Satellite evidence for significant biophysical consequences of the “Grain for Green” Program on the Loess Plateau in China

Xiao, J. F., 2014. Journal of Geophysical Research-Biogeosciences

Original research (primary data)
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Abstract

Afforestation has been implemented worldwide as regional and national policies to address environmental problems and to improve ecosystem services. China’s central government launched the Grain for Green Program (GGP) in 1999 to increase forest cover and to control soil erosion by converting agricultural lands on steep slopes to forests and grasslands. Here a variety of satellite data products from the Moderate Resolution Imaging Spectroradiometer were used to assess the biophysical consequences of the GGP for the Loess Plateau, the pilot region of the program. The average tree cover of the plateau substantially increased because of the GGP, with a relative increase of 41.0%. The GGP led to significant increases in enhanced vegetation index (EVI), leaf area index, and the fraction of photosynthetically active radiation absorbed by canopies. The increase in forest productivity as approximated by EVI was not driven by elevated air temperature, changing precipitation, or rising atmospheric carbon dioxide concentrations. Moreover, the afforestation significantly reduced surface albedo, leading to a positive radiative forcing and a warming effect on the climate. The GGP also led to a significant decline in daytime land surface temperature and exerted a cooling effect on the climate. The GGP therefore has significant biophysical consequences by altering carbon cycling, hydrologic processes, and surface energy exchange and has significant feedbacks to the regional climate. The net radiative forcing on the climate depends on the offsetting of the negative forcing from carbon sequestration and higher evapotranspiration and the positive forcing from lower albedo.

Case studies

Basic information

  • Case ID: INT-197-1
  • Intervention type: Created habitats
  • Intervention description:

    The GGP was launched in 1999, and its goals are to increase forest cover and to mitigate soil erosion by converting agricultural lands on steep slopes to forests and grasslands. These agricultural lands are typically characterized by low productivity and intensive soil erosion. The famers with loss of croplands are subsidized by grain and cash subsidies for up to 8 years. --> note although mentions conversion to grasslands, only appear to be investigating the areas converted to forests

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Other climate impact  Unclear results OTH = changes in local temperatures Measures = albedo, evapotranspiration (both proxies to understand how temp may be affected because these measures influence local temperatures), day and nighttime land surface temperature (LST)
    Biomass cover loss  Positive enhanced vegetation index (EVI) as a measure of forest productivity, leaf area index (LAI), photosynthetically active radiation (fPAR), GPP
  • Approach implemented in the field: Yes
  • Specific location:

    The entire Loess Plateau - The plateau consists of the entirety of two provinces (or autonomous regions)—Shanxi and Ningxia—and portions of five provinces (or autonomous regions): Shaanxi, Henan, Inner Mongolia, Gansu, and Qinghai

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

Evidence

  • Notes on intervention effectivness: To assess effectiveness: The correlations of spatially averaged EVI with spatially averaged percent tree cover, air temperature, and precipitation were conducted to examine the influence of climate and afforestation on vegetation productivity. --> percent tree cover is the indicator of the afforestation intervention "Despite the changes in the climate of the Loess Plateau [Wang et al., 2012], the increase in vegetation productivity was not correlated with elevated air temperature, changing precipitation, or rising atmospheric CO2 concentrations. The strong correlation between EVI and percent tree cover indicated that the increase in vegetation productivity was driven by the increase in tree cover resulting from the GGP. " Unclear outcomes for OTH because one of the measures (albedo) indicated a warming/negative effect on local temp but LST indicated a positive/cooling effect and authors state that more work is needed to determine the net effect on the local temps - they don't conclude whether it is positive or negative
  • 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?: No
  • Impacts on GHG: Not applicable
  • 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: