Forest plantations, water availability, and regional climate change: controversies surrounding Acacia mearnsii plantations in the upper Palnis Hills, southern India

Rangan, H., et al., 2010. Regional Environmental Change

Original research (primary data)
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Plantation forests not only impact carbon and water cycles, but also affect biodiversity, livelihoods, and shape regional economies. Each of these impacts differs across varying scales of analysis. This paper illustrates how forest, climate change and hydrology debates play out in the context of the forest plantations of Australian black wattle (Acacia mearnsii) in the upper Palni hills of southern India. We outline the contradictory perspectives of different local groups regarding the impact of plantations on catchment hydrology and water availability, and examine these in relation to changes in the regional economy and rainfall patterns. Our analysis indicates that changes in these two factors have played a more significant role than existing wattle plantations in affecting local and regional water availability. We suggest that ongoing debates regarding forest plantation-hydrology-climate change relationships need to broaden their scope to include changes in regional rainfall patterns and shifts in regional economic activity. This approach is likely to provide a more realistic assessment of plantation forests in a dynamic regional context, and offer more resilient strategies for regional landscape and catchment management under conditions of high variability in rainfall patterns.

Case studies

Basic information

  • Case ID: INT-192-1
  • Intervention type: Created habitats
  • Intervention description:

    Wattle (Acacia mearnsii) plantations. "A. mearnsii was introduced during the 1960s in State forest lands located in the upper altitudes of the Palni hills—an eastern offshoot of the Western Ghats, a mountain range that runs parallel to the southwest coast of peninsular India, near the hill-station of Kodaikanal (Mitchell 1972; Matthew et al. 1975; see Fig. 1). The tree species is well established on the southwest and western edges of the upper Palnis between 1,800 and 2,400 m both within state forest plantations and in non-state forest areas near towns and rural settlements (Matthew 1988)."

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Reduced water availability  Unclear results Qualitative assessment from interviews on water supply to the farmers; perception of wattle plantation impact on water supply
  • Approach implemented in the field: Yes
  • Specific location:

    The Kodaikanal Forest Division contains five forest ranges that have wattle plantations: Kodaikanal, Poombarai, Man- navanur, Berijam, and Vandaravu.

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


  • Notes on intervention effectivness: Effectiveness assessed qualitatively through interviews with local farmers but also they assess changes in rainfall (quantitatively) to test the farmers claims that changes in water availability has been driven by changes in rainfall not the plantations The results are unclear however because although the farmers state that the plantations are having no effect on water supply, the authors themselves make no such conclusions as to what the net effect of plantations are, although speculate that they have little effect
  • 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: n/a
  • Assess outcomes of the intervention on people: Yes
  • Impacts for people: Positive
  • People measures: Impacts of wattle plantations on livelihoods Black wattle contributes to local livelihoods by providing marketable goods and domestic goods. Women for instance harvest firewood from blackwattle, which provides a good source of heat in comparison with other tree species and can be used for construction as well. Overall, local perceptions were generally positive, and they no longer had to harvest wood from local, indigenous trees. Economic dimensions yes – they report on the sale of the marketable goods / the wood The black wattle also can serve as a source of security – to be harvested and sold in time of need by local households The perceptions of local respondents are that the black wattle plantations in contrast to eucalyptus does not negatively impat water availability for them, although early on there was reduced stream flow following conversion from grassland, but they recovered
  • 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: Mixed qualitative/quantitative
  • Is it experimental: No
  • Experimental evalution done: Not applicable
  • Non-experimental evalution done: Empirical case study
  • Study is systematic: