•Terrain and human activity intensity were integrated to construct resistance surface.•SCWT and KDE were applied to identify ecological corridors with widths.•Restoration coefficient was defined and ...used to extract key restoration areas.
Ecological corridors are effective to prevent ecosystem degradation and biodiversity loss through promoting the connection among discrete habitat patches. Identifying ecological corridors is of great importance for biodiversity conservation and landscape planning. Previous studies mainly focused on the directions of ecological corridors among habitat patches and the boundaries of ecological corridors were usually subjectively identified. In this study a new approach integrating spatial continuous wavelet transform and kernel density estimation was proposed to objectively identify the width thresholds of ecological corridors in the megacity of Beijing City, with the application of InVEST model to extract core habitat patches, and constructing the ecological resistance surface based on natural conditions and human activities. The restoration coefficient was also defined and applied to determine the key restoration areas. The results showed that the total area of core habitat patches in Beijing City was 3652.75 km2, with 1414.67 km2 for ecological corridors, mainly distributed in the western and northern mountainous areas. 36 key restoration areas were also extracted, mainly located in the narrow areas with large resistance. Identifying the range and key restoration areas of ecological corridors can provide spatial guidelines for ecological conservation and restoration, thus ensuring regional ecological security in megacities.
Abstract
Effective forestation policies are urgently required across the globe under the initiative of the UN Decade on Ecosystem Restoration. Rather than simply planting trees, such initiatives ...involve complex components of societal and biophysical systems. However, the underlying pathways by which forestation influences ecological outcomes are not well understood, especially given the lack of a unified quantification framework. In this study, such a framework was developed to reveal the pathways by which reforestation programs influenced ecological outcomes by identifying the linkages among reforestation efforts, societal changes, land system changes and ecological outcomes. The framework was applied to the reforestation program of the Grain for Green Program (GFGP), to explore how the GFGP influenced vegetation dynamics and ecosystem functioning in Guizhou Province, China, through direct and indirect pathways. Two remote sensing based indicators, namely the enhanced vegetation index, derived from the Moderate Resolution Imaging Spectroradiometer, and gross primary production (GPP), obtained from the Orbiting Carbon Observatory-2 solar-induced chlorophyll fluorescence (SIF) fine-resolution dataset GOSIF, were combined with inventory data and land-use maps to detect changes in social and ecological outcomes. Using the structural equation model to apply the framework, the results showed that the GFGP positively contributed to the increasing greenness and GPP of the study area through the direct conservation pathway. Although implementation of the GFGP encouraged the rural outmigration and led to a decrease in the area of farmland, the GFGP showed negative indirect effects on greenness and GPP because of the difficulty of reforestation during land-use conversion from farmland to forest land. This study revealed divergent impacts of the reforestation program through multiple pathways, which could provide valuable information for other parts of the globe for more precise design of ecological restoration policies.
Understanding the relationships among multiple ecosystem services could improve the landscape capacity to provide benefits to human society. However, the underlying mechanisms shaping ecosystem ...services relationships are still unclear although some studies have been conducted to explore how natural and socioeconomic factors influence the relationships among ecosystem services. In this study, the karst landscape in southwestern China, a vulnerable system with intensive human activities, was focused on, aiming to explore relationships between ecosystem services and associated social and ecological factors. The results showed that the distribution of eight individual ecosystem services were spatially heterogeneous and clustered based on the characteristics of the karst landscape. The relationships between provisioning services and regulating services, such as grain production and net primary productivity, as well as water yield and soil retention, were quite different between high karst coverage regions and low karst coverage regions. Among five ecosystem service bundles identified, ecosystem services in the urban development bundle were mainly determined by socioeconomic factors, while in the other four bundles of multifunction, grain production, habitat conservation, and carbon sequestration, ecosystem services were dominated by ecological factors. However, socioeconomic factors (i.e. population density and night-time light intensity) appeared to explain the overall ecosystem service delivery more than karst terrain. This study provided insights for sustainable ecosystem management in a vulnerable karst region through exploring social-ecological factors of the relationships among ecosystem services.
Display omitted
•This is the first case study to apply metacoupling framework to virtual water trade.•Different coupling types and processes in global virtual water trade were identified.•Intensity ...and linking relations of intra-, peri-, and tele-coupling were quantified.•Scenarios of with-trade, no-trade, only-distant-trade, only-adjacent-trade were set.•Impacts of various types of trade on global water stress pattern were distinguished.
With water scarcity increasingly becoming a growing global risk, it is prevalent to explore water supply-demand interaction within and beyond national borders driven by global virtual water trade and its effects on water sustainability. However, there is little study on system integration of differential environmental impacts of various types of trade. Based on metacoupling framework highlighting human-nature interactions across space- within a place (intracoupling), between adjacent places (pericoupling), and between distant places (telecoupling), this study quantified the linkages and intensities of three kinds of coupling processes during global virtual water trade for the first time. Correspondingly, water stress changes under a set of trade scenarios were evaluated based on the indicator of UN SDG 6.4.2 to distinguish the influence of trade taking place on different spatial scales. Results show that during 2005–2015, local water resources supported 80% of global water consumption. Distant virtual water import was about 5 times in volume as large as adjacent virtual water import, alleviating 99.8% of global average water stress. Virtual water trade reduced water stress in 86% of developed countries and increased that in 71% of developing countries in 2005. Owing to trade, water stress in many countries with poor water resources endowment declined while that of many with relatively good endowment went up from 2005 to 2015. Our findings can help to systematically understand the influence of virtual water trade on water stress change and provide scientific guidance for sustainable water management and regional regulations.
The considerable interest in detecting global vegetation changes based on satellite observations is increasing. However, studies rely on single indices to explore the driving mechanisms of the ...greening trend might exacerbate uncertainties of global ecosystem change. Thus, vegetation growth dynamics from various biophysical properties required to be monitored comprehensively. In this study, a consistent framework for evaluating vegetation growth trends was developed based on five widely used satellite‐derived products of MODIS Collection 6; the consistency in vegetation growth was mapped; and the factors that affected the consistency of vegetation growth were explored. The results showed that, during 2000‐2015, 45.6% of global vegetated area experienced inconsistent trends in vegetation greenness, cover and productivity, especially in evergreen broadleaf forests, grasslands, open shrublands, woody savannas and croplands. Only 5.4% of global vegetated area exhibited simultaneous trends in greenness, cover and productivity, and the inconsistent areas were expanding in the study period. Contradictory vegetation changes were mainly reflected in the opposite trends of vegetation greenness and productivity in evergreen broadleaf forests. Moreover, the inconsistency change was mainly manifested in the greenness‐dominated vegetation enhancement, without enhanced productivity. The increment difference between NPP and GPP also showed respiration losses greatly offset the effect of vegetation greenness or cover on productivity. This study provides integrated insights for understanding the inconsistency of vegetation structural and functional changes in the context of global greening.
Plain Language Summary
Terrestrial vegetation dynamics are extremely important to global environmental change and have consequences for the functioning of the Earth system and provisioning of ecosystem services. Recent greening of the global terrestrial ecosystems suggested an increasing trend in vegetation growth. However, different vegetation properties that were described by indices have not been comprehensively compared. In this study, a consistent framework for evaluating vegetation growth trends was developed based on five widely used satellite‐derived vegetation indices; the consistency in vegetation growth was mapped; and the factors that affected the consistency of vegetation growth were explored. We found that during 2000–2015, nearly half of global vegetated area experienced inconsistent trends in vegetation greenness, cover, and productivity, especially in evergreen broadleaf forests. The vegetation inconsistent change was manifested in the greenness‐dominated vegetation enhancement, but the productivity did not enhance. Relationship between vegetation cover and productivity was higher than that between vegetation greenness and productivity. It was also found that respiration losses greatly offset the effect of vegetation greenness or cover on productivity. This study provides integrated insights into vegetation growth trends, interpreting inconsistency of vegetation structural and functional changes in the context of global greening.
Key Points
Nearly half of global vegetated area experienced inconsistent vegetation trends
Inconsistency was manifested as the greenness and non‐productivity enhancement
Vegetation types differed in the greenness, cover, and productivity trends
Timely and accurate information of cotton planting areas is essential for monitoring and managing cotton fields. However, there is no large-scale and high-resolution method suitable for mapping ...cotton fields, and the problems associated with low resolution and poor timeliness need to be solved. Here, we proposed a new framework for mapping cotton fields based on Sentinel-1/2 data for different phenological periods, random forest classifiers, and the multi-scale image segmentation method. A cotton field map for 2019 at a spatial resolution of 10 m was generated for northern Xinjiang, a dominant cotton planting region in China. The overall accuracy and kappa coefficient of the map were 0.932 and 0.813, respectively. The results showed that the boll opening stage was the best phenological phase for mapping cotton fields and the cotton fields was identified most accurately at the early boll opening stage, about 40 days before harvest. Additionally, Sentinel-1 and the red edge bands in Sentinel-2 are important for cotton field mapping, and there is great potential for the fusion of optical images and microwave images in crop mapping. This study provides an effective approach for high-resolution and high-accuracy cotton field mapping, which is vital for sustainable monitoring and management of cotton planting.
•The increase of productivity was higher than greenness across grassland in China.•Temperature and precipitation were the main factors influencing grassland change.•The sensitivity of productivity to ...temperature and solar radiation was more than greenness.•Precipitation limited the increase of grassland GPP in subtropical and tropical regions.
Grassland, the most widespread vegetation type in China, has been greening recently.However, the extent to which the greenness has been translated into productivity and the underlying mechanism of the decoupled grassland greenness and productivity remains unclear. In this study, we detected the trend of normalized difference vegetation index (NDVI) and gross primary productivity (GPP) of grassland in China from 2000 to 2019 and analyzed the driving mechanism of the inconsistency between them. It was found that the relative increase rate of productivity (27.27%, p < 0.05) was much greater than that of greenness (14.54%, p < 0.05) across grasslands in China from 2000 to 2019, especially in temperate regions. The temperature and precipitation were the main factors influencing the grassland growth change, and the impact of temperature and shortwave radiation on productivity was greater than on greenness. However, the increase of grassland greenness was not fully translated into productivity in subtropical and tropical grass as well as shrub. This study revealed the dominance of climatic factors in the translation process from ecosystem structure to function, which highlighted the challenge in enhancing carbon uptake capacity of terrestrial ecosystem facing accelerated climate change.
Forest conservation and restoration are key components of ecological engineering. Previous studies often focused on the forest restoration impact on vegetation greening, ignoring the importance of ...forest conservation, and the link between forest conservation and restoration remains unclear. Based on land use data, forest cover loss data, and Moderate Resolution Imaging Spectroradiometer Leaf Area Index, in this study, we explored the spatial pattern of forest conservation and restoration from 2000 to 2020, and quantitatively calculated the contribution of forest conservation and restoration to vegetation greening. The results showed that the forest conservation area was 821,888 km2, and the forest restoration area was 100,266 km2 in South China karst. The forest conservation and restoration area with vegetation greenness increasing were 358,236 and 54,397 km2, respectively, which contributed 39.85% and 6.05% to vegetation greening. Moreover, there was a nonlinear relationship between forest conservation and restoration, and the results showed an inverted U‐shape in most provinces. This study evaluated ecological engineering from the perspective of forest conservation and restoration, which could provide the scientific basis for differentiated ecological engineering planning.
Plain Language Summary
Balancing the relationship between forest conservation and restoration is beneficial for promoting vegetation greening. Previous studies paid more attention to forest restoration when assessing the ecological engineering, while forest conservation was ignored, and the link between forest conservation and restoration remains unclear. In this study, we explored the relationship between forest conservation and restoration. We found from 2000 to 2020, the forest conservation area was 821,888 km2, and the forest restoration area was 100,266 km2 in South China karst. We also found there was a nonlinear correlation between forest conservation and restoration, and the results showed an inverted U‐shape in most provinces. It was worth noting that there was a significant trade‐off between forest conservation and restoration in karst areas of Yunnan Province. This study evaluated ecological engineering from the perspective of forest conservation and restoration, which can provide the scientific basis for differentiated ecological engineering planning.
Key Points
Ecological engineering was assessed in view of forest conservation and restoration
Forest conservation contributed far more than restoration to vegetation greening
Forest conservation‐restoration trade‐offs aggregated in Yunnan Province
Whether the world can achieve the United Nations Sustainable Development Goals (SDGs) largely depends on the ability of less‐developed areas to cope with multiple socio‐economic changes. The ...challenges that hinterland areas would face during the realization of SDGs has not yet received enough attentions. In this study, a context‐based assessment of regional food balances was conducted, considering key challenges related to socio‐economic development as well as land use competition under the framework of the shared socioeconomic pathways (SSPs) and the implementation of reforestation. We examined one of the poorest hinterland provinces in China as a case study, projecting its food deficit and exploring the potential threats to and opportunities for SDG realization by 2030, including population growth, urbanization, urban land expansion and reforestation. The projections revealed a crop deficit of 4.9–9.8 million tonnes, corresponding to the food demands of 10.2–20.6 million people. Approximately 76%–81% of this deficit was expected to be caused by increased food demand, rather than reforestation policies. Therefore, for this less‐developed area with low agricultural productivity and large groups of vulnerable people, population growth and urbanization are likely to result in demands for food that cannot be met locally. In addition, large‐scale reforestation projects, while enhancing a number of key ecosystem services, will increase the local food deficit by promoting the abandonment of cropland. This will result in greater reliance on food imports, with potential impacts on SDG realization in other regions. These findings highlight the need for integrated governance across multiple scales to ensure hinterland sustainability.
Plain Language Summary
The challenges related to the realization of the United Nations Sustainable Development Goals (SDGs) for hinterland areas are often masked by the overall prosperity and economic growth at the national scale. However, these areas are often characterized by delicate trade‐offs among multiple development goals. In this study, we established a context‐based framework to analyze the impacts of the implementation of multiple sustainable development strategies at different levels in hinterland regions. By combining socio‐economic development scenarios and reforestation policies, we quantified the impacts of population growth and urbanization on food demand; exploring the impact on local food production in 2030 of land competition between urban expansion, reforestation and agricultural land. The projections revealed a crop deficit of 4.9–9.8 million tonnes, equivalent to the food demands of 10.2–20.6 million people. Considering the current land use policy, the major reason for this crop deficit was an increase in food demand rather than reforestation. Furthermore, enlarging the scope of the Grain for Green Program, in which croplands on slopes steeper than 15° are converted into forests, would worsen the shortage of local food production. These findings highlight the need for integrated governance to ensure hinterland sustainability within the context of both socio‐economic development and climate mitigation.
Key Points
A context‐based framework for projecting sustainable challenges for a hinterland province was established
Shared socioeconomic pathways (SSP) and implementation of a reforestation program were considered in projected food deficit scenarios for 2030
The population growth, urbanization and ongoing reforestation will create extra demands for food that cannot be met locally
Shanghai is the biggest metropolis in China, and its local temperature change is affected not only by global warming but also by urbanization. Integrating the Mann-Kendall test, EMD (Empirical Mode ...Decomposition), Cross Wavelet Analysis and statistical methods, we studied the response of the local temperature change in Shanghai to global warming and urbanization. The results indicate that the local temperature at Shanghai present a significant warming trend under the background of global warming over the past 135 years. The local temperature at Shanghai displays 2-year, 6-year, 15-year, 23-year and 68-year periodic fluctuation, whereas global temperature shows 4-year, 9-year, 15-year, 23-year and 68-year cyclic variation. Although the two cycles are not exactly the same, they show some comparability. Urbanization facilitated the warming process of Shanghai. In the most recent 50 years, temperature difference between urban and suburban Shanghai has increased nearly 0.4 °C. The related indicators of urban development, such as population, built-up area, Gross Domestic Product (GDP), energy consumption and number of vehicles show significantly positive correlation with the temperature difference between urban and suburban area. In addition, the frequency of extreme high temperature has become higher, whereas the frequency of extreme low temperature has become lower over the most recent 55 years.
PDF
