Impacts of ecosystem degradation on Lake Abijata, vegetation and herbaceous biomass in and surrounding Abijata Shalla National Park

Abstract

This study aimed to assess changes in spatial cover of Lake Abijata and impacts of land use/land cover changes on the floristic composition and herbaceous biomass in and surrounding Abijata Shalla National Park. Data were collected using systematic sampling method from 64 quadrats of 400 m² established along eight line transects. Land use/land cover changes over time (from 1978 to 2018) were determined from satellite images of the study area using ArcGIS 10.5 and ENVI 5.0 software. Data were analyzed using both descriptive and inferential statistics. A total of 60 plant species belonging to 49 genera and 27 families were documented. Most species had mean Diameter at Breast Height (DBH)/Diameter at Stamp Height (DSH) less than 10 cm, few species (four) were in higher diameter classes (27.6–32.5) and only one species (Acacia tortilis) was in the 32.6– 37.5 and 37.5–42.5 diameter classes. Most species (77%) had low importance value index which imply the need for conservation attention in the area. Spatial cover of Lake Abijata decreased by 58.6% as its cover decreased from 20,676.51 ha in 1978 to 8,558.1 ha in 2018. Similarly, grassland, wetland and forest/shrub land decreased by 87.6%, 48.9% and 40.9%, respectively. Human settlements, crop land and bare land increased by 517.7%, 105.1% and 81.1%, respectively. Protected area had higher mean biomass (289 g/m² ) than the open access sites (71 g/m²). Coordinated and multidisciplinary interventions are recommended to restore the degraded terrestrial and aquatic ecosystems and conserve the diverse biodiversity in the study area.

Key words/phrases: Ecosystem restoration, Herbaceous biomass, Land use/land cover change, Species richness