Environmental and land-use change in Sulawesi, Indonesia

Elevational patterns in tree diversity of tropical montane rain forests with different soil nutrient conditions in Sulawesi, Indonesia

Summary
Elevational patterns in tree diversity of old-growth tropical montane rainforests with different soil nutrient conditions were investigated in Sulawesi, Indonesia. The region's flora and vegetation are insufficiently known and require more attention from researchers.
Our study aims at deepening the understanding of the factors that determine high tree diversity in tropical rainforests in terms of species richness, community composition and phylogenetic diversity.

It is hypothesised that:


  • changes in floristic and phylogenetic tree community composition are primarily explained by the elevational gradient, and tree species richness generally decreases with increasing elevation, supporting a linear relationship to the elevational temperature gradient;
  • tree community composition is secondarily related to the variation in soil nutrient conditions, and sites with intermediate soil fertility show highest tree diversity, supporting the hypothesis that tree species richness is a unimodal function of productivity or of other measures of nutrient supply rates;
  • tree community composition is further influenced by biogeographic patterns reflecting dispersal events as well as paleo-environmental processes like tectonic shifts and mountain building.


The project further addresses the importance of Southeast Asian montane rain forests as carbon stocks by evaluating the magnitude and variation in aboveground biomass (AGB) depending on tree species composition and related functional traits, following the hypothesis that:


  • regional variation in AGB of montane forests of Sulawesi is largely determined by the presence of tropical taxa of the Fagaceae.


Field-work in Sulawesi was conducted from February 2011 to April 2012 using a replicated factorial sampling design based on 27 plots of 0.24 ha. We collected a large number of herbarium specimens for plant identifications and recorded functional traits of the tree species.


Map of Lore Lindu National Park with research sites
Map of Lore Lindu National Park with research sites


Species identification is ongoing and will yield a considerable number of new occurrence records for Central Sulawesi as well as description of new species. Magnolia sulawesiana Brambach, Noot. & Culmsee has recently been described (see Brambach et al., 2013).

The montane forests in Lore Lindu National Park are still relatively undisturbed<The montane forests in Lore Lindu National Park are still relatively undisturbed