and in the urban labor market. By analyzing narratives from a survey of peasant households in Sichuan and Anhui, I emphasize the central role of state policies and institutions, especially the household registration (hukou) system, in channeling peasants to specific sectors and jobs and creating an exploitative migrant labor regime. The incorporation of maiden workers into migrant work and the relative absence of married women in the rural&ndash;urban migrant labor force, reflect interactions between institutional controls, gender ideology, and demands of the migrant labor regime. An approach that integrates gender and institutional perspectives is useful because it foregrounds the state&rsquo;s role in constructing differences based on hukou status, locality, class, and gender.</p>

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19
Gray C L, 2009. Rural out-migration and smallholder agriculture in the southern Ecuadorian Andes.Population and Environment, 30(4/5): 193-217.This study investigates the consequences of out-migration and migrant remittances for smallholder agriculture in a rural and environmentally marginal study area in the southern Ecuadorian Andes. Migration and remittances have the potential for transformative impacts on agriculture in origin areas of migration due to consequent declines in labor availability and increases in income, but previous...

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20
Gu L M, 2013. Relative analysis of China’s grain yield and influence factors based on criterion of least absolute deviation.Transactions of the Chinese Society of Agricultural Engineering, 29(11): 1-10. (in Chinese)Abstract: The relations between China's grain yield and some main factors influencing the grain yield, more present the exponential function and few exponent sign function relations. To describe with a new type of exponential production function can obtain a better result because of less error. The paper pointed out that the least absolute deviations (LAD) method, as its excellent properties, may be a best method to find the"implicit function"which is behind the data and control the data. To knead the two together, with the LAD method to fit the exponential production function, trying to find out some rules for China's grain change is a subject that is worth of exploring in theory and application. The paper introduces the LAD method and the exponential production function, establishes correlations between the China's grain yield and its 5 major influencing factors (consumption of chemical fertilizer, total sown area, total area affected by natural disaster, total agricultural machinery power, and total employed persons of primary industry). The production function model was fit with the LAD method, and the data of 1983-2011 were calculated. The results with Mae (mean absolute error) not over 3.93 million tons and Mape (mean absolute percentage error) not more than 0.87% for China's grain yield during the 29 years were obtained, and the conclusions were explained and analyzed; The analysis showed that, in the 29 years of 1983-2011, the growth of China's nation grain yield mainly depended on the consumption of chemical fertilizer and the total agricultural machinery power, of which the consumption of chemical fertilizer is still playing a positive roll up to now, while the total agricultural machinery power is dynamically in a saturated state. Theoretically it should have a "negative" effect now, but in reality it does not. The total sown area was the most influencing "positive" factor. The national grain yield may still grow further without increasing the total sown area, but increasing the sown area can rapidly boost the China's nation grain yield. The total area affected by natural disaster imposed "negative" effect on the growth; However, the trend of its influence is increasing in terms of absolute values, but is decreasing in terms of relative values. By the huge impact and lagged effects of the rapid growing of the total employed population of primary industry in China during 1983-1993 period, the reduction of the total employed population of primary industry to grain growth constituted "negative" impact. With the modernization of agriculture and urbanization development, this "negative" impact continued to reduce. These conclusions give the specific quantitative values. The paper predictes that the grain yield for year 2012 is t, the later result indicates the absolute error is t, and the relative error is 0.3%. For year 2013, the prediction is t. In the last the paper gives some discussion about the LAD method, the exponential production functions and so on, and is concluded that the exponential production function under the meaning of LAD criterion to describe the relationships between China's grain yield and the main effect factors, has a certain accuracy and guiding sense.

21
Hao H G, Li X B, Tian Y Jet al., 2010. Farmland use right transfer and its driving factors in agro-pastoral interlaced region.Transactions of the Chinese Society of Agricultural Engineering, 26(8): 302-307. (in Chinese)

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Hao H, Li X, Zhang J P, 2013. Impacts of part-time farming on agricultural land use in ecologically-vulnerable areas in North China.Journal of Resources and Ecology, 4(1): 70-79.Part-time farming has been increasing steadily in China. It is currently the largest segment among all the farm sectors in the country. Based on rural household survey data in Taipusi County as a case site ofecologically-vulnerable areas in North China, we firstly classify farm households into four types according to the proportion of non-farm income in total income, and then compare their agricultural land use patterns to empirically examine the impacts of part-time farming on agricultural land use in this area. The results suggest that non-farming households rent out all their land and give up farming, and this satisfies the expectation of other households to expand land area. The crop planting structure was not significantly different among the households, which reflected the farmers&rsquo; will to pursuit labor productivity. Part-time farming households invest more capital and materials than full-time faming households because the income derived from non-farm employment relaxes the financial constraint of households. However, the amount of labor input of part-time farming households tends to be less, and farming practices are dominated by the elderly, female and laborers with relative low educations.Yields of crops and the benefit of agricultural land use incline to reduce, which suggest that the potential of land use productivity is more elastic to labor inputs than capital inputs in the study area.

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23
Holden S, Shiferaw B, Pender J, 2004. Non-farm income, household welfare, and sustainable land management in a less-favoured area in the Ethiopian highlands.Food Policy, 29(4): 369-392.<h2 class="secHeading" id="section_abstract">Abstract</h2><p id="">A bio-economic model has been calibrated to the socio-economic and biophysical characteristics of a less-favoured area in the Ethiopian highlands. Land degradation, population growth, stagnant technology, and drought necessitates development of non-farm employment opportunities in the area. The model has been used to assess the impact of improved access to non-farm income on household welfare, agricultural production, conservation investments and land degradation in form of soil erosion.</p><p id="">The model simulations indicate that access to low-wage off-farm income is restricted by lack of employment opportunities since households otherwise would have engaged in more off-farm wage employment than observed. The simulations show that better (unconstrained) access to low-wage non-farm income has a substantial positive effect on household income. Total agricultural production (crop and livestock production) and farm inputs used are reduced when access to non-farm employment is improved and thus increases the need to import food to the area. Access to non-farm income reduces farm households&rsquo; incentives to invest in conservation and this leads to more overall soil erosion and more rapid land degradation even though intensity of production is reduced. Special policies are therefore needed to ensure land conservation and to sustain local food production.</p>

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Huang Z Z, 2014. Family farms are the way out of China’s agriculture development?Open Times, (2): 196-194. (in Chinese)

25
Jin S Q, Deininger K, 2007. Land rental markets in the process of rural structural transformation: Productivity and equity impacts from China.Journal of Comparative Economics, 37(4): 629-646.The importance of land rental for overall economic development has long been recognized in theory, yet empirical evidence on the productivity and equity impacts of such markets and the extent to which they realize their potential has been scant. Representative data from China's nine most important agricultural provinces illustrate the impact of rental markets on households'economic strategies and welfare, and the productivity of land use at the plot level. Although there are positive impacts in each of these dimensions, transaction costs constrain participation by many producers, thus preventing rental markets from attaining their full potential. The paper identifies factors that increase transaction costs and provides a rough estimate of the productivity and equity impacts of removing them.

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John K, Deng Q H, Li S, 2011. The puzzle of migrant labour shortage and rural labour surplus in China.China Economic Review, 22: 585-600.The paper examines the contentious issue of the extent of surplus labour that remains in China. China was an extreme example of a surplus labour economy, but the rapid economic growth during the period of economic reform requires a reassessment of whether the second stage of the Lewis model has been reached or is imminent. The literature is inconclusive. On the one hand, there are reports of migrant labour scarcity and rising migrant wages; on the other hand, estimates suggest that a considerable pool of relatively unskilled labour is still available in the rural sector. Yet the answer has far-reaching developmental and distributional implications. After reviewing the literature, the paper uses the 2002 and 2007 national household surveys of the Chinese Academy of Social Sciences to analyse and explain migrant wage behaviour, to predict the determinants of migration, and to examine the size and nature of the pool of potential rural-urban migrants. An attempt is also made to project the rural and urban labour force and migration forward to 2020, on the basis of the 2005 1% Population Survey. The paper concludes that for institutional reasons both phenomena are likely to coexist at present and for some time in the future. (C) 2011 Elsevier Inc. All rights reserved.

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Kung J K, 2002. Off-farm labor markets and the emergence of land rental markets in rural China.Journal of Comparative Economics, 30(2): 395-414.<h2 class="secHeading" id="section_abstract">Abstract</h2><p id="">A nascent land rental market is emerging in rural China after almost two decades of rural reforms. That the timing of its emergence coincides with the acceleration of an off-farm labor market suggests that the development of one factor market may have induced the emergence of the other. Using a recent farm survey, we are able to show that households with active participation in off-farm labor markets, measured by the number of days worked, have indeed rented less land. Contrarily, our analysis fails to substantiate the hypotheses that administrative land reallocations, which is a property of China's land tenure system, and respectively grain quotas, tend to hamper the development of land rental transactions. <em>J. Comp. Econ.</em> June 2002, <strong class="boldFont">30</strong>(2), pp. 395&ndash;414. Division of Social Science, Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China. <em>&copy; 2002 Association for Comparative Economic Studies. Published by Elsevier Science (USA). All rights reserved.</em></p><p id=""><em>Journal of Economic Literature</em> Classification Numbers: J22, J43, O12, O53, P23, P36.</p>

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Li Lihua, Wang Chenggang, Segarra Eduardoet al., 2013. Migration, remittances, and agricultural productivity in small farming systems in Northwest China. China Agricultural Economic Review, 5(1): 5-23.Purpose - The purpose of this study is to explore the relationship between migration, remittances and agricultural productivity by applying the new economics of labor migration model in the context of north-west China. The specific objectives are to examine the impacts of rural out-migration on agricultural productivity in various farming systems, and whether remittances have been reinvested in agriculture.<br/>Design/methodology/approach - Cross-sectional household survey data from three townships were analyzed with the three-stage least squares (3SLS) regression model.<br/>Findings - In multi-cropping small farming systems, at least in the short run, the loss resulting from losing family labour on lower-return grain crop production is likely to be offset by the gain from investing in capital-intensive and profitable cash crop production.<br/>Originality/value - This study provides empirical evidence for the MELM theory. It expands Taylor et al's studies by comparing investment behavior and production choices among multiple farm activities, and enriches previous studies by showing that the relation between remittances and agricultural investment depends on the farm activities' profitability.

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Lipton M, 1980. Migration from rural areas of poor countries: The impact on rural productivity and income distribution.World Development, 8(1): 1-24.

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Liu C W, Li X B, 2006. Diagnosis on the marginalisation of arable land use in China.Geographical Research, 25(5): 895-904. (in Chinese)The history of the land use of many developed countries shows that the courses of industrialization of economy and urbanization of population are usually accompanied by marginalization of agricultural land use.China is now in a developing stage with rapid industrialization and urbanization,and changes such as "the more rapid non-agriculturalization of agricultural land,the continuous loss of farmland,abandonment of arable land,the substantial loss of labor force sources from rural areas,the shrinkage of agriculture in the eastern littoral,etc." has occurred in the process of agricultural land use in recent years.Many scholars have studied these changes and their driving forces,mostly adopting a correlation analysis in statistics.These researches encountered a lot of criticism,deeper analyses of the mechanism are called,but little progress has been made.So seeking a new synthetical research approach is especially important. This paper firstly defined the essence of the marginalisation of arable land and its criterion to diagnose.Then,based on the cost-income data of three kinds of grain crops such as paddy,wheat and maize during the period 1980-2002, this paper diagnosed the marginalisation phenomena of cultivated land use in China.The results show that there were once suspicious marginalisation evidence and two times obvious marginalisation phenomena of the cultivated land utilization in the last two decades in China.The suspicious evidence only had a faint trace in 1987,and the first and the second ones were in evidence in 1991 and 1996,but the second one was wider and more serious.The marked decline of the degree of intensity of the cultivated land use,the notable shrinkage of the sown area of the grain crops and the severe abandonment of the cultivated land had causal relations with the action of the margilisation of arable land.Theory of the marginalisation of arable land use is useful to explain the changes of arable land use in China.

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Liu L, Zhang Y, Gao H, 2014. The transfer of labor force and food security.Statistical Research, 31(9): 58-64. (in Chinese)

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Lucas R E, 1987. Emigration to South Africas mines.American Economic Review, 77(3): 313-330.Temporary migration from five countries to South Africa's mines is examined; Both determinants of migration and economic consequences are investigated econometrically, during 1946-78. Emigration is shown to (1) diminish crop production in the short-run; (2) enhance crop productivity and cattle accumulation through invested remittances in the long-run; and (3) escalate plantation wages. Conflicting interests exist between local employers and the mines. Forms of state intervention adopted and discussed include forced labor, emigration quotas, and compulsory population relocation. Copyright 1987 by American Economic Association.

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Macdonald D, Crabtree J R, Wiesinger Get al., 2000. Agricultural abandonment in mountain areas of Europe: Environmental consequences and policy response.Journal of Environmental Management, 59(1): 47-69.Agricultural abandonment reflects a post war trend in western Europe of rural depopulation to which isolated and poorer areas are most vulnerable. The commercialisation of agriculture, through technological developments, and the influence of Common Agricultural Policy have increased productivity and focused agricultural activity on more fertile and accessible land thus transforming traditional approaches to farming. In many areas this has lead to a decline in traditional labour intensive practices and marginal agricultural land is being abandoned. The problems that these trends create are particularly marked in mountain areas. The social and economic impacts of these changes have been well documented. However, the implications for environmental policy are less well recognised. This paper reviews the literature on abandonment and gives a comparative analysis of European mountain case studies to assess the environmental impacts of land abandonment and decline in traditional farming practices. It finds abandonment is widespread and that, while the influence of environmental changes is unpredictable due to environmental, agricultural and socio-economic contextual factors, abandonment generally has an undesirable effect on the environmental parameters examined. The application of agri-environment policy measures in relation to abandonment is discussed and suggestions for future policy are proposed. Copyright 2000 Academic Press

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Mochebelele M T, Winter-Nelson A, 2000. Migrant labor and farm technical efficiency in Lesotho.World Development, 28(1): 143-153.

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Oseni G, Winters P, 2009. Rural nonfarm activities and agricultural crop production in Nigeria.Agricultural Economics, 40(2): 189-201.Although most rural households are involved in the farm sector, the nonfarm sector has grown significantly in recent decades, and its role in rural development has become increasingly important. This article examines the effect of participation in nonfarm activities on crop expenses of farm households in Nigeria. The relationship is modeled using a nonseparable agricultural household model that suggests that participating in nonfarm activities can relax the credit constraints facing farm households and reduce risk thereby helping households improve farm production and smooth consumption over time. The results show that participation in nonfarm activities by Nigerian farmers has a positive and significant effect on crop expenses and in particular on payments for hired labor and inorganic fertilizers. Separate analysis of the six geopolitical zones in Nigeria indicates that it is in the South-South and South-East zones where nonfarm participation appears to induce more hiring of labor. The results support the hypothesis that nonfarm participation helps relax liquidity constraints but suggests how that liquidity is used is zone-specific. In general, the results also indicate that liquidity is used more to pay for inputs into staple production as opposed to cash crops. Copyright (c) 2009 International Association of Agricultural Economists.

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Qin L J, Zhang N N, Jiang Z Y, 2011. Land fragmentation, labor migration and grain production in China: Based on a study in Anhui province.Journal of Agrotechnical Economics, (11): 16-23. (in Chinese)

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Rozelle S, Guo L, Shen Met al., 1999. Leaving China's farms: Survey results of new paths and remaining hurdles to rural migration.China Quarterly, 158: 367-393.ABSTRACT The overall goal of this article is to address the shortcomings of the current literature by providing a systematic estimate of the volume of labour flow, describing the composition of the labour force and analysing the determinants of labour flow. Having a better picture of China's labour movements may help leaders to understand how many people participate in China's trans-regional labour market, who benefits, and which factors encourage some to enter and prevent others from leaving home. This information should facilitate better policy-making. The article uses a theoretical framework to analyse the determinants of migration systematically, to formulate predictions of which factors affect labour movement and to test competing hypotheses raised in the literature. In this article we seek to answer several questions about the contribution of four factors to migration: the income level of those who choose to migrate, chain migration, rural institutions and human capital. First, are the poor and those without local wage-earning opportunities more likely to migrate, or the rich and those with skills valuable in the city? Secondly, is chain migration important? If so, what are the key elements that make it important? Do information and the social network that conveys that information matter most, or are transportation costs and proximity to urban regions vital? Thirdly, do rural institutions prevent people from leaving the village, push people off the farm, or are they neutral, perhaps weakened by the rise of markets? Finally, does human capital, in particular education, facilitate entrance into the migrant labour force? Or is education inconsequential? Drawing on our own extensive survey of 200 villages, we estimate that 154 million people from rural areas of China worked off-farm in 1995, including 54 million long-term migrants and over 15 million self-employed who have left their villages. Some of our major findings are that rural migration has created one of the main opportunities for women to enter the off-farm labour force and that rural migrants are moving progressively further away from home. Our analysis also demonstrates that being part of a network of labourers (or being involved in chain migration) is key to facilitating labour movement out of a village. Transportation and rural institutional barriers are not formidable obstacles to migration. The following section introduces our data. The next three sections offer descriptive evidence of labour movements in China's rural villages and present an analytical framework for explaining migration. The sixth section raises a number of hypotheses suggested by the descriptive data and previous studies, and the final sections present our results and offer conclusions.

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Stark O, Bloom D E, 1985. The new economics of labor migration.American Economic Review, 75(2): 173-178.

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Strijker D, 2005. Marginal lands in Europe: Causes of decline.Basic & Applied Ecology, 6(2): 99-106.This article, analyses the mechanisms behind changes in agricultural land use. Intensification of land use on the one hand, and abandonment on the other have had important consequences for landscape and biodiversity. The basic mechanism behind it is a change, in the relative prices of inputs and output. In this sense the general economic developments have been determining the changes in agricultural land use. In Western Europe, the rapid increase in the opportunity costs of tabour was the main factor behind mechanisation and intensification of agriculture. Also, the Common Agricultural Policy of the EU has stimulated intensification. Recent policy developments have cut down important incentives for further intensification. This, however, does not solve the problem of the decline of low input agricultural systems in Europe. The only way to maintain them is by specific nature-enhancing policies. (c) 2005 Elsevier GmbH. All rights reserved.

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Taylor J E, 1999. The new economics of labour migration and the role of remittances in the migration process.International Migration, 37(1): 63-88.In 1995, international migrant remittances exceeded US$70 billion. How have these remittances shaped development in migrant sending areas?Pessimistic views on migration and development pervade the literature. In contrast, the new economics of labour migration (NELM) argues that migration may set in motion a development dynamic, lessening production and investment constraints faced by households in imperfect market environments and creating income growth linkages.This article assesses the development potential of remittances from a NELM perspective and cites empirical evidence that remittances may be a positive factor in economic development.Governments in migrant origin countries may increase the development potential of remittances through a variety of economic policies. Creating a fertile ground for remittances to contribute to broad based income growth in migrant sending areas is a key to promoting development from migration.

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Taylor J E, López-Feldman A, 2010. Does migration make rural households more productive? Evidence from Mexico.The Journal of Development Studies, 46(1): 68-90.The migration of labor out of rural areas and the flow of remittances from migrants to rural households is an increasingly important feature of less developed countries. This paper explores ways in which migration influences incomes and productivity of land and human capital in rural households over time, using new household survey data from Mexico. Our findings suggest that a massive increase in migration to the United States increased per-capita incomes via remittances and also by raising land productivity in migrant-sending households. They do not support the pessimistic view that migration discourages production in migrant-sending economies, nor the view implicit in separable agricultural household models that migration and remittances influence household incomes but not production.

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Taylor J E, Rozelle S, De Brauw A, 2003. Migration and incomes in source communities: A new economics of migration perspective from China.Economic Development and Cultural Change, 52(1): 75-101.

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Tian Y J, Li X B, Ma G Xet al., 2010. Influences of labor emigration from agriculture on the production abandonment of cultivated land in ecological sensitive areas.China Land Science, 24(7): 4-9. (in Chinese)The purpose of this paper is to assess the influences of labor emigration from agriculture on cultivated land production abandonment in ecological sensitive areas by taking the mountain area in southern Ningxia as an example.Method employed is binary logistic regression model.The results indicate:(1t)he area of production abandoned cultivated land is positively correlated with the amount of labor emigration,the time of emigration and total area of cultivated land owned by farmer households;(2t)he slope farmland and dry land will be firstly abandoned.It is concluded that the labor emigration from agriculture can impel the farmer households to abandon partial cultivated land with lower quality,and the abandonment of which will be helpful to the restoration of ecological environment.

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Tian Y J, Li X B, Xin L Jet al., 2009. Impacts of the rise of labor opportunity cost on agricultural land use changes: A case study of Ningxia Hui Autonomous Region.Journal of Natural Resources, 24(3): 369-377. (in Chinese)

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Tzanopoulos J, Mitchley J, Pantis J D, 2007. Vegetation dynamics in abandoned crop fields on a Mediterranean island: Development of succession model and estimation of disturbance thresholds.Agriculture Ecosystems & Environment, 120(2): 370-376.

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Woodruff C M, Zenteno R, 2001. Remittances and microenterprises in Mexico. UCSD, Graduate School of International Relations and Pacific Studies Working Paper.

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Xin L J, Li X B, 2009. Changes of multiple cropping in double cropping rice area of southern China and its policy implications.Journal of Natural Resources: 24(1): 58-65.(in Chinese)In recent years,the area of cultivated land continues to decrease,and the demand for grain product is just contrary as a response to population and economic growth in China,so agricultural intensification becomes a key process to raise land productivity.Under this background,cropping frequency as one key indicator of agricultural intensity should become higher.But multi-cropping index of some provinces,especially in the major rice producing area of southern China,has shown a decreasing trend since 1998.Now it is a very common phenomenon to plant single late rice instead of double cropping rice in China.How many rice fields have been transferred from double cropping to single cropping? How much yield loss happens? What are the main influencing factors? It is necessary to answer these fundamental questions.We checked the dynamic characteristics based on agricultural statistical data and national cost-income data of agricultural products between 1998 and 2006.It was found that:(1) more than 174.4脳104 ha of rice fields were transferred from double cropping to single cropping between 1998 and 2006,which was more serious than the situation media reported recently;(2) due to the change of multi-cropping index of rice fields,China's rice planting area decreased by 13%,total paddy output by 5.4%,and total grain output by 2%.The phenomena were particularly serious in the developed provinces of south China,such as Fujian,Zhejiang and Guangdong provinces;and(3) the phenomena are mainly ascribed to two main factors,agricultural labour shortage due to the rising wage and low income of double cropping rice.In the end of this paper,the authors claim that the following points should be emphasized in laying and implementing agricultural courses in our country:(1) grain subsidies should be embodied and detailed to guarantee that grain farmers get the subsidies,but not land contractors;(2) the prices of early rice and double-cropping late rice should be uplifted,which can directly increase the benefit and cropping enthusiasm of grain farmers;and(3) agricultural science and technology extension ability should also be strengthened.

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Yamada S, Okubo S, Kitagawa Yet al., 2007. Restoration of weed communities in abandoned rice paddy fields in the Tama Hills, central Japan.Agriculture Ecosystems & Environment, 119(1): 88-102.Since paddy weed communities are declining with intensification and abandonment of agricultural activities, protecting these species has become important. The restoration of cultural ecosystems normally includes the concomitant recovery of indigenous management practices. Given that the abandonment of paddy fields is due largely to cost and the shortage of labour, reintroduction of annual farming is unlikely even if paddy fields are restored. Hence, to confirm the occurrence of species assemblages typically represented in paddy fields (typical paddy weeds: TPWs) and to determine how to decrease the expense and management burden, we instituted a restoration program in which traditional culture was restarted with some modifications such as introducing fallow periods in paddy fields abandoned for more than 10 years. We also investigated cultivated paddy fields where local farmers practise low-intensity farming and newly abandoned paddy fields as references. By comparing the floristic composition between restored and reference fields, we sought to meet two objectives: (1) to evaluate the efficacy of the restoration program in terms of the species composition of paddy weed communities in restored paddy fields, and (2) to identify the optimum fallow period to decrease the expense and management burden. Restarting agricultural practices in abandoned paddy fields successfully encouraged TPWs. Moreover, restoration of the TPW community was rapid, with no resilient or alternative state in the restoration program. Soil tillage and management appeared to be major factors determining the success of the restoration. Tillage restricted the dominance of rhizomatous perennials and provided habitats for low-stature summer annuals. Reintroduction of submergence as a management practice generally inhibits the occurrence of most TPWs. However, the unlevelled soil surface in the present study provided suitable conditions for these species. One-year fallow produced the highest abundance of TPWs in a transient stage influenced by antecedent effects of culture such as drainage after harvest, delay of competitive species incidence, and lack of submergence as an agricultural treatment. The number of TPWs declined steadily with increasing fallow period. This evidence indicates that to maintain paddy weeds in the emergent flora, it is appropriate to create 1-year fallow conditions; that is, to cultivate every other year.

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Yan J Z, Wu Y Y, Zhang Y L, 2010a. Livelihood diversification of farmers and nomads of eastern transect in Tibetan Plateau.Journal of Geographical Sciences, 20(5): 757-770.<p>Livelihoods of farmers and nomads in Tibetan Plateau are severely affected by grassland and herbal resources degeneration. How to help them achieve livelihood diversification is a key sustainable development issue. This paper examines livelihood assets, livelihood diversification level and livelihood strategies of farmers and nomads in 3 regions of eastern transect in Tibetan Plateau. The results show that livelihood diversification is a popular strategy. From high mountain gorge region to mountain plateau region and plateau region, livelihood diversification level is reduced, and livelihood activities and proportion of extended livelihood also decrease. Livelihood assets and livelihood diversification level decrease with the increase of elevation, mainly shown in human assets and natural assets. Livelihood diversification level is highly correlative with livelihood assets, mainly shown in natural assets, human assets and social assets. Livelihood improvement strategies of farmers and nomads are still based on existing livelihood assets, mainly raising livestock and digging herbs, and less farmers and nomads consider off-farm employment or doing business. Nomads in plateau region should learn much from experiences of extended livelihoods of people in high mountain gorge region and mountain plateau region. Therefore, aids of governments should focus on relieving restricted factors of livelihood diversification and help them improve their abilities to build up extended type livelihoods.</p>

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Yan J Z, Zhang Y L, Bai W Qet al., 2005a. Land cover changes based on plant successions: Deforestation, rehabilitation and degeneration of forest in the upper Dadu River watershed.Science in China Series D: Earth Sciences, 48(12): 2214-2230.

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Yan J Z, Zhang Y L, Bai W Qet al., 2005b. Livelihood succession and land use/cover change in the upper reaches of Dadu River watershed.Transactions of the Chinese Society of Agricultural Engineering, 21(3): 83-89. (in Chinese)Based on field survey, family questionnaire, historical datum analysis and interpretation of remote sensing data, this study presents livelihood succession during 1950～2000 and land cover change during 1967～2000 in Rangtang County, Maerkang County and Jinchuan County in the Upper Reaches of Dadu River watershed, by the combined using of geographic information systems (GIS) method and remote sensing (RS) method. The results show: there are different livelihood succession in the valley areas, middle-mountain areas, forest areas and pasture aresa in the Upper Reaches of Dadu River watershed. At the collective economy stage, livelihoods of all the residents rest on agriculture and herds, which resulting in involution of agriculture. As labor forces transferred to the second and third industry to seek better livelihoods after the 1980s, livelihood of the whole region has diverse successions, as it is easier for the labor forces in valley areas to transfer to the second and third industry, harder for labor forces in middle-mountain areas, impossible for labor forces in pasture areas. As a result, involution cultivation system in the valley areas and middle-mountain areas is given up and agricultural structure is adjusted according to market needs, while the mountain nomadism has no marked changes. The residents in the valley areas and forest areas are positive to environmental degradation, while residents in the middle-mountain areas and pasture areas are passive to it. Driven by diverse livelihood successions, land use change successions and response models, the land cover change dynamics are also different in the four regions. This paper also shows that changing livelihood models and transferring the labor forces to the second and third industry are the key countermeasures for social and economic development and ecological rehabilitation of ecotone.

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Yan J Z, Zhang Y L, Zhang L Qet al., 2009. Livelihood strategy change and land use change: Case of Danzam Village in upper Dadu River watershed, Tibetan Plateau of China.Chinese Geographical Science, 19(3): 231-240.<a name="Abs1"></a>Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers&#8217; livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.

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Yan J Z, Zhuo R G, Xie D Tet al., 2010b. Land use characters of farmers of different livelihood strategies: Cases in Three Gorges Reservoir Area.Acta Geographica Sinica, 65(11): 1401-1410. (in Chinese)lt;p>This study examines land use types and input level of every plot of sample farmers in three typical villages in Chongqing. Through stratified random sampling survey, participatory rural appraisal and investigation of plots, 227 households and 2250 plots are investigated and sampled. Farmers are divided into four types: pure agriculture households, agriculture-dependent households, off-farm dependent households and off-farm households. The results show: (1) Apart from 6.17% of off-farm households, who leave land uncultivated, abandoned or rent, land use types of pure agriculture households, agriculture-dependent households and off-farm dependent households are mainly intensive. Some 48.95% of arable land of pure agriculture households are relatively extensive due to the aging. The proportions of relatively extensive arable land of agriculture-dependent and off-farm dependent households are 71.08% and 67.20% , respectively. (2) Land inputs are different among the four farmer types. Off-farm household have no land input. Pure agriculture households have low agricultural labor input due to aging, and less agricultural machinery and labor-saving inputs due to lack of funds, so they prefer to choose manure, phosphate fertilizer, ammonium bicarbonate and other cheap fertilizers.</p>

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Yao Y, 2000. The Development of the land lease market in rural China.Land Economics, 76(2): 252-266.This paper examines the development of the land lease market in rural China. Special attention is paid to productive heterogeneity among farmers and the openness of the labor market in activating the land lease market. A theoretical model is employed to explore the underlying connections. An econometric model is implemented using a two-period panel data set gathered in three counties of China's Zhejiang province. The results show that productive heterogeneity and a freer labor market do promote more land leases. The implications for the institutional change literature are discussed.

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Zhang L P, Zhang Y L, Yan J Z, 2008. Livelihood diversification and cropland use pattern in agro-pastoral mountainous region of eastern Tibetan Plateau.Journal of Geographical Sciences, 18(4): 499-509.<a name="Abs1"></a>This study examined livelihood diversification and cropland use pattern in Keerma village, located in Jinchuan County, eastern Tibetan Plateau. Through stratified random sampling survey, participatory rural appraisal, investigation of households&#8217; plots and statistical methods, 63 households and 272 cropland plots were systemically investigated and sampled. The results show: (1) Different types of household have variety livelihood strategies, portfolio and income. Livelihood diversification and introducing and expanding off-farm activities can be the future trend, whereas, adverse natural environment, socio-economic conditions and peasants&#8217; capabilities together affect sustainable livelihood and land use. (2) Each livelihood strategy has its own impact on land use, mainly affecting land use type and land use intensification level. (3) Diversification into off-farm activities could be the key of building sustainable livelihood and the essential approach of realizing sustainable land use in the region.

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Zhang X B, Yang J, Wang S L, 2011. China has reached the Lewis turning point.China Economic Review, 22(4): 542-554.lt;h2 class="secHeading" id="section_abstract">Abstract</h2><p id="sp0130">In the past several years, labor shortage in China has become an emerging issue. However, there is heated debate on whether China has passed the Lewis turning point and entered a new era of labor shortage from a period of unlimited labor supply. Most empirical studies on this topic focus on the estimation of total labor supply and demand. Yet the poor quality of labor statistics leaves the debate open. In this paper, China's position along the Lewis continuum is examined though primary surveys of wage rates, a more reliable statistic than employment data. Our results show a clear rising trend of real wages rate since 2003. The acceleration of real wages even in slack seasons indicates that the era of surplus labor is over. This finding has important policy implications for China's future development model.</p><h4 id="secGabs_N1b35acd8N30fa82d8">Highlights</h4><p>? This paper examines the Lewis turning point using primary village surveys over different periods. ? Rural wage has accelerated since 2003 in both harvest and slack seasons. ? Male and female wages have experienced the same trend &ndash; slow growth prior to 2003 and a rapid increase since 2003. ? The era of surplus labor is over.</p>

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Zhang Y L, Li B Y, Zheng D, 2002. A discussion on the boundary and area of the Tibetan Plateau in China.Geographical Research, 21(1): 1-8. (in Chinese)The Tibetan Plateau is a unique geomorphic unit composed of some basic geomorphic types, such as extreme high mountains,high mountains, hills, plains, and tablelands of high altitude or sub-high altitude. Different opinions for the exact scope of Tibetan Plateau exist. According to latest research achievement and the long time fieldwork, questions related to the area and boundary of the Plateau have been discussed in view of geography, and the principles taking geomorphic characters as the main rule and considering the integrity have been made to define the boundary. The 1∶1 000 000 geomorphological map was compiled based on 1∶100 000 aerial photographic map,1∶500 000 topographic map and interpretation of satellite images. By refering to the 1∶3 000 000 relief map, the boundary of the Plateau was delineated.The position of the boundary was quantitatively determined with GIS and GPS.The map of electronic version of the Tibetan Plateau was compiled. The main conclusion is that Tibetan Plateau starts from the southern edge of the Himalayan Range, abuts on India,Nepal and Bhutan,connects the northern edge of Kunlun, Altun and Qilian Mts., and joins Tarim Basin and Hexi Corridor in Central Asia.The west of it is the Pamirs and Karakorum Mts., bordering on Kirghizistan, Tajikistan, Afghanistan, Pakistan and Kashmir. The east of it is Yulongxueshan, Daxueshan, Jiajinshan and Qionglaishan Mts.as well as south or east piedmont of Minshan Mts. Tibetan Plateau joins the Qinling Mts.and Loess Plateau with its eastern and northeastern part. Tibetan Plateau in China's territory starts from the Pamirs in the west and reaches to Hengduanshan in the east. It bestrides a longitude of 31 degrees with a length of 2 945 km from east to west,and bestrides a latitude of 13 degrees with a length of 1 532 km from south to north. It ranges from 26°00′12" N to 39°46′50" N and from 73°18′52"E to 104°46′59"E, covering an area of 2 572.4×10 3 km 2. Administratively, it embraces 201 counties (cities) in 6 provinces, namely, the Tibet Autonomous Region (73 counties/cities,1 176.0×10 3 km 2, part of Cona, Mêdog and Zayü), the Qinghai Province(40 counties/cities,721.0×10 3 km 2, some counties only partially), Dêqen Tibetan Autonomous Prefecture in Northwest Yunnan Province(9 counties/cities,33.5×10 3 km 2), West Sichuan Province ( 46 counties/cities about 254.0×10 3 km 2 ,such as Garze Autonomous Prefecture, Aba Tibetan and Qiangzu Autonomous Prefecture,and Muli Autonomous County, etc.),Gansu Province(21 counties/cities, 74.9×10 3 km 2), and Southern Xinjiang Uygur Autonomous Region (about 12 counties/cities, 313.0×10 3 km 2).

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Zhong Z B, Wang P.2003. Analysis of farmer households’ behavior in the transfer of the rural land.China Rural Survey, (6): 55-64. (in Chinese)By analyzing the differences of farmer households' behavior in rural land in two different economic development areas, this research finds out that within the given Land Tenure System farmer households' land transfer is not only an economic conduct, but also a social behavior. The paper points out that the popularity, the rationality and contract sense development as well as organization degree of land transfer can be improved on the bases of the development of the second and third industry along with the prosperity of the rural merchandise economy.

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Zou X Q, 2008. An empirical analysis of farmers’ cultivated land transfer behavior based on 537 household questionnaires in Jiangxi, Jiangsu and Guangxi Province.Journal of Jiangxi University of Finance and Economics, (6): 50-52. (in Chinese)

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