Understanding the interactions between humans and nature in the Anthropocene is central to the quest for both human wellbeing and global sustainability. However, the time-space compression, long range interactions, and reconstruction of socio-economic structures at the global scale all pose great challenges to the traditional analytical frameworks of human-nature systems. In this paper, we extend the connotation of coupled human and natural systems (CHANS) and their four dimensions—space, time, appearance, and organization, and propose a novel framework: “Coupled Human and Natural Cube” (CHNC) to explain the coupling mechanism between humans and the natural environment. Our proposition is inspired by theories based on the human-earth areal system, telecoupling framework, planetary urbanization, and perspectives from complexity science. We systematically introduce the concept, connotation, evolution rules, and analytical dimensions of the CHNC. Notably there exist various “coupling lines” in the CHNC, connecting different systems and elements at multiple scales and forming a large, nested, interconnected, organic system. The rotation of the CHNC represents spatiotemporal nonlinear fluctuations in CHANS in different regions. As a system continually exchanges energy with the environment, a critical phase transition occurs when fluctuations reach a certain threshold, leading to emergent behavior of the system. The CHNC has four dimensions—pericoupling and telecoupling, syncoupling and lagcoupling, apparent coupling and hidden coupling, and intra-organization coupling and inter-organizational coupling. We mainly focus on the theoretical connotation, research methods, and typical cases of telecoupling, lagcoupling, hidden coupling, and inter-organizational coupling, and put forward a human-nature coupling matrix to integrate multiple dimensions. In summary, the CHNC provides a more comprehensive and systematic research paradigm for understanding the evolution and coupling mechanism of the human-nature system, which expands the analytical dimension of CHANS. The CHNC also provides a theoretical support for formulating regional, sustainable development policies for human wellbeing.
To clarify the impact of non-agricultural employment on rural land circulation in China, we built logit models using the Chinese Household Income Project 2013 dataset, which includes 18,948 household samples over 15 provinces, 126 cities and 234 counties of China in 2013. We use the proportion of non-agricultural income, the proportion of non-agricultural laborers and non-agricultural fixed operating assets to reflect the degree of the households’ dependence on agriculture, the degree of the households’ laborers committed to non-agricultural employment and the stability of non-agricultural employment, respectively. The results show that the stability of non-agricultural employment is an important reason for farmers to transfer out their land, and an increase in non-agricultural income is the fundamental reason. The proportion of non-agricultural assets has the greatest impact on the decision to transfer land, followed by the proportion of non-agricultural income. Per unit increase in the non-agricultural income ratio has a stronger effect on the transfer-out decision than it does on the transfer-in decision, which is a 0.09 increase of the probability of transfer-out the land and a 0.07 decrease of the probability of transfer-in the land. In terms of regional differences, when considering the impact of non-agricultural employment on the land transfer-out decision, the impacts of non-agricultural income and labor force are the greatest in the Central region. The impact of non-agricultural assets is the greatest in the Eastern region. For the Eastern region, the decision to transfer out land is mainly affected by non-agricultural assets and the non-agricultural labor force, and the decision to transfer in land is mainly affected by non-agricultural assets. In the Central and Western regions, the decision to transfer out land is mainly affected by non-agricultural assets, non-agricultural income and the non-agricultural labor force, in that order. The decision to transfer in land in the Central region is not significantly affected by non-agricultural employment. The decision to transfer in land in the Western region is mainly affected by non-agricultural assets, non-agricultural labor force and non-agricultural income, in that order. We note that non-agricultural assets have a prominent impact on land transfer, which shows that the stability of non-agricultural employment has an important impact on land transfer decision-making. Vocational training for rural labor forces may be an effective means to promote stable non-agricultural employment and simultaneously facilitate rural land circulation, especially in Central and Western China.
This paper looks at the Green for Grain Project in northern Shaanxi Province. Based on remote sensing monitoring data, this study analyzes the locations of arable land in northern Shaanxi in the years 2000, 2010 and 2013 as well as spatio-temporal changes over that period, and then incorporates data on the distribution of terraced fields to improve the input parameters of a RUSLE model and simulate and generate raster data on soil erosion for northern Shaanxi at different stages with a accuracy verification. Finally, combined with the dataset of farmland change, compared and analyzed the characteristics of soil erosion change in the converted farmland to forest (grassland) and the unconverted farmland in northern Shaanxi, so as to determine the project’s impact on soil erosion over time across the region. The results show that between 2000 and 2010, the soil erosion modulus of repurposed farmland in northern Shaanxi decreased 22.7 t/ha, equivalent to 47.08% of the soil erosion modulus of repurposed farmland in 2000. In the same period, the soil erosion modulus of non-repurposed farmland fell 10.99 t/ha, equivalent to 28.6% of the soil erosion modulus of non-repurposed farmland in 2000. The soil erosion modulus for all types of land in northern Shaanxi decreased by an average of 14.51 t/ha between 2000 and 2010, equivalent to 41.87% of the soil erosion modulus for the entire region in 2000. This suggests that the Green for Grain Project effectively reduced the soil erosion modulus, thus helping to protect the soil. In particular, arable land that was turned into forest and grassland reduced erosion most noticeably and contributed most to soil conservation. Nevertheless, in the period 2010 to 2013, which was a period of consolidation of the Green for Grain Project, the soil erosion modulus and change in volume of soil erosion in northern Shaanxi were significantly lower than in the previous decade.
Based on the comprehensive analyses of 18 core profiles’ sedimentary sequences and lithological characteristics in Jianghan-Dongting Basin of the middle reaches of the Yangtze River and the spatial-temporal distribution of archeological sites in this area, we reconstructed the Holocene hydro-environmental evolution, and its relationship with human occupation. The comparison reveals: 11.5-5.5 ka BP, the water level of rivers and lakes in the middle Yangtze River appeared a rising trend, concurrently, under the development of Neolithic culture and rice agricultural activities, human occupation extended from piedmont plain to inner basin plain in the study area. The water level fell in 5.5-4.0 ka BP, meanwhile, the number of human settlements of Qujialing-Shijiahe culture rapidly increased, especially in the inner basin plain. The water level rose again around 4.0 ka BP, floods spread massively in this period, which led to the decline of Shijiahe culture. The main causes for hydro-environmental evolution in the study area are the fluctuation of sea level and the aggradation of fluvio-lacustrine sediments.
The effects of human activities on climate change are a significant area of research in the field of global environmental change. Land use and land cover change (LUCC) has a greater effect on climate than greenhouse gases, and the effect of farmland expansion on regional drought is particularly important. From the 1910s to the 2010s, cultivated land in Songnen Plain increased by 2.67 times, the area of cultivated land increased from 4.92×10 4km 2 to 13.14×10 4km 2, and its percentage of all land increased from 25% to 70%. This provides an opportunity to study the effects of the conversion of natural grassland to farmland on climate. In this study, the drought indices in Songnen Plain were evaluated from the 1910s to the 2010s, and the effect of farmland expansion on drought was investigated using statistical methods and the Weather Research and Forecasting Model based on UK’s Climatic Research Unit data. The resulting dryness index, Palmer drought severity index, and standardized precipitation index values indicated a significant drying trend in the study area from 1981 to 2010. This trend can be attributed to increases in maximum temperature and diurnal temperature range, which increased the degree of drought. Based on statistical analysis and simulation, the maximum temperature, diurnal temperature range, and sensible heat flux increased during the growing season in Songnen Plain over the past 100 years, while the minimum temperature and latent heat flux decreased. The findings indicate that farmland expansion caused a drying trend in Songnen Plain during the study period.
To study the effects of changes in the rainfall intensity on sediment concentrations in the Loess Plateau, the observed rainfall intensities and sediment concentrations from three typical small watersheds were used to analyze the relationship between these parameters. The results showed that the sediment concentration generally increased with the increasing rainfall intensity on slope scale. However, at watershed scale, a significant threshold phenomenon was observed for the effects of the rainfall intensity on the sediment concentration. When the rainfall intensity exceeds the threshold, the flood sediment concentration will no longer increase with the increase in the rainfall intensity. The rainfall intensity threshold increased with increasing vegetation coverage. The rainfall intensity threshold was 10-15 mm/h during 1956-1969, reached 20 mm/h from 1990 to 1997 and is approximately 40 mm/h at present. Due to a rainfall intensity of 10-15 mm/h almost happened every year, the vegetation did not change much from the 1950s to 1980s. Sediment yield mainly depends on soil erosion caused by surface flow, but the surface flow speed does not increase indefinitely with the increase in the flow discharge. Thus, the annual maximum sediment concentration of the tributaries in the loess area has been basically stable before the 1990s.
Based on the measured discharge, sediment load, and cross-sectional data from 1986 to 2015 for the lower Yellow River, changes in the morphological parameters (width, depth, and cross-sectional geomorphic coef?cient) of the main channel are analyzed in this paper. The results show that before the operation of the Xiaolangdi Reservoir (XLDR) from 1986 to 1999, the main channel shrunk continually, with decreasing width and depth. The rate of reduction in its width decreased along the river whereas that of depth increased in the downstream direction. Because the rate of decrease in the width of the main channel was greater than that in channel depth, the cross-sectional geomorphic coef?cient decreased in the sub-reach above Gaocun. By contrast, for the sub-reach below Gaocun, the rate of decrease in channel width was smaller than that in channel depth, and the cross-sectional geomorphic coef?cient increased. Once the XLDR had begun operation, the main channel eroded continually, and both its width and depth increased from 2000 to 2015. The rate of increase in channel width decreased in the longitudinal direction, and the depth of the main channel in all sub-reaches increased by more than 2 m. Because the rate of increase in the depth of the main channel was clearly larger than that of its width, the cross-sectional geomorphic coef?cient decreased in all sub-reaches. The cross-sectional geometry of the main-channel of the lower Yellow River exhibited different adjustment patterns before and after the XLDR began operation. Before its operation, the main channel mainly narrowed in the transverse direction and silted in the vertical direction in the sub-reach above Aishan; in the sub-reach below Aishan, it primarily silted in the vertical direction. After the XLDR began operation, the main channel adjusted by widening in the transverse direction and deepening in the vertical direction in the sub-reach above Aishan; in the sub-reach below it, the main channel adjusted mainly by deepening in the vertical direction. Compared with the rates of decrease in the width and depth of the main channel during the siltation period, the rate of increase in channel width during the scouring period was clearly smaller while the rate of increase in channel depth was larger. After continual siltation and scouring from 1986 to 2015, the cross-sectional geometry of the main-channel changed from wide and shallow to relatively narrow and deep. The pattern of adjustment in the main channel was closely related to the water and sediment conditions. For the braided reach, the cross-sectional geomorphic coef?cient was negatively correlated with discharge and positively correlated with suspended sediment concentration (SSC) during the siltation period. By contrast, the cross-sectional geomorphic coef?cient was positively correlated with discharge and negatively correlated with SSC during the scouring period. For the transitional and meandering reaches, the cross-sectional geomorphic coef?cient was negatively correlated with discharge and positively correlated with SSC.
Since the reform and opening-up policy launched in 1978, the number of inbound tourists increased from 1.8 million in 1978 to 139.5 million in 2017, and that of domestic tourists increased from 344 million in 1991 to 5 billion in 2017. This article conducts research on how the geographical pattern of China’s tourism has evolved in the last four decades on the national-scale and regional-scale, for rare studies before could focus on such an extended date and utilize inbound and domestic tourism data simultaneously. Grounded on viable datasets and multiple vibrant data analysis approaches (including the Gini coefficient, primacy index analysis, hot spot analysis and Pearson correlation analysis), this article unpacks triple vital realities. (1) The overall geographical pattern of China’s tourism development can arguably summarize as “high in the eastern and low in the western part, high in the southern and low in the northern part.” Meanwhile, China’s inbound tourism has long shown a pattern of polarized distribution; While, domestic tourism has experienced a shift from the polarized distribution to the equilibrium distribution. (2) According to the features and characteristics, China's tourism development can be divided into four stages. They are precisely the initial modern tourism stage (1978-1988), the domestic tourism cultivating stage (1989-1996), the rapid development stage (1997-2007) and the new normal stage (2008-present). (3) This article also identified multiple factors underlying the inbound and domestic tourism development in China, including policies, management systems, tourism demand, tourist attractions, economic level, consumption level, industrial development, investment status, traffic conditions, accommodation services, intermediary services and degree of openness.
