Restoring tropical landscapes with resilient forests in the context of climate change mitigation

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Tropical forests are critical in the face of climate change. They hold over 40% of terrestrial carbon, occupy 12% of terrestrial surface and harbour more than half of terrestrial diversity. While avoiding deforestation is one way to reduce global greenhouse gas emissions, reforestation and forest restoration offer an opportunity to remove CO2 from the atmosphere. With a climate mitigation potential estimated at >11 PgCO2e yr-1 up until 2030, tropical landscapes are at the forefront of climate action. In this context, my NSERC Discovery Grant focuses on tropical forests' resilience to the changing climate. It has been suggested that climate-related increases in temperature and drought could globally shift tropical forests from a carbon sink to source. The potential of forests to serve as climate solutions rests on their long-term resilience and ability to withstand chronic effects of climate change and other anthropogenic drivers of degradation. I therefore propose to combine research on an experimental forest, established to study the relationship between tree diversity and ecosystem function, and on the attributes of climate resilience in forested landscapes. In 2001, I planted an experimental forest in Central Panama with monoculture plots and mixture plots. Since then, it has experienced one extreme wet event, one extreme wet dry spell over three consecutive years and one tropical storm. Long-term monitoring of tree growth and other ecosystem functions, such as the production of leaf litter and of coarse woody debris, offers a unique opportunity to unravel the mechanism that makes mixture plots more resilient to extreme climate events. In addition, I will advance the understanding of climate resilience by measuring a number of functional traits related to drought resistance in canopy trees and saplings of both moist and tropical dry planted forests. The hypothesis being tested is that, as the climate is becoming drier, saplings harbouring traits related to drought tolerance will increase in abundance, thereby enhancing forest resilience. I will also examine landscape connectivity as a key element of landscape resilience, comparing saplings and canopy tree diversity and functional traits in intact and fragmented landscapes. My research will advance our understanding of the climate resilience of tropical forests at a time of worldwide concern over the fate of the Amazonian forests. Furthermore, under the leadership of Germany, a number of countries have joined the Bonn Challenge, a global effort to bring 150 million hectares of deforested and degraded land into restoration by 2020 and 350 million hectares by 2030. My Discovery Grant research holds the potential of having a major real-world impact by providing guidance on how to enhance the climate resilience of reforestation and forest restoration projects.