SPATIOTEMPORAL DYNAMICS OF WOODY SPECIES DIVERSITY AND ECOSYSTEM SERVICES OF SHEKA FOREST, SOUTHWEST ETHIOPIA

Abstract

Although forest biosphere reserve interventions are crucial for sustaining forest ecological functions and services, there is a dearth of information on whether the biosphere reserves in the southwest of Ethiopia contribute to the offset of the three intermingled contemporary challenges, including biodiversity loss, climate change, and livelihood sustainability. This dissertation therefore aimed to quantify (i) land use/land cover (LULC) dynamics and its driver in Sheka Forest Biosphere Reserve (SFBR), (ii) the spatiotemporal dynamics of woody species diversity, (iii) changes in ecosystem services value (ESV), (iv) Greenhouse Gas (GHG) emission and sink, and (v) contribution of forest to the livelihoods of local communities. Landsat images were used to assess LULC changes and the perceived drivers of LULC changes were identified through a socioeconomic survey. Vegetation data and soil samples were collected from a total of 139 quadrats to evaluate the dynamics of woody species diversity, changes in ESV and carbon stock. The IPCC tier 1 approach was used to quantify GHG emissions. Carbon stock dynamics for the years 2030, 2040, and 2050 were predicted using the InVEST model. The household survey was employed to quantify the contribution of forests to household income and food supply. Multiple socioeconomic factors induced prominent LULC changes in the area. Demarcation and registration of the SFBR in 2012 didn’t reduce the deforestation rate. LULC conversion destruct woody species diversity and reduced total ESV by 21.6% from 1999 to 2020. The woody species diversity substantially declined, and the composition and structure changed. The total carbon stock of SFBR was 579.54± 47.58 ton ha-1 in 2021. However, it has been declining at the rate of 2.5 tons C ha-1 yr -1 and thereby contributing to GHG emissions. LULC change induced a 13% rise in GHG emissions in 2010 and 40% in 2020. Forest income accounted for 45.2% of the annual household income, and food from forests was considered to be 62% as important as food from agriculture. Although conserving the Sheka forest is crucial, maintaining the forest and its ecosystem services with a conventional forest management approach would become challenging. Harmonizing the need for nature conservation and use, enhancing environmental law enforcement, and restoring degraded forest landscapes in the Biosphere reserve are recommended.