Satellite observations of one of the world’s biggest ecological experiments on the island of Borneo have revealed that replanting logged forests with diverse mixtures of seedlings can significantly accelerate their recovery. The results have been published in the journal Science Advances. Source: Timberbiz
The experiment was set up by the University of Oxford’s Professor Andy Hector and colleagues over 20 years ago as part of the SE Asia Rainforest Research Partnership (SEARRP).
This assessed the recovery of 125 different plots in an area of logged tropical forest that were sown with different combinations of tree species. The results revealed that plots replanted with a mixture of 16 native tree species showed faster recovery of canopy area and total tree biomass, compared with plots replanted with four or just one species. However, even plots that had been replanted with one tree species were recovering more quickly than those left to restore naturally.
“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 important ecosystem services such as carbon sequestration.’
Greater diversity gives greater resilience,” Lead Scientist of the study, Professor Andy Hector (Department of Biology, University of Oxford) said.
According to the researchers, a likely reason behind the result is that different tree species occupy different positions, or ‘niches’, within an ecosystem. This includes both the physical and environmental conditions that the species is adapted to, and how it interacts with other organisms.
As a result, diverse mixtures complement each other to increase overall functioning and stability of the ecosystem. For instance, some tropical tree species are more tolerant of drought because they produce a greater amount of protective chemicals, giving the forest resilience to periodic times of low rainfall.
In turn, a diverse mix of trees can support a much wider range of animal life. For instance, hornbills specifically require large mature trees with holes where the females can nest.
Tropical forests cover just 6% of the planet’s land surface but are home to around 80% of the world’s documented species (WWF), and act as major carbon sinks.
Restoring logged tropical forests is a crucial component of efforts to tackle both the nature and climate crises. Up to now, however, it has been unclear whether this is best achieved through allowing forests to restore themselves naturally (using dormant seeds in the soil) or through active replanting.
The study ‘Positive effects of tree diversity on tropical forest restoration in a field-scale experiment’ is published in Science Advances at http://www.science.org/doi/10.1126/sciadv.adf0938
