•Geography naturally links with sustainability science with its transdisciplinary perspective.•Current geographical knowledge is inadequate to answer scientific questions in sustainability ...science.•Geographical process and ecosystem service linking natural and social elements are basic research areas.•Mechanisms in human-environmental systems and sustainable development are frontier research areas.•Geo-data and models for sustainability is the fundamental tool to support those key research areas.
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The discipline of geography encompasses both natural and social sciences and has the natural advantage of enabling the study of sustainability from a transdisciplinary perspective. There are great opportunities for geographers to participate in sustainability research. However, while geographers have set sustainability goals, they have rarely clarified the details for reaching those goals. Current knowledge on the relationship between humans and the environment and the methodologies for studying this relationship are inadequate to solve the transdisciplinary questions in sustainability science. Five research areas: geographical processes; ecosystem services and human wellbeing; human-environmental systems; sustainable development; and geo-data and modelling for sustainability are proposed as those needed to help geography achieve sustainability. The key objective of promoting geography for sustainability is to reveal the mechanisms of human-environmental system dynamics. This depends on understanding the processes in the natural and social systems and their mutual feedback as well as clarifying the relationships between the structures, functional characteristics and interactions in the human-environmental systems at multiple scales. The advancement of geography and its methodologies and technologies will provide a more profound understanding of the future. Geographers have the responsibility of promoting the discipline as the key pathway for carrying natural and social sciences towards sustainability.
Due to the lengthy historic land use by humans and the climate change characterized by warming and drying, the Loess Plateau has been plagued by ecosystem degradation for a long time. A series of ...ecological conservation projects launched since the 1970s altered the land use pattern greatly, and exerted a profound influence on the ecosystem services. Based on the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) and Carnegie–Ames–Stanford Approach (CASA) models, we assessed the historical fluctuation of sediment control, water yield, and net primary production (NPP) in the Loess Plateau. The results showed that sediment retention was greatly consolidated indicated by the sharp decrease of sediment export. Water yield decreased at first and increased later. Both sediment export and water yield showed an increasing ‘spatial homogenization’ tendency during the period. NPP was steady between 1990 and 2000, and then increased greatly after 2000. Ecosystem services are interlinked closely and complexly. Correlation analyses indicated a positive relationship between the difference in sediment export and water yield (r2=0.776⁎⁎) from 1975 to 2008, with negative correlations between the difference of NPP and water yield (r2=−0.422⁎⁎)/sediment export (r2=−0.240⁎) from 1990 to 2008. This, to some extent, implies that there are tradeoffs between the services of water yield and sediment control/NPP, and there is synergy between sediment control and NPP. Climatic and land use changes are the major drivers on ecosystem services fluctuation. Correlation analyses showed that the decrease of precipitation significantly hindered water yield (r2=0.980⁎⁎) and sediment export (r2=0.791⁎⁎). The increase of temperature exerted a slight negative influence on water yield (r2=−0.350⁎⁎). A spatial concordance existing between the ‘cropland to grass/woodland’ area and the high sediment control (r2=0.313⁎⁎)/NPP (r2=0.488⁎⁎) area indicated that the land use change from cropland to woodland/grassland significantly consolidated sediment control and NPP production. The observed spatio-temporal variation of ecosystem services and their correlations provide an operable criterion for land use management policies.
► Sediment control, water yield, carbon sequestration are assessed by InVEST/ CASA. ► Tradeoffs exist between water yield and sediment control / carbon sequestration. ► Synergy exists between sediment control and carbon sequestration. ► Temperature, precipitation, land use influence ecosystem services’ evolutions.
Water is a limiting factor and significant driving force for ecosystem processes in arid and semi-arid areas. Knowledge of plant water uptake pattern is indispensable for understanding soil–plant ...interactions and species coexistence. The ‘Grain for Green’ project that started in 1999 in the Loess Plateau of China has led to large scale vegetation change. However, little is known about the water uptake patterns of the main plant species that inhabit in this region. In this study, the seasonal variations in water uptake patterns of three representative plant species, Stipa bungeana, Artemisia gmelinii and Vitex negundo, that are widely distributed in the semi-arid area of the Loess Plateau, were identified by using dual stable isotopes of δ2H and δ18O in plant and soil water coupled with a Bayesian mixing model MixSIAR. The soil water at the 0–120cm depth contributed 79.54±6.05% and 79.94±8.81% of the total water uptake of S. bungeana and A. gmelinii, respectively, in the growing season. The 0–40cm soil contributed the most water in July (74.20±15.20%), and the largest proportion of water (33.10±15.20%) was derived from 120–300cm soils in August for A. gmelinii. However, V. negundo obtained water predominantly from surface soil horizons (0–40cm) and then switched to deep soil layers (120–300cm) as the season progressed. This suggested that V. negundo has a greater degree of ecological plasticity as it could explore water sources from deeper soils as the water stress increased. This capacity can mainly be attributed to its functionally dimorphic root system. V. negundo may have a competitive advantage when encountering short-term drought. The ecological plasticity of plant water use needs to be considered in plant species selection and ecological management and restoration of the arid and semi-arid ecosystems in the Loess Plateau.
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•Seasonal variations of water uptake pattern were determined by dual stable isotopes (δD and δ18O) and MixSIAR model.•Soil water in the 0–120cm depth contributed 75–80% to the total water uptake in the growing season.•Vitex negundo displayed larger degree of ecological plasticity to switch water between shallow and deep soil layers.•Functionally dimorphic root systems were related to flexible water uptake pattern.
Payment for Ecosystem Services (PES) is now widely accepted as a policy tool for advancing both ecological and social progress. The Chinese government's Grain to Green Program (GTGP) is the world's ...largest PES program. It was initiated nearly 20 years ago to reverse previous environmental degradation. However, it is difficult to achieve both conservation and economic “win-win” gains, and care is needed in monitoring environmental and socioeconomic outcomes. Here we choose the Loess Plateau (LP), the area where GTGP was implemented most intensively, to study the social-ecological changes after GTGP and determine whether these changes are related to GTGP. The results show that LP has achieved “win-win” gains of restoring environment and promoting socioeconomic development: normalized difference vegetation index (NDVI) time series show a significant greening trend, and soil retention and carbon sequestration services have improved from 2000 to 2015. Simultaneously, grain output from the LP has increased by 56.7%. We also analyzed the effects of afforestation on changes of socio-ecological factors, and find that the changes of NDVI, soil erosion, and carbon sequestration mainly reflect the degree of afforestation rather than climate change, while the correlations between changes of socioeconomic factors and degree of afforestation are insignificant. We conclude that, despite some adverse outcomes such as water yield reduction, GTGP in LP has achieved considerable overall success in environmental factors. However, comprehensive and quantitative evaluation of the social impacts of GTGP is needed, as the impacts are clouded by multiple socioeconomic factors.
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•Comprehensive assessment of the socio-ecological changes on the Loess Plateau•LP has achieved “win-win” gains of restoring environment and promoting development.•Degree of afforestation affects the changes of ecological factors on the LP.
China's Loess Plateau is both the largest and deepest loess deposit in the world, and it has long been one of the most severely eroded areas on Earth. Since the 1970s, numerous soil- and ...water-conservation practices have been implemented: terracing, planting of vegetation, natural vegetation rehabilitation, and check-dam construction. With the implementation of the Grain-for-Green Project in 1999, the Loess Plateau has become the most successful ecological restoration zone in China. However, these large-scale restoration measures and drought have significantly reduced both runoff and sediment from the Loess Plateau. This situation has both advantages and disadvantages for the lower Yellow River. Some local soil erosion has been successfully controlled, but the whole regional ecosystem remains very fragile. Therefore, it is necessary to balance each ecosystem service, for example, by determining the region's vegetation capacity and its spatial distribution for the sustainable development of the socioecological system of the Loess Plateau.
Land use/land cover (LULC) change models are powerful tools used to understand and explain the causes and effects of LULC dynamics, and scenario-based analyses with these models can support land ...management and decision-making better. This paper provides a synoptic and selective review of current LULC change models and the novel frameworks that are being used to investigate LULC dynamics. Existing LULC models that explore the interactions between human and the environment can be pattern- or process-based, inductive or deductive, dynamic or static, spatial or non-spatial, and regional or global. This review focuses on the spectrum from pattern- to process-based approaches and compares their strengths, weaknesses, applications, and broad differences. We draw insights from the recent land use change literature and make five suggestions that can support a deeper understanding of land system science by: (1) overcoming the difficulties in comparing and scaling Agent Based Models; (2) capturing interactions of human-environment systems; (3) enhancing the credibility of LULC change modeling; (4) constructing common modeling platforms by coupling data and models, and (5) bridging the associations between LULC change modeling and policy-making. Although considerable progress has been made, theoretical and empirical efforts are still needed to improve our understanding of LULC dynamics and their implications for policy-oriented research. It is crucial to integrate the key elements of research involved in this study (e.g., use of common protocols and online portals, integration of top-down and bottom-up approaches, effective quantification and communication of modeling uncertainties, generalization and simplification of models, increased focus on the theoretical and empirical bases of models, and open comparative research) to bridge the gaps between small-scale process exploration and large-scale representation of LULC patterns, and to use LULC change modeling to inform decision-making.
Understanding hydrological effects of ecological restoration (ER) is fundamental to develop effective measures guiding future ER and to adapt climate change in China's Loess Plateau (LP). Streamflow ...(Q) is an important indicator of hydrological processes that represents the combined effects of climatic and land surface conditions. Here 14 catchments located in the LP were chosen to explore the Q response to different driving factors during the period 1961–2009 by using elasticity and decomposition methods based on the Budyko framework. Our results show that (1) annual Q exhibited a decreasing trend in all catchments (−0.30 ∼ −1.71 mm yr−2), with an average reduction of −0.87 mm yr−2. The runoff coefficients in flood season and nonflood season were both decreasing between two periods divided by the changing point in annual Q series; (2) the precipitation (P) and potential evapotranspiration (E0) elasticity of Q are 2.75 and −1.75, respectively, indicating that Q is more sensitive to changes in P than that in E0; (3) the two methods consistently demonstrated that, on average, ER (62%) contributing to Q reduction was much larger than that of climate change (38%). In addition, parameter n that entails catchment characteristics in the Budyko framework showed positive correlation with the relative area of ER measures in all catchments (eight of them are statistically significant with p < 0.05). These findings highlight the importance of ER measures on modifying the hydrological partitioning in the region. However, ER actions over the sloping parts of the landscape weakened the impact of those in channels (i.e., check‐dams) on Q, especially after the implementation of the Grain‐for‐Green project in 1999.
Key Points:
Annual streamflow exhibited a decreasing trend in all catchments
Ecological restoration is the primary reason for streamflow reduction
Slope measures gradually weakened the impact of channel measures on streamflow
The maintenance of soil health in agro-ecosystems is essential for sustaining agricultural productivity. Through its positive impacts on various soil physical and biological processes, cover cropping ...can be an important component of sustainable agricultural production systems. However, the practice of cover cropping can be complex, and possible trade-offs between the benefits and side effects of cover crops have not been examined. To evaluate these benefits and potential trade-offs, we quantitatively synthesized different ecosystem services provided by cover crops (e.g., erosion control, water quality regulation, soil moisture retention, accumulation of soil organic matter and microbial biomass, greenhouse gas (GHG) emission, weed and pest control, as well as yield of the subsequent cash crop) using data from previous publications. We used a simple indicator (δ), defined as the ratio of an observed variable (i.e., ecosystem service) under cover crop and under fallow condition, to evaluate the impacts of cover crops on a given ecosystem service. Our results showed that cover crops provided beneficial ecosystem services in most cases, except for an increase in GHG emission (δCO2 = 1.46 ± 0.47 and δN2 O = 1.49 ± 1.22; x¯ ± SD) and in pest (nematode) incidence (δnematode abundance = 1.29 ± 1.61). It is also important to highlight that, in some cases, tillage could offset the extent of ecosystem service benefits provided by cover crops. Based on this synthesis, we argue that cover crops should be incorporated into modern agricultural practices because of the many environmental benefits they offer, particularly the maintenance of soil and ecosystem health. More importantly, there was generally an increase in cash crop yield with cover cropping (δyield = 1.15 ± 0.75), likely due to improvement in various soil processes. Despite its benefits, the complexity of cover crop management should not be overlooked, and site-specific factors such as climate, soil type, cover crop species and tillage practices must be considered in order to optimize the benefits of cover cropping. In addition to crop yield, detailed economic analyses are needed to calculate the direct (e.g., reduction in the amount of chemical fertilizer) and indirect monetary benefits (e.g., the improvement of soil quality) of cover crops. Such a comprehensive analysis could serve as incentive for producers to integrate cover crops into their management practices.
Restoring disturbed and over-exploited ecosystems is important to mitigate human pressures on natural ecosystems. China has launched an ambitious national ecosystem restoration program called Grain ...to Green Program (GTGP) over the last decade. By using remote sensing techniques and ecosystem modelling, we quantitatively evaluated the changes in ecosystem carbon sequestration since China's GTGP program during period of 2000-2008. It was found the NPP and NEP in this region had steadily increased after the initiative of the GTGP program, and a total of 96.1 Tg of additional carbon had been sequestered during that period. Changes in soil carbon storage were lagged behind and thus insignificant over the period, but was expected to follow in the coming decades. As a result, the Loess Plateau ecosystem had shifted from a net carbon source in 2000 to a net carbon sink in 2008. The carbon sequestration efficiency was constrained by precipitation, and appropriate choices of restoration types (trees, shrubs, and grasses) in accordance to local climate are critical for achieving the best benefit/cost efficiency.
•Examining over 3000 publications on ecosystem services research in China from 2001 to 2020.•Suggesting four strict criteria for selecting relevant studies.•Identifying 151 observations with spatial ...information and 478 records on ecosystem services value.•Establishing a national ecosystem services value database for China.
Since the turn of the millennium, studies on the value of ecosystem services have grown significantly in China, producing a rich and diverse literature. However, a systematic review of these findings remains lacking. In this paper, we examine over 3000 studies that have been published over the past twenty years (2001–2020), selecting from this vast corpus 63 articles for more in-depth analysis according to four strict review criteria, in order to provide the basis for building a national database of ecosystem services value. Based on this database, we illustrate the spatial distribution of study sites and ecosystem types, identify the methods applied to quantify physical amounts of ES supply and monetary values, analyze the spatial variation of ES values in different provinces of China, and establish a national empirical value table. We further compare our value table to other value tables in the existing literature and indicate the advantages and shortcomings of our database. Finally, we suggest future research needs in this growing field.
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