Effects of large-scale afforestation project on the ecosystem water balance in humid areas: An example for southern China

Zheng, H. W. et al., 2016. Ecological Engineering

Original research (primary data)
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Massive afforestation and reforestation programs have been implemented around the world to restore degraded land and respond to climate change. Many studies suggest that such large-scale campaigns may be counterproductive if there is insufficient water to sustain the trees, especially in dryland. However, we suggest the large-scale afforestation may become a new problem even in humid regions with abundant water, and that the problem will be exacerbated by climate change. To test this hypothesis, we compared the water surplus (evapotranspiration) of natural vegetation and planted trees in 15 provinces of southern China using eight evapotranspiration models. The planted forests consumed considerably more water than natural vegetation, thereby utilizing water that would otherwise be available to support other uses. It may raise water conflicts among sectors in climatic change. We found that if artificial restoration by afforestation or reforestation were replaced by restoration of the natural vegetation, water-use efficiency would improve by 9.97-16.34% in different regions. Uncritical acceptance of large-scale planting of woody vegetation may therefore reduce the ecosystem’s resilience against climate change in the short term and increase the long-term risks of water conflict in society in long run if major climatic shifts over. It is therefore necessary to carefully assess whether the benefits of the planted forests outweigh the potential negative environmental and socioeconomic consequences.

Case studies

Basic information

  • Case ID: INT-205-1
  • Intervention type: Created habitats
  • Intervention description:

    Afforestation … afforestation in southern China has been achieved on the lands which were almost covered by grass and steppe vegetation, especially in mountainous regions

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Reduced water availability  Negative Water surplus (WS = Precipitation - evapotranspiration of afforested plots)
  • Approach implemented in the field: Yes
  • Specific location:

    the 15 provinces of southern China

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


  • Notes on intervention effectivness: determine effectiveness of intervention by comparing to sites of natural vegetation which act as proxy to what the water supply would have been without the intervention (because tree planting occurred mostly on natural vegetation) --> We then calculated the dif- ference between the water surplus of the planted forests and by the natural vegetation, which we used to represent the amount of water that could potentially be saved if the natural vegetation had been preserved or restored instead of being converted into forest
  • 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: Yes
  • Experimental evalution done: In-situ/field
  • Non-experimental evalution done: Not applicable
  • Study is systematic: