The sound of diversity : the use of soundscapes to measure animal diversity in restored tropical rainforest in Sabah, Malaysia

Animal diversity is rapidly decreasing across the globe as their habitats are being degraded by human activities. At the same time, forest restoration is an increasing practice, contributing to preserving nature values, but to what extent? On Borneo, only a fraction of its previous tropical rainforest remains today as conversion into monoculture tree plantations has been increasingly profitable. This study aims at investigating the potential of tropical reforestation in sustaining native animal diversity, a group that is often overlooked when it comes to studying restoration success. I collected audio recordings from four different land uses in Sabah, Borneo, Malaysia (oil palm and eucalypt plantations, primary and restored forest) to compare their soundscapes, i.e., all the sounds stemming from the different landscapes. I also created a list of 57 species based on the recordings, used it to compare species richness and presence of threatened species within the land uses. Both the animal diversity and soundscape composition differed significantly between restored forest and tree plantations, with more than twice as many species found in the rainforest both in total and per plot. The largest difference was observed comparing oil palm and restored forest plots; the latter harbored an average of 3.7 times more species. The soundscape from the restored forest showed high similarity to primary forest and the mean number of threatened species were the same in both land uses. More species were on average found in the restored plots than in the primary sites, 26 compared to 21. The findings from this study are promising, giving insight in the possibility to restore animal diversity simultaneously to restoring plant diversity. At the same time, it also stresses the need for a more sustainable alternative to the present plantation forestry and more comprehensive studies on how tropical rainforest restoration affects animal diversity.