Understanding the Changing Planet: Strategic Directions for the Geographical Sciences (UCP), published by the National Research Council (USA), and its comments in The Professional Geographer propose that uppercase and plural "Geographical Sciences" (GS) is the strategic direction for geography in the next decade for better understanding of our rapidly changing planet. According to these comments, UCP valued technologies and tools excessively ("task"), and did not pay much attention to methodology ("discipline"). Actually, both "task" and "discipline" are geographical wings, especially in the time of "big science". Enlightenment from UCP and its comments is the strategic direction that should be balanced between "task" and "discipline", GS should be a three-dimensional construct of a disciplinary system, methodology, and technologies and tools, and this system should be scientific humanism based on scientific spirit and directed by humanism. During the last 60 years, Chinese geographers devoted themselves to GS, including practice and theory. Obviously progress and outlook are proposed as interdisciplinary GS, Earth Surface Sciences (ESS) and Geographical Construction (GC). The disciplinary system of GS is very complex, and is composed of such human knowledge domains as sciences, technologies, engineering, and philosophy. The main mission is to research the open, complex, and macro earth system (not only scientifically, but also humanistically), and one significant methodology is "comprehensive integration of qualitative and quantitative means" (CIQQM). At the same time, another changing direction in Chinese geography is Human-Economic Geography (HEG).
Land use/cover change is an important parameter in the climate and ecological simulations. Although they had been widely used in the community, SAGE dataset and HYDE dataset, the two representative global historical land use datasets, were little assessed about their accuracies in regional scale. Here, we carried out some assessments for the traditional cultivated region of China (TCRC) over last 300 years, by comparing SAGE2010 and HYDE (v3.1) with Chinese Historical Cropland Dataset (CHCD). The comparisons were performed at three spatial scales: entire study area, provincial area and 60 km by 60 km grid cell. The results show that (1) the cropland area from SAGE2010 was much more than that from CHCD; moreover, the growth at a rate of 0.51% from 1700 to 1950 and -0.34% after 1950 were also inconsistent with that from CHCD. (2) HYDE dataset (v3.1) was closer to CHCD dataset than SAGE dataset on entire study area. However, the large biases could be detected at provincial scale and 60 km by 60 km grid cell scale. The percent of grid cells having biases greater than 70% (<-70% or >70%) and 90% (<-90% or >90%) accounted for 56%-63% and 40%-45% of the total grid cells respectively while those having biases range from -10% to 10% and from -30% to 30% account for only 5%-6% and 17% of the total grid cells respectively. (3) Using local historical archives to reconstruct historical dataset with high accuracy would be a valuable way to improve the accuracy of climate and ecological simulation.
It is believed that the global CO2 emissions have to begin dropping in the near future to limit the temperature increase within 2 degrees by 2100. So it is of great concern to environmentalists and national decision-makers to know how the global or national CO2 emissions would trend. This paper presented an approach to project the future CO2 emissions from the perspective of optimal economic growth, and applied this model to the cases of China and the United States, whose CO2 emissions together contributed to more than 40% of the global emissions. The projection results under the balanced and optimal economic growth path reveal that the CO2 emissions will peak in 2029 for China and 2024 for the USA owing to their empirically implied pace of energy efficiency improvement. Moreover, some abatement options are analyzed for China, which indicate that 1) putting up the energy price will decrease the emissions at a high cost; 2) enhancing the decline rate of energy intensity can significantly mitigate the emissions with a modest cost; and 3) the energy substitution policy of replacing carbon intensive energies with clean ones has considerable potential to alleviate emissions without compromising the economic development.
Rice's spatial-temporal distributions, which are critical for agricultural, environmental and food security research, are affected by natural conditions as well as socio-economic developments. Based on multi-source data, an effective model named the Spatial Production Allocation Model (SPAM) which integrates arable land distribution, administrative unit statistics of crop data, agricultural irrigation data and crop suitability data, was used to get a series of spatial distributions of rice area and production with 10-km pixels at a national scale - it was applied from the early 1980s onwards and used to analyze the pattern of spatial and temporal changes. The results show that significant changes occurred in rice in China during 1980-2010. Overall, more than 50% of the rice area decreased, while nearly 70% of rice production increased in the change region during 1980-2010. Spatially, most of the increased area and production were in Northeast China, especially, in Jilin and Heilongjiang; most of the decreased area and production were located in Southeast China, especially, in regions of rapidly urbanization in Guangdong, Fujian and Zhejiang. Thus, the centroid of rice area was moved northeast approximately 230 km since 1980, and rice production about 320 km, which means rice production moved northeastward faster than rice area because of the significant rice yield increase in Northeast China. The results also show that rice area change had a decisive impact on rice production change. About 54.5% of the increase in rice production is due to the expansion of sown area, while around 83.2% of the decrease in rice production is due to contraction of rice area. This implies that rice production increase may be due to area expansion and other non-area factors, but reduced rice production could largely be attributed to rice area decrease.
Rubber plantation is the major land use type in Southeast Asia. Monitoring the spatial-temporal pattern of rubber plantation is significant for regional land resource development, eco-environmental protection, and maintaining border security. With remote sensing technologies, we analyzed the rubber distribution pattern and spatial-temporal dynamic; with GIS and a newly proposed index of Planted Intensity (PI), we further quantified the impacts and limits of topographical factors on rubber plantation in the border region of China, Laos and Myanmar (BRCLM) between 1980 and 2010. The results showed that: (1) As the dominant land use type in this border region, the acreage of rubber plantation was 6014 km2 in 2010, accounting for 8.17% of the total area. Viewing from the rubber plantation structure, the ratio of mature- (≥10 year) and young rubber plantation (<10 year) was 5:7. (2) From 1980 to 2010, rubber plantation expanded significantly in BRCLM, from 705 km2 to 6014 km2, nearly nine times. The distribution characteristics of rubber plantation varied from concentrated toward dispersed, from border inside to outside, and expanded further in all directions with Jinghong City as the center. (3) Restricted by the topographical factors, more than 4/5 proportion of rubber plantation concentrated in the appropriate elevation gradients between 600 and 1000 m, rarely occurred in elevations beyond 1200 m in BRCLM. Nearly 2/3 of rubber plantation concentrated on slopes of 8°-25°, rarely distributed on slopes above 35°. Rubber plantation was primarily distributed in south and east aspects, relatively few in north and west aspects. Rubber planted intensity displayed the similar distribution trend. (4) Comparative studies of rubber plantation in different countries showed that there was a remarkable increase in area at higher elevations and steeper slopes in China, while there were large appropriate topographical gradients for rubber plantation in Laos and Myanmar which benefited China for rubber trans-boundary expansion. (5) Rubber plantation in BRCLM will definitely expend cross borders of China to the territories of Laos and Myanmar, and the continuous expansion in the border region of China will be inevitable.
Understanding the driving forces and mechanism of land use change is a key issue in land change science, and has received much attention over the past 30 years. While many driving forces have been identified, the mechanism of land use change is still unclear, mainly because of limited knowledge of the underlying motivation for land use change. Traditionally, the underlying motivation for land use change was ascribed to people's pursuit of satisfying their own demands or that of profit maximization. However, those theoretical hypotheses combine all productive factors without highlighting certain predominant factor. In this paper, a case study was conducted on the variation of land productivity, capital productivity and labor productivity in agricultural land use in Xinjiang Uygur Autonomous Region of China. The case study revealed that only labor productivity presented a long-term increasing trend in regional cotton and grain production. This result implies that people's pursuit of increasing labor productivity is probably the underlying motivation for land use change. Additional details identified in agricultural and non-agricultural land use in China support the above implication. As labor productivity is a determinant of people's living standards, increasing labor productivity means improving people's living standards. Therefore, it is concluded that land use change results from people's pursuit of increasing labor productivity in a changing environment.
In Northeast Thailand, the climate change has resulted in erratic rainfall and temperature patterns. The region has experienced both periods of drought and seasonal floods with the increasing severity. This study investigated the seasonal variation of vegetation greenness based on the Normalized Difference Vegetation Index (NDVI) in major land cover types in the region. An assessment of the relationship between climate patterns and vegetation conditions observed from NDVI was made. NDVI data were collected from year 2001 to 2009 using multi-temporal Terra MODIS Vegetation Indices Product (MOD13Q1). NDVI profiles were developed to measure vegetation dynamics and variation according to land cover types. Meteorological information, i.e. rainfall and temperature, for a 30 year time span from 1980 to 2009 was analyzed for their patterns. Furthermore, the data taken from the period of 2001-2009, were digitally encoded into GIS database and the spatial patterns of monthly rainfall and temperature maps were generated based on kriging technique. The results showed a decreasing trend in NDVI values for both deciduous and evergreen forests. The highest productivity and biomass were observed in dry evergreen forests and the lowest in paddy fields. Temperature was found to be increasing slightly from 1980 to 2009 while no significant trends in rainfall amounts were observed. In dry evergreen forest, NDVI was not correlated with rainfall but was significant negatively correlated with temperature. These results indicated that the overall productivity in dry evergreen forest was affected by increasing temperatures. A vegetation greenness model was developed from correlations between NDVI and meteorological data using linear regression. The model could be used to observe the change in vegetation greenness and dynamics affected by temperature and rainfall.
Cryophenological records (i.e. observational series of freeze and breakup dates of ice) are of great importance when assessing the environmental variations in cold regions. Here we employed the extraordinarily long observational records of river ice breakup dates and air temperatures in northern Fennoscandia to examine their interrelations since 1802. Historical observations, along with modern data, comprise the informational setting for this analysis carried out using t-test. Temperature history of April-May season was used as climatic counterpart for the breakup timings. Both records (temperature and breakup) showed seven sub-periods during which their local means were distinctly different relative to preceding and subsequent sub-periods. The starting and ending years of these sub-periods occurred in temporal agreement. The main findings of this study are summarized as follows: (1) the synchrony between the temperature and river ice breakup records ruled out the possibility that the changes would have occurred due to quality of the historical series (i.e. inhomogeneity problems often linked to historical time-series); (2) the studied records agreed to show lower spring temperatures and later river ice breakups during the 19th century, in comparison to the 20th century conditions, evidencing the prevalence of cooler spring temperatures in the study region, in agreement with the concept of the Little Ice Age (1570-1900) climate in North-West Europe; (3) the most recent sub-period demonstrate the highest spring temperatures with concomitantly earliest river ice breakups, showing the relative warmth of the current springtime climate in the study region in the context of the past two centuries; (4) the effects of anthropogenic changes in the river environment (e.g. construction and demolition of dams) during the 20th century should be considered for non-climatic variations in the breakup records; (5) this study emphasizes the importance of multi-centurial (i.e. historical) cryophenological information for highly interesting viewpoints of climate and environmental history.
Crop water productivity (CWP) is one of the important indicators for sustainable agricultural development in water scarcity area. There is serious conflict between water supply and requirement in the Haihe River Basin. CWP of winter wheat and summer maize from 2003 to 2007 in the Haihe River Basin is estimated based on large-scale evapotranspiration (ET) and crop yield obtained by remote sensing technology. Spatial and temporal distribution of CWP of winter wheat and summer maize is investigated in this study. Results show that CWP of winter wheat in most parts of the study area varies from 1.02 kg/m3 to 1.53 kg/m3, and CWP of summer maize varies from 1.31 kg/m3 to 2.03 kg/m3. Multi-year averaged CWP of winter wheat and summer maize in the study area is about 1.19 kg/m3 and 1.59 kg/m3. CWP results show certain promotion potential to alleviate the water shortage in the Haihe River Basin. Correlation analysis of CWP, crop yield and ET shows that there is great potential for crop yield promotion without the growth in irrigation water. Large-scale CWP estimated by remote sensing technology in this study shows spatial distribution features, which could be used to real-time agricultural water resource management combined with crop yield and ET.
Soil erosion is a major threat to our terrestrial ecosystems and an important global environmental problem. The Loess Plateau in China is one of the regions that suffered more severe soil erosion and undergoing climate warming and drying in the past decades. The vegetation restoration named Grain-to-Green Program has now been operating for more than 10 years. It is necessary to assess the variation of soil erosion and the response of precipitation and vegetation restoration to soil erosion on the Loess Plateau. In the study, the Revised Universal Soil Loss Equation (RUSLE) was applied to evaluate annual soil loss caused by water erosion. The results showed as follows. The soil erosion on the Loess Plateau between 2000 and 2010 averaged for 15.2 t hm-2 a-1 and was characterized as light for the value less than 25 t hm-2 a-1. The severe soil erosion higher than 25 t hm-2 a-1 was mainly distributed in the gully and hilly regions in the central, southwestern, and some scattered areas of earth-rocky mountainous areas on the Loess Plateau. The soil erosion on the Loess Plateau showed a deceasing trend in recent decade and reduced more at rates more than 1 t hm-2 a-1 in the areas suffering severe soil loss. Benefited from the improved vegetation cover and ecological construction, the soil erosion on the Loess Plateau was significantly declined, especially in the east of Yulin, most parts of Yan'an prefectures in Shaanxi Province, and the west of Luliang and Linfen prefectures in Shanxi Province in the hilly and gully regions. The variation of vegetation cover responding to soil erosion in these areas showed the relatively higher contribution than the precipitation. However, most areas in Qingyang and Dingxi prefectures in Gansu Province and Guyuan in Ningxia Hui Autonomous Region were predominantly related to precipitation.
The precipitation regime of the low latitude highlands of Yunnan in Southwest China is subject to the interactions between the East Asian Summer Monsoon and the Indian Summer Monsoon, and the influence of surface orography. An understanding of changes in its spatial and temporal patterns is urgently needed for climate change projection, hydrological impact modelling, and regional and downstream water resources management. Using daily precipitation records of the low latitude highlands over the last several decades (1950s-2007), a time series of precipitation indices, including annual precipitation, number of rainy days, mean annual precipitation intensity, the dates of the onset of the rainy season, degree and period of precipitation seasonal concentration, the highest 1-day, 3-day and 7-day precipitation, and precipitation amount and number of rainy days for precipitation above different intensities (such as ≥10 mm, ≥25 mm and ≥50 mm of daily precipitation), was constructed. The Trend-Free Pre-Whitening Mann-Kendall trend test was then used to detect trends of the time series data. The results show that there is no significant trend in annual precipitation and strong seasonal differentiation of precipitation trends across the low latitude highlands. Springs and winters are getting wetter and summers are getting drier. Autumns are getting drier in the east and wetter in the west. As a consequence, the seasonality of precipitation is weakening slightly. The beginning of the rainy season and the period of the highest precipitation tend to be earlier. In the meantime, the low latitude highlands has also witnessed less rainy days, more intense precipitation, slightly longer moderate and heavy precipitation events, and more frequent extreme precipitation events. Additionally, regional differentiation of precipitation trends is remarkable. These variations may be associated with weakening of the East Asian summer monsoon and strengthening of the South Asian summer monsoon, as well as the "corridor-barrier" effects of special mountainous terrain. However, the physical mechanisms involved still need to be uncovered in the future.
As one of the most important metropolitan areas in China, Xi'an City plays a leading role in the development of the western regions. To impede the decision and policy preferences for environmental and ecological factors, this paper took account of the natural capital depletion of Xi'an City during 1995-2011, considered in terms of constant 1990 price levels. The results are as follows. (1) Natural capital depletion in Xi'an City consistently increased from1995 to 2011, increasing from 14.31×108 yuan to 42.28×108 yuan, with an average annual growth rate of 12.22%. The primary component of natural capital depletion in Xi'an City was the cost associated with fossil fuel resource depletion, while the cost associated with ecological services contributed the least to the total cost. (2) During 1995-2011, the proportion of natural capital depletion to Xi'an City in Yanta and Lianhu districts dropped, whereas in counties such as Gaoling County, Chang'an District and Lintong District, it increased. In 2011, the proportion of natural capital depletion varied between the different counties: Yanta District (15.75%), Weiyang District and Lianhu District (10%-15%), Huxian County, Xincheng District, Beiling District, Chang'an District, Baqiao District, and Gaoling County (5%-10%), and in Lintong District, Lantian County, Zhouzhi County and Yanliang District, it was <5%. (3) The spatial pattern of natural capital depletion varied with different perspectives, for example, from a total value perspective, a nuclear pattern around the administrative center of Xi'an City was evident, whereas from a density per capita of natural capital depletion perspective, a bi-nuclear spatial distribution visible in 1995 had become a poly-nuclear distribution by 2011. Conversely, from a density per hectare perspective, a "core-edge" pattern characterized by three circles was observed. (4) The natural capital depletion relative to GDP curve was in accordance with the environmental Kuznets curve, while the proportion of natural capital depletion to GDP was the highest in circle III and the lowest in circle I.
Despite rapid urbanization, more than 200 million people living in urban areas are still registered as‘agricultural’and are ineligible for most social benefits under China's Hukou (or household registration) system. This paper identifies the regional suitability for settling rural migrants in urban China based on three indicators (the degree of urgency, the skills and ability of the resettled community to adapt, and the ability of the government to support that resettlement). It takes 2008 government socioeconomic data from a county level into consideration. Spatial, statistical, and decision tree analyses, supported by SPSS, Geodata, and ArcGIS software, show that there are five separate population types, each with different degrees of suitability. These include highly suitable region, region suitable for settling migrants to outside regions, region suitable for settling migrants from outside regions, region with moderate potential, and unsuitable region. This paper suggests that regional policies for settling rural migrants are meaningful, since the five regions are distributed relatively separately. Due to the suitability for different bodies across regions, equal treatment should be applied to both the native migrants and that across counties and provinces. Furthermore, demolishment of the social welfare discrimination adhered to Hukou system and equalization of basic public services will be of more practical significance than the so-called settling rural migrants actively and steadily.
