Restoring aboveground carbon and biodiversity: a case study from the Nile basin, Ethiopia

Mekuria, W., et al., 2015. Forest Science and Technology

Original research (primary data)
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In Ethiopia, exclosures in landscapes have become increasingly important to improving ecosystem services and reversing biodiversity losses. The present study was conducted in Gomit watershed, northern Ethiopia, to: (i) investigate the changes in vegetation composition, diversity and aboveground biomass and carbon following the establishment of exclosures; and (ii) analyse the economic returns of aboveground carbon sequestration and assess the perception of local communities on land degradation and exclosures. A space-for-time substitution approach was used to detect the changes in aboveground carbon, species composition, and diversity. Exclosures of 1-, 2-, 3-, 4-, 5-, and 7-years-old and a communal grazing land were selected. Household surveys, key informant interviews, and a financial analysis were used to assess the perception of local communities and the value of exclosure impacts, respectively. Significant (P = 0.049) differences in species diversity and considerable increases in aboveground carbon (ranged from 0.6 to 4.2 t C ha?1), CO2 storage (varied between 2.1 and 15.3 t CO2 ha?1), woody species composition, and richness (ranged from five to 28) were observed following the establishment of exclosures. Exclosures generated temporary certified emission reductions (tCER) of 3.4, 2.1, 7.5, 12.6, 12.5, and 15.3 Mg CO2 ha?1 after 1, 2, 3, 4, 5, and 7 years, respectively. The net present value (NPV) of the aboveground carbon sequestered in exclosures ranged from US$6.6 to US$37.0 per hectare and increased with exclosure duration. At a watershed level, 51.4 Mg C ha?1 can be sequestered, which represents 188.6 Mg CO2 ha?1, resulting in tCER of 139.4 Mg CO2 ha?1 and NPV of US$478.3 per hectare. This result would suggest that exclosures can potentially improve local communities’ livelihoods beyond rehabilitating degraded lands if carbon stored in exclosures is traded. Communities in the watershed demonstrated that exclosures are effective in restoring degraded lands and they are benefiting from increased fodder production and reduced impacts of soil erosion. However, the respondents are also concerned over the sustainability of exclosure land management, as further expansion of exclosures aggravates degradation of remaining communal grazing lands and causes fuel wood shortages. This suggests that the sustainability of exclosure land management can be attained only if these critical concerns are addressed by a joint effort among government agencies, nongovernmental organizations, and communities.

Case studies

Basic information

  • Case ID: INT-033-1
  • Intervention type: Combination
  • Intervention description:

    Ecological restoration; restoration of degraded watersheds through exclosures Exclosures are areas closed off or protected from interference from people and domestic animals, with the goal of promoting natural regeneration of plants and reducing land degradation of formerly degraded communal grazing lands (Mekuria et al. 2011). In exclosures, grass harvesting (using a cut and carry system) is the only activity allowed, and is conducted once a year. In exclosures, SWC structures such as hillside terraces, stone bunds, and microbasins have been constructed. The purpose of constructing SWC structures in exclosures is to enhance biological regeneration of degraded indigenous trees and shrubs, and promote grass production through increasing the availability of water in the root zone.

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Loss of food production  Mixed results Food/agriculture – Outcome measures – aboveground standing biomass measured within the exclosures in comparison with common grazing land Household surveys, key informant interviews - ""Perception of local communities on the effectiveness of exclosures in restoring degraded landscapes and their contribution to improving the livelihoods of watershed communities "
    Soil erosion  Mixed results Perception of local communities on the effectiveness of exclosures in reducing erosion
  • Approach implemented in the field: Yes
  • Specific location:

    Gomit watershed located in Libo Kemkem Wereda, South Gondar administrative zone of Amhara region in northwestern Ethiopia. Gomit watershed covers an area of 1483 ha

  • Country: Ethiopia
  • Habitat/Biome type: Montane/Alpine |
  • Issue specific term: Not applicable


  • Notes on intervention effectivness: “All the respondents elaborated that the restoration efforts increased vegetation cover, rehabilitated large gullies, and reduced loss of crops and grazing lands” Perception that “Income from carbon credit contributes to diversifying household income and improve livelihoods “ However “exclosures as carbon sink projects are economically unattractive at an average price of US$25 per permanent credit”, but they have high potential if the price of carbon increases. 'benefits for crop production – most say they notice no effect, few says benefits because reduce soil erosion/sedimentation, others say negative because of opportunity costs' The authors concluded that “Exclosures help achieve sustainable intensification of agricultural production by reducing soil erosion, improving vegetation cover, and sequestering CO2 and are therefore an adaptive strategy to climate change or variability.” However they are clear that in reality, over the landscape which they are implemented the results are mixed as per the perception of respondents - “Respondents stressed that exclosure land management reduced the availability of fuel wood, as fuel wood collection from exclosures is not permitted, and aggravated soil and vegetation degradation in the remaining communal grazing lands due to increased grazing and human pressure. In addition, exclosure land management forced households to reduce livestock numbers.” Therefore, we code for mixed for all impacts because “while respondent perceptions are positive in relation to the intervention's impact on reducing land-degradation (and erosion and gully formation) respondents also reported that this led to increased grazing pressure outside of exclosures and thus contributing to increased degradation over the rest of the landscape. Similarly, for the ecosystem impact, while the exclosures have a positive impact WITHIN the exclosure, the fact is it has, as per the perception of respondents, promoted the degradation of land outside/degrading ecosystems, thus I would code for mixed not positive.
  • 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: Unclear
  • Assess outcomes of the intervention on natural ecosystems: Yes
  • Impacts for the ecosystem: Mixed
  • Ecosystem measures: Investigate the changes in vegetation composition, diversity A space-for-time substitution approach (Mekuria et al. 2011) was used to detect changes in plant species richness, diversity the differences among exclosures and between an exclosure and grazing land in vegetation parameters such as species richness, diversity, similarity in species composition However, the study also reports that while the exclosures have a positive impact WITHIN the exclosure, the fact is it has, as per the perception of respondents, promoted the degradation of land outside/degrading ecosystems.
  • Assess outcomes of the intervention on people: Yes
  • Impacts for people: Mixed
  • People measures: Same as the main outcome measures, perception of local communities on the effectiveness of exclosures in restoring degraded landscapes and their contribution to improving the livelihoods of watershed communities. “Income from carbon credit contributes to diversifying household income and improve livelihoods “ In addition they assess potential issues related to intervention management which may disenfranchize certain groups. Authors report "the total beneficiary population consists of 360 households.' trade-offs - households without adequate labour may benefit less from grass products compared to households who do have adequate labour. also 'poor representation of women in the CWT' 'In addition, local cultural perceptions that precluded women's participation in watershed management decisions and that do not allow women to express their opinions in a public situation could contribute to their limited participation in decision making.'
  • Considers economic costs: Yes
  • Economic appraisal conducted: Yes
  • Economic appraisal described:
  • Economic costs of alternative considered: No
  • Compared to an alternative: Not reported

Evaluation methodology

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