Identifying drivers of forest resilience in long-term records from the Neotropics

New research from the University of Oxford suggests that making sure that forests are diverse will likely improve their ability to respond to an increase in disturbances associated to climate change.

Lead author Dr Carole Adolf, from the Department of Zoology, and colleagues looked at how tropical forests from Mexico to Brazil responded to past disturbances, trying to discern what may be the factors that positively influence a faster recovery after a disturbance. Published in Biology Letters, this research attempts to answer forest management questions with two particular focuses: Firstly, what characteristics does a forest need to be more resilient? And secondly, are there specific geographic locations that due to their combination of abiotic conditions are more resilient to disturbance?

The team used long-term vegetation dynamics data from pollen in lake-sediment cores, because the generation time of forests can range up to hundreds of years and therefore recent vegetation surveys cannot be used to address these questions. A range of forest types were tested, concluding that  high species richness - an important component of biodiversity - positively influences forest resilience by improving forest recovery rates after a disturbance. 

To determine if there are certain locations that harbour more resilient forests, Adolf and team looked at the resilience of present forests by using a previously published vegetation sensitivity index which used remote sensing data to test vegetation resilience towards water availability, cloudiness and temperature.

“What we found is that the same forests that are more resilient today were not necessarily as resilient in the past”, said Adolf. “We found that there was no significant link between better forest recovery rates in the past and their resilience today.” 

Cuyabeno National Park, Ecuador (c. Daniele Colombaroli)

The Cuyabeno National Park in Ecuador (c. Daniele Colombaroli)

The team found that local abiotic factors that currently favour the resilience of a forest may change over time, providing no guarantee for functioning forests faced with increasing environmental stress.

This is the first time that the insurance hypothesis - stating that more diverse ecosystems are more resilient - has been tested on many different forest types. The study highlights the importance of actively supporting forest species diversity to best protect against future disturbances, such as wildfires, droughts and hurricanes. For sustainable forest management and conservation, maintaining diversity in forests should be a main priority.