Logged Tropical Rainforests Still Support Biodiversity Even When the Heat Is On

Tropical rainforests continue to buffer wildlife from extreme temperatures even after logging, a new study involving the University of York has revealed.

Tropical rainforests
Wallace's flying frog. Credit: University of Sheffield, Rebecca Senior

Tropical rainforests continue to buffer wildlife from extreme temperatures even after logging, a new study involving the University of York has revealed.

Scientists had previously assumed that cutting down trees caused major changes to local climates within tropical forests – something which would have a devastating effect on the animals living there.

However, new research conducted by the Universities of York, Sheffield and Universiti Malaysia Sabah, shows logged forests on the island of Borneo were thermally indistinguishable from the nearby pristine forest.

This is good news for the huge diversity of globally important species that live in logged forests, which may have previously been further destroyed or converted into agricultural land.

Rebecca Senior, a NERC ACCE student from the University of Sheffield’s Department of Animal and Plant Sciences, led the study which is published in the journal Global Change Biology.

Professor Jane Hill of the University of York’s Department of Biology is Rebecca’s co-supervisor.

Professor Hill said: “Rebecca’s study is important for helping us conserve tropical species in human-affected landscapes. Demonstrating the high value of degraded forest is good news for those species that may be vulnerable to climate change.”

Tropical rainforests
Bornean keeled pit viper. Credit: University of Sheffield, Rebecca Senior

The international team of scientists examined the impact that commercial selective logging had on local temperature nine to 12 years after the trees had been chopped down. This type of logging removes a large amount of timber and can be extremely disruptive to rainforest habitat – this is particularly evident in Southeast Asia.

Rebecca said: “This study highlights the resilience and conservation value of logged tropical rainforests. At a first glance it may be tempting to condemn these forests as disturbed beyond repair and convert them to agriculture.

“But to do this would be sacrificing a biological haven, capable of supporting diverse species both in the present day and under the increasing threat from climate change.”

Temperature change

Logging activity affects 20 per cent of the world’s tropical rainforests and in many places only logged rainforest remains. The researchers say it is therefore extremely positive news that even after trees have been logged the forest can continue to support many species of conservation.

Rebecca said: “For long-term survival in logged forests it is vitally important that tropical species are able to respond to other threats – particularly climate change.

“Many tropical species are picky about the temperatures they prefer but have limited options for coping with temperature change. When exposed to extreme heat, a common strategy for animals like frogs and insects is to move to a cool refuge – like people in a warm room moving towards an open window.”

Cool refuges

During the study the researchers travelled to Borneo to establish whether intensive logging activity had altered the availability of cool refuges for animals like the Bornean horned frog, Bornean keeled pit viper, and Wallace’s flying frog.

They recorded temperature using a thermal camera and tiny temperature loggers and found that after nine to 12 years of recovery post-logging, the logged forest had a very different structure with fewer large trees and more young saplings.

Surprisingly, though, they discovered the average temperature and the availability of cool refuges was comparable with a pristine forest that had never been logged.

Rebecca said: “What this means is that regardless of whether the forest was logged or not, the animals that live there should be equally capable of hiding out when it gets too hot.

“This will be increasingly necessary as average global temperatures rise, so it’s important that we recognise the value of degraded forests and the speed with which they can recover, given the chance.”

Source : University of York