Assessing Vegetation Cover Dynamics Induced by Policy-Driven Ecological Restoration and Implication to Soil Erosion in Southern China

Zhang, J. W. et al., 2015. Plos One

Original research (primary data)
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Abstract

In the aftermath of the severe droughts and floods at the end of the 20th century, the Chinese government launched several ecological restoration projects, including the Natural Forest Protection Program in 1998 and the Grain-for-Green Program in 1999, to promote afforestation and reforestation to reduce surface runoff and consequent soil erosion nationwide. However, it is still unclear how vegetation has changed in southern China since the launch of these programs. In this study, we used the MODIS Enhanced Vegetation Index (EVI) to analyze the vegetation cover dynamics in southern China from 2000 to 2009 and evaluate the resulting effects of controlling soil erosion. Our observations indicate that 5.3% of the study area significantly increased and 0.98% significantly decreased in EVI value (p < 0.05). The spring EVI had largest increase in space. The conversions of croplands on steep slopes to forests resulting from national policies led to significant increases in EVI. The increase in EVI was not driven by annual average temperature and annual precipitation. By referencing ecological restoration statistical data and field observations, we showed that ecological restoration programs significantly improved vegetation cover in southern China. Increase in the area of farmland-converted forestlands has reduced soil erosion based upon monitoring sediment yields at hydrologic stations in the Yangtze River. This study displays the spatial patterns of trend in vegetation growth since the beginning of the 21st century in southern China and highlights the important role of China's afforestation program.

Case studies

Basic information

  • Case ID: INT-212-1
  • Intervention type: Mixed created/non-created habitats
  • Intervention description:

    GFGP ...Crop fields and barren lands on the slopes are the particular foucs of the restoration projects. Tree species selected for reforestation planted include Pinus armandii, Pinus massoniara, Cryptomeria fortune, Cunninghamia laceo- lata, Cupressus spp., Eucalyptus spp. and Populus deltoids....data assessed was the GGP from 1999 to 2008 and includes the total area of recovered cropland, converted cropland, fenced-off lands, and afforested lands + data for the NFPP including the total area of protected land. There were areas of overlap between these two forestry programs (GGP and NFPP), and the respective scope for each was difficult to distinguish; therefore, we inte- grated these two projects to consider just the general ecological restoration. ...From our field validations, it was clear that natural vegetation had recovered since the begin- ning of GGP in 2000 (S1 Fig). In addition, fencing for reforestation was adopted and felling was forbidden. Local government has been recovering the barren mountain through aerial seeding, which significantly helps vegetation recovery. From our field validations, it was clear that natural vegetation had recovered since the begin- ning of GGP in 2000 (S1 Fig). In addition, fencing for reforestation was adopted and felling was forbidden. Local government has been recovering the barren mountain through aerial seeding, which significantly helps vegetation recovery.

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Soil erosion  Positive Sediment yield collected from hydrological data at seven monitoring sites along the main reaches of the Yangtze River
    Biomass cover loss  Positive BIO_CV: MODIS Enhanced Vegetation Index (EVI) to analyze the vegetation cover dynamics - also validate results with visits to field sites
  • Approach implemented in the field: Yes
  • Specific location:

    The study was performed in southern China. It is located between 18°90-36°290N and 78°230- 122°570E, covering a total area of 362.84×104 km2. This region spans from the Tibetan Plateau, with an average elevation of 5000 m, to the East China Sea … GGP covers 11 provinces, including Anhui, Jiangxi, Hubei, Hunan, Guangxi, Hai- nan, Chongqing, Sichuan, Guizhou, Yunnan and Tibet.

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

Evidence

  • Notes on intervention effectivness: Effectiveness for BIO_CV was determined by monitoring changes in vegetation within areas where interventions have been implemented between 2000 and 2011 Effectiveness for erosion determined by measuring sediment yield at hydrological field stations, look at changes in measure over time and assume changes are due to intervention implementation "We adopted the hydrological data of seven monitoring sites along the main reaches of the Yangtze River (Fig 1) to study the effects of vegetation restoration on water and soil loss on a large scale." Coded positive for effectiveness for erosion because although they do state they don't know the full contribution of restoration to erosion reduction, their analysis still indicates a positive relationship "These results suggest that the forest cover improvement induced by the policy in southern China during the past 10 years has started to have measurable positive impacts on soil erosion of steeply sloped lands. To have better under- standing of the relationship between vegetation change and sediment load, it is essential to distin- guish the complex interactions among climate, ecological factor and human activities using erosion model. However, this study was not capable of distinguishing these factors. Our future studies will definitely pay more attention to the spatial context of these processes."
  • 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: