Growth and distribution modeling of lowland rainforest tree species in eastern Madagascar

The rainforests of Madagascar are widely considered among the most bio-diverse ecosystems on earth. While many floral descriptions have been made over the past century, the species composition and distribution dynamics of the eastern lowland rainforest ecosystem remains poorly understood. In this study, I provide baseline data on community composition and forest structure of a lowland rainforest in eastern Madagascar and I apply growth and distribution data toward a FORMIX3 growth model parameterization. An intensive survey of vegetation and environmental factors was conducted over two consecutive field campaigns in Reserve Naturelle Integrale de (RNI) Betampona, an isolated primary forest reserve located northwest from the eastern city of Toamasina, Madagascar. Multivariate statistical analyses were used to investigate patterns of successional dynamics and the interrelationship of the variation in species composition within the survey plots with variation in soil nutrients, texture and other environmental variables. Tree species were then aggregated into functional groups based on size and light tolerance to test a FORMIX3 Model version for Madagascar's lowland rainforests. The model's output was then compared to survey plot data and findings suggested that the ability to accurately simulate RNI Betampona rainforest is reduced by the aggregation of tree species into size and light requirement functional type groupings. Overall, the results from this study provide the first quantitative description of the primary lowland rainforest of RNI Betampona as well as one of the first detailed descriptions of eastern lowland rainforest in Madagascar as a whole.