Land use optimization based on ecosystem service assessment: A case study in the Yanhe watershed

Wu, X. T., et al., 2018. Land Use Policy

Original research (primary data)
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Abstract

Regional land use change can significantly change the ecosystem patterns and processes, resulting in changes of ecosystem services supplies. Large-scale ecological restoration programmes have been implemented in China to restore and sustain ecosystem services. We selected the Yanhe watershed on China’s Loess Plateau, which has experienced the Grain for Green Programme (GFGP), as study area, and we used specialized models to quantify four ecosystem services (water provision, soil conservation, carbon sequestration, and agricultural production) under land use scenarios relative to actual land use change from 2000 to 2015. These scenarios were set according to slope, land use type and water constraint of the watershed to improve water quantity, carbon sequestration, soil retention, agricultural production, and sub-watershed water sustainability. The results show that from 2000 to 2015, 66% of farmlands converted to grassland, 12% of farmlands converted to forest, and farmland proportion declined from 42.0% to 5.3%, while water provision and agricultural production services declined by 12% and 87%, and soil conservation and carbon sequestration services increased by 13% and 3%. Furthermore, under five specific scenarios that converted all retired farmland to grassland in the water-short area and maintained farmland at 0–10° slope in the water-adequate area, all four ecosystem services improved compared with 2015 levels. By identifying optimized land use scenario of retired farmland, we refined general principles of future analyses and decision making in ecological restoration. Comprehensively analyzing slope, land use type and water constraint of the watershed when choosing land use scenarios for GFGP can effectively resolve trade-offs among multiple ecosystem services and can promote regional sustainable development.

Case studies

Basic information

  • Case ID: INT-202-1
  • Intervention type: Created habitats
  • Intervention description:

    From 2000–2015, farmland proportion of the Yanhe watershed declined because of GFGP. Retired farmland converted to grassland, forest, and shrub land.

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Reduced water availability  Negative annual water yield, determined using InVEST + compared water yield to minimum water demand for maintaining socio- economic services
    Soil erosion  Positive Sediment retention, modeled using InVEST - mapped over entire study area and defined as "the difference between se- diment delivered by current watershed and a hypothetical watershed where all LULC types are bare soil." Sediment export
  • Approach implemented in the field: Yes
  • Specific location:

    The Yanhe watershed (36°21′–37°19′ N, 108°38′–110°29′ E) is lo- cated in northern Shaanxi province in China, the middle part of the Loess Plateau

  • Country: China
  • Habitat/Biome type: Created forest | Created grassland | Created other |
  • Issue specific term: Not applicable

Evidence

  • Notes on intervention effectivness: to determine effectiveness, measure land-use change over time (assumed to be result of intervention) and change in outcome measures over time - change in outcome measures therefore assumed to be due to the intervention that has changed the land-use for water availability also compare to minimum water demand for maintaining socio- economic services "However, land use change also caused a decline of water sustainability of sub-watersheds (Fig. 3c). In 2000, all 67 sub- watersheds met the minimum water demand for maintaining socio- economic services across the Loess Plateau, and only 2 sub-watersheds were in the minimum water demand range. In 2015, 3 sub-watersheds missed the minimum water demand, and 9 sub-watersheds were in the minimum water demand range." they measure ‘agricultural production services’ which inevitably decline because the program entails converting agricultural land to forests or grasslands. we did not code for it because there is no framing of changes in agricultural production as caused by a climatic impact.
  • Is the assessment original?: Yes
  • Broadtype of intervention considered: Not applicable
  • Compare effectivness?: No
  • Compared to the non-NBS approach: Not applicable
  • Report greenhouse gas mitigation?: Yes
  • Impacts on GHG: Positive
  • Assess outcomes of the intervention on natural ecosystems: No
  • Impacts for the ecosystem: Not reported
  • Ecosystem measures:
  • Assess outcomes of the intervention on people: No
  • Impacts for people: Not reported
  • People measures:
  • Considers economic costs: No
  • Economic appraisal conducted: No
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

  • Type of data: Quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: