Rehabilitating logged rainforests...

Green broadbill (Calyptoman viridis). A common frugivore in naturally regenerating forest of the study site. Image credit, Doug JansoA study finds that the practice of forest rehabilitation can improve avian biodiversity in selectively logged tropical forests.

The global concern about climate change has put increased focus on reforesting logged areas to increase carbon sequestration. Most efforts have been put into afforestation, which usually entails establishing fast-growing monoculture plantations on abandoned lands - a practice found to have limited sequestration value and little benefit to biodiversity.

Forest rehabilitation, a lesser-used sequestration practice, tries to jumpstart forest establishment in selectively logged areas. The practice involves planting native saplings and cutting down climbers that impede regeneration and growth.  This study represents one of the first efforts to quantify the biodiversity benefits from forest rehabilitation.

The researchers were curious about how forest rehabilitation affects bird habitat. They theorized that rehabilitation returns avian conditions closer to those seen in unlogged forests. The scientists tested the hypothesis on the island of Borneo, Indonesia - where over 50% of the 420 avian species are endemic. The study conducted transect sampling of birds in three types of areas:

1) An active rehabilitation project spanning 11,000 hectares on a selectively logged site.

2) Nearby selectively logged forest regenerating naturally (i.e. not subject to rehabilitation)

3) Unlogged forest in the nearby Danum Valley Conservation Area.

Overall, they found that avian species richness and diversity were significantly higher in the rehabilitated forest compared to the forest regenerating naturally.  Bird diversity in rehabilitated forests had returned to pre-logging levels.

However, they found that the results were mixed depending on the bird type. For example, insectivores  were more common in rehabilitated and unlogged forests, but frugivores were more common in forests regenerating naturally. They speculate that the cutting of vines and shrubs in rehabilitation may reduce availability of fruit.

Based on these results, the researchers call for increased use of forest rehabilitation as a sequestration strategy. However, they recommend that future programs should refrain from cutting vines and shrubs in certain areas to improve the overall habitat for a wider group of species.

--Reviewed by Rob Goldstein

EDWARDS, D., ANSELL, F., AHMAD, A., NILUS, R., & HAMER, K. (2009). The Value of Rehabilitating Logged Rainforest for Birds Conservation Biology DOI: 10.1111/j.1523-1739.2009.01330.x