Temporal and spatial changes in land use patterns and biodiversity in relation to farm productivity at multiple scales in Tigray, Ethiopia

Loss of biodiversity, including agro-biodiversity affects smallholders in dry-land regions by decreasing the buffering capacity of the agro-ecosystem and increasing proneness to yield variability including crop failure due to weather extremes. Loss of biodiversity is associated with land use/land cover (LULC) changes that are related to a range of biophysical and socio-economic drivers. This thesis is focused on the Tigray region in northern Ethiopia which has experienced severe loss of biodiversity over the last decades at the regional scale, while loss of genetic variation of crops at the farm and field scale are ongoing as a result of agricultural technology adoption processes. The overall goal of this thesis research was to identify and analyse factors affecting loss of agro-biodiversity in Tigray, Ethiopia, and relate agro-biodiversity loss to LULC changes, soil erosion, farming practices and agricultural productivity. A multi-scale approach was adopted. At the regional scale, LULC changes over the last decades were investigated using a time-series of remotely sensed data to assess changes in biodiversity. At the farm scale, changes in farming practices and land use between 2000 and 2005 were described along with their effects on agro-biodiversity. These changes were related to biophysical and socio-economic drivers. Finally, at the field scale, the consequences of the presence of Acacia albida trees for productivity were assessed. A survey among 151 farms in Tigray indicated that higher numbers of species of trees and shrubs, along with cultivation of land races was associated with traditional farming practices of smallholders in 2000 and 2005. Classified maps from remotely sensed data indicated that significant changes in LULC were accompanied by loss of biodiversity and intensification of agricultural production. At the same time, overall caloric yields were highest and soil erosion lowest in sparsely cultivated areas with high biodiversity, where traditional farming practices still dominate. At the farm scale, it was shown that A. albida trees contribute significantly to soil fertility and barley yield. Results of this project may assist policy development on agro-biodiversity restoration by providing information on long-term historical trends, insight into their drivers, and consequences for food security among resource poor smallholders in the region.