Borneo as a Carbon Sink

Posted by Richard B. Primack

“The woods I walked in in my youth are cut off. Is it not time that I ceased to sing?” 

-Thoreau in his Journal, 1852 

During the 1980s and 1990s I used long-term forest plots in Malaysian Borneo to determine how so many tree species could co-exist in one place, and how many years forests took to recover from logging. Forest plots from across Borneo are now being combined to examine how the island’s forests are responding to climate change. The results have recently been published as an article in Nature Communications titled Long-term carbon sink in Borneo’s forests halted by drought and vulnerable to edge effects.

Figure 1. Changes in forest biomass in Borneo were studied using 71 long-term plots. 

The main result is that these forests are gaining biomass, meaning they are out of equilibrium and are a net sink for atmospheric carbon dioxide.

Figure 2. Forests in Borneo are showing a net increase in biomass over time in the forest interior; this has also been observed in the Amazon and in Africa. Forests on the edges of fragments are declining in biomass.

Forest fragmentation from human activity has had negative effects as shown by the declining biomass of forests on the edges of fragments. Borneo’s forests are also vulnerable to the effects of climatic variation as a drought in 1997-1998 temporarily halted the increase in biomass and caused an increase in tree mortality. These forest plots will become more valuable in coming decades as a way of documenting the continued impacts of climate change.