Allegheny Hardwood Forests Research Articles

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 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.

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.

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.

Deer and diversity in Allegheny hardwood forests: managing an unlikely challenge

High white-tailed deer ( Odocoileus virginianus) density and interfering vegetation were identified as factors affecting the regeneration of hardwood forests in the Allegheny National Forest and surrounding forests in northwestern Pennsylvania. Research was designed by Forest Service scientists to quantify these effects. A high degree of interest in the impact of these effects on the diversity of forest resources led to additional research. Scientists, natural resource managers, and private timber interests used the research findings on the impacts of deer and interfering vegetation on regeneration and diversity to produce newsletters, tours, symposia, and to make presentations to groups of legislators, environmentalists and other influential segments of the public. This combined research-educational effort has been associated with the enactment of hunting regulations designed to reduce deer density and for registration and continued use of herbicides to control interfering vegetation. Both actions have the potential to increase the diversity of songbirds and woody and herbaceous vegetation in forest lands. The challenge is to sustain directed management of deer density and interfering vegetation until these factors are controlled to the point where they no longer negatively impact the diversity of forest resources.

Control of Herbaceous Weeds in Allegheny Hardwood Forests with Herbicides

Bromacil (5-bromo-3-sec-butyl-6-methyluracil), glyphosate (N-phosphonomethylglycine), picloram (4-amino-3,5,6-trichloropicolinic acid), simazine [2-chloro-4,6-bis (ethylamino)-s-triazine], and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione] were evaluated at four application rates and five application dates, May 1, June 1, July 1, August 1, and September 1, for their ability to control seven herbaceous, forest ground covers, hayscented fern (Dennstaedtia punctilobula (Michx.) Moore), New York fern (Thelypteris noveboracensis L.), short husk grass (Brachyelytrum erectum Schreb.), bracken fern [Pteridium aquilinum (L.) Kuhn var. latiusculum (Desv.) Underw.], wild oat grass (Danthonia compressa Aust.), rough goldenrod (Solidago rugosa Mill.), and flattop aster (Aster umbellatus Mill.) without residual effects on black cherry (Prunus serotina Ehrh.) seed stored in the forest floor, or on survival and growth of natural or planted black cherry seedlings. Control of most of the target species depended on the date and rate of application. Simazine had no herbicidal effect on these extremely acid (pH 3.9 to 4.4) Allegheny Plateau sites. None of the herbicides interfered with germination of black cherry seed stored in the forest floor or with establishment of seedlings. Bromacil applied at 22.4 kg/ha, picloram, at 9.0 kg/ha, and hexazinone at 13.4 kg/ha reduced survival, or growth, or both, of black cherry seedlings planted in a forest opening. Glyphosate was the most economical herbicide that met the control criteria. Application of 1.1 kg/ha between August 1 and September 1 produced acceptable control of all target species for at least 3 yr.

Deer and Rabbit Browsing and Available Winter Forage in Allegheny Hardwood Forests

Those dealing with wildlife management are aware of the problems created when overpopulation by occurs in a given locality such as the Kaibab plateau in Arizona, portions of the Lake States, central and northern Pennsylvania and the Adirondacks of New York: Lack of balance between the population and its food can easily result when predators are few or are strictly controlled and when hunting pressure is inadequate to remove surplus animals. Scarcity of forage for during the critical winter months has long been a problem in the central and northern counties of Pennsylvania. In 1937 Seth Gordon issued a timely plea for understanding by the sportsmen of the need for control of an excessive xdeer herd by removing female as well as male during the hunting season. The situation was practically out of hand, however, and starvation losses cut heavily into the herd on areas where past browsing had depleted the available forage plants. As early as 1930 on the southern half of the Allegheny National Forest so numerous that their needs far exceeded the long term forage supply (McCain, 1941). By 1938 this forest, with a gross area of 739,000 acres, supported about 50,000 deer, or roughly one animal to 15 acres. A record kill of 24,000 does during the 6-day season of 1938 reduced this surplus. legal kill was even larger than the total that most sportsmen had been willing to admit existed in the area, yet nearly two animals remained for each one killed (McCain, 1941). Despite this reduction 4,500 died of cold and starvation during the winter of 1938-39. Through subsequent hunting and starvation this peak population on the Allegheny has been reduced to about 16,000 deer, an average of one to 46 acres in 1946. Large concentrations of are known to shelter on the southand west-facing lower slopes and valley bottoms during the severe winter months (Ehrhart, 1936). It is only natural that repeated browsing tends to kill back most of the available low cover of food plants on such sites. Past heavy use has reduced or removed many of the favored browse species and has created a socalled deer line on larger tree growth, particularly in these valley bottom areas. How much of this damage is actually due to the activities of and how much to other animals cannot be determined by general observation. While the population was building up to its peak, four half-acre plots in different stands on the Kane Experimental Forest were fenced against and half of each enclosure was also fenced to keep out rabbits. This work was done in the fall of 1935. During the next growing season a complete census of all tree growth 1.0 foot in I Northeastern Forest Experiment Station.