School of
Forest Resources and
Environmental Science
Managing Forest Resources in the 21st Century: An Integrated Approach
Invited Speakers
July 6, 2004
North American Forest Biology Workshop
July 12-15, 2004
Michigan Technological University
Houghton, Michigan, U.S.A.

Invited Speakers

An Overview of the Forested Ecosystems of the Northern Lake States - click here for abstract
Dr. Dennis Albert
Ecology Program Leader
Michigan Natural Features Inventory
PO Box 30444
Lansing, MI 48909-7944

Gradients of Management Intensity in the Context of Natural Disturbance Regimes click here for abstract
Wayne Bell
Research Scientist
Ontario Ministry of Natural Resources
Ontario Forestry Research Institute
1235 Queen St. East
Sault St. Marie, ON P6A 2E5

Forest Management Opportunities for Increasing Carbon Sequestration - click here for abstract
Dr. Richard Birdsey
Northeast Research Station
USDA Forest Service
Northern Global Change Research Program
11 Campus Blvd.
Suite 200
Newton Square, PA 1907373-3294

The Case for Contextual Forest Management in the 21st Century - click here for abstract
Dr. Thomas Crow
Research Ecologist
USDA Forest Service, WFWAR
1601 N, Kent Street, 4th Floor
Arlington, VA 22209
phone: 703-605-5289 fax: 703-605-0279

Natural Disturbance Regimes in Great Lakes Forests - click here for abstract
Dr. Lee Frelich
Department of Forest Resources
University of Minnesota
Forest Resources
1530 N Cleveland Ave.
St. Paul, MN 55108

Integrated Assessment of Two Decades of Land Cover, Forest, and Socio-Economic Change in the Midwest - click here for abstract
Dr. Eric Gustafson
North Central Research Station
5985 Highway K
Rhinelander, WI 54501

A Century of Watershed Lessons and Emerging Information Needs - click here for abstract
Dr. George Ice
PO Box 458
Corvallis, OR 97339-0458

Copper Mining Industry Use of Forest and Aquatic Resources of the Keweenaw - click here for abstract
Dr. Larry Lankton
Department of Social Sciences
Michigan Technological University
Houghton, MI 19931

Fine Hardwood Tree Improvement - An Approach to Individual Tree Selection - click here for abstract
Dr. Charles H. Michler
Hardwood Tree Improvement and Regeneration Center
USDA Forest Service, North Central Research Station
Purdue University
195 Marsteller Street
Lafayette, IN 47907-2033

N Deposition and Forest Function - click here for abstract
Dr. Knute Nadelhoffer
University of Michigan Biological Station
University of Michigan
2014 Natural Sciences Bldg.
830 North University Ave.
Ann Arbor, MI 48109-1048, USA

Forest Productivity in a CO2 Enriched Atmosphere - click here for abstract
Dr. Richard Norby
Environmental Sciences Division
Oak Ridge National Laboratory
Oak Ridge TN 37831-6422

Silvicultural Approaches for the Matrix: Balancing Ecological and Production Goals at Multiple Scales - click here for abstract
Dr. Brian Palik
North Central Research Station
1831 Hwy. 169 E.
Grand Rapids, MN 55744-3399

Ozone and Forest Productivity: State of Science and Risk - click here for abstract
Dr. Kevin Percy
Natural Resources Canada
Canadian Forest Service-Atlantic Forestry Centre
1350 Regent St.
Fredericton, New Brunswick
Canada, E3B 5P7

Exploiting the Pre-European Settlement Forest: Michigan's Enduring Ecological Legacy - click here for abstract
Dr. Kurt Pregitzer
School of Forest Resources and Environmental Science
Michigan Technological University
Houghton, MI 19931

Canceled Ecophsysiology Based Analysis of Integrated Forest Responses to
Changing Environmental Conditions

Dr. Peter Reich

Department of Forest Resources
University of Minnesota
115 Green Hall
1530 N. Cleveland Ave.
St. Paul, MN 55108

Tree Improvement in the Lake States - Current Status - Future Opportunities - click here for abstract
Dr. Donald Riemenschneider
North Central Research Station
5985 Highway K
Rhinelander, WI 54501

CO2 Recycling in Trees - click here for abstract
Dr. Robert Teskey
Warnell School of Forest Resources
University of Georgia
Athens, Georgia

Functional Genomics and Forest Tree Improvement: A Case Study on Resource Allocation - click here for abstract
Dr. Chung-Jui Tsai
School of Forest Resources and Environmental Science
Michigan Technological University
Houghton, MI 19931

An Overview of the Forested Ecosystems of the Northern Lake States
Dr. Dennis A. Albert

Development of regional ecosystem classifications and maps, a focus of university and USFS ecologists within the northern Lake States, will be briefly discussed. Regionalization will be used as a framework for discussing the ecological diversity of the Lake States, with a focus on forested systems. Major factors controlling the vegetation of Lake States forests include climate, bedrock geology, glacial geology, and resulting soils and hydrology. The author will introduce the audience to major forested ecosystems, providing highlights on the disturbance history, natural processes, floristic affinities, and rare species associated with each ecosystem. Non-forested ecosystems characteristic of the Lake States will also be introduced.

[back] [top]
Gradients of Management Intensity in the Context of Natural Disturbance Regimes
F. Wayne Bell

Abstract: Ontario, like many other jurisdictions, is keeping pace with international standards for forest sustainability. The Brundtland Commission, the Earth Summit, the Montreal and Kyoto Protocols, Agenda 21, the Canadian Council of Forest Minister's Criteria and Indicators, and the Ontario Crown Forest Sustainability Act all guide sustainable forest management in Ontario.

In 1999, the Ontario Ministry of Natural Resources (OMNR) set aside 2.4 million hectares, bringing Ontario's parks and protected areas to more than 9.5 million hectares (12% of the landbase). To offset associated fibre losses, OMNR, forest industry, and non-government organizations agreed to intensify forest management on other public lands. To address uncertainties about the potential IFM gain, three linked research approaches have been undertaken.

The Forest Research Partnership (OMNR, Canadian Forestry Services, and Tembec)1 , is applying an adaptive management approach to four forest licensed areas Northeastern Ontario. The core of this approach is to use spatial simulation modeling of various management intensities to simulate wood supply, economic, and biodiversity outcomes in the future based on current knowledge of silvicultural intensities, economics and impacts on biodiversity. Included in this approach is a considerable effort on knowledge transfer about intensifying forest management to managers, policy and operations staff of the forest industry and government.

Linked to the FRP is the NEBIE Plot Network 2, led by OMNR, to evaluate the gains and impacts of a range of intensities within 8 major commercial forest types in the boreal and Great Lakes-St. Lawrence forests. Researchers are studying fibre production, species and genetic diversity, nutrient and carbon cycling, and economics. The NEBIE acronym stands for: Natural disturbances, and Extensive, Basic, Intensive, and Elite silviculture.

The Legacy Forest 3, led by Lakehead University and Bowater Canadian Forest Products, is located west of Thunder Bay Ontario, and covers 46 20,000+ hectare (experimental) units. Distinct management portfolios based on average mean annual increments ranging from 1.0 (i.e., natural forests) to 4.0+ m3 ha-1 yr-1 are proposed for each unit. This scale permits "replication" within forest types, creating a new plot network for studying fibre production, biodiversity, socio-economics, and soils and water quality.

This presentation will show how gradients of management intensities can be studied at appropriate scales (2 to 2 million ha) using the three plot networks as case studies.


[back] [top]
Forest Management Opportunities for Increasing Carbon Sequestration
Richard A. Birdsey

Abstract: Forests of the U.S. currently sequester approximately 200 MMTC/yr of CO2 from the atmosphere. This estimate includes C sequestered in forest ecosystems and harvested wood products. The rate of forest carbon sequestration varies by State and region. For example, the Lake States and the Midwest had a higher rate of sequestration than other areas of the U.S. over the last decade. Most of the recent increase in forest carbon stocks in the U.S. is in live biomass and wood products. There was a small net loss of forest C from recent land-use change.

The influence of historical land use and forest management on carbon stocks is clearly shown in the trends since 1950. Significant factors include (1) afforestation in the East; (2) increased timber production and management intensity in the South; (3) fire suppression in the Rocky Mountains; and (4) harvesting trends in the Pacific Coast. How forests are managed over the next 50 years can have an equally significant effect, including the potential to increase the rate of C sequestration in forests and wood products. There are many kinds of forestry activities that either reduce emissions, increase sequestration, or both.

In 2002 the President directed USDA to develop accounting rules and guidelines for reporting and crediting carbon sequestration and emissions reduction by forestry and agriculture. This is a voluntary program designed to establish a fair market for trading carbon credits. The rules and guidelines are needed to provide a basis for consistent estimation of the quantity of carbon sequestered and emissions reduced by different forestry activities, and will be used to determine the value of the credits. Also under consideration are incentives to enhance carbon sequestration in forests. Successful implementation of these actions would require an expanded program of research and development aimed at forest management technology, improved measurement and monitoring, and landowner assistance.

[back] [top]
The Case for Contextual Forest Management in the 21st Century
Thomas R. Crow

Landscape ecology is a rapidly advancing field of study that provides useful concepts, theories, and methods for addressing management issues such as timber production, wildlife habitat, biodiversity conservation, and land-use planning. One such concept is the consideration of spatial context when making resource management decisions. Individual patches that comprise a landscape are not isolated entitles, but rather are embedded in local, regional, and global ecosystems that include social, economic, and ecologic elements and conditions. Furthermore, patches tend to be open systems in which materials, energy, and organisms move across their boundaries and thereby affect internal processes. Using the National Forests in the Lake States as examples, I will consider the importance of spatial context as it relates to developing Forest Plans. Thinking beyond the boundaries of an individual forest stand or an individual ownership is essential to practicing good stewardship.

[back] [top]

Natural disturbance regimes in the Great Lakes forests
Lee. E. Frelich

Abstract: Three major historic disturbance regimes occurred in Great Lakes Forests. Near-boreal forests experienced high-severity fires with rotation periods of 50-150 years. On shallow rocky soils of the Canadian Shield these forests were dominated by jack pine and black spruce, with succession to black spruce, balsam fir, northern white cedar and paper birch in the absence of fire. On better sites aspen and paper birch regenerated after fires and succeeded to spruce and fir by the time of the next fire. Forests of white pine, red pine and oak had surface fires of low to
moderate severity with rotations of 10-50 years. Severe fires set succession back to aspen and birch while lack of fires allowed succession to spruce, fir, cedar and maple. Sugar maple-hemlock forests experienced canopy-leveling winds with long rotations of 500-2000 years. There is little succession after such blowdowns unless the slash burns, in which case succession from birch to white pine and back to sugar maple-hemlock occurs. The dynamics of these mesic forests is dominated by small-scale treefalls caused by tree death and wind, leading to a majority of multi-aged stands on the landscape. Interactions between disturbance types and characteristics of the dominant trees regulate the size, frequency and impacts of disturbance, the patch structure, and species composition at the landscape scale.

[back] [top]

Integrated assessment of two decades of land cover, forest and socioeconomic change in the midwest.
Dr. Eric Gustafson

Abstract: We developed a spatial database of changes in the biophysical and socioeconomic landscape across 7 states in the Midwestern US between 1980 and 2000. We mapped change in three primary characteristics: 1) the distribution of what is on the land (land cover), 2) the distribution and characteristics of people across the region, and 3) the characteristics of the forests within the region. Land cover change was documented at a 1-km resolution using novel methods to compare maps derived from aerial photos (USGS LUDA) and satellite imagery (AVHRR). Human demographic and economic changes were mapped at the county and community/neighborhood level using US Census and Bureau of Economic Analysis data. Changes in the area, structure, condition, and ownership of forests were mapped at the county level using US Forest Service (FIA) data. Changes in other natural resources, such as songbird and deer abundance, forest insect outbreaks, and recreational opportunities were also documented to illustrate effects related to changes in the three primary characteristics. We used this database to model how ecologic factors contribute to the pattern of population and housing density change within the region.

] [top]

A Century of Watershed Lessons and Emerging Information Needs
Dr. George Ice

Abstract: A special session on watershed management was held at the 2000 Society of American Foresters (SAF) National Convention. That session allowed some of the grandmasters of watershed management to synthesize forest and wildland watershed lessons learned over the twentieth century. An expanded version of that material has been collected into a book for SAF. Despite a rich history of forest and wildland watershed research, there remain many research challenges. Because extreme events can often dominate watershed processes, it is important to have high-quality, long-term records, especially for least-impaired watersheds. Innovative new technologies are allowing rapid collection of precise watershed data, but it is important to compare these new methods with the methods used in the past. Models are often seen as replacing watershed research, but they really complement one another. There continue to be several difficult but important watershed issues that must be addressed. Some of these include: the effectiveness of Best Management Practices (BMPs); cumulative watershed effects; the scale of natural disturbance effects (e.g., wildfire) on watershed processes and our ability to alter those effects, either positively or negatively; and opportunities to manage forest and wildland watersheds to augment flow in regions experiencing water shortages. Of special relevance to the North American Forest Biology Conference is the emerging recognition that physical and biological watershed components interact. Climate influences forest type and water resource characteristics that are essential for aquatic species including fish. Concerns about global warming in the Pacific Northwest include a possible reduction in precipitation as snow, leading to diminished spring and summer runoff. Vegetation, in turn, influences sediment channel roughness and sediment routing, and anadromous fish returns can modify soil nutrient status in a watershed. The twentieth century provided many important lessons about forest watersheds and how we can manage them, but there remain tremendous opportunities to advance forest watershed science in the twenty-first century.

[back] [top]

Copper Mining Industry Use of Forest and Aquatic Resources of the Keweenaw
Dr. Larry Lankton

Abstract: In the mid-1840s, mining companies arrived on the Keweenaw Peninsula for the purpose of exploiting its deposits of native, metallic copper. The companies were the leading institutions in "civilizing" this remote wilderness as they established their industry. As they began mining copper, they also made heavy use of other natural resources on the Keweenaw, namely its forests and lakes. This paper examines the mining companies' attitudes concerning the natural environment, the uses to which they put water and woods, and the new landscape they helped create on the Keweenaw.

[back] [top]

Improving Disease Resistance of Butternut (Juglans cinerea), a Threatened Fine Hardwood: A case for single tree selection through genetic improvement.
Dr. Charles H. Michler

Butternut is a threatened fine hardwood throughout its natural range in Eastern North America due to invasion of the exotic fungus, Sirococcus clavigignenti-juglandacearum, which causes butternut canker. Early efforts were made to identify and collect putatively resistant germ plasm, identify vectors, and to characterize the disease. More recent, molecular techniques have been employed to make genetic characterizations of both the pathogen and resistant germ plasm. Of interest to many, it has been found that much of the host resistance may originate from hybridization with a close Asian relative and from a few natural phenotypic variants. Further genetic characterization is needed before classical breeding or genetic modification can be used to produce the next generation of resistant trees. Answers are needed from this genetic characterization before deployment and risk management strategies can be tested for successful species restoration.

[back] [top]

N Deposition and Forest Function
Dr. Knute Nadelhoffer

Elevated production and release of reactive N (NR) to the atmosphere due to fossil fuel combustion and intensive agricultural practices have led to substantially elevated NR deposition across large regions of North America, Europe and Asia. Because primary productivity (tree growth) is typically assumed to be limited by the rate at which NR becomes available for plant uptake, widespread deposition of NR on forests could be stimulating primary productivity. If NR deposition is, in fact, stimulating forest growth, it could be contributing to the north temperate CO2 sink, which is functioning to slow the rapid rise in atmospheric CO2 concentration. Decadal-scale additions of N fertilizer to forest plots are providing insights into the long-term effects of elevated NR deposition on forested ecosystems. As part of a long-term study of forest response to N deposition at the Harvard Forest in central Massachusetts (USA), isotope mass balances were used to track the fates of 15N tracer additions to oak- and red pine-dominated plots to determine whether tree growth and primary production were enhanced by chronic N additions. Recoveries of 15N tracers (added as either 15NH4 or 15NO3 to chronically fertilized and reference plots) at 1 and at 7 years after a 2-year labeling period showed that soils (mineral and organic) were the primary sinks for 15N tracer additions. Forest trees were a secondary sink, but only small percentages of N added as either 15NH4 or 15NO3 were sequestered in woody biomass. Results suggest that NR inputs to temperate forests may not greatly stimulate growth when inputs are spread across growing seasons or entire years. Isotopic tracer movements and recoveries at annual and decadal scales, at the Harvard Forest and elsewhere, suggest that atmospheric N inputs become distributed among plant and soil pools in approximate proportion to the distribution of native N among plant and soil pools. Because trees compete for only small proportions of total NR inputs, the likelihood that N deposition is increasing primary productivity and temperate forest removal of CO2 from the atmosphere is low.

back] [top]
Forest Productivity in a CO2 Enriched Atmosphere
Dr. Richard Norby

Abstract: Experiments with young trees have for decades demonstrated that tree species respond to elevated concentrations of atmospheric CO2 as do other green plants: the rate of carbon assimilation increases and the plants grow faster. The relevance of these observations to forest productivity in a future CO2-enriched atmosphere remains subject to debate. The long life and large size of trees make direct assessment of forest responses to CO2 enrichment difficult, but experiments with young or isolated trees confound structural changes with functional responses, and the results are not directly applicable to fully developed forest stands. Free-air CO2 enrichment (FACE) technology has enabled multi-year studies of intact forest stands. These studies are demonstrating sustained increases in productivity but important differences in the fate of the assimilated carbon.
A closed-canopy stand of sweetgum (Liquidambar styraciflua) trees on the Oak Ridge National Environmental Research Park has been exposed since 1998 to elevated CO2 in two 25-m diameter plots. Annual production of fine roots was more than doubled in plots with 550 ppm CO2 compared to plots in ambient air. This response was the primary component of the sustained 22% increase in NPP. Aboveground wood production, however, increased significantly only during the first year of treatment. The preferential allocation of additional carbon to fine roots, which have a fast turnover rate in this species, rather than to stemwood reduces the possibility of long-term enhancement by elevated CO2 of carbon sequestration in biomass. The allocation pattern is the primary difference between the response of this deciduous stand and that of a loblolly pine stand of similar age and s
ture in a FACE experiment in North Carolina. NPP of the pine stand has been stimulated by elevated CO2, and the !
stimulation has persisted through time, but the extra C has been recovered in stems, not in root production. Understanding the belowground response to elevated CO2 and how it varies with ecosystem attributes is critical to understanding the potential for forests to sequester C.
Although much of the research on forest response to elevated CO2 has focused on productivity and C dynamics, other ecosystem responses may be just as important in coming decades. As the C questions are gradually resolved, we should turn our attention to how increases in atmospheric CO2 concentration will interact with other environmental changes to influence the capacity of forests to provide critical goods and services for many decades into the future.

back] [top]
Silvicultural Approaches for the Matrix: Balancing Ecological and Production Goals at Multiple Scales
Dr. Brian Palik

The purview of silviculture has expanded greatly. In addition to managing for growth and yield, silviculture is called upon to restore degraded ecosystems, to increase ecological complexity and diversity in production systems, to maintain ecological reserves, and to sustain an array of ecosystem goods and services. A conceptual framework for organizing diverse silvicultural goals is a model that arrays stand-level management along a gradient of desired outcomes. On the right is the benchmark condition (reserve management). On the left is the intensively-managed condition (high-production management). There is a wide array of conditions between the end points, within the domain of integrative management. When applied to landscapes, the linear model is similar to the "triad" model, where the landscape contains production and reserve forests, within a matrix managed to conserve biological diversity. In reality, stands in the matrix will be managed in a variety of ways. The resultant conceptual landscape suggests a spectrum, where approaches grade into one another. While the triad model is widely cited, its implementation is illusive. Comprehensive approaches for intensively managed systems are not widely applied. Silvicultural strategies for the matrix, to sustain biological diversity while maintaining quality wood production, are under-explored. A guiding truth for matrix forestry is that traditional silviculture simplifies systems in ways not wholly conducive to sustaining biological diversity. Consequently, there a need for innovative approaches that sustain (or restore) ecological complexity, while maintaining quality timber production as an objective. Moreover, there is a need to apply these widely on the landscape. Three principles guide the development of such approaches, i) incorporation of "biological legacies", ii) incorporation of natural stand development processes; and iii) allowing for appropriate recovery periods. Several key questions need to be answered, at multiple scales, including the shape of the relationship between wood productivity and stand complexity and to what degree can productivity be maintained while increasing complexity. We are addressing these and related questions in pine systems using various types of overstory retention. For example, we have learned that stand-wide biomass production of longleaf pine seedlings in two-cohort stands can be increased three-fold by retaining "legacy" overstory trees in aggregates, rather then in dispersed patterns. In both cases, post-harvest stands retain structural complexity, but the environment for new cohort productivity differs dramatically between alternatives. Similar studies are needed to predict productivity in responses to types and amounts of other structural elements, including dead wood and habitat trees.

[back] [top]

Ozone and Forest Productivity: State of Science and Risk
Dr. Kevin Percy

Tropospheric ozone (O3) exerts an important role in atmospheric chemistry. It absorbs infrared radiation and is in fact the third most effective (after CO2, CH4) greenhouse gas. At the surface level O3 is transported long over distances and is damaging at certain levels of exposure. It is the most widely-distributed air pollutant affecting North American forests. Global background levels have risen from 10 - 15 ppb in the late 1880's to 30 - 40 ppb today. The pattern and severity of O3 injury at the stand level is dependant upon tree species, genotype, canopy dynamics, O3 dose, and meteorological factors which control O3 flux into the leaf. Ozone is generally detrimental to tree growth, reduces ecosystem productivity, and lowers resistence to commonly co-occurring stresses such as insects, disease and drought. While many advances have been made through controlled exposure experiments in our understanding of the physiological injury mechanisms, as well as in O3 pattern recognition through tree condition monitoring, the development of scientifically defensible O3 exposure B forest response relationships applicable to air quality regulation and risk has been difficult due to serious limitations encountered in scaling-up experimental data.
The US and Canada have recently implemented new air quality standards that use the same metric but have set different target levels in order to protect both human health and the environment. For risk analysis purposes, large scale, long-term, chamber-less controlled experiments such as Aspen FACE that couple air quality and climatology measurements with effects studies are essential to establish realistic O3 dose-response relationships in support of policy on air quality. Following six years O3 exposure at Aspen FACE, annual net primary productivity has been reduced 29% in pure aspen, 12% in mixed aspen/birch, and 12% in mixed aspen/maple communities. Reduced primary productivity due to O3 is a consequence of interacting effects operating over several years at different levels. The key messages coming from AspenFACE are not only important to advancing our understanding of how O3 affects forest productivity, but will provide essential science support towards air quality standard development.

[back] [top]

Exploiting the Pre-European Settlement Forest: Michigan's Enduring Ecological Legacy
Kurt S. Pregitzer

Abstract: An emerging challenge in ecology is to improve our understanding of the properties and processes that allow ecosystems to persist in the face of environmental change. Ecologists sometimes compare the response of today's ecosystems to those of simulated, future environments. However, today's ecosystem processes depend on both the current environment and past events. Ecological legacies are the persistent effect of past events, which sometimes push ecosystems to a new state, implying that current ecosystem function cannot be fully understood with reference only to the present environment. Between the opening of the Erie Canal in 1825 and 1900, Michigan's forest landscape was exploited by immigrants in a way that is today perhaps difficult to fully appreciate. The population grew from less than 1000 Europeans to over 2,500,000 permanent residents. Most of the original forest was exploited, 8,000 miles of railroad were constructed, stumps were pulled and roughly 40% of the landscape was converted to agriculture. This was a dynamic period in the history of the State, but are there persistent ecological legacies from this period in history? How are today's ecological processes regulated by the historical legacy from this period of human exploitation of both terrestrial and aquatic ecosystems? These questions will be explored through a retrospective analysis of changes caused by human exploitation of Michigan's forest landscape more than 100 years ago.

[back] [top]

Tree Improvement in the Lake States: Current Statues, Future Opportunities
Don E. Riemenschneider

Abstract: Tree genetics research and tree improvement programs have existed in the Lake States for many years. Records of research conducted by the Forest Service, North Central Research Station extend historically to at least 1922 when several red pine provenance tests were established. Many other institutions such as universities and state conservation agencies have also made significant contributions to both basic research and applied tree improvement.

Historically, tree improvement in the Lake States has focused on conifers. Major studies have been conducted on white spruce, black spruce, all the native pines, balsam fir, and tamarack. Additionally, a long standing aspen improvement program was initiated by the Institute of Pulp and Paper Chemistry and continued by its descendent, the Aspen-Larch Genetics Cooperative at the University of Minnesota. Significant progress was and is being made in the development of inter-specific hybrids of both aspens and larches.

More recently, significant effort has been expended on the development of clonal varieties of hybrid cottonwoods using both inter-specific and intra-specific breeding strategies. Of all potential commercial tree species, hybrid poplars appear to offer an opportunity to test the limits of productivity in our Region.

I discuss, briefly, the history of genetics and tree improvement in the Lake States in both a biological and institutional context. Given that many of the principal workers in tree improvement have retired and given that the profession has faced considerable down-sizing in the last 10 to 15 years, I also discuss some of the challenges we face in regard to knowledge and legacy management.

[back] [top]

Woody Tissue Respiration and Recycling of CO2 in Trees
Robert O. Teskey and Mary Anne McGuire
Abstract: The rate of respiration of woody tissues has been commonly estimated from measurements of CO2 efflux to the atmosphere. These estimates are based on the assumption that all CO2 efflux originates from respiration of local tissues and that all CO2 produced by local tissues escapes to the atmosphere through the bark. However, dissolved CO2 can be transported in the xylem and the CO2 concentration in the stem can be up to three orders of magnitude greater than that of the atmosphere, suggesting that measurements of CO2 efflux to the atmosphere do not account for all CO2 produced by respiration. In addition, it appears that a portion of the dissolved CO2 is re-fixed and recycled within the tree. Recently we have developed a new approach for estimating the respiration rate of tree stems that accounts for both external and internal fluxes of CO2. This has become possible because of new methodology for measuring CO2 concentrations in tree stems in situ. This mass balance approach uses simultaneous measurements of CO2 efflux to the atmosphere, sap flux, and internal CO2 concentration to calculate the total rate of CO2 production in a segment of stem tissue. In this talk we will describe a) the theoretical basis of the mass-balance approach, b) how the measurements are made, c) provide estimates of actual stem respiration in different tree species and discuss the potential for recycling respired CO2 in trees. We have found that CO2 produced by respiration of stem tissues moves in internal and external flux pathways in different proportions at different times of day and in different environmental conditions. Our calculations show that a substantial portion of respired carbon is not accounted for in measurements of efflux to the atmosphere alone. In some cases, more than 75% of the respired CO2 moved in the internal pathway, with less than 25% released to the atmosphere. During daylight hours when sap is flowing, the largest proportion of respired CO2 is carried away in the xylem stream, while at night more respiratory CO2 escapes to the atmosphere through bark. Measurements made using the mass balance approach can lead to an improved understanding of woody tissue respiration and better estimates of the rate of respiration and the carbon budget of trees.

[back] [top]

Functional Genomics and Forest Tree Improvement: A Case Study on Resource Allocation
Dr. Chung-Jui Tsai

Abstract: Completion of the first tree genome sequence and continuing rapid development of high throughput technologies promise to advance all facets of forest biology research. As the favorite model perennial, Populus is particularly well suited for linking functional genomics to ecological research and tree improvement. We are applying a functional genomics approach to dissect the molecular, physiological and biochemical events orchestrating resource allocation between growth and defense in several species of Populus and Salix under varying growth regimes. The study capitalizes on the extremely wide natural variation in foliar concentration of defensive phenolic glycosides (PGs) and condensed tannins (CTs) among these species. Ultimately, tree allocation of metabolic resources influences ecosystem community structure and overall site productivity in undomesticated habitats as well as in commercial plantations. To understand the regulation of resource allocation between growth and fitness, we are using hydroponics to perturb sink allocation and growth of selected cottonwood and willow hybrids. Hydroponic cottonwood and willow lines exhibited the same ranking in terms of foliar CT and total phenolics content as potted and field-grown plants. Height correlated negatively with foliar phenolics content among pot-grown cottonwood lines. Short-term, hydroponic nitrogen starvation under non-limiting light intensity resulted in large perturbations in CT and total phenolics in these tree lines. The use of microarray gene expression profiling and metabolic fingerprinting analyses for identification of molecular and metabolic markers associated with growth-fitness allocation will be presented.

[back] [top]