vesting of hemlock in advance of mortality, in contrast, causes immediate mortality and removal of biomass from the site. Although both processes affect thousands of acres of forest annually we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore we designed an experiment to simulate these contrasting impacts, by logging or girdling hemlock stands. Results from the experimental treatments will be compared to the changes observed in forests that are being infested by the adelgid, and can also be included in integrated analyses of a suite of large experiments that form a core component of the Harvard Forest LTER program. Deer and moose foraging can play a key role in shaping forest regeneration after disturbance in temperate forest. In 2008, we initiated a browsing survey of woody stems in the Simes hemlock removal experiment plots. There are regular moose sightings in the study area, and moose pellets are commonly found within the plots. Also, extensive browsing of tree regeneration in the logged plots was Noted starting in 2007.

ndirect consequences of HWA-induced damage in the form of salvage and pre-emptive logging of hemlock (Tsuga canadensis (L.) Carriere) forests. The study was conducted within an area extending from southern Connecticut up to and including the Connecticut River lowlands west to the Berkshire Plateauin central Massachusetts, USA. Overstory and understory vegetation and ecosystem function parameters such as decomposition and nitrogen cycling were examined in logged and unlogged portions of 10 hemlock stands varying in HWA damage intensity.

sture will shift the competitive balance between species that compete for light and water, changing their abilities to produce seed, germinate, grow, and survive. Large scale experiments are being used to determine the effects of warming on the most sensitive stage of species distributions, i.e., recruitment, in mixed deciduous forests in southern New England and in the Piedmont region of North Carolina. Two questions organize our proposed research: (1) Might temperate tree species near the "warm" end of their range in the eastern United States decline in abundance during the coming century due to projected warming? and (2) Might trees near the "cool" end of their range in the eastern United States increase in abundance, or extend their range, during the coming 100 years because of projected warming? To explore these questions, seedlings are exposed to air and soil warming experiments in two eastern deciduous forest sites; one at the Harvard Forest (HF) in central Massachusetts, and the other at the Duke Forest (DF) in the Piedmont region of North Carolina. The focus is on tree species common to both Harvard and Duke Forests.

les summarize a series of field experiments conducted from 1993 to 1995 evaluating the response of seed germination and seedling growth and survival to experimental understory manipulation. These field studies involved three experimental manipulations of the fern understory: 1) removal of ferns 2) ferns tied back (to remove above-ground shading) 3) ferns left intact (control). These manipulations were established in 180 - 1m2 plots spanning six field sites and 2 different fern species (3 understory manipulations x 2 understory fern species x 6 sites x 5 replicates/site = 180 experimental plots).

ap partitioning hypothesis. Trees were felled to create a total of six cleared, elliptical canopy gaps of two sizes (8m x 12m, 75m2; 16m x 24m, 300m2). Naturally-established, undamaged, unbranched seedlings (15-30 cm tall, 10-20+ years old) of the three study species (2160 total, 720 per species) were transplanted into five plot locations (center and NW, NE, SW, and SE gap edges) within all six gaps and matching understory sites one year before gap creation. All plots were weeded regularly and spaded annually along the edges to remove above and below-ground competition. Measurements of microclimates and Non-competitive seedling responses were made over one year before and two years following gap release.

intensive study of hemlock dynamics within the stands.

four hemlock-dominated plots in Harvard Forest for community vegetation structure and composition.

of these forests. The investigators of this project are monitoring how forest structure and function changes as the adelgid invades hemlock stands in Harvard Forest. To do this, this study surveyed community vegetation structure and composition prior to adelgid infestation as well as during the progress of the infestation.

Forest in severely damaged stands (many of which were logged subsequent to the hurricane) to assess forest succession. Most of the plots involved successions following the blowdown of white pine on glacial till or outwash soils. From 1940 to 1948, and in 1978 and 1991, tree density and presence or absence of herb and shrub species were tallied. Pioneer species regenerating from seed and advance regeneration of longer-lived species quickly established at the sites; hemlock was the only species successfully regenerating after year 10, and most tree species were present within 2-4 years of the hurricane. By 1978, pioneer species such as gray birch and pin cherry declined or disappeared and red maple, white pine, paper birch and red oak dominated the plots. By 1991, most understory species present before the hurricane had returned, although there was a small group of understory species that apparently were more sensitive to disturbance and did not recover.

ard Forest in severely damaged stands (many of which were logged subsequent to the hurricane) to assess information about forest succession. Most of the plots involved successions following the blowdown of white pine on glacial till or outwash soils. From 1940 to 1948, and in 1978 and 1991, tree density and the presence or absence of herb and shrub species were tallied. Pioneer species regenerating from seed and advance regeneration of longer-lived species quickly established at the sites.

0% of the towns in Massachusetts and, as a result, many landowners are considering pre-emptively harvesting their eastern hemlock (Tsuga canadensis) stands. To examine the local impacts of this cutting activity, this study examined stand and ecosystem dynamics in 10 hemlock-dominated sites on public and private lands where hemlocks were harvested between 1 to12 years ago with nearby uncut forests.

across southern New England since the time of its arrival in 1985; (3) to examine environmental and stand factors that are associated with declines in crown vigor and mortality of hemlock; (4) examine the dynamics of HWA and EHS in hemlock stands over time; and (5) assess whether there is a difference in the response of these insects to abiotic conditions (winter temperature, summer temperature, summer precipitation), and whether the distribution and abundance of each insect species is dependent on biotic interactions with the co-occurring insect species.

mlock (Tsuga canadensis (L.) Carriere), one of the most abundant, long-lived shade tolerant species, across its range. In addition, a second invasive pest, the elongate hemlock scale (Fiorinia externa; EHS), often co-occurs with HWA on hemlock with unknown long-term consequences. This study was started to analyze Hemlock tree stands, the damage created by HWA and the long term consequences of EHS.

cales.

e primary and secondary growth hemlock forests (230 and 132 years old, respectively), recently disturbed stands (5 and 18 years old) that now have rapidly growing black birch saplings, and a mature black birch stand of age similar to the second-growth hemlock stand.

d to identify browse species preferences of moose, and step-wise multiple regression was used to identify habitat variables that are strong predictors of browse intensity.

ystems that are often vastly different from those that occurred before these animals were extirpated. Moose, the Northeast’s largest Holocene browser, have recently expanded across southern New England’s temperate forest landscape after an absence of 200 years, realizing a natural re-wilding experiment. Moose have been well-studied throughout the boreal forest biome; however, because they are rare today in temperate forests, almost Nothing is known of their ecology, behavior, or potential impacts to these ecosystems. This study investigated patterns of winter moose browse in order to: (1) gain insight into the likely influences of this herbivore on the vegetation patterns of the region; and (2) to identify the most important habitat features influencing moose winter foraging activity at a landscape and site scale.

forest located in the Pisgah State Forest in southwest New Hampshire, the collection of a long term data set from 1907-1995 has made it possible to consider how the hurricane of 1938 altered forest structure, species composition, and subsequent forest development in the stand. Various types of information were gathered throughout the century that allowed the quantification of forest structure and composition: species identification, diameter measurements, tree status (living or dead), tree cores, and individual tree growth and mortality have recently been tracked.

xisting experimental and correlative evidence from field sites suggests that temperature rise will significantly modify soil processes, nutrient availability, and plant growth. We investigated the responses of temperate deciduous forest vegetation to artificial soil warming at 20 sampling dates during the 1992 and 1993 growing season. We explored whether soil warming measurably altered growth and the temporal dynamics of leaf and fruit production in 26 species of three contrasting plant growth forms (herbaceous perennials, shrubs, and canopy trees). We hypothesized that soil warming would exert differential effects on emergence, phenology, leaf expansion rates, growth, photosynthesis, and vegetative and sexual reproduction among species, with implications for changing community structure in these forests.

tory is harvested or senesces.

nd predict future dynamics in harvested and early seral habitats. An initial objective of the baseline survey was to characterize current tree regeneration and understory flora that will, in large part determine the future composition of these forests as the overstory is harvested or senesces.

otaled about 270 acres (10% of Harvard Forest’s land base). The tending of the plantations was conducted and carefully documented; however, this work ceased about 1950. Since then, some plantations were out-competed by native tree species, with only scattered planted trees remaining, a few acres of plantations were harvested in the 1950, and about 40 acres of plantations were harvested in the 1990s. As of 2007, approximately 135 acres of plantations remained and ranged in age from 60 to 90 years old. Some stands have substantial areas blown down. In 2008, Harvard Forest developed a management plan to harvest 80 acres of mature plantation forests to terminate these long term experiments, regenerate a diversity of native tree species, restore native forests to these sites, and to initiate a new suite of long term experiments. For the next 10-15 years, the harvested areas will provide early successional habitat for a variety of wildlife species. A suite of permanent vegetation plots was established throughout the plantations to assess vegetation structure in plantations and predict future dynamics in harvested and early seral habitats.

soil temperature is critical for predicting population recruitment in the future hardwood forests of Northeastern North America, particularly as environmental conditions and thus optimal microhabitat availabilities change. We examined the effect of 5˚C soil warming during the first growing season on germination, survival, phenology, growth, and stem and root biomass allocation in Acer rubrum (red maple) seedlings.

lfth year in 2001.

rowsing but protected from moose browsing.

rs earlier. Intensive moose browsing in the boreal forest has caused declines in forest density and shifts in species composition in some areas, generating considerable interest and concern among foresters, wildlife managers, and ecologists as to how moose, along with white-tailed deer, will impact forest development in this region. Harvard Forest, in collaboration with researchers at the USGS Massachusetts Cooperative Research Unit, initiated a long-term study of the role of moose and deer in SNE forests using experimental enclosures: full enclosure, partial enclosure, and a control plot.

browsing but protected from moose browsing.

rs earlier. Intensive moose browsing in the boreal forest has caused declines in forest density and shifts in species composition in some areas, generating considerable interest and concern among foresters, wildlife managers, and ecologists as to how moose, along with white-tailed deer, will impact forest development in this region. Harvard Forest, in collaboration with researchers at the USGS Massachusetts Cooperative Research Unit, initiated a long-term study of the role of moose and deer in SNE forests using experimental enclosures: full enclosure, partial enclosure, and control plot.

investigated species present in the seed bank (in 2004 and 2010), the seedling bank (in 2004 and 2010), and seed rain (from 2005-2015) in the Harvard Forest Hemlock Removal Experiment.

idences successional changes in recruitment, survival, and associated self-thinning, and can be used to quantify an accumulation of aboveground live biomass post-clearing with corresponding allometric relationships.

is region. Massachusetts requires all commercial harvest operations above 87 m3 to file a Forest Cutting Plan (FCP) with the state. We have digitized these FCPs (see McDonald et al. 2006), covering all harvests from 1984 to 2003. Our study area is Massachusetts, west of the coastal basin, as defined by Motts and O’Brian (1981). We selected 126 sites for sampling. Two-thirds of the sites (89) were harvested once between 1984 and 2003, and these were selected randomly from the larger FCP database. The remaining one-third of the sites (37) were control sites selected randomly from all unharvested forest in the study area. The boundaries for our field surveys were those filed with the FCP for harvested sites, and were circular for control sites, proportional in size to the mean FCP in the physiographic region (Motts and O'Brien 1981): Connecticut River Valley (10.7 ha), Central Upland (11.3 ha), Berkshire Valley and Taconic Mountains (12.6 ha), and the Western Upland (15.9 ha). Note that our sampled sites were well-dispersed over the study area, and encompassed the variety of past agricultural land-use.

carbon uptake.

changes in carbon storage through time in three forest stands: an early-20th-century conifer plantation, a naturally regenerating former conifer plantation harvested in the 1990s, and a conifer plantation scheduled for harvest next winter. The first three years of this project determined the initial carbon budget of these forest stands, measured carbon fluxes into and out of these stands, and laid the groundwork for future investigations. Subsequent years will investigate larger-scale questions, such as how successional patterns affect carbon sequestration, and how these patterns change with stand age. The work also addresses how forestry practices influence carbon sequestration, and provide guidance for how forest management could enhance terrestrial carbon uptake in the future.

ect mortality in the form of pre-emptive logging. The efficacy of regeneration of vegetation following hemlock decline depends upon advance regeneration of seedlings and saplings, seed dispersal, and recruitment. This study investigated (1) whether the basic parameters of height of release and wind velocity affected seed dispersal distance and (2) the fit of a basic ballistic model of seed dispersal to empirical data in areas both with and without canopies. Empirical data was collected from seed dropping and seed rain experiments at Harvard Forest. Height and wind velocity only affected seed dispersal distance in open areas. Predicted values of dispersal distance generated by the basic ballistic model did not provide a good fit to observed dispersal data. Poor fits of the ballistic model to the data were due to the model’s inability to account for rare, long distance dispersal events. More complex models with additional parameters are necessary to model Non-localized seed dispersal.

cies on a 1 x 1 m resolution across six land use legacy sites (2 plowed, 2 pastured, 2 permanent woodlot) in summer 1996 were recorded to test several predictions about seedling abundance, diversity, and dispersion patterns, and their relationships to forest structure, microclimates, and soil resources.

vesting of hemlock in advance of mortality, in contrast, causes immediate mortality and removal of biomass from the site. Although both processes affect thousands of acres of forest annually, we have only a limited understanding of their effects on forest ecosystem function and productivity and the nature of the subsequent forest community. We anticipate that harvesting will yield different consequences than gradual mortality from the insect. Therefore we designed an experiment to simulate these contrasting impacts, by logging or girdling hemlock stands. Results from the experimental treatments are compared to the changes observed in forests that are being infested by the adelgid, and can also be included in integrated analyses of a suite of large experiments that form a core component of the Harvard Forest LTER program

nty-two forest plots were sampled across several ecoregions in central and western Massachusetts, southern Vermont and New Hampshire and Northern Connecticut. Tree seedlings, overstory characteristics, browsing, pellet piles, and shrub densities were sampled; and site attributes such as mean annual temperature and forest fragmentation were examined.

, other biota, and ecosystem processes.

le browse. Despite the often significant role that ungulates play in disturbed forests, surprisingly little is known about ungulate-disturbance interactions. Ungulate herbivory is often excluded from examinations of forest response to disturbance. In the Northeastern United States, a large-scale insect outbreak, the hemlock wooly adelgid (HWA), has begun to have important effects on hemlock forests, both directly and indirectly (i.e., by preemptive salvage logging). No studies have examined the interactions of both moose and deer activity with these associated canopy disturbances. The authors examined the relative abundance of moose and deer in four treatments (2 replicates) at the Hemlock Removal Experiment using three indices of ungulate activity: pellet group density, evidence of past browsing on seedlings and saplings, and the occurrence of animals using game cameras. They also monitored the response of vegetation to ungulate browsing by sampling woody and herbaceous vegetation in fenced enclosures and paired controls in disturbed and undisturbed plots.

and browsing of ungulates in forest openings, the importance of browsing relative to abiotic factors such as light on forest regeneration is often unclear. In southern New England, medium-intensity harvesting is the predominant forest disturbance attracting white-tailed deer and moose. Oaks, which are in decline, are the foundation hardwood taxon and predominant timber tree in the region. Hence, the effects of ungulate browsing on oak forests are of great interest to ecologists, conservationists and forest and wildlife managers. We sampled tree regeneration and ungulate foraging activity across a range of canopy disturbances (35-90% basal area removed) in 34 stands of the Quabbin and Ware River Watershed Forests. Browsing was very high across the plots with about 80% of red maple and oak stems browsed. Taller stems were generally browsed more frequently than shorter stems. Oak regeneration in the smaller size classes was generally lower in stands with higher percent cover of hay-scented fern. The proportion of browsed red maples and oaks generally increased with increasing density of these taxa. Despite intensive herbivory, oaks appear to be regenerating well with increased light in these partially harvested stands.

on experiment was initaited in a 0.8 ha manipulation (pulldown) and 0.6 ha control area of a maturing Quercus rubra/Acer rubrum forest in New England. 276 trees were toppled in the pulldown, using a winch and cable, in the Northwesterly direction of natural treefall from major hurricanes. Eighty percent of canopy trees and two-thirds of all trees greater than 5 cm dbh suffered direct and indirect damage. Twenty years of measurements were used to evaluate the trajectory and mechanisms of forest response after intense disturbance. Based on the patch size and disturbance magnitude, we expected pioneer tree and understory species to drive succession.