Allegheny Hardwood Research Articles

Influence of stand age, soil attributes, and cover type on Rubus (Rosaceae) seed bank abundance

We assessed Rubus seed bank abundance and variability in 39 stands located throughout northern Pennsylvania as part of a replicated chronosequence of age classes. Seed abundance declined precipitously after stand age 60 in the Allegheny hardwoods or after stand age 50 in the northern hardwood and oak forests. Variability among sites increased with stand age, resulting in less predictability of Rubus seed abundance. Rubus seed banks were more than twice as abundant in Allegheny and northern hardwoods as in mixed oaks. Rubus seed bank abundance decreased as percent clay in the soil increased. Given that Rubus seed bank abundance declines with age and seed abundance becomes more variable, we suggest that there will be less Rubus immediately following the standreplacing disturbances in older stands, potentially changing plant competition dynamics and wildlife food sources.

Managing Understory Fagus grandifolia for Promoting Beech Bark Disease Resistance in Northern Hardwood Stands

AbstractMany Allegheny hardwood stands contain dense understories of very shade-tolerant American beech, resulting from partial disturbances that have accelerated root sucker development. The low-shade produced by these sprouts hampers silvicultural regeneration efforts to maintain species diversity in new cohorts. An increasing proportion of sprouts result from stressed trees infested with beech bark disease. The clonal sprouts also have a genetic affinity for the disease. A mixture of Accord® and Oust® herbicides, applied to understory vegetation after shelterwood establishment cuts, can significantly reduce understory beech density. Yet, retention of some overstory beech, with demonstrated disease resistance, is ecologically desirable. The root sprouts from these parent trees should also have resistance to the disease. We used broadcast herbicide application to kill understory vegetation after shelterwood harvests in three stands, and tested the effect of herbicide on beech sprouts associated with resistant trees. Eight years after treatment, plots that had received herbicide had similar densities of beech to no-herbicide plots. However, there were significant differences in seedling densities among stands (P = .0303) and species (P = .0014). Our results indicate that there is much temporal variability in regeneration dynamics after treatment. Resistant beech sprouts are still competitive in the long term, even after herbicide application.

The Spotted Wing Drosophila, Drosophila suzukii (Diptera: Drosophilidae): A New Pest of Concern for Black Cherry, Prunus serotina, on the High Allegheny Plateau in Pennsylvania

Drosophila suzukii (Matsumura) is an invasive insect pest native to Southeastern Asia that is now reported to have established populations in North America. We used traps baited with red wine vinegar to detect and monitor D. suzukii in four black cherry (Prunus serotina Ehrh.) and maple (Acer spp.) stands in the Allegheny National Forest in northwestern Pennsylvania. Stands ranged in age from 70 to 110 years old, with average basal area from 40 to 45 m2/ha. All stands are characterized as the intermediate Allegheny hardwood forest type with black cherry being the dominant species making up > 70% of the total stand basal area at each site (Eyre, 1980). Traps were placed in the crowns of mature black cherry from May to October 2012. In total, 11,000 D. suzukii were collected. The appearance of D. suzukii on the High Allegheny Plateau in northwestern Pennsylvania could have negative implications for fruit production, dispersal, and seed viability of black cherry and other forest species. With D. suzukii's predilection toward Prunus spp. and its unusual method of oviposition, this could be a contributing factor that impacts black cherry regeneration on the Plateau.

The SILVAH Saga: 40+ Years of Collaborative Hardwood Research and Management Highlight Silviculture

The advent of even-age management in eastern forests in the 1960s improved regeneration of shade-intolerant and shade-intermediate species through much of the region. However, in the Allegheny hardwood stands of northern Pennsylvania, half of the even-aged regeneration harvests failed to create new forests. USDA Forest Service Research and Development (FSR&D) initiated a partnership with federal, state, industrial, and private forest landowners to solve this problem using silviculture. The partners developed inventory procedures and decision charts to identify regeneration assets and barriers as well as silvicultural treatments to mitigate the barriers. FSR&D training sessions ensured a common silvicultural vocabulary and common practices, later computerized in the SILVAH decision support system. In 2000, the partnership expanded SILVAH to mixed-oak forests of the mid-Atlantic region. Land management agencies in Pennsylvania and several other eastern states have adopted SILVAH. It provides a consistent framework for research-management cooperation, for sharing the results of silvicultural research, and for making silvicultural decisions in the forest types covered by the system.

Condition varies with habitat choice in postbreeding forest birds

Many birds that are experiencing population declines require extensive tracts of mature forest habitat for breeding. Recent work suggests that at least some may shift their habitat use to early-successional areas after nesting but before migration. I used constant-effort mist netting in regenerating clearcuts (4-8 years postcut) and dense mature-forest understories to assess (1) whether most bird species of mature forests show habitat shifts after breeding; and (2), on the basis of several measures of condition, whether birds using early-successional habitats garnered any benefits or penalties, compared with those that remained in forests. I captured 3,845 individual birds of 46 species at four pairs of sites in mature Allegheny hardwood forests in northwestern Pennsylvania during the postbreeding periods of 2005-2008. Most, but not all, forest birds were captured at higher rates in cuts than in forests, and that pattern persisted through the postbreeding season. Using an information-theoretic approach, I found strong support for a species-habitat interactive effect on both molt progression and body condition as measured by residuals from species- specific regression of mass on wing chord. Some, but not all, forest birds appeared to be in better condition when captured in cuts than when in forests. I found no support for a habitat effect on presence of fat or ectoparasites. My results reveal that habitat choice in the postbreeding season is correlated with physiological condition for a subset of forest birds, which suggests that the maintenance of such early-successional habitats in mature forest may benefit these species. Received 15 November 2012, accepted 2 May 2103.

Indirect Effects of Pandemic Deer Overabundance Inferred from Caterpillar‐Host Relations

Externally feeding phytophagous insect larvae (i.e., caterpillars, here, larval Lepidoptera and sawflies, Hymenoptera: Symphyta) are important canopy herbivores and prey resources in temperate deciduous forests. However, composition of forest trees has changed dramatically in the eastern United States since 1900. In particular, browsing by high densities of white-tailed deer (Odocoileus virginianus) has resulted in forests dominated by browse-tolerant species, such as black cherry (Prunus serotina), and greatly reduced relative abundance of other tree species, notably pin cherry (Prunus pensylvanica) and birches (Betula spp.). To quantify effects of these changes on caterpillars, we sampled caterpillars from 960 branch tips of the 8 tree species that comprise 95% of trees in Allegheny hardwood forests: red maple (Acer rubrum), striped maple (Acer pensylvanicum), sugar maple (Acer saccharum), sweet birch (Betula lenta), yellow birch (Betula allegheniensis), American beech (Fagus grandifolia), black cherry, and pin cherry. We collected 547 caterpillar specimens that belonged to 66 Lepidoptera and 10 Hymenoptera species. Caterpillar density, species richness, and community composition differed significantly among tree species sampled. Pin cherry, nearly eliminated at high deer density, had the highest density and diversity of caterpillars. Pin cherry shared a common caterpillar community with black cherry, which was distinct from those of other tree hosts. As high deer density continues to replace diverse forests of cherries, maples, birches, and beech with monodominant stands of black cherry, up to 66% of caterpillar species may be eliminated. Hence, deer-induced changes in forest vegetation are likely to ricochet back up forest food webs and therefore negatively affect species that depend on caterpillars and moths for food and pollination.

Ten-year response of bird communities to an operational herbicide–shelterwood treatment in a northern hardwood forest

Use of herbicides in forestry to direct successional trajectories has raised concerns over possible direct or indirect effects on non-target organisms. We studied the response of forest birds to an operational application of glyphosate and sulfometuron methyl herbicides, using a randomized block design in which half of each 8 ha block received herbicide and the other acted as a control, on shelterwood seed-cut Allegheny hardwood stands in northwestern Pennsylvania. We monitored birds using 50 m radius point counts in two pretreatment years and for 10 years post-treatment (1992–2004). Fences were erected six years after herbicide treatment in response to increased deer browsing at a subset of sites. Avian responses to herbicide treatment varied by nesting guild: we detected no response by cavity-nesters, but documented declines in the shrub-, ground- and canopy-nesting guilds. Responses were short-lived (2–4 years post-treatment), but shrub-nesters did not recover until fencing provided regenerating vegetation respite from browsing. Thus, apparent responses of birds to herbicide were confounded with deer browsing in this study. High species turnover, even within control plots, suggests that avian communities may be assessed more appropriately assessed at larger spatial scales than those used in this study (6.5–8 ha).

Ten-year response of the herbaceous layer to an operational herbicide-shelterwood treatment in a northern hardwood forest

Shelterwood seed cutting in conjunction with herbicide site preparation has proven effective at regenerating Allegheny hardwood forests, but the long-term impact of this silvicultural system on herbaceous vegetation has not been determined. From 1994 to 2004, we studied the impacts of operational herbicide site preparation using glyphosate plus sulfometuron methyl herbicides in the context of a shelterwood seed cut. Our study took place on 10 partially cut sites on the Allegheny National Forest in northwestern Pennsylvania. Half of each site received herbicide and half did not in a split-plot design with repeated measures. Fences were erected after year six because deer impact had increased. Resilience of individual species and the community were determined using measures of percent cover by species or species groups and indices of diversity and similarity comparing post-treatment to pre-treatment conditions and controls. In the short term, abundance of all species was reduced and there were four fewer species on average in treated areas. No species was eliminated by herbicide across all sites in the long term. Graminoids were more abundant on treated plots after year six. Targeted ferns remained less abundant on treated than control plots after 10 years. Species richness recovered within 4 years following treatment. Shannon Diversity and Shannon Evenness were greater in treated than in control plots over the full study period, but the differences were not significant in any single year. The richness-based Jaccard index of similarity did not differ between control and treatment plots after year two, while relative abundance influenced indices showed significant differences through year eight. Results suggest that herbaceous layer vegetation is resilient to the disturbance created by herbicide-shelterwood treatments.

The Carbon Consequences of Thinning Techniques: Stand Structure Makes a Difference

Abstract Using results from a 25-year study of thinning in a northwestern Pennsylvania Allegheny hardwood stand, we assess whether and how thinning method affected carbon sequestration and merchantable volume production. Plots were thinned to similar residual relative density by removing treesfrom different portions of the diameter distribution. Plots that were thinned from below had greater volume production and carbon sequestration rates than plots that were thinned from the middle or thinned from above. Control plots, which were not thinned, also had higher carbon sequestrationrates than plots thinned from the middle and higher merchantable volume production and carbon sequestration rates than plots thinned from above. In this forest type, changing stand structure by thinning can affect carbon sequestration and stand growth either positively or negatively. Thoseeffects can be significant, with long-term implications for the growth of the stand. In general, structures that favored volume production also favor carbon sequestration.

Controlling Beech Root and Stump Sprouts Using the Cut-Stump Treatment

Abstract Application costs and efficacy were determined for cut-stump treatments applied to American beech (Fagus grandifolia Ehrh.) to control root and stump sprouts in central West Virginia. Glyphosate as Glypro (53.8%) was applied to the outer 2 in. of beech stumps from trees >6.0-in. dbh within 1 hour after cutting. In addition to treatment plots, individual beech stumps were treated to determine mortality patterns. The treatments were applied in early September 2001 and evaluated 12 months after treatment. A rating system ranging from 1 to 7 (0 to 100% crown affected) based on visual estimates of symptoms was used to evaluate the efficacy of the treatments. Trees with a rating of 5 (75% crown control or greater) were considered controlled. After 12 months, more than 90% of beech root sprouts ≥1-ft tall to 5.9-in. dbh on treated plots were controlled. Complete control of stump sprouting also was achieved. An average of 93 beech stems was controlled around each treated stump. Mortality around treated stumps declined as the radial distance from stumps increased and stump size decreased. Average application cost (chemical and labor) ranged from $39.43 to 62.34 per acre depending on the basal area and number of stems treated. After two growing seasons, the number of beech root sprouts on more than 90% of the treated regeneration plots remained below levels considered as interfering according to guidelines for Allegheny hardwoods. This study demonstrated that herbicide is readily translocated from the surfaces of freshly cut beech stumps via parent root systems to attached live beech stems. The cut-stump method can be applied in areas where beech is the primary species interfering with the establishment and development of desirable regeneration.

When Is Pin Cherry (Prunus pensylvanica L.) a Problem in Allegheny Hardwoods?

Abstract Pin cherry (Prunus pensylvanica L.) has important effects on early stand development when it occurs at high densities. We used data describing the first 15 years of stand development in eight clearcuts and used plots that had at least 25 black cherry or 100 desirable seedlings at age 3, as well as different levels of pin cherry stocking. Our findings identified seven pin cherry >5 ft tall at age 3 on 6-ft-radius plots as the threshold for negative effects on stocking of seedling-origin trees of desirable species at age 15. We incorporated these finding into the regeneration followup chart used as part of the Silviculture of Allegheny Hardwoods (SILVAH) decision support framework. Of eight stands used in this study, four had a pin cherry interference problem, and four did not. By age 15, there were one-third as many desirable seedling-origin stems, mostly black cherry (Prunus serotina Ehrh.), in stands with pin cherry above the critical threshold density. We suggest some silvicultural options for addressing the problem.

Developing ecotourism in First World, resource-dependent areas

Ecotourism, an economic diversification tool most commonly applied in the Third World as a means to protect ecosystems, preserve local cultures, and spur economic development, has recently been applied in First World resource-dependent areas. While ecotourism has traditionally focused on Third World ‘undisturbed’ protected lands, it has also been developed in their First World equivalents (i.e., old-growth forests) as well as in First World sites of past resource extraction and in places where current agricultural practices maintain cherished cultural landscapes. Forest County, Pennsylvania, a timber-dependent area, sought to diversify its economy by developing ecotourism based on its unique Allegheny hardwood forests, which are produced by timber harvesting. This ecotourism would encourage amenity-based, locally-driven economic development and maintain timber harvesting. While government and foundation supported ecotourism development efforts in areas dependent on resource extraction have incorporated some of ecotourism’s ideals, these operations have had mixed success. Such isolated areas, which have traditionally drawn visitors independently engaging in traditional outdoor recreation activities, have not been able to draw enough customers willing to pay for natural and cultural history tours. If ecotourism is to be successful, such areas may need further government support and destination branding to increase name recognition in order to counter the global orientation of the nature tour industry. For true community development, local collaborative efforts including resource and environmental interests are also required in which primary production is connected to processing and consumers through value-added and service sector activities such as tourism.

Roost tree selection by northern long-eared bat ( Myotis septentrionalis) maternity colonies in an industrial forest of the central Appalachian mountains

As part of a bat ecology research effort in managed forests, we tracked seven lactating northern long-eared bats ( Myotis septentrionalis Trouessart) to 12 roost trees used by maternity colonies ranging in size from 11 to 65 individuals in the central Appalachians of West Virginia. Lactating females switched among roosts on average every 5 days. Roosts were located in nine tree species, with 11 roosts in tree cavities and 1 under exfoliating bark. Eight of the roosts were located in snags; the other four were located in cavities in living trees. Black locust ( Robinia pseudo-acacia L.) snags were selected as a roost sites more than expected based on their occurrence in the forests we surveyed. Only 3 of the 24 habitat characteristics differed between actual roost trees and randomly located cavity trees. Structurally, actual roosts tended to be closer to neighboring trees than did suitable roosts in randomly located cavity trees. Tree species was an important factor that influenced roost tree selection, with black locusts being used significantly more than expected based on their abundance across the managed forest landscape we studied. All northern long-eared bat roosts were located in or below the forest canopy which suggests that solar exposure may not be as critical for selection of roost trees by maternity colonies of this species as opposed to other species of tree-roosting bat at more northern latitudes in North America. Although many previous studies have demonstrated the importance of old-growth habitat in providing roosting habitat for tree-roosting bats, use of roosting habitat and characteristics of roost sites have been little documented within intensively managed forests. Our research indicates that in managed, Allegheny hardwood–northern hardwood forests of the central Appalachians, short-lived, early successional species such as black locust may provide suitable roosting habitat for northern long-eared bats, as well as other species of bats.

Sampling to Assess Species Diversity of Herbaceous Layer Vegetation in Allegheny Hardwood Forests

The optimum frequency and time of sampling required to generate comprehensive diversity indices of herbaceous species in Allegheny hardwood forests was studied. Four 8-ha sites on the Allegheny National Forest were sampled monthly from May to August in 1992 and 1993 for herbaceous layer species composition and percent cover.

Gap dynamics in Allegheny northern hardwood forests in the presence of beech bark disease and gypsy moth disturbances

To determine changes in gap dynamics over a 6-year period in forests affected by beech bark disease and gypsy moth infestations, we conducted line transect surveys of gaps and gap makers in three Allegheny hardwood forests in central New York. Gap makers were defined as any trees whose death or loss of >50% of the branches caused an opening in the canopy, and were divided into three categories: decline (standing live trees with >50% branch loss), standing dead, and treefall. Total land area in gaps increased significantly ( p≤0.00) from 19.7 to 31.9% over the 6-years of the study. American beech ( Fagus grandifolia Ehrh.) represented 52.4% of the gap makers in 1990 and 1996. Of the total beech gap makers, 30% were decline and 53% were treefall gap makers in 1990, but by 1996, only 8% were decline as compared to 76% treefall gap makers. In contrast, the majority of oak ( Quercus spp.) gap makers were standing dead in 1990 and 1996. Although the rate of gap formation slowed at the end of this study, the predominance of beech in the subcanopy and regeneration layers poses persistent challenges for forest managers.

Impact of liming on the abundance and vigor of Armillaria rhizomorphs in Allegheny hardwoods stands

Abundance of rhizomorphs of Armillaria was characterized in 1995-1996 in 32 plots located in sugar maple (Acer saccharum Marsh.) stands in the Susquehannock State Forest (Pennsylvania, U.S.A.). All of the plots were thinned, and half of the plots were limed in 1985 when the plots were established. Frequency and abundance of Armillaria rhizomorphs in soil samples, on dead wood food bases (stumps, snags, fallen logs), and on the root collar of living sugar maples were determined in each plot. Rhizomorph vigor was evaluated by measuring their ability to colonize fresh striped maple (Acer pennsylvanicum L.) stem sections in the soil, or potato tubers in the laboratory. Isolates of Armillaria were obtained from rhizomorphs in the soil samples and species were determined by somatic incompatibility tests. Armillaria calvescens Bérubé & Dessureault was the major species present, representing about 66% of the isolates. Armillaria gemina Bérubé & Dessureault and Armillaria mellea (Vahl:Fr.) Kummer were also identified in the plots. Frequency of rhizomorphs in the soil, on food bases, abundance of rhizomorphs on root collars, as well as the proportion of rhizomorphs per plot that regenerated and (or) colonized fresh substrates were all correlated. However, abundance of ectotrophic rhizomorphs on the root collar was only weakly correlated with the other components of rhizomorph abundance and vigor. Frequency of the rhizomorphs as well as their ability to colonize fresh substrates were greater in plots either limed or with a high proportion of the basal area in sugar maple prior to thinning. By contrast, abundance of ectotrophic rhizomorphs on root collars was not affected by these factors.

Impact of liming on the abundance and vigor of <i>Armillaria</i> rhizomorphs in Allegheny hardwoods stands

Abundance of rhizomorphs of Armillaria was characterized in 1995-1996 in 32 plots located in sugar maple (Acer saccharum Marsh.) stands in the Susquehannock State Forest (Pennsylvania, U.S.A.). All of the plots were thinned, and half of the plots were limed in 1985 when the plots were established. Frequency and abundance of Armillaria rhizomorphs in soil samples, on dead wood food bases (stumps, snags, fallen logs), and on the root collar of living sugar maples were determined in each plot. Rhizomorph vigor was evaluated by measuring their ability to colonize fresh striped maple (Acer pennsylvanicum L.) stem sections in the soil, or potato tubers in the laboratory. Isolates of Armillaria were obtained from rhizomorphs in the soil samples and species were determined by somatic incompatibility tests. Armillaria calvescens Berube & Dessureault was the major species present, representing about 66% of the isolates. Armillaria gemina Berube & Dessureault and Armillaria mellea (Vahl:Fr.) Kummer were also identif...

Pin cherry effects on Allegheny hardwood stand development

Pin cherry effects on Allegheny hardwood stand development

Pin cherry effects on Allegheny hardwood stand development

Pin cherry (Prunus pensylvanica L.) develops an early height advantage over associated species. Data from three long-term studies, extending up to 70 years after complete overstory removal, were used to evaluate the effects of pin cherry density on associates. 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 the 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 the density of pin cherry at age 3 was > 1 stem > 1.5 m tall per 0.0004 ha (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 when it occurred at low density (< 1 stem > 1.5 m tall per 0.0004 ha). 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.

Woody understory response to changes in overstory density: thinning in Allegheny hardwoods

Understanding the effects of silvicultural treatments on understory vegetation is important in predicting the consequences of such treatments, not only on regeneration but also on wildlife habitat, visual qualities, and recreation. We sought to develop an empirical model of understory response that could be generalized to other forest types. We analyzed understory populations of tree species for 15 years following thinning to different residual relative densities in 50- to 55-year-old Allegheny hardwoods. The average number of stems 1 ft (0.3 m) tall to 1 in (2.5 cm) dbh increased for 3 to 5 years after thinning and then leveled-off or decreased after 10 or 15 years. The greatest density of understory stems developed at low residual density. In stems 1 to 3 ft (0.3 to 0.9 m) tall, the densities of shade-tolerant species were unresponsive to thinning while the shade-intolerant were most responsive. The shade-intolerant and -intermediate species increased in importance over time in the more heavily thinned treatments. In the 3 ft (0.9 m) tall to 1 in (2.5 cm) dbh size class, shade-intolerant and -intermediate species were more responsive to thinning than tolerant species, but shade-tolerant species remained more important numerically throughout the study. Ingrowth to > 1 in diameter classes was greatest by shade-tolerant stems, increased over time, and was enhanced by thinning. We used repeated measures analysis of variance to model the number of stems in these three size classes and three shade-tolerance classes as a function of residual relative density at thinning and time since treatment. These models explained 0.08 to 0.80 of the variation in stem numbers, depending on the size and tolerance class. These descriptions might be improved by reference to prior conditions of the regeneration or interfering herbaceous competition, but a model that required this information would not be capable of predicting responses to future treatments.