Climate change and insect defoliation in the New Jersey Pine Barrens

CBI, in collaboration with the US Forest Service, will assess and predict the interactive effects of insect defoliation events (principally gypsy moth), fire management, and climate change on forest productivity, species composition, and tree mortality in the New Jersey Pine Barrens.  Using management scenarios developed based on current management practices and potential carbon management practices; we will determine how interactions among these disturbances affect management goals. This project will help provide a predictive framework for working through landscape to regional management scenarios in areas with multiple, interacting management priorities that can be applied across the US, especially in areas where insect and fire disturbances interact.

Gypsy moth is a major defoliator throughout the northern hemisphere. It is estimated that gypsy moth in the US are currently infesting only 23% of the land area that they could potentially occupy (Morin et. al. 2005), and will very likely spread to all of the hardwood forest in the U.S and Canada in the near future.  Gypsy moth first appeared in forests in New Jersey in 1966.  Since then, three major defoliation events have occurred; 1972 (256,000 acres), 1981 (798,000 acres) and 1990 (431,000 acres). In the New Jersey Pine Barrens (NJPB), another frequent disturbance, fire, can affect thousands of acres each year.  Individually, these disturbances can cause strong reductions in annual forest productivity and longer-term changes in species composition, but it is unclear how insect defoliation and fire events interact and what the effects of these interactions are.  A likely interaction might include species composition changes due to insect defoliation related tree mortality increasing fire risk by selecting for fire prone early successional species like pines.  Furthermore, climate change is certain to have its own effects on forest productivity and species composition in the NJPB, and may interact with insect defoliation and fire in ways that are as yet unknown.

Management of insect defoliation and fire in the NJPB are typically considered separately.  In the last decade, however, officials in the state of New Jersey have become increasingly interested in managing carbon as indicated by participation in the Regional Greenhouse Gas Initiative (www.rggi.org) and statements by the Department of Environmental Protection regarding managing for carbon sequestration on state lands.  Given that insect defoliations and fire both can alter the carbon storage and fluxes of forests, it is apparent that a system of integrated management will be necessary for achieving carbon sequestration goals in the face of defoliation events, fire, and climate change.

For more information about this ongoing project, contact Robert Scheller.