Ecosystem water imbalances created during ecological restoration by afforestation in China, and lessons for other developing countries
Abstract
Land degradation is a global environmental problem that jeopardizes human safety and socioeconomic development. To alleviate severe soil erosion and desertification due to deforestation and overgrazing, China has implemented historically unprecedented large-scale afforestation. However, few studies have accounted for the resulting imbalance between water supply (primarily precipitation) and water consumption (evapotranspiration), which will affect ecosystem health and socioeconomic development. We compared the water balance results between restoration by means of afforestation and restoration using the potential natural vegetation to guide future ecological restoration planning and environmental policy development. Based on estimates of water consumption from seven evapotranspiration models, we discuss the consequences for water security using data obtained since 1952 under China’s large-scale afforestation program. The models estimated that afforestation will increase water consumption by 559-2354 m(3)/ha annually compared with natural vegetation. Although afforestation is a potentially important approach for environmental restoration, China’s current policy has not been tailored to local precipitation conditions, and will have therefore exacerbated water shortages and decrease the ability to achieve environmental policy goals. Our analysis shows how, both in China and around the world, future ecological restoration planning must account for the water balance to ensure effective and sustainable environmental restoration policy.
Case studies
Basic information
Evidence
- Notes on intervention effectivness: Effectiveness determined by comparing the calculated water consumption of afforestation to corresponding estimates for the natural grassland or steppe vegetation that the forests replaced. (i.e. what would have occurred in a do-nothing situation – therefore is a modeled control)
“We compared the water needs of the surviving trees with those of natural vegetation based on the assumption that land with stable natural vegetation (generally, degraded natural grassland or steppe vegetation with little perceived economic value) would not be converted to forest. Note that the analysis does not calculate the change in water con- sumption between the pre- and post-afforestation states, since insufficient data was available to support such a comparison; instead, the comparison was between water use by two hypothet- ical vegetation types (natural vegetation versus forest).”
- Is the assessment original?: Yes
- Broadtype of intervention considered:
Another NbS
- 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:
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- 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:
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Basic information
Evidence
- Notes on intervention effectivness: Effectiveness determined by comparing the calculated water consumption of afforestation to corresponding estimates for the natural grassland or steppe vegetation that the forests replaced. (i.e. what would have occurred in a do-nothing situation – therefore is a modeled control)
“We compared the water needs of the surviving trees with those of natural vegetation based on the assumption that land with stable natural vegetation (generally, degraded natural grassland or steppe vegetation with little perceived economic value) would not be converted to forest. Note that the analysis does not calculate the change in water con- sumption between the pre- and post-afforestation states, since insufficient data was available to support such a comparison; instead, the comparison was between water use by two hypothet- ical vegetation types (natural vegetation versus forest).”
- Is the assessment original?: Yes
- Broadtype of intervention considered:
Another NbS
- 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:
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- 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:
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Basic information
Evidence
- Notes on intervention effectivness: Effectiveness determined by comparing the calculated water consumption of afforestation to corresponding estimates for the natural grassland or steppe vegetation that the forests replaced. (i.e. what would have occurred in a do-nothing situation – therefore is a modeled control)
“We compared the water needs of the surviving trees with those of natural vegetation based on the assumption that land with stable natural vegetation (generally, degraded natural grassland or steppe vegetation with little perceived economic value) would not be converted to forest. Note that the analysis does not calculate the change in water con- sumption between the pre- and post-afforestation states, since insufficient data was available to support such a comparison; instead, the comparison was between water use by two hypothet- ical vegetation types (natural vegetation versus forest).”
- Is the assessment original?: Yes
- Broadtype of intervention considered:
Another NbS
- 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:
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- 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:
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