Conserve and Enhance Biodiversity and Structural and Functional Complexity of Forests

Biodiversity and structural and functional complexity of forests have relatively recently been recognized as critical concerns for public and private land management. The health and stability of ecosystems are closely related to their biodiversity. Land-use planners, land managers and policy makers frequently do not understand the full complexities inherent in the concept and NRS scientists have developed a conceptual framework that relates the different types of diversity and the different social stakes and stakeholders to scales ranging from the gene to the planet. Other NRS scientists are examining the effects of various silvicultural treatments on wildlife and forest diversity, forest dynamics, nutrient cycling, and disturbance processes, particularly those from destructive invasive insect and plant species.

Research Studies

Spatiotemporal response of the male Kirtland’s warbler population to changing landscape structure over 26 years
Species conservation remains an important challenge for ecologists and managers given the rate of habitat transformations occurring worldwide.  Strategic planning for wildlife restoration programs over broader geographic regions will become the standard rather than the exception as increasing numbers of populations become smaller and more isolated.  However, there continues to be a lack of synthesis between general principles of the fragmentation process and field evidence.  To further our understanding of habitat loss/fragmentation, we need to examine how populations that currently exist in patchy environments respond to increasing habitat amounts and changing arrangements over long time periods and broad spatial scales simultaneously.    

Impacts of harvesting forest residues for bioenergy on nutrient cycling and community assemblages in northern hardwood forests
The increasing demand to utilize slash for bioenergy purposes will compete with other ecological services forests provide.  Current site-level guidelines emphasize retaining large diameter coarse woody debris (CWD) based on many studies documenting the important role it plays in managing biodiversity and contributing to nutrient cycling.   However, little information exists to help guide land managers on appropriate levels of fine woody debris (<6 inch diameter) retention for biodiversity and nutrient cycling concerns. 

Designing Pest-Resistant Forest Landscapes: The Importance of Spatial Pattern
Defoliating insects damage millions of acres of forested land annually in the United States.  The balance of evidence suggests forest insect outbreaks today are more damaging than ever because of changes in forest composition and structure induced by fire suppression and post-harvest proliferation of tree species intolerant to herbivory.  Our central hypothesis is that landscape connectivity of acceptable host types increases defoliator population connectivity, altering the dynamics and spatial structure of defoliator populations, and thus increasing forest susceptibility to insect pest damage.   

Studying fire mitigation strategies in multi-ownership landscapes: Balancing management of fire-dependent ecosystems and fire risk.
Fire risk mitigation within multi-owner landscapes containing flammable but fire-dependent ecosystems epitomizes the complexities of managing public lands.  The cumulative effects of fire and forest management over the last century have exacerbated fire risk in some regions and threatened fire-dependent systems in many others.  The issue is further complicated by the recent encroachment of human homes into fire prone ecosystems that simultaneously increase fire ignitions and increase demands on fire suppression agencies to protect lives and property.  Consequently, the balance between forest restoration, human rural development, and fire risk remains an issue of major concern to natural resource agencies.

The Working Forest Initiative: Simulating the cumulative effects of the forest management strategies of multiple landowners on landscape pattern and biodiversity
Sustainable forestry involves the extraction of forest products while maintaining ecosystem integrity to conserve biodiversity and to provide other non-commodity benefits to society.  Population viability is a function of the combined actions of multiple landowners, which create a dynamic mosaic of forest types, stand structures and age distributions.  Consequently, it is necessary to understand how the actions of individual land owners interact with the actions of others to determine the spatial pattern of the landscape mosaic, and therefore its ability to maintain biodiversity. 

Tree roots made visible in "Rhizotron"
Trees contribute massive amounts of organic matter to forest soils in the form of fine root inputs and litterfall. Soils, in turn, supply trees with water and nutrients essential for growth. All of this is mediated by an intricate web of interactions between tree roots and soil organisms. NRS scientists are studying how forest management and environmental change affect these biological processes, which will help us determine what can be done to increase the productivity and sustainability of our forests

Silvicultural treatments can increase forest complexity
In many areas of the Northeast and the upper Midwest, clearing for agriculture and intensive logging have resulted in many even-aged forests with little biodiversity. Many land managers are struggling to restore some semblance of the age, species, and structural diversity of forest types found in pre-settlement hardwood forests. Many management guides have suggested cutting small gaps, resulting in forests dominated by sugar maple. NRS researchers are studying the ecological response to small and large gaps and their effectiveness in creative forest diversity