A groundbreaking ecological experiment led by the University of Oxford on Borneo Island demonstrates the remarkable potential of replanting logged tropical forest with diverse seedlings in expediting their recovery. Published in the journal Science Advances, the study underscores the significance of biodiversity preservation in pristine forests and its restoration in recovering logged forests.
Conducted over two decades as part of the SE Asia Rainforest Research Partnership (SEARRP), the experiment assessed the recovery of 125 plots in logged tropical forests, each sown with varying combinations of tree species.
BIODIVERSITY’S VITAL ROLE
The results reveal that plots replanted with a diverse mixture of 16 native tree species exhibit faster recovery of canopy area and total tree biomass compared to those replanted with only four or a single species. Intriguingly, even plots with just one tree species recover more rapidly than those left to restore naturally. Professor Andy Hector, the lead scientist of the study, notes, “Our new study demonstrates that replanting logged tropical forests with diverse mixtures of native tree species achieves multiple wins, accelerating the restoration of tree cover, biodiversity, and vital ecosystem services such as carbon sequestration.”
WHY DIVERSITY MATTERS
The researchers attribute this success to the fact that different tree species occupy distinct niches within an ecosystem, adapted to various physical and environmental conditions and interactions with other organisms. Diverse mixtures complement each other, enhancing the overall functioning and stability of the ecosystem. This diversity acts as an insurance effect, akin to a diversified investment portfolio, providing resilience to challenges like drought.
Moreover, a diverse mix of trees supports a wider range of animal life, such as hornbills that require large mature trees for nesting. This ecological richness is vital for maintaining biodiversity.
PROTECTING CRITICAL HABITATS
Tropical forests, though covering only 6% of the Earth’s land surface, host approximately 80% of documented species and serve as crucial carbon sinks. Unfortunately, these invaluable habitats are rapidly disappearing due to logging and conversion to palm oil plantations. Between 2004 and 2017, an area roughly the size of Morocco was lost to deforestation. Restoring logged tropical forests is imperative for addressing both the nature and climate crises.
This study challenges the traditional approach of allowing forests to restore naturally and suggests that active replanting with diverse seedlings is more effective. It also underscores the need to conserve biodiversity in undisturbed forests to aid in restoration efforts in logged areas.
FUTURE RESEARCH AND CONSERVATION
The Sabah Biodiversity Experiment team, responsible for this study, is embarking on a new three-year project funded by the UK Natural Environmental Research Council. Their goal is to conduct a comprehensive census of surviving trees in the experiment using advanced remote sensing methods, further enhancing our understanding of forest health and recovery.