It’s well known that loss of habitat is one of the most prevalent reasons for declining animal populations, and a lot of time, effort, and research has gone into finding out how to best preserve the inhabitants of these dwindling territories. So, it came as a surprise when researchers from Imperial College London discovered that “degraded” forests in Southeast Asia are actually playing an important role in the conservation of mammal diversity.
The new study, published in the journal Ecological Applications, attributes this discovery to the different approach of studying the biodiversity of Borneo by looking at small-scale landscapes rather than large-scale areas.
According to the researchers, most studies focus on the impact that changes to landscapes on a grand scale have on overall mammal biodiversity, whereas many practical decisions on the land are actually made on a much smaller scale by local landowners, which means that many previously logged forests have been overlooked as a safe haven for animals.
To look into this, they identified previously “selectively logged” forests, where only one particular type of tree was removed, and used motion-sensing cameras and trap-and-release techniques over a period of three years to see what they could find.
Remarkably, they collected 20,000 records of an incredibly diverse group of species across logged forests, old-growth forests, and palm oil plantations.
Not surprisingly, the palm oil plantations had the least mammal diversity, with the researchers suggesting the animals discovered there were actually spilling over from neighboring habitats. However, both old-growth forests and logged forests contained an unexpectedly diverse selection of large mammals, including clouded leopards, banteng, and orangutans, while smaller animals such as rodents actually had a higher diversity in logged forests.
Leopard cat caught on camera. Oliver Wearn
In a statement, lead author Dr Oliver Wearn explained how the results may be because of the way the habitats are distributed: "The logging process creates a greater variation in habitat types in a smaller area, from untouched areas on steep slopes to completely denuded areas of open grassland. Old-growth forests would likely have the same diversity if we looked at them on a much larger scale."
However, he warns not to get too excited by these positive results just yet.
"What we can say from this study is that protecting those large areas of forest that have already been logged could help conserve mammal species better than preserving fragmented pockets of forests inside oil palm landscapes," he added. "Where old growth forests remain, however, these are still the best habitats for mammals and other native species, and should be the absolute top priority for conservation."