Rapid: Assessing Temporal Dynamics of Disturbance Interactions as a Driver of a Novel Forest Mortality Event

University Of Connecticut, Storrs CT

Investigators

Abstract

In many forested regions of the world, disturbances caused by introduced pests and pathogens, along with changing climatic conditions, has resulted in forest health impacts. As these types of disturbances become more frequent, the interactions between them can greatly amplify the impacts on forest health and sustainability. This project will study an unprecedented, ongoing forest mortality event that affects oak-dominated forests in southern New England. Tree mortaility appears to be related to the interaction of both drought and multiple canopy defoliations by non-native Gypsy Moth caterpillars. This project will evaluate how the timing and interactions of those disturbances matters in forest health. The research will assess if areas that have greater tree mortality are those that experienced the most intense initial drought or if they underwent defoliation closer in time to the drought. The results of the project will be very valuable to forest stakeholders, helping them understand the underlying causes of the tree mortality event and potentially allowing prediction of future impacts. The investigators are highly engaged with the regional forest management community and the results of the project will be used in planning forest management strategies including tree removals related to this mortality event. The project is important as it will communicate the potential ramifications for wood products markets, forestry and arboriculture practices, and general forest use by the public. Interactions between climate-mediated disturbances, such as droughts, and biotic disturbances, such as defoliating insect pests, are increasingly driving continental-scale forest structure and function. However, the temporal lags associated with drought effects on biotic disturbance are not well understood and empirical data to address this topic are lacking. The central hypothesis of this project is that the effect of interacting drought and defoliation disturbance will be mediated by temporal proximity between disturbances and initial drought severity. The project will combine high temporal and spatial resolution remote sensing analysis with dendrochronological reconstruction of forest growth patterns to assess how the timing and severity of interacting disturbances affects patterns of disturbance resistance, forest productivity, and tree mortality in temperate forest ecosystems. The study will be conducted in a network of forest stands, identified through the remote sensing analysis, which will be replicated across categories of defoliation timing in relation to the initial drought disturbance. The results of the project will support hypothesis generation, model parameterization, and general conceptual frameworks for future experimental and modeling studies that can evaluate the mechanistic basis for, and consequences of, disturbance interactions in terrestrial ecosystems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.