Transpiration (Tc) is a critical component of the global water cycle. Soil moisture (SM) and vapor pressure deficit (VPD) are key regulators of Tc, and exploring their contributions to changes in Tc can deepen our understanding of the mechanisms of water cycling in terrestrial ecosystems. However, the driving roles of VPD and SM in Tc changes remain debated because of the coupling of SM and VPD through land-atmosphere interactions which restrict the quantification of the independent effects of SM and VPD on Tc. By decoupling the correlations between SM and VPD using a novel binning approach, this study analyzed the dominant drivers of vegetation transpiration in subtropical China from 2003 to 2018 based on multi-source data, including meteorological reanalysis, remotely sensed soil moisture, transpiration, and land cover data. The results show that Tc first increased and then remained stable with an increase in SM across the study area but changed slightly with increasing VPD. Overall, the relative contribution of SM to the change in Tc was approximately five times that of VPD. The sensitivities of Tc to SM and VPD differed among vegetation types. Although the sensitivity of Tc to SM was greater than that of VPD for all four vegetation types, the thresholds of Tc in response to SM were different, with the lowest threshold (approximately 35%) for the other forests and the highest threshold (approximately 55% ) for short wood vegetation. We infer that this is associated with the differences in ecological strategies. To verify the reliability of our conclusions, we used solar- induced chlorophyll fluorescence (SIF) data as a proxy for Tc based on the tight coupling between photosynthesis and transpiration. Consistent results were obtained by repeating the analyses. The results of this study, in which the impacts of SM and VPD on Tc were decoupled, are beneficial for further understanding the critical processes involved in water cycling in terrestrial ecosystems in response to climate change.
The increasing frequency of recent droughts has an adverse effect on the ecosystem of the Mongolian Plateau. The growth condition of NPP is considered an indicator of the ecological function. Therefore, identifying the relationship between NPP and drought can assist in the prevention of drought-associated disasters and the conservation of the ecological environment of the Mongolian Plateau. This study used the Carnegie-Ames-Stanford Approach (CASA) model to simulate the NPP capacity of the Mongolian Plateau between 1982 and 2015, as well as drought indicators (drought probability, vulnerability, and risk) to explore the drought risk of NPP. The findings pointed to an overall increase in NPP with regional variances; however, the NPP rate in Inner Mongolia was considerably higher than that in Mongolia. The standardized precipitation evapotranspiration index (SPEI) showed an overall downward trend, with Inner Mongolia experiencing a substantially lower rate of decline than Mongolia. The areas most likely to experience drought were primarily in the center and north while the areas with the highest drought vulnerability were primarily in the northeast, center, and southeast. Mongolia showed a higher probability of drought compared to Inner Mongolia. Drought-prone regions of the Mongolian Plateau increased during the 21st century while drought-vulnerable areas increased and shifted from north to south. Alpine grasslands and coniferous forests were least vulnerable to drought, while other vegetation types experienced temporal variation. In the 21st century, the primary determinants of drought risk shifted from precipitation and the normalized difference vegetation index (NDVI) to temperature and relative humidity.
The Qinghai-Tibet Plateau (QTP), also known as the Third Pole of the Earth, is a vital ecological security barrier for China. It is a tremendously sensitive region affected by the impacts of global climate change. The escalating intensity of climate change has presented profound challenges to its ecosystem functions and stability. This study first analyzes the spatiotemporal variations of the QTP ecosystem patterns and the key functions of the Plateau including water conservation, soil conservation, and windbreak and sand fixation from 2000 to 2020. It clarifies the regional differences in ecosystem functions and their importance, further evaluates the stability of ecosystem functions, and lays a scientific foundation for an ecological civilization on the Plateau by implementing conservation and restoration projects. The main results show that: (1) From 2000 to 2020, the wetland area in the QTP increased, while the grassland area significantly decreased. There were improvements in water conservation and windbreak and sand fixation capacities, with annual rates of change being 3.57 m3·ha-1·a-1 and 0.23 t·ha-1·a-1, respectively. However, the overall soil conservation trend declined during the same period, with an annual change rate of -0.16 t·ha-1·a-1. (2) The core areas of water conservation, soil conservation, and windbreak and sand fixation on the QTP accounted for 12.7%, 13.9%, and 14.2% of the total area, respectively. The core water conservation areas are mainly the southeastern QTP, Sanjiangyuan, and Naqu, while the core windbreak and sand fixation areas were concentrated in the central and western parts of the Plateau. The core soil conservation areas surrounded the entire interior of the Plateau. (3) From 2000 to 2020, the water conservation, soil conservation, and windbreak sand-fixation function on the QTP had higher stability in the southeastern and central parts, while stability was lower in the western region. Considering the stability assessment and ecological protection and restoration practices, the QTP can be divided into three major categories and 16 ecological functional zones. Differentiated ecological protection and restoration efforts can be implemented based on the different core ecosystem functions and zoning.
Global warming is causing melting of glaciers, which is affecting socioeconomic development. It is essential to study the combined influence of changes in structures of glaciers on human well-being and socioeconomic systems. Herein, we considered Qilian Mountains as an example, quantified the regional socioeconomic benefits of glaciers and human well-being, and attempted to draw a correlation between glacier service value and human well-being. The findings of our study reveal that the value of glacier services in Qilian Mountains decreased from 1.84 × 1010 yuan in 1998 to 1.72 × 1010 yuan in 2018, with a spatial trend of circling down from the central region to the western and eastern regions. The distribution of human well-being showed an increasing trend, and a phenomenon of “low value central and western clustering, high value eastern sporadic distribution.” There is an increasing degree of coordination between human well-being and glacier services value; the spatial distribution shows a decreasing trend from the west to the east, with differences in the nature of coordinated development in different regions at the same coordination stage being obvious. We analyzed the changes in glacier services value and their relationship with human well-being from both micro and macro perspectives to provide theoretical support for formulating management strategies for glacier resource conservation and improving the interface between glacier service evaluation results and government decision-making.
Quantitative assessments of the impacts of climate change and anthropogenic activities on runoff help us to better understand the mechanisms of hydrological processes. This study analyzed the dynamics of mountainous runoff in the upper reaches of the Shiyang River Basin (USRB) and its sub-catchments, and quantified the impacts of climate change and human activities on runoff using the improved double mass curve (IDMC) method, which comprehensively considers the effects of precipitation and evapotranspiration on runoff, instead of only considering precipitation as before. The results indicated that the annual runoff depth in the USRB showed a slightly increased trend from 1961 to 2018, and sub-catchments were increased in the west and decreased in the east. The seasonal distribution pattern of runoff depth in the USRB and its eight sub-catchments all showed the largest in summer, followed by autumn and spring, and the smallest in winter with an increasing trend. Quantitative assessment results using the IDMC method showed that the runoff change in the USRB is more significantly affected by climate change, however, considerable differences are evident in sub-catchments. This study further developed and improved the method of runoff attribution analysis conducted at watershed scale, and these results will contribute to the ecological protection and sustainable utilization of water resources in the USRB and similar regions.
Exploring the coupling coordinated level of rural population-land-industry (PLI) and its underlying driving mechanism contributes to the scientific decision-making on rural sustainable development. This study assessed the coupling coordinated level of PLI based on an improved evaluation index system and then revealed the regional differentiation and driving mechanism in China’s rural areas in 2020. The results showed that the rural PLI coupling coordinated degree was 0.4694, and thus was in the stage of approximate incoordination. In addition, China’s rural PLI coupling coordinated degree formed a spatially heterogeneous pattern with high levels in the northeast, eastern and central regions, and the intragroup difference contributed more than 80% to the total difference. The rural PLI coupling coordinated level was influenced by the combined effects of rural kernel and peripheral systems, but the rural kernel system mostly determined the differentiation. In the future, rural areas should first exploit population quality improvement projects, land consolidation projects and industrial integration development strategies to promote benign mutual feedback of PLI. Second, driving factors should be comprehensively regulated by implementing a “one village, one product” strategy, breaking the urban-rural dual system, improving agricultural machinery subsidies policy, and promoting urban-rural integrated development.
Exploring the spatial zoning of urban territories and their ecological effects under different decision preferences is an important approach to promote the sustainable utilization of regional resources. This paper constructs an index system for evaluating the suitability of territorial space development from the perspectives of urban development, agricultural production, and ecological conservation. It predicts and simulates the trade-offs between territorial space development and protection in Ezhou under different decision preferences using the Analytic Hierarchy Process (AHP) and Ordered Weighted Averaging (OWA) method. The modified equivalent factor method is used to analyze the ecosystem service values of different functional areas. The results indicate the following: (1) the preferences of decision-makers considerably influence the level of territorial space suitability. Higher (lower) levels of concern for risk result in more optimistic (pessimistic) evaluators, and this affects the priority given to ecological protection (development and utilization). (2) Under the ecological priority scenario, the status quo scenario and development priority scenario, there are significant differences in regional suitability levels. The ecological priority scenario gives high importance to ecological protection, resulting in the absolute protection of the Liangzi lake area, with 42.59% of Liangzihu district considered unsuitable for development. In contrast, the development orientation scenario designates Echeng district, an economic and political center, as highly suitable for development, with over 60% of the area available for development. (3) The total value of ecosystem services in Ezhou city was 213.355 billion yuan in 2018. Ecosystem service values were mainly provided by the water area in the permanently unsuitable development zone, leading to a mismatch between the supply and demand of ecosystem services under different scenarios.
Regional and persistent PM2.5 pollution seriously undermines the development of urban ecological civilizations and the advancement of high-quality economies. The producer service sector, an example of a typical knowledge-intensive service industry, plays an important role in advancing the manufacturing industry and fostering economic growth while concurrently improving urban environmental conditions. Based on panel data of prefecture-level cities in the Yellow River Basin from 2006 to 2019, this study constructed a Spatial Durbin Model and a mediation effect model to comprehensively explore the impact of producer services agglomeration on PM2.5 pollution. The main conclusions are as follows: (1) From 2006 to 2019, PM2.5 pollution in the study area exhibited an initial rise followed by a subsequent decline, with notable spatial heterogeneity. PM2.5 pollution in the lower reaches of the Yellow River was significantly higher than in the middle and upper reaches. In addition, the spatial pattern of producer services agglomeration showed distinct “core-edge” characteristics. (2) The agglomeration of producer services had a significant negative impact on local and adjacent PM2.5 pollution, and there was a more pronounced haze reduction effect in the case of specialized agglomerations of producer services and low-end producer services. (3) The agglomeration of producer services indirectly improved PM2.5 pollution by promoting technological innovation and optimizing industrial structure, with the latter playing a greater mediating effect. This study not only helps expand the theoretical and empirical research on producer services agglomeration but also offers valuable insights for pursuing a green transformation of the Yellow River Basin by optimizing industrial patterns through the producer services sector. This approach represents a reference for curbing PM2.5 pollution and guiding the region toward a greener future.
Resource-based cities are important bases for resources and energy in China. However, the world and the country’s sustainable development goals require them to undergo transformation. The complexity of this transformation poses challenges for these cities. This study aims to evaluate the transformation performance of resource-based cities in Shaanxi, Gansu, and Ningxia. The findings will help understand their capabilities and achievements in transformation and provide guidance for future transformation planning. To evaluate the transformation performance, this study employs the entropy weight Technique for Order of Preference by Similarity to Ideal Solution method. An index system is constructed, including the industrial diversification and specialization indices. These indices serve as benchmarks for assessing the transformation performance. The period 2010-2019 is considered, and the transformation performance of resource-based cities is evaluated based on different development stages and regions. The results reveal the following insights: (1) Most resource-based cities demonstrate favorable transformation performance. Although variations exist between cities, the gaps are gradually narrowing. (2) Over an extended period, the transformation performance of each city undergoes continuous changes, with high-performing areas shifting. (3) The transformation performance of resource-based cities varies significantly across different development stages. (4) An imbalance exists among the regions where resource-based cities are located, and a diffusion effect can be observed. Accordingly, the following enlightenment and policy suggestions are obtained: (1) exploring targeted management policies for resource-based cities; (2) fostering a dynamic and open transformation environment; (3) promoting the concept of regional cooperation in transformation; (4) improving the business environment; (5) promoting enterprise innovation; (6) establishing and improving a long-term mechanism for sustainable development and a compensation mechanism for resource development; and (7) optimizing the talent training system.
Settlements are excellent spatiotemporal indicators for studying historical human activities and environmental change. This paper discusses the spatial and temporal changes of sites on the Ordos Plateau in China since the Neolithic Age, based on an analysis of spatiotemporal distribution characteristics of the human settlements. The frequency of human settlements on the Ordos Plateau presented a phased fluctuation process, and the sizes were mainly small and medium. The spatial distribution of human settlements was fractal, and the D value of the aggregation dimension was generally small, indicating that the spatial distribution of the sites was agglomerated. Affected by the desert, the sites were mainly distributed in the south and east of the Ordos Plateau. The spatiotemporal distribution pattern of human settlements in the Ordos Plateau resulted from the combined action of natural and human factors, especially climate change. Moreover, local livelihood patterns significantly affected the frequency of human settlements. The number of human settlements in the farming period was large, and the distribution was concentrated. In contrast, the number of sites in the nomadic period was small and scattered. The central government’s policies and the conflicts between farming and nomadic groups further affected the spatiotemporal distribution of human settlements. This study may contribute to a better understanding of historical environmental change and human-land relationships in the Ordos Plateau.
