Last modified 09/19/2006
by Tim Stone
Ecology and Management of Northern Forests
Provide the scientific foundation for sustainable management of northern forests through research and technology transfer .
The Northeast-from Ohio and West Virginia to Maine-is over 60 percent forested, making it the most densely forested region of the country. Northern New England is the most densely forested section of the Northeast with over 85 percent covered in a diverse mix of forest types. It was not always so. From colonial times until after the Civil War, much of New England was cleared for pasture or crops and the landscape was a patchwork of farms and small woodlots. Maine was settled later than the rest of New England and vast areas on the interior were never cleared for agriculture, although sawmilling in America began in Maine in the 1600s.
Before European settlers cleared the land, American Indians made openings and used fire to manage the forest for crops and game. Centuries of manipulation have shaped the composition and structure of New England forests and the wildlife populations that depend on those forests. These human-caused changes are overlain on complex physiography resulting from a rich geological history and repeated glaciation. Thus, the forested landscape of New England and adjacent New York and Canada, which share similar forest types and histories, provides a tremendous challenge to understanding effects of natural and anthropogenic disturbances on ecological processes, function and structure.
In addition to being the most densely forested region, the Northeast is also the most densely populated. Nine of the 10 most densely populated states are in the Northeast (US Census Bureau). Even the most remote corners of northern New England are within a day or two drive for over 50 million people. The demands these people have for forest resources are diverse, often competing, and sometimes incompatible. The complex social structure of the region adds to the challenge of meeting our mission of providing the scientific knowledge required for managing northern forest ecosystems sustainably.
The National Research Council recently stated that forestry research is at a crossroads (Cubbage and others 2002). As population grows, demands on forests for commodity production, recreation, and environmental services increase, social and market forces change ownership patterns, and population and economic pressures divide the landbase into increasingly smaller parcels. Discovering and developing new knowledge through research, then putting that knowledge to use, are the only means for meeting increasing demands with decreasing supply. Forestry research spans a continuum from the foundation disciplines of biology, ecology, and management to emerging fields like remote sensing and process modeling. Although research on the foundation has been ongoing for a century, the need to meet ever stricter environmental and social standards, international pressure for sustainable forest management, increases in forest recreation, concerns about invasive species, advances in biotechnology, and many other factors, require new knowledge that can only be achieved through a continued focus on biology and management research. At the other end of the continuum, research on more contemporary subjects leads to new knowledge that improves our understanding of the forest and new tools that enable managers to better manage and utilize resources. The continuum provides a feedback mechanism that advances the science and practice of forestry. Research by the staff of NRS-4155 spans the continuum. Our research program is complemented with a vigorous effort at technology transfer and implementation, striving to ensure that new knowledge is put to effective use on the ground.
Given the strengths of the RWU and current and anticipated resources, the staff of NRS-4155 has identified four researchable problem areas to address under this Research Work Unit Description (RWUD); that is, over the next five years. The problems include both foundation and contemporary issues related to forest sustainability and fit within the Northern Research Station's strategic framework. They are:
1. To understand the current condition and past development of northern forests and to manage these forests in a sustainable manner, we must improve our knowledge of short- and long-term ecosystem responses to silvicultural treatments.
2. To predict the effects of silvicultural treatments on wildlife habitat, we must understand relationships between composition and structure of forest vegetation, and the needs of wildlife throughout their life cycles.
3. To predict the effects of management on northeastern forest ecosystems, we must understand the complex interactions among forest dynamics, nutrient cycling, and disturbance processes, particularly from destructive invasive species.
4. To address emerging issues in forest ecosystem sustainability, we will integrate remote sensing and process modeling with field studies in order to develop indices of ecosystem function and health that will be applicable across landscapes.
In addition to these RWUD-associated problems, RWU-NRS-4155 has a mission problem that spans multiple RWUDs: Long-term manipulative research and monitoring will be maintained at Bartlett, Massabesic, and Penobscot Experimental Forests as sources of knowledge discovery and development, and as demonstration and education sites . The mission problem provides for continued management of our three experimental forests and the ongoing long-term studies located on them (for information about experimental forests see Adams and others 2004).(top)
To understand the current condition and past development of northern forests and to manage these forests in a sustainable manner, we must improve our knowledge of short- and long-term ecosystem responses to silvicultural treatments.
This problem focuses on ongoing, decades-long research and builds upon work under Problem One of our old RWUD. The forests of northern New England are located at the northern edge of the eastern broadleaf forest and the southern edge of the boreal region, making them complex and variable in both pattern and process. Society demands multiple values from these forests; wood products, wildlife habitat, recreation, and aesthetics, to name a few. To meet those demands, we must improve both our knowledge of basic ecosystem processes and our ability to influence these processes through manipulation. Such influence is applied to the forest when knowledge about ecological principles is used to define management practices; i.e., silvicultural treatments.
Past and current societal demand for commodity products and noncommodity values has created a forest landscape shaped by management activities. Though the products and values desired have constantly changed, demand has not lessened. The most successful forest managers are those who understand ecological principles and apply that knowledge to devise silvicultural prescriptions with a high probability of success, regardless of objective. It is our task to provide the forest practitioner with this knowledge, and we can only do so by continuing existing long-term studies and installing new manipulative experiments to address emerging questions.
Ongoing silvicultural experiments on the Bartlett and Penobscot Experimental Forests enable us to study both short- and long-term responses to natural disturbances and planned treatments, and to develop guidelines for managing the diverse species that make up these forests. These studies are unique in the region and provide demonstrated results (as opposed to predictive results from modeling or retrospective studies) from the application of designed treatments for what is now more than half an even-aged rotation in these forest types. Thus, they are an invaluable source of both basic and applied knowledge about forest response to manipulation. In addition, they provide the capacity to address questions about contemporary issues that new experiments would take decades to answer. However, the value of these studies can be enhanced. Additional replications and repeated harvest treatments will lead to better science-based recommendations. More work with shelterwood systems, particularly shelterwood with reserves which leaves varying numbers of residual trees, will increase our knowledge about even-aged regeneration and wildlife-habitat characteristics.
Although the value of our long-term studies is immense, questions frequently arise that existing studies cannot answer. Consequently, new research must be planned and initiated. For example, ongoing long-term research in northern hardwoods has resulted in silvicultural practices that work well with some species, such as birches and ash. However, across the region there is increased interest in regenerating and managing sugar maple, currently the highest value species in New England. Similarly, there is a vital need to begin research on the equally complex task of regenerating mixed stands of eastern white pine and oak, and thereby meet the needs of owners and managers of small, mostly family forests across the region. An important need to increase biodiversity in the northern hardwood region requires a reliable method of regenerating groups or patches of conifers to increase the softwood component in these stands. Among northern conifers, northern white-cedar is a largely neglected species and little is known about the silvics and ecology of the species in northern New England and adjacent Canada. Nevertheless, interest in managing white cedar is increasing. New research is required to address the many complex factors that must be understood to ensure successful outcomes to these latest management challenges.
We are uniquely positioned to meet these challenges. The experimental forests we manage in New Hampshire and Maine are an invaluable resource. These forests provide us with the opportunity to establish and maintain treatments with a very long temporal perspective, an opportunity unique in New England because of rapid changes in land use and ownership patterns. Furthermore, the staff of NRS-4155 has the necessary education, experience, and skill to capitalize on the unique opportunities provided by our experimental forests and provide critical information regarding responses of ecosystem components to manipulation and the economic implications of alternative treatments. For example, we currently conduct research on topics such as the feasibility of various silvicultural tools and treatments; the effects of exploitive cutting; the interrelationships between management activities and invasive species (e.g., balsam and hemlock woolly adelgid, beech bark disease, etc.); tree and stand growth, yield, and quality; regeneration dynamics; and wildlife habitat characteristics.
Accomplishments planned for the next five years:
1. Use results from ongoing long-term experiments in northern hardwoods and northern conifers to update management guidelines for regenerating new stands and tending immature stands for sustainable productivity and desirable wildlife habitats.
2. Determine the influence that pioneer and mid-tolerant species, previously established in small, even-aged groups and patches, have on regeneration of shade-tolerant sugar maple.
3. Determine the effects of selection system silviculture on the development of disease resistant American beech.
4. Establish methods of regenerating even-aged northern hardwood stands using shelterwood with reserves in order to provide greater vertical structure early in the rotation to benefit wildlife and improve stand aesthetics.
5. Initiate research to develop silvicultural treatments that increase the conifer component in stands that are predominately northern hardwood, and treatments designed to meet various objectives in mixedwood (e.g., pine - oak, northern hardwood - softwood) stands without converting them to either predominately hardwood or softwood.
6. Initiate research on regeneration, growth, and productivity of northern white-cedar, and provide preliminary management guidelines for sustaining cedar in stands of mixed northern conifers.
7. Determine financial outcomes from the long-term silvicultural studies and provide managers publications and training so they can critically compare a range of management alternatives.
8. Apply innovative analytical techniques, such as Kalman Filtering, to stumpage price data to better understand market influences and provide results to landowners and managers in publications and training to help them achieve economic sustainability.(top)
To predict the effects of silvicultural treatments on wildlife habitat, we must understand relationships between composition and structure of forest vegetation, and the needs of wildlife throughout their life cycles.
This problem builds on work under Problem Two of our old RWUD and depends largely on continuing existing long-term research into the effects of silviculture on habitats and populations of amphibians, breeding birds, small mammals, and bats; and using knowledge gained to provide management guidelines. An integral part of the effort will be coordinating silvicultural operations with wildlife habitat studies on the Bartlett, Massabesic, and Penobscot Experimental Forests.
The northern forest of New England is becoming increasingly mature. This trend is on both public and private lands and is due, at least in part, to reduced acreages in clearcut areas or regeneration harvests, as well as active fire suppression. While some groups advocate a higher proportion of mature forests for aesthetic and diversity values, approaches like reducing the size of regeneration cuts may create future problems. For example, such cutting may produce inadequate pockets of habitat for early successional species while simultaneously fragmenting the landscape for birds that require large, unbroken tracts of mature forest. The diversity of wildlife species in the region requires a diversity of forest structures and compositions. Some wildlife species depend on large tracts of mature forest, while others require significant areas of regenerating and immature forest. Ultimately, the creation and development of early-successional wildlife habitat depend on disturbance, either by natural causes or through management. Thus, it is likely that wildlife diversity will decline because of the trend toward later successional stages and smaller areas of regenerating and developing forest. The relationship between the amount of mature forests and wildlife diversity needs more research, and reliable surveying and monitoring techniques need further development, particularly for sampling forest-dwelling diurnal and nocturnal raptors.
Habitat in relation to successional stage is one issue to be investigated in this problem, another is the question of the scale at which habitat is considered. Guidelines for managing to meet wildlife habitat objectives are often vague and limited in scope (i.e., usually targeted at the stand level). Several wildlife habitat management techniques that are successful elsewhere are untested in northern forests. Questions of species diversity, disturbance patterns, species-habitat relationships, and wildlife habitat-human interactions need to be addressed for specific forest types. Silvicultural techniques need to be developed in mixedwood forest types to promote wildlife habitat. In addition, while ecological land classification provides a valuable framework for management, defining how wildlife habitat descriptions fit into such classification systems is essential to the advancement of wildlife habitat management.
The species-habitat relationships for forest-dwelling wildlife described in DeGraaf and others (1992) provide a basis for conducting research to address questions of both successional stage and scale. The authors outline a number of working hypotheses to test the effects of various silvicultural practices on species composition, occurrence/abundance, habitat quality, species productivity, and predator-prey relationships. Answers to some of these questions will permit biologists to further integrate silviculture and wildlife habitat management.
Accomplishments planned for the next five years:
1. Publish a landowner's guide to forest wildlife habitat that uses visualization technology to display management options and their effects on wildlife diversity (with RWU-NRS-4251).
2. Publish a revision of General Technical Report NE-144 by DeGraaf and others (1992), "New England wildlife: management of forested habitats," to reflect new findings (with RWU-NRS-4251).
3. Test a number of hypotheses posed by DeGraaf and others (1992 and revision mentioned above) about silviculture and habitat development for a range of wildlife species with the objective of presenting an integrated approach to wildlife habitat management.
4. Refine and expand the wildlife habitat component of the ecological classification system.
5. Describe the longevity and habitat value of standing dead trees and downed coarse woody material.
6. Publish new knowledge about the distribution of amphibians and small mammals along gradients of elevation in the White Mountains.
7. Describe northern goshawk nesting habitat attributes and reproductive success in the White Mountains at the stand and landscape levels.(top)
To predict the effects of management on northeastern forest ecosystems, we must understand the complex interactions among forest dynamics, nutrient cycling, and disturbance processes, particularly from destructive invasive species.
This problem combines elements of Problem Three of the old RWUD with new areas of focus, primarily understanding the ecological impacts of emerging and potentially destructive invasive species. Virtually all forested lands in the northeastern U.S. have been affected by human activity. Perhaps the greatest current threat to northeastern forests is the introduction of exotic invasive plants, insects, and diseases with potentially dramatic impacts on the composition, structure, and health of our forests. Maintaining forest ecosystem sustainability requires an understanding of biological cycles and interactions among myriad biotic and abiotic factors involved in a healthy forest. Forest management takes place across a mosaic that reflects ecosystem response to previous natural disturbances and intentional human manipulation. To achieve and maintain sustainability, managers must anticipate the effects of future perturbations from such factors as expanding ranges of destructive invasive species, increasing deposition of pollutants, and accelerating global change.
Our research on this problem is centered on gaining a better understanding of the nature of resource gradients and environmental factors across the Northeast, how these factors interact with change agents to affect ecosystem dynamics and structure, and their context in a regional, continental, and even global ecology. Knowledge gained from this research will be transferred to forest managers so they can better understand the effects of their decisions. This new knowledge can also provide the basis for making site-specific, science-based decisions to address existing, emerging, and unforeseen stresses on the forest ecosystem.
Specifically, our research will focus on the following areas:
. Although Ca-oxalate in soils represents a potentially significant source of calcium, it has traditionally not been considered available to plants. However, recent research on plant nutrition suggests that it may be. If Ca-oxalate is available to plants in sufficient quantities, that knowledge would redefine our understanding about calcium cycling and depletion dynamics in forested ecosystems.
. Sugar maple is particularly sensitive to stress on soils with low levels of nutrients. Gaining a better understanding of the mechanisms involved in sugar maple health and decline will help us understand the consequences of environmental change.
. Most research on hemlock woolly adelgid (HWA) infestation emphasizes impacts to the ecosystem after eastern hemlock is killed. Our research explores alternative hypotheses based on observations of hemlock stands persisting for over a decade after infestation on some sites.
Our preliminary research enables us to identify critical site factors, nutrient thresholds and disturbances linked to susceptibility and decline of sugar maple and eastern hemlock. Our ability to map foliar chemistry on a landscape scale, coupled with other pertinent GIS data layers (defoliation events, mineralogy maps, digital elevation models) will enable us to create susceptibility models for these species.
Accomplishments planned for the next five years:
1. Quantify Ca-oxalate pools in forest soils and revise calcium depletion models.
2. Determine nutrient thresholds in soils and foliage that may be effective indicators of forest health and productivity, and develop indices of sugar maple health that would support silvicultural prescriptions for maintaining vigorous trees.
3. Determine how foliar and soil nutrient status influence HWA infestation and subsequent decline of eastern hemlock, leading to development of a stand susceptibility model to assist managers in making decisions, such as where to focus biological control efforts.
4. In conjunction with Problem 4, develop methods to predict and map susceptibility to HWA, sugar maple decline, and other such agents.(top)
To address emerging issues in forest ecosystem sustainability, we will integrate remote sensing and process modeling with field studies in order to develop indices of forest ecosystem function and health that will be applicable across landscapes.
This problem combines elements from Problem Three of our old RWUD with more emphasis on process modeling and a greater focus on ecosystem health. The ability to assimilate information obtained at one scale and apply it to patterns and processes that manifest themselves at another scale is an issue common to all fields of science. In terrestrial ecology, developing methods that relate leaf-, plant- and stand-level observations to landscapes, regions and continents is an active area of research. Field-based investigations are limited to relatively small areas. Remote platforms provide the only means of viewing large portions of the earth's surface at regular intervals, and the selective absorption and reflectance of light by plant tissues allows sensors to gather tremendous amounts of ecologically relevant data. Thus, linkages between data from field studies and remote sensing investigations are critical to scale from the plot to the region and beyond. Similarly, progress toward understanding and predicting ecosystem response to changing environmental conditions requires strong linkages between data collected in the field or by remote sensing and modeling endeavors. It is important that field- and remote sensing-based investigations are relevant to the hypotheses of model based studies, and that models are constrained and improved by such observations. For example, preliminary results show a relationship between foliar N and Ca and stream water concentrations of nitrate and Ca. Once these relationships are determined, hyperspectral remote sensing data can assist with assessments of stream water quality at the landscape scale.
To fully explore and understand ecological processes and forest health issues between and among scales, research under this problem will utilize a multi-tiered approach, including:
. Building on our other problems by identifying emerging issues and gaining knowledge about the fundamental nature of forest ecosystem processes and the effects of management on ecosystem structure and function.
. Developing methodologies based on remote sensing and spatial modeling to extend plot- and stand-level understanding to larger landscapes.
. Improving landscape-scale spatial modeling approaches to more accurately predict, monitor and assess forest structure, health and ecosystem processes.
Current cooperative research among NRS-4155, other NRS RWUs, other federal research organizations (e.g. NASA, USGS, NSF), and universities addresses these issues through a combination of field studies, remote sensing approaches, and ecosystem modeling. Field and remote sensing data are combined to derive spatial data layers of forest composition, structure, health, nutrient status, and susceptibility to stress. These data are input for GIS-based forest ecosystem models (such as PnET-II, PnET-CN) that estimate and evaluate ecosystem condition and function at broad spatial and temporal scales.
Our ongoing and new research under this problem includes extending development and evaluation of remote sensing and modeling approaches from the northern temperate forest, where they were first explored, to other biomes. In the Northeast, we also propose to expand from our current focus on HWA to other forest stress agents, such as the Asian Longhorned Beetle. This research will utilize the extensive data sets available from our experimental forests, RNAs in New England, and an existing network of plots across the region.
Accomplishments planned for the next five years:
1. Develop methods based on hyperspectral remote sensing and GIS technologies to spatially model and evaluate ecosystem productivity and biogeochemical cycles at landscape and sub-regional scales.
2. Initiate research to examine carbon uptake and storage in northern forest ecosystems in conjunction with ongoing work examining whether canopy nitrogen can serve as a scalar for ecosystem-level carbon uptake and storage.
3. Initiate research to examine combining airborne LIDAR and hyperspectral image data to describe forest ecosystem structure.
4. In conjunction with research being carried out under Problem 3, develop hyperspectral techniques to map and monitor the spread of exotic invasive insect pests and forest declines.
5. Adapt existing hyperspectral technologies to sensors that are available for use by land managers and publish guidelines detailing steps necessary to fully utilize these instruments.
6. Summarize data collected during the most recent decadal remeasurement of Bartlett Experimental Forest permanent plots and analyze changes and trends in aboveground forest productivity and mortality since the 1930s.
Mission Problem. Long-term manipulative research and monitoring will be maintained at Bartlett, Massabesic, and Penobscot Experimental Forests as sources of knowledge discovery and development, and as demonstration and education sites.
A majority of the research in RWU-NRS-4155 is conducted at our three experimental forests. Experimental forests provide locations where long-term research can be conducted without concern of conversion to some other use or loss of administrative control. More significantly; however, existing long-term research on these forests, much of it ongoing for decades, has created combinations of forest structure and composition in near proximity without which many other important studies could not be initiated. Similarly, the datasets associated with these long-term studies provide detailed histories of forest response required for many kinds of research.
Soon after Bartlett Experimental Forest was established in 1932, a grid of permanent cruise plots was laid out across the forest prior to installation of forest management experiments. Over time, a number of silvicultural and wildlife habitat studies have been installed that have altered the structure and composition of the forest in various ways. The cruise plots have been remeasured periodically across both those parts of the forest that have been altered by experimentation and those portions left unmanaged. Data collected from the cruise plots have been instrumental for understanding the effects of natural disturbances and silvicultural manipulations on structure, composition, and productivity of northern hardwood forests. At the Penobscot Experimental Forest a silvicultural experiment was installed between 1952 and 1957 that included an array of treatments including an unmanaged reference area. Subsequently, other studies were added to compliment the original long-term experiment. Those areas are regularly sampled on permanent plots. The Penobscot silvicultural studies are the primary source of knowledge about the ecology and silviculture of mixed northern conifer forests in the Northeast.
These studies attract a number of cooperators from other Forest Service research work units, universities, and non-governmental research organizations. RWU-NRS-4155 is responsible for coordinating the large number of scientists who work on the experimental forests. It is also responsible for maintaining treatment structures and monitoring change through remeasuring plots on the Bartlett and Penobscot Experimental Forests and for developing a similar long-term research program at the Massabesic Experimental Forest. Maintaining these experimental forests requires facilities, roads, and research infrastructure management as well as conducting the research itself.
RWU-NRS-4155 also manages the data sets associated with these studies. Data are collected, entered for electronic processing, and archived so they are available to unit scientists and cooperators. Samples such as soils and tree cores are also stored in a manner to preserve them for later retrieval.
Considerable effort is spent presenting information about research results from these experimental forests. Collectively these forests host several hundred visitors each year including scientists and science managers; practicing professional land managers; conservation groups; educators; primary, secondary, and college students; and the public.
In addition to the mission problem, RWU-NRS-4155 will continue to coordinate the Research Natural Area (RNA) program in the eastern portion of Region 9 for the Northern Research Station. RNAs are designated areas that receive no anthropogenic treatments; they serve a critical role in our understanding the effects of management on forest ecosystems. However, they are not nature museums. They are areas where natural conditions predominate and provide an opportunity to collect baseline data against which to assess effects of management activities and to study structure, function, composition, and productivity of natural ecosystems.(top)
Almost all research done by RWU-NRS-4155 is done in cooperation with colleagues at universities, other Forest Service units or other federal agencies, state agencies, private companies and institutions, or non-governmental organizations. Major cooperators in RWU-NRS-4155's research program, by problem, include:
. Other NRS RWUs, especially 4104 (Problems 1 and 2), 4152 (Problem 3), 4251 (Problems 1 and 2), 4352 (Problem 3), 4454 (Problem 1), 4455 (Problem 4), 4501 (Problem 3), 4502 (Problem 3), 4505 (Problems 1 and 3), 4558 (Problem 3), 4803 (Problem 1), and 4805 (Problem 1).
. University of New Hampshire (Problems 1-4, Mission Problem)
. University of Vermont (Problem 1)
. State University of New York, College of Environmental Science and Forestry (Problems 1 and 3)
. Brown University (Problem 3)
. Laval University (Problem 1)
. White Mountain National Forest (Problems 1-4, Mission Problem)
. Green Mountain National Forest (Problems 1-4)
. Northeastern Area, S&PF (Problems 1-4)
. National Aeronautics and Space Administration (Problem 4)
. United States Geological Service (Problems 3 and 4)
. Canadian Forest Service, Atlantic Forestry Centre (Problems 1 and 4)
. New Hampshire Department of Resources and Economic Development (Problems 1 and 2)
. New Hampshire Fish and Game Department (Problem 2)
. Maine Department of Conservation, Maine Forest Service (Problems 1 and 3)
. Vermont Department of Forests, Parks and Recreation (Problem 1)
. Massachusetts Department of Conservation and Recreation (Problems 1 and 3)
. New York Department of Environmental Conservation (Problem 3)
. Manomet Center for Conservation Sciences (Problems 1 and 2)
. Audubon Society of New Hampshire (Problem 2)
. Maine Audubon (Problem 2)
. The Nature Conservancy (Problem 1)
. Small Woodland Owners Association of Maine (Problems 1, 2, and 3)
. York County Soil and Water Conservation District (Mission Problem)
. Alfred (ME) Conservation Commission (Mission Problem)
. International Paper Company (Problems 1 and 2)
. Seven Islands Land Company (Problem 1)
. V.N. Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences (Problems 1 and 4)(top)
The permanent, full-time staff of RWU-NRS-4155 consists of 8 scientists and 4 support personnel. Two of the support staff have advanced degrees in wildlife biology and contribute additional scientific expertise in that area. We also provide about 40 percent of the salary (9-month appointment) of a cooperating scientist who is on the faculty of The University of Maine. Consequently, there are a total of 8.3 scientist-years (SY) available within the RWU. The support staff is supplemented with term and temporary appointments throughout the year but especially during the field season.
Table 1. Allocation of 8.3 SYs by problem for the next several years.
Salaries and costs associated with managing facilities and infrastructure (e.g., utilities) of three experimental forests account for nearly all of the funds appropriated annually to RWU-NRS-4155. Among the problems, the mission problem has the highest priority for remaining appropriated funds. Thus, external funds are critical to ensure a viable and vigorous research program, especially for aspects not associated with ongoing long-term research on an experimental forest. Although all four problems under this RWUD require some outside funding, research under Problems 1 and 2 is tied more closely to the mission problem and consequently is less dependent on external sources than Problems 3 and 4.
Adams , M.B.; Loughry, L.; Plaugher, L., comps. 2004. Experimental forests and ranges of the USDA Forest Service. Gen. Tech. Rep. NE-321. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northeastern Research Station. 178 p.
Cubbage, F.W.; Brown, P.J.; Crow, T.R.; Gordon, J.C.; Humke, J.W.; McCullough, R.B.; Sederoff, R.R. 2002. National capacity in forestry research. National Research Council. National Academy Press, Washington, D.C. 144 p.
DeGraaf, R.M.; Yamasaki, M.; Leak, W.B.; Lanier, J.W. 1992. New England wildlife: Management of forested habitats. Gen. Tech. Rep. NE-144, Radnor, PA: USDA Forest Service, Northeastern Forest Experiment Station. 271 p.(top)