So Paulo/ Leipzig. Deforestation in tropical rain forests could have an even greater impact on climate change than has previously been thought. The combined biomass of a large number of small forest fragments left over after habitat fragmentation can be up to 40 per cent less than in a continuous natural forest of the same overall size. This is the conclusion reached by German and Brazilian researchers who used a simulation model on data from the Atlantic Forest, a coastal rain forest in the state of So Paulo, Brazil, around 88 per cent of which has already been cleared. The remaining forest fragments are smaller, so the ratio between area and edge is less favourable. The reason for the reduction in biomass is the higher mortality rate of trees at the edges of forest fragments, according to the results published by researchers from the Helmholtz Centre for Environmental Research and the University of So Paulo in Ecological Modelling. This reduces the number of big old trees, which contain a disproportionately high amount of biomass.
Altered wind conditions and light climate lead to a general change in the microclimate at the forest edges. Big old trees are particularly vulnerable to these factors. With the help of FORMIND, a forest simulation software developed at the UFZ, the researchers modelled different sizes of forest patches left over after landscape fragmentation. The smaller a patch of forest is, the worse is the ratio between edge and area. Simulation results suggest that a natural tropical forest of our study area contained approximately 250 tonnes of aboveground biomass per hectare, a forest fragment measuring 100 hectares has around 228 tonnes of biomass per hectare, while a patch of rain forest m
|Contact: Tilo Arnhold|
Helmholtz Association of German Research Centres