Spatio-Temporal Evolution of the Fragmentation Classes of the Mikea Dry Deciduous Forest (Southwestern Madagascar)

Abstract

In southwestern Madagascar, the Mikea forest is a highly diverse ecosystem of great biodiversity, which mixes dry deciduous forest in the eastern part and xerophytic thicket in the western coastal area. However, dry forests and shrubs are rapidly destroyed due to slash-and-burn cultivation (hatsaky) and exploitation of forest resources by riparian communities and external operators. The aim of this paper is to evaluate forest fragmentation in the Mikea national park, by comparing past and recent forest maps. The analysis of forest fragmentation is based on landscape indices. The changes in forest cover have been detected from time-series SPOT satellite images registered over 15 years (1999, 2005, and 2014). Between 1999 and 2014, forest area is reduced by 39.8% which is equivalent to an annual forest loss rate of 4.6%. The forest fragmentation is associated with a significant decrease in forest patch size. The mean patch size decreases from 37,228 to 18,731 ha from 1999 to 2014. The primary direct causes are economic driven due to intense anthropogenic activities such as wood charcoal production, logging, accompanied by frequent wild land fires. The indirect cause is the absence of a sustainable environmental management and conservation strategy.