Warren Forestry Sciences Laboratory


Abstracts and Current Work

Below, please find some abstracts of presentations or papers given recently by Warren Forestry Sciences Laboratory Scientists and their colleagues, or studies we have recently initiated. The abstracts are organized by Research Problem. For more informat ion, or for a reprint of papers whose abstracts are listed here, please e-mail us at: cweldon@fs.fed.us.


Impact of glyphosate and sulfometuron methyl on diversity of plants and wildlife in Allegheny hardwoods

Part I: Assessing short-term impacts on understory plant communities.
Todd E. Ristau and Stephen B. Horsley

Executive Summary: The short-term impact of the herbicides glyphosate and sulfometuron methyl combined with shelterwood seed cutting on diversity of regeneration species and non-target herbaceous species was assessed using ten 16-20 acre stands in a split-plot sampling design. Two pre-treatment assessments of understory plant communities were made, with one occurring during heavy overstory defoliation by elm spanworm. Herbicide was applied to half of each 16-20 acre site, and cutting was done on 5 of the 10 sites. The other 5 sites had received a shelterwood seed cut prior to the start of the study. Data were collected at 1,2, and 4 years post herbicide treatment using 30 temporary milacre plots. In the short-term, glyphosate and sulfometuron methyl included in prescriptions with shelterwood seed cuts have little effect on diversity of herbaceous and woody species. Herbicide temporarily reduced the average number of species found, but after 3 years the numbers returned to pre-treatment levels. Differences in frequency of seed years in various species encountered are likely the reason for the delay in recovery of some species. Stocking of desirable regeneration is improved through use of herbicides, however control plots were adequately stocked on average as well. This is not usually the case under high levels of interfering plants. Heights of black cherry and red maple were unaffected by the shelterwood cut after 3 years of growth. Measurements of white-tailed deer density at all locations suggest that excessive browsing is an important contributor. The herbaceous species Oxalis montana and Politricum sp.showed negative responses to herbicide being dramatically reduced in area covered. The targeted fern species also remained very low in abundance following treatment. The targeted grass species and some other non-targeted but affected species recovered their brief loss of abundance. Spring ephemerals were not negatively affected. This study will continue to be monitored for 6 more years.

PRESENTATION: Progress Report

OUTLET: Internal Publication


Seventy-two years of change in the herbaceous vegetation layer of Heart's Content Scenic Area, Warren County, PA.
Todd E. Ristau

Research Problem: Forest Regeneration & Renewal

ABSTRACT: Heart's Content Scenic Area is an old-growth remnant of the northern hardwood forest type. A quantitative assessment of the vegetation was conducted in 1928. In recent years many trees have been dying due to beech bark disease, lightning strikes, biological maturity of white pine, and other stresses. The purpose of this work was to assess background changes to species composition in the absence of direct anthropogenic disturbance. We used methods described in 1928 to re-measure the exact 1928 sample plots during the summer of 2000. Sixty acres on the eastern half of the area were sampled using 160 1-m2 plots. Additionally, a systematic search was conducted to compile a more complete species list. Dramatic changes occurred in abundance of shrub and some herbaceous species. In 1928, 50 percent of the plots contained Viburnum alnifolium. In 2000 that species was only found in the systematic search. Twenty-three other species found on plots in 1928 were missing in 2000, with 16 of the 23 being found in the systematic search. Thirty-two species not encountered in 1928 were found in the 2000 search, many of them early successional, and found adjacent to an interpretive trail. Rhizomatous ferns increased in abundance from 3 to 21 percent on average. Since 1928, the white-tailed deer herd in the region has become overabundant, and is likely directly or indirectly responsible for most of the vegetation composition changes.

PRESENTATION: Submitted for oral presentation

OUTLET: Procedings Ecological Society of America Annual Meeting, 2001.


Use of Pyrolysis Molecular Beam Mass Spectrometry (py-MBMS) to Characterize Forest Soil Carbon: Preliminary Results from an Old-Growth Forest in Northwestern Pennsylvania
Hoover, C. M., Magrini, K. A., and Evans, R.J.

Research Problem: Forest Regeneration & Renewal

ABSTRACT: This study uses an unmanaged old-growth forest in northwestern Pennsylvania that has experienced major stand-replacing wind events as a natural laboratory in which to examine the effects of natural disturbance on soil carbon dynamics. In addition, we test the utility of a new and rapid analytical method, pyrolysis molecular beam mass spectrometry (py-MBMS), for the measurement and characterization of carbon in forest soils. The data show that soil carbon increases with increasing time since disturbance in the Tionesta Scenic and Research Natural Areas. Although the exact shape of the carbon accumulation curve is not known, it appears that the rate of accretion is initially rapid and then begins to level off, with a possible maximum of 86 metric tons/ha to a depth of 30 cm. This study also demonstrates that py-MBMS is a valid and reliable method for measuring soil carbon, and can be used with little sample preparation. In addition, multivariate analysis of the mass spectra from Tionesta soils can distinguish both sites and depths on the basis of their pyrolysis products; both long-lived and short-lived carbon forms were identified.

Status: in review

Outlet: Environmental Pollution Special Issue: Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.
Also: Oral paper given at conference Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.


Use of Pyrolysis Molecular Beam Mass Spectrometry (py-MBMS) to Characterize Forest Soil Carbon: Method and Preliminary Results
Magrini, K. A.,* Evans, R. J., Elam, C. C., Davis, M. F., and C.M. Hoover

Research Problem: Forest Regeneration & Renewal

ABSTRACT: Carbon content and dynamics in forest soils are rarely studied and poorly understood, due to time-consuming sample collection, preparation, and difficulty of analyzing and identifying major components of soil organic matter (SOM). Little work has been done on the characterization of SOM in whole soils, and changes in chemical composition as a result of age, forest type, or disturbance have not been examined. We have applied pyrolysis molecular beam mass spectrometry (py-MBMS), which provides rapid characterization of SOM of whole soil samples, to the Tionesta soil samples collected by the Forest Service and described by Hoover (this volume). Our goals in this work are: 1) developing and demonstrating an advanced, rapid analytical method for characterizing SOM in whole soils, and 2) developing data based models to predict soil carbon content and residence time from easily obtainable and measurable variables. Analysis of pyrolysis products of whole soil samples from four Tionesta sites and at three depths using py-MBMS and pattern recognition techniques showed an increase in pyrolysis products of more highly decomposed plant materials as a function of increasing sample depth. As well, samples could be distinguished according to the site of origin. These results indicate that this type of analysis could be used to rapidly characterize SOM for the purpose of developing a model to predict composition, which could be used in monitoring the effect of forest management practices on carbon uptake and storage.

Status: in review

Outlet: Environmental Pollution Special Issue: Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.
Also: Oral paper given at conference Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.


How Landowners and Forest Managers Can Estimate Carbon Sequestration

Coeli M. Hoover, Richard A. Birdsey, Linda S. Heath, Susan L. Stout

Research Problem: Forest Regeneration & Renewal

ABSTRACT: Recent international climate change agreements may eventually allow carbon stored as a result of afforestation and reforestation to be used to offset CO2 emissions, which gives foresters the opportunity to play a significant role in efforts to control greenhouse gases. A methodology developed for estimating forest carbon storage at the management unit scale is described in this report. We also tested the impacts of different hypothetical forest management scenarios on carbon sequestration over an extended planning period. We demonstrate the use of the procedure on two military installations in the southeastern US and discuss some practical considerations.


Type: journal article
Outlet: Jour. of Forestry 2000 98(9):13-19


Using Forest Health Monitoring Data to Integrate Above and Below Ground Carbon Information

Barbara L. Conkling, Coeli M. Hoover, William D. Smith, and Craig J. Palmer

Research Problem: Forest Regeneration & Renewal

ABSTRACT: The national Forest Health Monitoring (FHM) program conducted a remeasurement study in 1999 to evaluate the usefulness and feasibility of collecting data needed for investigating carbon budgets in forests. This study indicated that FHM data are adequate for detecting a 20 percent change over 10 years (2 percent change per year) in percent total carbon and carbon content (MTC/ha) when sampling by horizon, with greater than 80 percent probability that a change in carbon content will be determined when a change has truly occurred, at a significance level of 0.33. The data were also readily usable to produce estimates of forest floor and soil carbon stocks by depth. The scale at which the data were collected lends itself to producing standing stock estimates needed for carbon budget development and carbon cycle modeling. The availability of site-specific forest mensuration data enables the exploration of above ground and below ground linkages.

Status: in review
Outlet: Environmental Pollution Special Issue: Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.
Also: Oral paper given at conference Advances in Terrestrial Ecosystem Carbon: Inventory, Measurement, and Monitoring.


Denitrification at a Long-Term Forested Land Treatment System in the Piedmont of Georgia

Meding, S. M., Morris, L. A., Hoover, C. M., Nutter, W. L., and Cabrera, M. L.

Research Problem: Forest Regeneration & Renewal

ABSTRACT:Spray irrigation of forested land can provide an effective system for nutrient removal and treatment of municipal wastewater. Evolution of N2 + N2O from denitrifying activity is an important renovation pathway for N applied to forested land treatment systems. Federal and state guidance documents for design of forested land treatment systems indicate the expected range for Denitrification to be up to 25% of applied N, and most forest land treatment systems are designed using values from 15-20% of applied N. However, few measurements of Denitrification following long-term wastewater applications at forested land treatment sites exist. In this study, soil N2 + N2O-N evolution was directly measured at four different landscape positions (hilltop, mid-slope, toe-slope, and riparian zone) in a forested land treatment facility in the Georgia Piedmont that has been operating for more than 13 years. Denitrification rates within effluent-irrigated areas were significantly greater than rates in adjacent non-irrigated buffer zones. Rates of N2 + N2O-N evolved from soil in irrigated forests ranged from 5-10 kg ha-1 yr-1 N on the three upland landscape positions and averaged 38 kg ha-1 yr-1 N within the riparian zone. The relationship between measured riparian zone denitrification rates and soil physical and chemical properties was poor. The best relationship was with soil temperature with an r2 of 0.18. Overall, on a landscape position weighted basis, only 2.4% of the wastewater-applied N was lost through denitrification.


Status: in press
Outlet: Journal of Environmental Quality


FACTORS ASSOCIATED WITH THE DECLINE-DISEASE OF SUGAR MAPLE ON THE ALLEGHENY PLATEAU

Research Problem: Stress and Nutrient Relationships for Allegheny Plateau Plant Species

Stephen B. Horsley, Robert P. Long, Scott W. Bailey, Richard A. Hallett, and Thomas J. Hall

Unusual mortality of sugar maple (Acer saccharum Marsh.) has been occurring across northern Pennsylvania since the early to mid-1980s. We rated health of sugar maple in 43 stands and evaluated the influence of glaciation, topographic position, site characteristics (elevation, aspect), stand characteristics (species composition, structure, density), disturbance history (management, defoliation), and foliage chemistry on sugar maple health. Percent dead sugar maple basal area (PDEADSM) and crown vigor index (SMVIG) were the most reliable health indicators (healthy = PDEADSM < = 11, SMVIG < = 2.2; unhealthy = PDEADSM > = 21, SMVIG > = 2.4). All unhealthy stands were found on unglaciated sites in summit, shoulder or upper backslope topographic positions. Stands on glaciated sites and unglaciated lower topographic positions were healthy. The most important factors determining sugar maple health were foliar levels of Mg and Mn and defoliation history. The lowest foliar Mg, the highest foliar Mn and the highest number and severity of insect defoliations were associated with unglaciated summits, shoulders and upper backslopes. Mg appears more important than Mn; trees with > ~ 700 mg kg-1 Mg could withstand > 3700 mg kg-1 Mn and remain healthy. Unhealthy stands were those with < ~ 700 mg kg-1 Mg and > = 2 moderate to severe defoliations in the past 10 years; both conditions were required for decline to occur. The decline-disease of sugar maple appears to be the result of an interaction between Mg (and perhaps Mn) nutrition and stress caused by defoliation.

PRESENTATION: Published paper.

OUTLET: In review.


FOREST REGENERATION: CAN WE OVERWHELM DEER?

Research Problem: Forest Regeneration & Renewal

Richard K. Lawrence,Susan Stout, David S. deCalesta, William F. Porter, and H. Brian Underwood

Foraging impact on forest regeneration and biological diversity is high at deer densities commonly found throughout the northeast. Previous research shows that the deer impact problem is complex, with demonstrable long-term implications. Until very recently, managers have relied strictly on direct population control or exclusion devices to control deer impoact on forested ecosystems. We explored the potential to influence deer impact through varying the scale of silvicultural activities across a landscape. The central hypothesis underlying our research is that managers can control deer impact by planning and implementing silvicultural treatments at or above the scale required to produce sufficient forage to overwhelm deer foraging response. We used a modeling environment in which deer move across a simulated landscape containing habitats of differing quality. We used a single, simulated regeneration cut, with a high deer-use affinity value of 0.9 in a replicated, randomly located application to each background habitat map. The deer affinity for the background habitat was 0.1, signifying low quality habitat relative to the simulated clearcuts. Six treatment sizes, ranging from 2 to 41 acres, provided a broad test of treatment sizes for simulations. Deer impact was measured as the cumulative time spent by all deer in any given map cell. Our findings showed that about 30 acres was the minimum treatment size at which deer impact became consistent. Cuts smaller than 30 acres produced highly variable responses by deer. This might explain why small clearcuts (10-20 acres) resulted in inconsistent and unpredictable regeneration success. Lrger cuts showed a higher degree of deer impact predictability. Our examination suggests that the placement of clearcuts relative to local deer concentrations can greatly affect regeneration success. As forest managers experiment with silvicultural treatments, they should work at scales > 30 acres, and be aware of landscape features that influence local deer distributions.

PRESENTATION: Oral.

OUTLET: Wildlife Society Fifth Annual Conference 1998.


RELATIVE DEER DENSITY AND SUSTAINABILITY: A CONCEPTUAL FRAMEWORK FOR INTEGRATING DEER MANAGEMENT WITH ECOSYSTEM MANAGEMENT

Research Problem: Forest Regeneration & Renewal

David S. deCalesta and Susan L. Stout

ABSTRACT: Relative deer density (RDD) provides managers with a way to broaden their approach to issues of deer overabundance from single-species management and carrying capacity to multiple-species management and ecosystems. In 1984, McCullough published a deer recruitment curve for the George Reserve, Michigan, USA. Net annual recruitment of deer was expressed as a function of the relationship between deer density and K, the ecological carrying capacity of the George Reserve. We propose that this deer recruitment curve also can be used to provide a framework for predicting deer impacts on supporting resources (Fig. 1), and that similar resource impacts occur at similar relative deer densities on landscapes with widely varying Ks. We suggest a framework for describing these impacts based on McCullough's (1984) definition of K carrying capacity, the population density at which mortality is balanced by recruitment, so that net recruitment is zero. The conceptual framework that we propose is Relative Deer Density (RDD), or current deer density as a proportion of deer density (DD) at K carrying capacity: RDD = (DD/K)*100. Further, we suggest using McCullough's (1979) deer population-recruitment curve (Fig. 1) as a backdrop for defining relative deer density as it relates to sustaining deer harvest or ecosystem components. Without explicitly using the concept of RDD, McCullough (1984) described the probability of seeing deer in the forest and the rate of recruitment as predictable functions of RDD. When interactions between deer and their environment are scaled to K, we have a standardized method for describing impacts of deer on ecosystem components and for making integrated predictions of the impacts of management choices. If we can estimate K and ambient deer density for a landscape, then we can derive RDD.

deerrd.jpg
PRESENTATION: Published paper

OUTLET: Wildlife Society Bulletin - 25(2) 252-258


WOOD VOLUME INCREMENT IN THINNED, 50- TO 55-YEAR OLD, MIXED SPECIES ALLEGHENY HARDWOODS

Research Problem: Stand Development and Intermediate Treatments

Christopher A. Nowak

Abstract: A thinning study in 50- to 55-yr-old, even-aged, mixed species Allegheny hardwoods produced highly variable merchantable stemwood volume increment responses. Regression equations relating parameters of stand growth (ingrowth, mortality, survivor growth, net growth and gross growth) to relative stand density had R2 values ranging from 0.07 to 0.48. When study plots with similar pretreatment species composition were assigned to four groups using cluster analysis, R2 values were increased to 0.94-0.99. There were significant differences in the relationships between relative stand density and growth response variables among all plot groups. At all densities, plots with a high percentage of black cherry (Prunus serotina Ehrh.) had the highest volume increment. Plots with a high percentage of black cherry and a low percentage of sugar maple (Acer saccharum Marsh.) showed a decrease in volume increment, relatively high ingrowth, and relatively low mortality with a decrease in relative stand density. Plots with a high percentage of sugar maple and a high percentage of black cherry showed an increase in volume increment, relatively low ingrowth, and relatively high mortality with decreases in relative stand density. Guidelines for thinning Allegheny hardwoods recommend a residual relative stand density of 60%. These guidelines may need to be revised to incorporate considerations of species composition. Stands of pole-sized to small sawtimber-size trees dominated by black cherry may require a residual density higher than 60% to maximize the volume increment of merchantable stemwood. The volume increment in similarly structured stands dominated by sugar maple may be maximized at densities lower than 60%.

PRESENTATION: Published Paper

OUTLET: Canadian Journal of Forest Research 26: 819-835


SHORT-TERM IMPACT OF HERBICIDE APPLICATION ON SMALL MAMMALS IN NORTHWESTERN PENNSYLVANIA

Research Problem: Forest Regeneration & Renewal

Julie L. Smithbauer and David S. deCalesta

ABSTRACT: Herbicides used to control interfering plants in the forest understory are not toxic to small mammals at operational application rates. However, the indirect impact of herbicides on small mammals in eastern deciduous/conifer mixed forests by alteration of habitat is unknown. This study tested whether application of herbicide affects wildlife habitat and small mammal populations. Ten 20 acre northern hardwood stands in the Allegheny National Forest in northwestern Pennsylvania were split in half and a tank mix of glyphosate and sulfometuron methyl was applied to one half (treatment): the other half (control) received no herbicide. Pre-spray data (1992, 1994) and post-spray data (1995-96) were collected on habitat and small mammal populations. Habitat components (ferns, grasses, shrubs, seedlings) within 7m of the ground were nearly eliminated after spraying. Small mammal species richness did not differ (P >0.50) between treated and control sites prior to application of herbicides, but was significantly(P<0.08) lower on treated sites one and two years after treatment. However, herbicide application was not associated with loss of any individual mammal species. Numbers of small mammals captured prior to herbicide application were not different between treated and control sites (P> 0.50), but after treatment, numbers of red-backed voles (Clethrionomys gapperi), eastern chipmunks (Tamias striatus), and masked shrews (Sorex cinereus) captured were significantly lower (P< 0.1) on treated sites. Herbicide application depressed abundance and species richness of small mammals in the short run but did not result in consistent loss of species. The study will continue to evaluate impact of herbicide application on small mammals and their habitat for 6 more years.

PRESENTATION: Oral.

OUTLET: 78th Annual Meeting of the American Society of Mammalogists


DO POINT COUNTS OF SINGING MALE SONGBIRDS REFLECT DEMOGRAPHY?/STRONG>

Research Problem: Forest Regeneration and Renewal

Linda D. Ordiway AND David S. deCalesta

ABSTRACT: Point counts of singing males are a rapid and inexpensive means of gathering information on songbirds. However, uncertainty exists whether such counts reflect demographic events. We conducted counts of singing male songbirds on 21 forested sites on the Allegheny National Forest in northwestern Pennsylvania during 1992, 1994, and 1995. Sites included representatives of early-mid-maturing northern hardwood forest successional sites. A major irruption of the elm spanworm (Ennomos subsignarius) began in 1992, peaked in 1993, and crashed in 1994, aided by local applications of BT (Bacillus thuringensis). Recruitment changes in songbird populations should have lagged one year behind the irruption and crash: populations should have increased greatly from 1992 to 1994, and crashed in 1995. We tested whether counts of singing male songbirds reflected these expected demographic results. We used counts of a ground-nesting species (ovenbird, Seiurus aurocapillus), a mid-story canopy nesting species (red-eyed vireo, Vireo olivaceus), a mid-upper canopy nesting species (American redstart, Setophaga ruticilla), and an upper canopy nesting species (black-throated green warbler, Dendroica virens) conducted three times throughout the breeding season for the three study years. For each species we used counts from four high bird density sites, four medium bird density sites, and four low bird density sites. For all species on high, medium, and low density sites, analysis of variance revealed that singing male counts were significantly higher (P <0.001) one year after the spanworm peak abundance than two years before, and were significantly (P <0.001) lower the second year following the crash than the first year. Singing male counts mirrored expected changes in recruitment across a wide range of singing male densities, suggesting that such counts can reflect demography.

PRESENTATION: Oral

OUTLET: Proceedings of Fifth Annual Conference of the Wildlife Society, 1998


EFFECTS OF DEER ON FOREST RESOURCES: ECOSYSTEM, LANDSCAPE, AND MANAGEMENT PERSPECTIVES

Research Problem: Forest Regeneration and Renewal

David S. deCalesta

ABSTRACT: There is a growing awareness that comprehensive and effective management of white-tailed deer (Odocoileus virginianus) impacts on natural resources within some forest ecosystems in the eastern United States is failing. The problem results partly from incomplete understanding of differential impacts on different classes of natural resources fostered by different deer densities, and partly from lack of appreciation of the influence local and regional landscapes have on deer impacts. The major tool for mitigating impacts of deer on ecosystems is population reduction by legal hunting. Unfortunately, wildlife managers have been unable to communicateeffectively to the hunting public how sustained levels of deer harvest must be tailored to fit the limits imposed by local and regional landscapes. Without such understanding neither deer nor other affected forest resources can be managed for sustainability. A proposed framework, annotated by examples within different local and regional landscapes, integrates the confounding issues of differential deer impact, effect of landscape, and management of deer numbers into a landscape model for managing deer impact within forest ecosystems.

PRESENTATION: Oral

OUTLET: Proceedings of Fifth Annual Conference of the Wildlife Society, 1998


COMPARISON OF TWO TECHNIQUES FOR ASSESSING SPECIES RICHNESS IN ALLEGHENY HARDWOOD FORESTS.

Research Problem: Forest Regeneration & Renewal

Todd E. Ristau

ABSTRACT: I compared species richness assessed using two methods: 1) a systematic grid of 0.0004-ha fixed-area quadrats, where all species were identified and abundance was measured, and 2) a timed-meander search, where a species list was compiled while wandering through the site -- time was recorded every 10 minutes until no new species were encountered. We sampled twenty-eight Allegheny hardwood sites using both methods during the spring of 1997. The number of quadrats sampled ranged from 16 to 35 depending on site size, and required 2-3 hours for completion. Timed-meander searches typically required 1-3 hours for completion, and also depended on site size. A paired t-test was used to evaluate differences in richness between methods. Mean richness for quadrats (21) differed from that for the timed-meander (35)(p<0.001) method. The timed-meander approach is more effective for determining species richness because it allows investigation of micro-habitat conditions within the site. Fixed-area quadrats allow assessment of abundance, but confine richness assessments to a small portion of the site.

PRESENTATION: Oral presentation

OUTLET: Procedings Ecological Society of America Annual Meeting, 1998.


VARIATION IN NON-ARBORESCENT VASCULAR SPECIES DIVERSITY DURING THE GROWING SEASON IN ALLEGHENY HARDWOODS

Research Problem: Forest Regeneration & Renewal

Todd E. Ristau

ABSTRACT: Measurement of plant diversity often is difficult because species have different phenologies. The timing and frequency of sampling conducted for diversity studies are crucial to an adequate assessment. The purpose of this study was to determine the best time and frequency of sampling required to assess diversity of non-arborescent vascular plant species in Allegheny hardwood forests. Four 16-20 acre sites on the Allegheny National Forest were chosen from a large-scale diversity study being conducted by the USDA Forest Service, Northeastern Forest Experiment Station, Forestry Sciences Laboratory in Warren, PA. Each of the study sites was divided into two sides for later use in a split-plot experimental design. Percent cover by species was ocularly estimated on thirty 1-milacre plots per side per site in the middle of each month from May through August of 1992 and 1993. Plant species were grouped using TWINSPAN, a multivariate clustering technique. Four groups were identified: 1) Spring ephemerals; 2) Species with a constant abundance throughout the growing season; 3) Species with changing abundances throughout the growing season; and 4) Rare or infrequent species found in one or two months at low abundance. Species richness and the Shannon, Margalef, Berger-Parker, and Shannon Evenness indices were calculated for non-arborescent vascular species by month, and for combinations of months created by combining sample times. A p-value of <0.1 was considered as significant. The best sampling time or combination of times was dependent on the index being used. Measures of dominance (Berger-Parker) and evenness (Shannon Evenness) were not influenced by time or frequency of sampling. Evaluation of richness and indices emphasizing richness (Shannon and Margalef indices) showed that sampling in May is critical for the inclusion of spring ephemerals, and for identification of plants, since many species flower during that time. Inclusion of a second month in calculations increased the numerical value of the index due to changing abundance, especially of dominant species such as fern. For the Shannon index, sampling in May alone produced values similar to those when sampling was conducted in multiple months, however, maximum value of the index was obtained by combining data from May and August. For the Margalef index and species richness, May-June or May-July combinations produced the highest. Description of plant diversity should include a variety of indices that capture changes in richness and abundance. Given a mixture of richness and evenness oriented indices, sampling for non-arborescent plant diversity in Allegheny hardwoods should include an early spring sample to assure the inclusion of ephemerals and should include a second month, preferably July or August, to accurately represent abundance.

PRESENTATION: Masters thesis

OUTLET: A thesis in Forest Science, The Pennsylvania State University


PIN CHERRY EFFECTS ON ALLEGHENY HARDWOOD STAND DEVELOPMENT

Research Problem: Stand Development and Intermediate Treatments

Todd E. Ristau, Stephen B. Horsley

ABSTRACT: Pin cherry (Prunus pensylvanica L) develops an early height advantage over associates. Data from three long-term studies, extending up to 70 years after complete overstory removal was used to evaluate effects of pin cherry density on associated species. Survival of seedling-origin stems of black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.) and sugar maple (Acer saccharum Marsh.) at age 15 decreased as density of pin cherry > 1.5 m tall at age 3 increased. The regression of pin cherry with black cherry was particularly strong (R2=0.632). Height of the tallest black cherry and white ash (Fraxinus americana L.) at age 15 also decreased. If pin cherry density at age 3 was >1 stem >1.5 m tall x 0.0004 ha -1 (high density), the number of black cherry fell below full stocking at age 15. When pin cherry occurred in high density, it lived longer than at low density(<1 stem >1.5 m tall x 0.0004 ha-1). High pin cherry density early in stand development delayed the time when shade-intolerant and shade-intermediate species reached a stable proportion of the total basal area. In the long term, pin cherry reduced stand diameter and volume growth, particularly of black cherry.

PRESENTATION: Published paper.

OUTLET: Canadian Journal of Forest Research.


IMPACT OF FOREST LIMING ON GROWTH AND CROWN VIGOR OF SUGAR MAPLE AND ASSOCIATED HARDWOODS

Research Problem: Stress and Nutrient Relationships for Allegheny Plateau Plant Species

Robert P. Long, Stephen B. Horsley and Paul R. Lilja.

ABSTRACT: Sugar maple (Acer saccharum Marsh.) has been declining across the unglaciated Allegheny Plateau in northwestern and north central Pennsylvania since the mid-1980s. A long-term study to evaluate the effects of fencing, herbicide, and liming on growth, crown vigor, and regeneration of sugar maple and associated Allegheny hardwoods was initiated in 1985. The study is a split-plot design with fencing (fence - no fence) as the whole-plot treatment and four subplot treatments: applications of herbicide (glyphosate) to control interfering vegetation, dolomitic lime (22.4 Mg ha-1) to reduce soil acidity, dolomitic lime and herbicide, and an untreated control. Liming significantly increased diameter growth and improved crown vigor of overstory sugar maple, but did not affect growth or vigor of overstory black cherry (Prunus serotina Ehrh.) and American beech (Fagus grandifolia Ehrh.). Basal area (adjusted by covariance) of sugar maple on limed plots increased by 11% from 1986 to 1993 but by only 4% on unlimed plots. Liming increased exchangeable cations in the upper 15 cm of the soil, especially Ca and Mg, and reduced levels of exchangeable K, Al, and Mn Changes in soil chemistry were reflected in the chemistry of overstory sugar maple foliage. Concentrations of Ca doubled on limed plots and Mg increased fourfold on limed versus unlimed plots. Liming also increased the size (in 1989 and 1992) but not the frequency of sugar maple flower and seed crops. The results demonstrate the importance of Ca and Mg nutrition in maintaining the health of sugar maple on unglaciated sites.

PRESENTATION: Published paper.

OUTLET: The Canadian Journal of Forest Research 27: 1560 - 1573.


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