Air photo evidence of historical land cover change in the highlands: Wetlands and grasslands give way to crops and woodlots

Abstract

Madagascar’s high plateau – where people farm, graze cattle, and set periodic fire in a grass dominated landscape – receives disproportionately little conservation attention. An aerial photograph-based analysis of land - cover change in the latter half of the 20th century, based on a stratified random sample of twenty eight sites, reveals dramatic trends associated with an increasing human population that is building a cultural landscape of villages and agro-ecosystems to assure its livelihoods. On average across the sample sites, about 23 % of grassland areas present in 1949–1950 were converted to crops fields, farm trees and built - up areas by the 1990s. Of all land - cover transitions, the most dramatic changes included the loss of approximately 60 % of wetlands and 37 % of riparian forests. These land covers, which are dispersed along the fine - grained dendritic stream network, are habitat for crayfish, frogs, and other fauna, yet are also prized locations in the rice - based Malagasy agricultural system. The results of this study suggest that attention be given to highland grassland, wetland and riparian forest ecosystem restoration and conservation; however, any on - the - ground initiatives should incorporate respect for local needs and allow sustainable use of these ecosystems, given their cultural and subsistence importance.