Spatio-temporal changes in habitat quality and linkage with landscape characteristics in the Beressa watershed, Blue Nile basin of Ethiopian highlands

Abstract

An increase in human population generally exerts pressure on natural habitats and leads to a decline in biodiversity resources. As a proxy for biodiversity study, an evaluation of habitat quality (HQ) change caused by land use/land cover (LULC) and associated landscape structural changes may provide a scientific basis for ecological protection and landscape management. This study analyzed spatio-temporal changes in HQ over the last four decades and predicted the trends over the next three decades. The Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model was employed to evaluate the state of HQ. Criteria of habitat naturalness, habitat complexity and a soil degradation index were used to classify habitat types. Results showed that, between 1972 and 2017, areas with high HQ indicators declined by about 20% while areas with poor HQ increased by 11%. An unprecedented expansion of anthropogenic LULC changes related to the growth of human settlements and artificial plantations and a decline in natural and semi-natural habitats resulted in the total loss of HQ by about 35%. The mean value of HQ decreased from 0.60 to 0.45 during the study period. The distribution of moderate levels of HQ, primarily in farmlands, remained essentially unchanged. Predicted HQ values are expected to follow a similar trend to past decades with 41.5% of the areas continuing to decline, although with a slight HQ improvement in some areas. The spatial distribution of HQ is negatively correlated with habitat degradation (R2 = 0.95 at p < 0.01) and slope (R2 = 0.84 at p < 0.05). HQ change also appears more strongly influenced by landscape composition than by configuration in the watershed. The most important landscape structure variables accounted for HQ change were LPI, PLAND and MPS of anthropogenic habitats, suggesting reducing habitat modifications and restoring degraded natural habitats is crucial to maintain biodiversity in the study area.