A new study has found that forests with a higher diversity of tree species are more effective at reducing temperature peaks during summer and winter, highlighting the importance of biodiversity in combating climate change.
A recent study spearheaded by researchers from the German Centre for Integrative Biodiversity Research (iDiv), Leipzig University and Martin Luther University Halle-Wittenberg (MLU) has uncovered compelling evidence that forests with a higher diversity of tree species are significantly better at buffering extreme temperature fluctuations than those with fewer species.
Published in the journal Ecology Letters, the findings suggest that diversifying tree species in forest ecosystems can play a crucial role in mitigating the adverse effects of climate change.
Mitigating Climate Extremes
As global temperatures rise due to increasing greenhouse gases, the frequency and intensity of heat peaks are becoming more pronounced.
Conversely, the frequency of cold peaks is diminishing.
Trees have long been recognized for their ability to buffer temperature extremes, yet it remained unclear whether the number of tree species — referred to as “tree species richness” — could amplify this effect.
Co-first author Florian Schnabel from the University of Freiburg, who supervised the research while working at iDiv and Leipzig University and continued this work in Freiburg, explained the importance of buffered temperatures.
“Former research has shown that the buffered temperatures below the tree canopy are important for forest biodiversity as they slow down the climate change-driven shift towards species that prefer warm temperatures,” she said in a news release.
Largest Planted Tree Diversity Experiment
To explore the relationship between tree species richness and temperature buffering, the researchers used data from the BEF-China project, the world’s largest planted tree diversity experiment situated in subtropical China.
The experiment included several hundred thousand trees planted in plots containing one, two, four, eight, 16 or 24 different tree species. Over six years, forest temperature measurements were meticulously recorded.
Key Findings
The study’s results were telling.
Forests with a rich variety of tree species showed a more significant reduction in temperatures below the canopy during heat peaks, especially during midday in the summer, compared to monoculture forests.
During cold periods, species-rich forests also maintained higher temperatures more effectively at night.
The research identified canopy density and structural diversity as critical factors in these buffering effects. Experimental plots with many tree species demonstrated a higher canopy density and greater structural diversity, which likely prevented rapid air mass mixing and enhanced temperature regulation.
“Temperature buffering effects are nice for humans seeking relief during a heatwave, but they also affect the ecosystem itself,” added co-first author Rémy Beugnon from iDiv, Leipzig University and the Centre d’Ecologie Fonctionnelle et Evolutive. “A buffered microclimate creates more favorable conditions for ecosystems and protects the services they offer.”
A Call to Action
The findings bolstered the argument for promoting tree species richness in forests worldwide, emphasizing not just biodiversity but the practical benefits of temperature regulation.
“Although typical tree monocultures as they are planted globally are important for providing timber, they do not only harbor less biodiversity than natural or diverse planted forests but provide fewer other services than wood production,” added senior author Helge Bruelheide from iDiv and MLU. “Our study clearly showed that this temperature buffering effect of tree species richness has the potential to mitigate negative effects of global warming and climate extremes on the whole forest ecosystem.”
The research underscores the significance of diverse planted forests for initiatives aimed at large-scale restoration and urban forestry projects. By promoting tree species diversity, such projects could help reduce thermal stress and build more resilient ecosystems in an increasingly warming world.