Thresholds and tipping points in ecosystem responses to global warming

Terrestrial ecosystems are important in providing key services to humankind, but under global warming the provisioning of such ecosystem services is at risk.

However, there is little consensus on how the functioning of terrestrial ecosystems will change under projected scenarios of global warming, or when we will reach or surpass thresholds and tipping points.

This is largely because most studies have failed to unravel ecosystem responses to increasing temperatures in terms of the underlying non-linear responses of plants, soil organisms, and their communities.

Since plants and their associated soil organisms (i.e., pathogens, mutualists, and decomposers) can vary in their responses to temperature change, global warming may disrupt or decouple interactions among coexisting and co-evolved species.

This may have unforeseen consequences for key ecosystem functions, such as carbon and nutrient cycling.THRESHOLD will use a novel cross-disciplinary approach to advance our fundamental knowledge of how non-linear temperature responses transcend different levels of ecological organization.

Specifically, this project aims to:1) Establish a global network of forest-tundra and forest-alpine ecotone sites, to assess how responses of ecosystem carbon and nutrient cycling to global warming will be pushed across thresholds and tipping points.2) Perform mesocosm experiments under different temperatures, to estimate how ecosystem process responses to global warming can be predicted from the reordering of plant and soil communities, as well as from the functional traits that they possess and express.3) Reveal how community responses to warming and extreme temperatures can be predicted from the physiological responses of their component species.To achieve these aims, this work will utilize a powerful approach that harnesses an array of cutting-edge tools, and it will advance our conceptual understanding in an area of urgent importance for ecology and society.