Conserve and Enhance Biodiversity and Structural and Functional Complexity of Forests and Grasslands

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

A “Serious Game” to Explore Possible Forest Futures
We adapted IMPACT: A Foresight Game created by Idea Couture to a game that focuses on forests. Players take on an avatar with a forestry job of the future – like experience concierge or bug wrangler – and play impact cards to achieve the desired future condition for their avatar. Each impact is based on real-world events that signal change in one of ten domains: forest ecosystems, water, recreation, community & culture, energy, work, transportation, medicine & wellness, forest products, and food, agriculture & ranching. Disrupter cards create significant change immediately – these are the wild cards.

American Chestnut Restoration
Non-native pest and pathogen invasions have had catastrophic impacts on an increasing number of tree species worldwide. One of the most well-known tree species restoration efforts is that of American chestnut (Castanea dentata). American chestnut was a dominant forest tree throughout much of the Eastern United States through the early 20th century. The tree was ecologically important as a source of mast for wildlife, and economically valuable for its rot-resistant lumber, high-tannin content, and edible nuts.

American Elm Restoration
A fungal disease affecting elms was first described in 1919 in the Netherlands, and was therefore named Dutch elm disease (DED). From this initial outbreak, DED spread rapidly throughout Europe and, by 1934, was found across the continent. The disease, which entered the United States on European shipments of unpeeled veneer logs, was first observed in Ohio in 1930. By 1976 only 34 million of the estimated 77 million elms present in urban locations remained, and far fewer are present today – making DED one of the most commonly known and destructive tree diseases in the world.

Identifying Plant Compounds in Northern White Cedar that Protect Against White-Tailed Deer Browse
Northern white cedar (Thuja occidentalis L.), also known as arborvitae, is an important tree species notable for its use in agroforestry windbreak systems. Difficulties in natural regeneration of northern white cedar in forested landscapes have caused concerns for the long-term sustainability of the species.

The PHiLL Project: Creating Pollinator Habitat in Log Landings
Log landings, open areas in forests where logs are processed and stacked before being loaded onto logging trucks, have been identified as sites with potential to boost floral resources and in turn bee populations. On the Hoosier National Forest in Indiana, forest staff have been leading an effort to facilitate the rapid establishment of ephemeral pollinator habitat in recent log landings. They have run into several barriers to success, however. Soil compaction, fertility, and erosion, residual mulch and logging debris, and competition from invasive species have limited germination and growth of seeded species. Soil remediation and biochar as a soil amendment coupled with enrichment plantings could increase success.

Anthropogenic Actions Trigger the Rise and Fall of Black Cherry
Scientists aimed to determine the underlying causes of observed declines in black cherry by using a combination of synthesis of existing work and new analyses. They focused on five factors known or assumed to influence forest health broadly and black cherry dynamics specifically: climate variability, deer browsing, senescence, negative plant–soil microbe feedback loops (i.e., pathogens), and reduced nitrogen availability.

Forest Management Improves Health of Eastern White Pine
An interdisciplinary team, representing experts in the fields of insects, disease, and forest management, have come together to produce a field guide aimed at improving long-term health and resiliency in white pine forests as the environment changes.

Leaving an Uncut Tree Facilitates Tree Seedling Diversity in Forest Openings
Researchers with the Northern Research Station and Michigan Technological University experimented with harvesting configurations and resurrected a century-old logging practice to devise a strategy that could preserve the long-term health and diversity of future forests

Management Guides Target Red Oak and White Pine Regeneration in New England
The historical events that resulted in the abundance of red oak and white pine can no longer be replicated because of how developed the northeastern United States has become and the patchwork of mixed land ownership. However, a collaboration of researchers from the Northern Research Station, other Federal and State agencies, and academic institutions has produced two management guides (one for each tree species) containing silvicultural methods that can mimic those disturbances and replicate their results.

Restoring a Gradient of Canopy Openness in Northern Dry Forests - A Research-Management Partnership at Lakewood Southeast
Fire suppression combined with succession has drastically reduced open barren and savannah systems in northern Wisconsin.  These fire-prone systems are now rare and exist primarily as remnant patches.  In 2014, the Chequamegon-Nicolet National Forest (CNNF) began a landscape-scale effort to restore Pine Barrens and Northern Dry Forest ecosystem attributes (37,000 acres).  The desired future condition is a landscape with a gradient of open conditions to pine/oak forest types that will be achieved by increasing fire disturbance, decreasing fuel loading/fire risk, lowering forest stocking/tree density, and altering stand age structure with establishment of new age cohorts.

Does Soil Heating from Fire Accelerate Pine Barren Restoration? A Research-Management Partnership at Moquah Barrens
Fire suppression combined with succession has drastically reduced open barren and savannah systems in northern Wisconsin.  These fire-prone systems are now rare and exist primarily as remnant patches.  In 2014, the Chequamegon-Nicolet National Forest (CNNF) began a landscape-scale effort to restore Pine Barrens and Northern Dry Forest ecosystem attributes (37,000 acres).  The desired future condition is a landscape with a gradient of open conditions to pine/oak forest types that will be achieved by increasing fire disturbance, decreasing fuel loading/fire risk, lowering forest stocking/tree density, and altering stand age structure with establishment of new age cohorts.

Evaluating Restoration and Reconstruction Techniques in Missouri Prairie, Savanna, and Woodland
Northern Research Station scientists based in Columbia are collaborating with faculty from the University of Missouri on research addressing management concerns on the Prairie Fork Conservation Area, including controlling an invasive plant called sericea lespedeza in reconstructed prairie and establishing the diverse communities of native plants that are found in savanna and woodland ecosystems, both of which are restoration needs at the Prairie Fork Conservation Area and throughout Missouri.

Goats, Fire, and Woodlands
With colleagues at the Mark Twain National Forest and the University of Missouri, Northern Research Station scientists are determining the effects of prescriptive grazing and fire on woodland management.

Understanding How Soil Bacteria and Fungi Affect Forest Health
Northern Research Station scientists are conducting genetic and field research to identify soil microbes and to better understand how deficiencies in forest soil nutrients affect forest health and ecosystem function.

Using Biotechnology to Emphasize Desirable Tree Characteristics
Northern Research Station scientists used a process called somatic embryogenesis in which a plant or a plant embryo is derived from a single cell or group of cells from normal plant tissue, as opposed to the cells that are normally involved in embryo development. This process can be used to guide plant breeding efforts and to study the molecular and biochemical processes that occur during plant embryo development.

Fungi Control Nutrient Availability to Trees
Our research focusses on how decay fungi influence nutrient cycling, soil carbon sequestration and its effects on nutrient exchange with tree roots, beneficial mycorrhizal fungi that are needed for nutrient uptake by trees, and the role of mycorrhizal fungi in tree nutrition. Many of these studies are coupled with measurement of forest productivity, and some of them are associated with natural forest disturbances and forestry operations.

Identification and Classification of Boletes
It is important to determine which species of boletes are associated with particular host tree species in order to understand the host-fungal relationship. Our research also looks for connections between fungi from the eastern and western continental USA and the Caribbean Basin, providing important data on dispersal patterns of ectomycorrhizal fungi as changes occur in the ranges of host trees.

Mycorrhizal Fungi
Mycorrhizal fungi grow along tree roots and play critically important roles in maintaining tree health in forests and urban areas throughout the world. They help trees obtain nutrients and water more efficiently. The fruiting bodies of truffles and similar ectomycorrhizal fungi are an important source of food for small mammals. Many kinds of trees including pines, spruces, firs, oaks, chestnuts, beech and aspen are strongly dependent on their mycorrhizal fungal partners.

Brown-Rot Fungus Fomitopsis pinicola
Fomitopsis pinicola, a fungus with an important role in carbon cycling, is found on decaying logs and live trees throughout forests in the northern hemisphere. Based on its varied appearance and host range, scientists were not sure if F. pinicola was one species or a few species with overlapping characteristics. For a fungus with an important ecological impact, it is critical to have exact species identification and a good working description of the characteristics and host range.

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.  Our goal is to investigate the impact of fine woody debris (FWD; <6 inches diameter) removal on nutrient availability and above and belowground community assemblages on rich soils under regenerating northern hardwood stands in Wisconsin. 

Regeneration by Oak Seedlings and Stump Sprouts in Pennsylvania
Oak regeneration results from larger oak seedlings and stump sprouts. Guidelines to measure possible future regeneration are important for good forest management planning. Although guidelines have been developed for many oak forest types, no studies have been done in Pennsylvania or in areas with significant deer browsing pressure. Previous work has shown that oak dominance probabilities vary by site index, slope position, aspect, and geographic region, pointing out the need to produce data for Pennsylvania conditions. 

Oak Seedling Development
Regenerating mature oak forests after harvest to develop thrifty new stands with a young oak component is a serious problem throughout the range of oak in the Northeast and Midwest.  Large oak seedlings present before harvest are necessary for good regeneration, and small oak seedlings seldom grow to gain dominance in the new developing stands.  Many factors can limit good regeneration---excessive deer browsing, especially when combined with competition from understory plants or ferns (“fern deserts”), and dense shade from the midstory. 

Patch Retention
Patch retention can be used to maintain certain components of biodiversity by leaving trees normally cut during a timber harvest. Patch retention (patch retention, tree islands, leave patches, buffer strips, trail corridors) is applied during harvests, thinnings, regeneration cuts, and other silvicultural treatments to achieve desired ecological characteristics at different scales, ranging from sub-stand to watersheds and landscapes. Landowners and managers need information about the tradeoffs between economic costs and ecological benefits to determine how to apply patch retention at levels consistent with their management goals. 

Riparian Zone Protection
Streams, wetlands, and riparian areas are some of the most valuable natural areas. From an ecological / biological perspective, riparian areas are among the most productive wildlife habitat on the continent. Because of their ecological importance, the protection of riparian areas is a top priority with most state and federal conservation agencies. Riparian areas also are some of the best sites for producing high-quality wood products.  

Soil Compaction/Disturbance
All harvesting operations cause some soil compaction, but the degree of compaction varies with harvesting equipment, techniques, intensity, and soil properties, especially moisture content and texture. Soil compaction and disturbance may lead to erosion and sedimentation. The degree of soil compaction also varies with the number of times a loaded/unloaded machine travels over a given path (traffic intensity) and the payload. High levels of compaction can lead to reduced growth of young and larger trees in the residual stand.

Long-Term Soil Productivity
The USDA Forest Service’s Long-Term Soil Productivity (LTSP) program began in 1989 in the Southern Research Station to address land managers’ concerns about the long-term consequences of soil disturbance on fundamental forest productivity.  It eventually grew into a national program of the USDA Forest Service.

Agroforestry Practices for Biodiversity Conservation
Agroforestry in the temperate region is the intentional integration of trees and shrubs with livestock or crops into intensive land management systems. It can include practices such as alley-cropping, silvopastural, and riparian buffers. Integrating woody vegetation with grasses and forbs provides a wider range of habitats than would typically be found in most agricultural systems and can also enhance the production of clean water.

The Role of Fire in Restoration of Woodlands and Savannas
Our research is focused on understanding the role of fire in sustaining woodland and savanna composition and structure. Our goals are to develop fundamental information about how to manage and regenerate oak and oak-pine woodlands and savannas with timber harvests and prescribed fire and to use this information to develop management guidelines to be applied on both public and private land.

The Ecology and Silviculture for Restoration of Shortleaf Pine
There is renewed interest in restoring shortleaf pine throughout its native range in the Ozark Highlands and elsewhere in the Central Hardwood Forest Region and in the southeastern United States. Restoring shortleaf pine on former pine and oak-pine sites is viewed as a long-term strategy for mitigating chronic oak decline. There also is an increasing interest in restoring native oak-pine woodland communities where they once were abundant.

Computer-Coded Content Analysis as a Research Method
Analysis of news media content has repeatedly produced results that parallel the findings of attitude surveys for many public policy issues, including environmental and natural resource issues. Studies have found that the news media strongly influence agenda setting for public policy issues; that is, there is a relationship between the emphasis that the media give to an issue and how prominent the topic is among the general public. Therefore, analysis of the public debate about social issues in the news media is not simply ‘‘media analysis’’; it is a window into the broader social debate and a way to gauge, indirectly, public attitudes and values.

Forest Value Orientations in Australia
We used computer-coded content analysis to explore forest values expressed in the public news media discussion in Australia between 1997 and 2004. The final database included 14,413 paragraphs from 4034 relevant stories over the eight-year period.

Long-term Change at Hearts Content and Tionesta Scenic and Research Natural Area
Our ability to understand how unmanaged forests develop over time through various climatic and environmental changes depends on long-term data from unmanaged forests, especially remnants of the forest that predated European settlement of our region. Impacts of acid deposition, deer overabundance, beech bark disease, recovery of vegetation after windthrow, climate change, invasive plants – all are better understood by examining their effects in forests that have not been directly manipulated by humans, as well as those that have been managed.

Planning Informed by Alternative Future Watershed Ecosystem Services
Scientists from the USDA Forest Service Northern Research Station, University of Minnesota, and the Harvard Forest are involved in a research project focused on creating plausible scenarios or “storylines” about the future of forests and ecosystem services within a large watershed basin of northeast Minnesota, including Duluth MN and Superior WI.

Testing Silvicultural Approaches to Reintroduce American Chestnut to the Allegheny National Forest

Mature American chestnut vanished nearly a century ago. In forests now altered by invasive species – both plants and insects – and fragmented by urban development, how can it be successfully planted back into the landscape?

To address this question, specifically for the Allegheny National Forest (ANF), we are establishing a 10-year study to evaluate the influence of light availability and abundance of competing seedlings on long-term growth and survival of hybrid American chestnut seed and seedlings. The main objective is to test the long-term survival and growth of chestnut planted in each of the three stages of the three-stage shelterwood sequence used to regenerate oak.

Intensive Management of Hardwood Plantings
In the 1960s the diminishing supply of quality hardwood saw timber, especially black walnut, raised the question of how best to grow hardwoods in plantations to assure future supplies.  At the time, we determined the most promising native hardwood for timber production in intensively managed plantings was black walnut, white ash, and several of the oak species.  

Native Invasive Species
Recent changes in disturbance and browsing regimes have strongly impacted species composition in forest understories worldwide.  In some cases, these changes have led to large increases in the density and cover of a small number of native understory plant species which may then expand to form interfering vegetation layers. 

Catastrophic Wind Disturbance
In eastern forests, severe wind disturbances are common and salvaging occurs after these disturbances.  The Allegheny Plateau region alone receives an average of 11 high wind events and one tornado per year (National Climate Data Center) making wind the predominant natural disturbance event.  Given the ubiquity of storm damage and salvaging on the Allegheny and elsewhere, there is a surprising paucity of experimental work demonstrating the impact of salvage logging on post-disturbance forest regeneration patterns. 

Regeneration of Northern and Allegheny Hardwoods
The Allegheny hardwood forest type is a variant of the northern hardwood type consisting primarily of black cherry, red maple, sugar maple and American beech. Associated species include white ash, yellow‑poplar, black birch, yellow birch, cucumber magnolia and hemlock. Black cherry and the maples usually dominate stands in Pennsylvania and southward; white ash and sugar maple tend to be more important, and red maple less important, in the New York portion of the range.

Restoration of Mixed Oak Forests in Southern Ohio with Prescribed Fire
In the eastern U.S., fire suppression has been implicated as a primary factor facilitating shifts in forest composition from oak to other species, often maples. The state of Ohio began suppressing fires in 1923. Oaks are considered well-adapted to a regime of frequent low- to moderate-intensity fires because they possess thick bark, the ability sprout repeatedly after being topkilled, and are intermediate in shade tolerance.

Central Appalachian Forests: Past and Present
There is increasing acceptance of the historical role of fire in shaping the composition and structure of oak forests in the eastern United States.  There is evidence that fires in the Central Appalachians occurred at intervals of 5 to 15 years during the previous four centuries. 
 

Restoration of Red Spruce Forest Ecosystems
Central Appalachian montane red spruce (Picea rubens) forests have been greatly reduced in extent and integrity over the past century.  This decline has put several species at risk from habitat loss, most notably the Virginia northern flying squirrel and the Cheat Mountain salamander.  Also, these forests are no longer considered a commercially viable forest type in the region.   

Understanding and Using Prescribed Fire
There is increasing acceptance of the historical role of fire in shaping the composition and structure of oak forests in the eastern United States.  There is evidence that fires in the Central Appalachians occurred at intervals of 5 to 15 years during the previous four centuries.   

Coarse Woody Debris
A proportion of the carbon in forest ecosystems is contained in coarse woody debris on the forest floor. Estimating the carbon stock and other attributes of coarse woody debris can be time consuming and error-prone. New methods for field sampling of coarse woody debris are needed for efficient estimation of the carbon stock in this forest pool.

Sustaining Central Hardwood Forests
A number of challenges to sustain central hardwood forests face managers today. For example, it is difficult to sustain the current level of oak stocking in mature forests in many areas, especially on more productive sites. Oak species are often replaced by either more shade-tolerant species such as maples, or by fast growing species such as tulip tree (yellow-poplar) when forests are regenerated either by managed harvesting or natural disturbances. This is a problem in both upland and bottomland forests.

Restoring Forests in Bottomland Fields
We have identified several promising practices and seedling types that can be used to successfully restore oak to future bottomland forests when bringing marginal agricultural lands back into forest production.

Contrasting Silvicultural Systems
In order to provide science-based guidance to society and landowners to support their silvicultural decisions, scientists must implement replicated examples of different silvicultural treatments and assess their outcomes. Such research often requires decades of measurements, and outcomes and outputs vary by forest type and ecoregion. Results can also be complicated by interactions among silvicultural systems and treatments and other landscape scale disturbances

Ecosystem Management Study: Restoration of Mixed-oak Forests with Prescribed Fire
Historically, fire was a frequent disturbance process in the mixed-oak forests of the central hardwoods region. Fire control has altered forest structure and composition. Forests are more dense and the sustainability of oak and hickory dominance is now threatened by an abundance of shade-tolerant and fire sensitive tree species such as red maple, sugar maple, and beech. Prescribed fire has been advocated to promote and sustain open-structured mixed-oak forests and the plants and animals that have adapted to these communities. However, long-term research on fire effects is lacking.

Plant Diversity in Managed Forests
The great majority of plant diversity in forests is contained in the herbaceous layer, comprised of both herbaceous and woody species.  We seek a better understanding of how forest management activities affect plant diversity.  NRS-2 scientists are investigating the direct and indirect effects of timber harvesting, prescribed burning, herbicide application, and deer browsing (alone and in combination) on plant composition and diversity in mixed oak, Allegheny, and Northern Hardwood forests.

Thinning in Mixed Hardwood Forests
Very little was known about managing the growth and quality of hardwood forests in the east as the second- and third-growth forests were developing. Studies of “growth and yield” were established to quantify the growing capacity of these forests.

Site, Stress, Nutrition, and Forest Health Interactions
A range of stressors including defoliating insects, pathogens, droughts, inadequate soil base cations, and changing climate have interacted to affect the health and regeneration of selected northern and central hardwood forest species. In the 1980s and 1990s sugar maple dieback and mortality was extensive across the unglaciated Allegheny Plateau in northern Pennsylvania. 

Interactions between Fire, Gaps, and Deer Browsing
In eastern deciduous forests, low-intensity understory fires, canopy gaps, and ungulate browsing are generally regarded as the main forces influencing vegetation dynamics.  Over the past 100 years, all three of these historic disturbance and herbivory regimes have been altered to some extent (e.g., fire suppression, smaller, less frequent gap formation in 2nd growth forests, and overabundant deer herds) and have been putatively linked to observed changes in regeneration patterns and losses in understory herbaceous diversity. 

SILVAH - Training Sessions and Computer Software
The SILVAH framework has been adopted by many public and private forest management agencies, and many depend upon the decision-support software to analyze inventory data and recommend prescriptions.  Initially developed for Allegheny hardwood forests, much of the focus in recent years has been expanding the SILVAH framework to incorporate recommendations for sustaining the oak component of mixed oak forests. 

Deer Impacts: Primary, Secondary (Interfering Plants), Tertiary (Faciltated Seed Predation)
Overabundant white-tailed deer (Odocoileus virginianus) herds have been shown to be a key determinant of understory plant species composition in  many parts of eastern North America over the last century.   The primary, direct effect of chronic overbrowsing is the reduction in growth and survival of browse-intolerant plant species which ultimately shifts species composition towards a few highly browse-tolerant or unpalatable species.  Such shifts in plant dominance patterns may secondarily result in altered plant-plant competitive dynamics in forests understories.  Finally, through modification of plant composition and structure, deer overbrowsing may also exert indirect effects on the habitat and foraging patterns of other animal species.

Landscape-level Effects of Thinning and Burning
Oak regeneration continues to be a problem in the Central Hardwoods region of the US. In the absence of regular fire (as was common before European settlement and fire regulatory agencies in the ~1920’s), the canopy closes and oak regeneration is often preempted by more shade-tolerant species like maples. The Fire and Fire Surrogates Study (FFS) is aimed to better understand the influence of multiple fires and thinning on oak regeneration. This research is a component of the FFS work in Ohio.

Fire and Fire Surrogate Treatments: The Central Appalachian Plateau Site
Current forests in many fire-dependent ecosystems of the United States are denser and more spatially uniform, have many more small trees and fewer large trees than did their presettlement counterparts. Causes include fire suppression, past livestock grazing and timber harvests, and changes in land use. The results include a general deterioration in forest ecosystem integrity and the threat of losing important, widespread forest types. Such conditions are prevalent nationally, especially in forests with historically short-interval, low- to moderate-severity fire regimes, such as the upland oak forests of the central hardwoods region.   

SILVAH NNIS
As we have planned to increase our SILVAH training and decision support in Ohio, several of our partners suggested that ignoring NNIS was not an option.  Pending development of better guidelines for recognizing when NNIS are abundant enough to pose a threat to management objectives and treatment options, SILVAH currently provides a format for recording presence absence and frequency data about several NNIS that are important in Ohio and elsewhere in the mixed hardwood forests of the east.  SILVAH flags the presence of such species and encourages users to investigate treatment options for NNIS before undertaking the silvicultural treatments that SILVAH recommends. 

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. 

Conserving Wildlife in Managed Forests
Public land managers are mandated to sustain viable populations of all species on their lands, which requires an understanding how wildlife populations respond to forest management practices. Our research focuses on forest birds, as populations of many species of eastern deciduous forests are declining across their range, raising concerns over possible negative effects of timber management.  

Saving the Butternut
The butternut canker disease is killing butternut and threatening the future of this important hardwood species throughout its range in North America.

Tropical Forest Mycology
The Center for Forest Mycology Research (CFMR, part of the Northern Research Station of the US Forest Service) leads critical research on the biology of tropical fungi native to Hawaii, US territories in the Caribbean (Puerto Rico and the US Virgin Islands) and to other countries in the Caribbean Basin.

Collections at the Center for Forest Mycology Research
Forest fungi are critically important for forest health and productivity. Of the estimated 1.5 million species of fungi worldwide, only about 5% have been described and named. Key characteristics used to identify species and the relationships among species are in a critical period of change. 

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. 

Earthworm Invasion
Populations of exotic European earthworms have been expanding into formerly worm-free forests in the north central and northeastern United States.  These earthworms consume the organic horizons of the forest floor, often removing leaf litter within several years of invasion.  This leads to changes in soil carbon, nutrients (e.g. nitrogen and calcium), soil microclimate, hydrology, soil organisms, and plant community assemblages. 

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