Tillväxt hos inhemska trädslag i Borneo : en jämförelse av 34 arter inom ett återbeskogningsförsök

Abstract: Degradation of tropical forests have had a major negative impact on biodiversity in these speciesrich systems, as well as lowering carbon sequestration. This results in these systems losing their potential to bind parts of the carbon dioxide that is causing the ongoing climate change. When working with reforestation of degraded tropical forests, with the goal of reintroducing the ecosystem services that have been lost, exotic tree species such as Eucalyptus and Acacia are often used. These tree species are well documented and have high growth rates and high potential for carbon sequestration. The exotic tree species are lacking when it comes to contributing to the native biodiversity, they also show invasive tendencies and can lower the biodiversity by competing with native tree species. The goal with this article was to investigate the potential for carbon sequestration among native tropical tree species originating from Borneo, and finding native tree species that can compete with the exotic tree species. This was accomplished by analyzing data from 34 different tree species that had been planted in a reforestation project in Sabah, Borneo, Malaysia. We found that the variation in carbon sequestration could be predicted by using wood density; species with lower wood density generally had higher carbon sequestration than species with a higher wood density. We also found four tree species that showed significantly higher carbon sequestration than predicted with the wood density, these species all belonged to the family Shorea sp. These tree species exhibited a carbon sequestration potential that was equal to 30-50% of the potential found in Acacia mangium and Eucalyptus pellita. Our results indicate that when it comes to carbon sequestration and growth, the native tree species cannot compete with the exotic tree species. The reason for this conclusion is that the highest values from the native tree species are still only 50% of the potential found in the exotic tree species. We found that the exotic tree species have a negative impact on biodiversity in areas where they are introduced. Our conclusion is that if the goal is to preserve biodiversity while increasing the potential for carbon sequestration, the native tree species are the better choice. However, if the goal is to maximize carbon sequestration, the exotic species are the better alternative.