Fire impact on the woody plant components of dry deciduous forest in Central Menabe, Madagascar

Questions: We investigated the effects of human-induced fires on woody plant components of dry deciduous forest in Madagascar. Specifically, we addressed the following questions: (1) which forest layers are most affected by fire; (2) how is forest structure, species richness, diversity and composition affected by fire disturbance; and (3) does the forest recover after fire disturbance? Location: Kirindy Forest in Central Menabe, western Madagascar. Methods: We conducted our investigations in seven areas of the Kirindy Forest, which was burned between 1984 and 2009. Vegetation data were collected in nested plots for the different forest layers in the burned and unburned forest. Using GLM, we assessed fire impact on forest structure, species richness and diversity of the different forest layers. The recovery of burned forest was investigated using correlation analysis. In addition, we used descriptive methods to analyse fire impact on species composition. Results: Fire mainly influenced the middle forest layers, trees >1.50-m high and diameters <15cm, and significantly reduced tree density, basal area, species richness and diversity. Fire had no significant impact on the measured parameters of the shrub and top layers. Despite the severe impact of fire on the middle forest layers, most of the measured parameters of these layers were able to recover from fire disturbance within a short time. Twelve years after fire disturbance, tree density, basal area, species richness and diversity in burned forest areas no longer differed from unburned forest areas. However, species composition differed substantially between burned and unburned forests. Conclusions: We conclude that fire severely impacts the middle forest layers and alters forest structure, i.e. species richness and tree diversity, of the dry deciduous forest of Central Menabe.