Spatial assessment of the impact of land use and land cover change on supply of ecosystem services in Phewa watershed, Nepal

Paudyal, K. B., et al., 2019. Ecosystem Services

Original research (primary data)
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Abstract

Community-managed forested landscapes are complex social-ecological systems that supply a variety of ecosystem services (ES) to society. The flow of these services depends on land use and land cover (LULC) changes, ecological factors such as types, pattern and composition of vegetation, as well as anthropogenic factors. ES assessment helps to deal with the complexity of the interrelationships among LULC, ES supply and societal benefits. Using the case of the Phewa watershed, Nepal, this paper presents a quantitative and qualitative assessment of priority ES to understand how the supply of ES and their societal benefits have changed over the past 40 years. LULC changes were analysed using satellite images, ecosystem services were assessed using biophysical data and expressed spatially using ArcGIS. Results reveal a substantial reversal of land degradation and indicate forest recovery over the last 40 years. Dense forests increased by 1471 ha (88%) while sparse forests, grasslands and agricultural lands declined by 26%, 77% and 15%, respectively. These significant changes in LULC had a positive impact on ES due to the conversion of agricultural/grasslands and degraded forests to dense forests. ES varied significantly across the watershed. Dense forests provided relatively higher sediment retention (soil erosion rate decreased from > 30 ton ha(1) yr(1) to < 15 ton ha(-1) yr(-1)), carbon stocks (from < 50 m(3) ha(-1) to > 100 m(3) ha(-1)), habitat provision, and raw materials than other types of land cover, but reduced the water discharge. Increased aesthetic value from the restored landscape provides higher opportunities for recreation and ecotourism. Analysis of benefit-relevant indicators revealed that the perceived societal benefits from most of the ES were significantly lower than the potential supply of ES in the watershed.

Case studies

Basic information

  • Case ID: INT-253-1
  • Intervention type: Mixed created/non-created habitats
  • Intervention description:

    From the late 1970s on, local people began to participate in restoring degraded forests and were granted formal rights to utilise forest pro- ducts with support from the government and donor agencies… the initiation of the government’s decentralised forestry policy with provision for local community participation in forest management from the late 1970s proved to be a useful tool for CBF and watershed conservation…. During the 1970s and 1980s, the government and local communities planted trees in a large area of barren land and conserved degraded forests with support from bilateral aid projects … large parts of forests have been set aside as ‘protected regions’ … creation of plantations also mentioned (CRT)

  • Landscape/sea scape ecosystem management: Yes
  • Climate change impacts Effect of Nbs on CCI Effect measures
    Reduced water availability  Positive Outcome measures are ‘Benefit-relevant Indicators’ listed below as determined through combination of biophysical data collected from area + perceptions of six up- stream community forest user groups (CFUGs), downstream business people and experts were consulted using focus group discussions to understand their perceptions and opinions for qualitative assessment of E and their benefits to society. Soil erosion: Annual sediment load to the Lake (ton ha−1 yr−1) Landslides: Number and impact of landslides (Severe, low or no) Water quality: Annual sediment load to the Lake (ton ha−1 yr−1) Water availability: Amount and duration of dry season flow for hydropower (m3 ha−1 yr−1/number of months (or days)) **Positive for all impacts
    Reduced water quality  Positive Outcome measures are ‘Benefit-relevant Indicators’ listed below as determined through combination of biophysical data collected from area + perceptions of six up- stream community forest user groups (CFUGs), downstream business people and experts were consulted using focus group discussions to understand their perceptions and opinions for qualitative assessment of E and their benefits to society. Soil erosion: Annual sediment load to the Lake (ton ha−1 yr−1) Landslides: Number and impact of landslides (Severe, low or no) Water quality: Annual sediment load to the Lake (ton ha−1 yr−1) Water availability: Amount and duration of dry season flow for hydropower (m3 ha−1 yr−1/number of months (or days)) **Positive for all impacts
    Mudslides / Landslides  Positive Outcome measures are ‘Benefit-relevant Indicators’ listed below as determined through combination of biophysical data collected from area + perceptions of six up- stream community forest user groups (CFUGs), downstream business people and experts were consulted using focus group discussions to understand their perceptions and opinions for qualitative assessment of E and their benefits to society. Soil erosion: Annual sediment load to the Lake (ton ha−1 yr−1) Landslides: Number and impact of landslides (Severe, low or no) Water quality: Annual sediment load to the Lake (ton ha−1 yr−1) Water availability: Amount and duration of dry season flow for hydropower (m3 ha−1 yr−1/number of months (or days)) **Positive for all impacts
    Soil erosion  Positive Outcome measures are ‘Benefit-relevant Indicators’ listed below as determined through combination of biophysical data collected from area + perceptions of six up- stream community forest user groups (CFUGs), downstream business people and experts were consulted using focus group discussions to understand their perceptions and opinions for qualitative assessment of E and their benefits to society. Soil erosion: Annual sediment load to the Lake (ton ha−1 yr−1) Landslides: Number and impact of landslides (Severe, low or no) Water quality: Annual sediment load to the Lake (ton ha−1 yr−1) Water availability: Amount and duration of dry season flow for hydropower (m3 ha−1 yr−1/number of months (or days)) **Positive for all impacts
  • Approach implemented in the field: Yes
  • Specific location:

    the Phewa watershed which includes a combination of urban, peri-urban and rural landscapes. It has a four- decade history of participatory watershed conservation and CBF and contains a variety of forest types. It lies between 28°11′39′′ and 28°17′25′′ north and 83°47′51′′ and 83°59′17′′ east, adjacent to the city of Pokhara. It covers an area of 12,300 hectares and extends over the whole or parts of six former village development committees and seven wards of the southwestern part of Pokhara Metropolitan City

  • Country: Nepal
  • Habitat/Biome type: Created forest | Tropical and subtropical forests | Montane/Alpine |
  • Issue specific term: Community-based (general)

Evidence

  • Notes on intervention effectivness: "effectiveness determined by assessing change in outcome measures over time over the entire landscape since interventions have been implemented (although intervention did not stretch across entire landscape considered) but also compared measures in sites where the intervention was thought to have affected (dense forest cover) to areas where it did not take effect (sparse forests, grasslands, agricultural lands) Although the intervention has mixed effects on water, the outcomes linked to how water is impacted by a climate hazard show it to have a positive effect therefore coded as positive ""Water-related BRIs re- vealed that the total freshwater yield gradually decreased over recent years. In contrast, groundwater recharge increased and the amount of dry season flow that provided additional water for hydropower and irrigation in the dry season improved.""" This study is looking at landuse change but here changes in forest cover have been assumed to be driven by policies encouraging forest restoration "This study illustrates how LULC change between 1975 and 2015 in the Phewa watershed affected the supply of ES as a result of devolving forest management rights to local communities." Sediment retention relevant for water quality and soil erosion b/c : "The restored watershed protects land from erosion and reduces sedimentation in Phewa Lake."
  • 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: Positive
  • Assess outcomes of the intervention on natural ecosystems: Please select
  • Impacts for the ecosystem: Positive
  • Ecosystem measures: Habitat provision: Number of flora & fauna viewed, The integrity of aquatic ecosystems, presence of invasives
  • Assess outcomes of the intervention on people: Yes
  • Impacts for people: Mixed
  • People measures: "Climate impact measures are applicable b/c linked explicitly to community benefits. Mixed because negative for water supply but positive for others. Total list of social benefits: Harvested timber and firewood People benefiting free consumption Annual cash income from selling Net water discharge Amount of groundwater recharge Amount and duration of dry season flow for hydropower People benefiting from quality water for drinking and irrigation People using water for recreation Water sources in the upland area Annual sediment load to the Lake Number and impact of landslides Amount of carbon sequestered Earning from carbon trading Existence values of species Research & scientific studies Number of flora & fauna viewed The integrity of aquatic ecosystems Food sources from hunting & crops Human-wildlife conflicts Presence of invasive plants Landscape greenery Recreational attributes (lookout points, picnic spots, road access Presence of tourism-related businesses Presence visitors in the watershed Availability of tourism-based jobs Earning from tourism Amount pollutant materials deposited"
  • Considers economic costs: Yes
  • 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: Yes
  • Experimental evalution done: In-situ/field
  • Non-experimental evalution done: Not applicable
  • Study is systematic: