Sao Paulo: A recent research conducted on deforestation in tropical rain forests has indicated that it could have an even greater impact on climate change than has previously been thought.
According to research by the Helmholtz Centre for Environmental Research and the University of Sao Paulo in Ecological Modelling, 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.
The reason for the reduction in biomass is the higher mortality rate of trees at the edges of forest fragments, the report said.
The result also suggested that altered wind conditions and light climate lead to a general change in the microclimate at the forest edges, while 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 measuring one hectare has only 140 tonnes of biomass per hectare.
In other words, the biomass in the forest remnants in this study fell by as much as 40 per cent.
“This finding is of great significance for the function of rain forests as a biomass store. It is important to be clear about the fact that we are losing more than just the deforested areas. Even the remaining forest is thinned out as a result. It is a mistake to think only in terms of total area,” Dr Jurgen Groeneveld of the UFZ said.
“We have to start thinking in terms of the spatial configuration of the remaining forest fragments as well,” he added.
First Published: Thursday, December 10, 2009, 16:08