Spatially Explicit Mapping of Soil Conservation Service in Monetary Units Due to Land Use/Cover Change for the Three Gorges Reservoir Area, China

Shicheng Li,Gui Jin,Zilu Bing

doi:10.3390/rs11040468

Abstract

Studies of land use/cover change (LUCC) and its impact on ecosystem service (ES) in monetary units can provide information that governments can use to identify where protection and restoration is economically most important. Translating ES in monetary units into decision making strongly depends on the availability of spatially explicit information on LUCC and ES. Yet such datasets are unavailable for the Three Gorges Reservoir Area (TGRA) despite its perceived soil conservation service value (SCSV). The availability of remote sensing-based datasets and advanced GIS techniques has enhanced the potential of spatially explicit ES mapping exercises. Here, we first explored LUCC in the TGRA for four time periods (1995–2000, 2000–2005, 2005–2010, and 2010–2015). Then, applying a value transfer method with an equivalent value factor spatialized using the normalized difference vegetation index (NDVI), we estimated the changes of monetary SCSV in response to LUCC in a spatially explicit way. Finally, the sensitivity of SCSV changes in response to LUCC was determined. Major findings: (i) Expansion of construction land and water bodies and contraction of cropland characterized the LUCC in all periods. Their driving factors include the relocation of residents, construction of the Three Gorges Dam, urbanization, and the Grain for Green Program; (ii) The SCSV for TGRA was generally stable for 1995–2015, declining slightly (<1%), suggesting a sustainable human–environment relationship in the TGRA. The SCSV prevails in regions with elevations (slopes) of 400–1600 m (0°–10°); for Chongqing and its surrounding regions it decreased significantly during 1995–2015; (iii) SCSV’s sensitivity index was 1.04, 0.53, 0.92, and 1.25 in the four periods, respectively, which is generally low. Chongqing and its surrounding regions, with their pervasive urbanization and dense populations, had the highest sensitivity. For 1995–2015, 70.63% of the study area underwent increases in this sensitivity index. Our results provide crucial information for policymaking concerning ecological conservation and compensation.

Highlights

Ecosystems provide a range of services, many of which are of fundamental importance to human well-being and livelihoods [1]
We analyzed the characteristics of land use/cover change (LUCC) in the Three Gorges Reservoir Area (TGRA) for 1995–2015 and its four 5-year sub-periods, mapping the soil conservation service value (SCSV) in monetary units due to LUCC using the value transfer method and identifying sensitive areas of SCSV to LUCC
Three major findings were supported. (i) The expansion of construction land, water body, and reduced cropland are the most notable LUCC characteristics across the four periods. Drivers for this included the relocation of residents, construction of the dam project, and interception of Yangtze River to store water in the reservoir, and the implementation of the Grain for Green Program. (ii) The SCSV was generally stable for 1995–2015, indicating a harmonious human–environment relationship in the TGRA

Summary

Introduction

Ecosystems provide a range of services, many of which are of fundamental importance to human well-being and livelihoods [1]. Valuation of ES in monetary units based on land use/cover maps is a crucial approach central to ES mapping [7] It is appropriate for geographical areas where data availability is limited, in contrast to mapping based on process-based ecosystem models [9,10], providing additional information to public entities for identifying where protection and restoration efforts are economically most important, on which they could base policy concerning ecological conservation and compensation schemes. Compared with spatially explicit mapping in biophysical terms, most of these monetary assessments are administrative division-based valuations [14,16,20]; they cannot reflect fine-scale details of spatial patterning and variation in ES, limiting their widespread applicability [24]

Methods

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Discussion

Conclusion