Dry forest community types and their predicted distribution based on a habitat model for the central dry zone of Myanmar

Abstract

Tropical dry forests are some of the world’s most endangered ecosystems, but are the least studied habitats. The lack of information on their ecology and distribution is a constraint for restoration and conservation of these forests. The last study to describe dry forest communities in Myanmar was conducted in the 1960s, and was based on their physiognomy and the dominant tree species. We investigated the species composition of the dry forest communities in the central dry zone of Myanmar, and developed environmental distribution models. Based on presence/absence vegetation surveys, we classified the community types using TWINSPAN. We obtained 14 statistically significant basic community types, which we combined into five alliances and two orders. Community types were generally divided into two groups at the order level: woody communities in the forest landscapes and in the anthropogenic (agricultural and residential) landscapes. Tectona hamiltoniana and Terminalia oliveri were abundant in the forest landscapes, whereas Prosopis juliflora and Borassus flabellifer were common in the anthropogenic landscapes. Acacia catechu and Waltheria indica were distributed in communities with intermediate characteristics between the forest and anthropogenic landscapes. Communities in the anthropogenic landscapes lacked species from the forest landscapes. Forest landscape communities were endemic to Myanmar’s dry zone, and T. hamiltoniana was dominant. A novel community of alien P. juliflora which is common to the world’s dry forests, was detected in the anthropogenic landscapes. We predicted the distribution of dry forest communities across the study area using a logistic regression model based on landscape types and mesoscale environmental variables. Landscape was the most significant factor that explained the distribution of the communities, followed by elevation. The forest landscape communities, especially the Shorea siamensis–T. hamiltoniana and T. hamiltoniana–T. oliveri forest alliances were rare in the study area. The limited area of these communities suggested their importance for conservation planning.