New global maps of temperatures within tropical forests demonstrate that global warming has distinct effects in different sections of the forest. The temperature of the undergrowth in tropical woods can be up to 4 degrees lower than the area’s average temperature.
Tropical forests are home to up to half of the world’s biodiversity, but ecological studies on tropical forests have traditionally relied on large-scale datasets depicting open-air temperatures, which can differ by several degrees from temperatures inside the forest. This constraint created a significant obstacle to our knowledge of how species will respond to climate change.
The research coordinated at the University of Helsinki and the Finnish Meteorological Institute by associate professor Eduardo Maeda, has now achieved a major step to overcome this limitation. The results have been published in the scientific journal Nature Communication.
Our research demonstrates that these variations exist not only in terms of magnitude (i.e., the absolute difference between temperature inside and outside the forest), but also in terms of geographical and temporal heterogeneity.
Eduardo Maeda
Hotspots of microclimate refugia
Temperature is a critical element in determining the survival, growth, and reproduction rates of organisms living in tropical forests. A new study gives temperature maps inside forests, which ecologists may use to significantly improve the robustness of species distribution models.
“The maps will help to predict with higher confidence how species will respond to climate change, such as to where species are more likely to migrate,” Maeda said in a press release.
Furthermore, we can detect hotspots of microclimate refugia. These places are anticipated to become increasingly essential in a warming future; using this study’s highly accurate maps, we can now show policymakers where these areas are, allowing them to be protected more efficiently.
Building on an extensive international collaboration effort, the researchers compiled data from hundreds of temperature sensors installed inside tropical forests across the world. The study also used satellite data that provided information on different characteristics of the forests, such as the height of the trees and the leaf density. All this information were combined in a machine learning algorithm that was able to estimate temperatures inside tropical forests throughout the entire planet.
The result of this study demonstrates an amazing variability in the temperatures experienced inside forests, which were not visible from other available datasets. For example, the differences between temperatures inside and outside forests are larger in regions with a distinct dry season (e.g., in the southern Amazon forest). Areas with lower rainfall are usually associated with higher temperatures, but this study demonstrate that the deep roots of tropical trees can still access water reserves, thus maintaining their ‘airconditioning’ function in the ecosystem.
“We already knew that temperatures inside woods fluctuate significantly from those outside them. Our research demonstrates that these variations exist not only in terms of magnitude (i.e., the absolute difference between temperature inside and outside the forest), but also in terms of geographical and temporal heterogeneity,” explains Maeda.
Similarly, many other human-caused disturbances, such as selective logging or fires, can have an impact on forest temperatures. Without a baseline of expected temperatures, we would have no idea how these disruptions are affecting the climate conditions inside forests.
