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Proteolytic Enzyme Activity in Temperate Forest Soils at Harvard Forest and Pisgah State Forest 2007-2010
The objective of this research is to investigate the processes that limit or promote the activity and production of proteolytic enzymes in temperate forest soils. To meet this objective, we performed a series of integrated observations and experiments to investigate a conceptual model of proteolytic enzyme activity whereby activity is a function of the interaction between four parameters: soil temperature and moisture, substrate concentration, and the enzyme pool size. We used four dominant temperate forest tree species that differ in SOM chemistry and the enzymatic capabilities of their fungal symbionts as a model system. These four species differed in mycorrhizal association, with white ash (Fraxinus americana) and sugar maple (Acer saccharum) supporting arbuscular mycorrhizal (AM) fungi and eastern hemlock (Tsuga canadensis) and American beech (Fagus grandifolia) supporting ectomycorrhizal (ECM) fungi. Further, the ECM associated species have leaf litter and SOM that is characterized by higher ratios of C:N than the AM associated. Soil samples were collected two sites, one located at the Prospect Hill Tract of the Harvard Forest and the other at the Pisgah State Forest. The sites have similar land use history and stand age. Soils at both sites are inceptisols classified as Typic Dystrochrepts derived from glacial till overlying granite-schist-gneiss bedrock. Experimental plots dominated by one of four target tree species were established at each site. Stands of sugar maple (Acer saccharum) and American beech (Fagus grandifolia) were located in Pisgah. Stands of Eastern hemlock (Tsuga canadensis) and white ash (Fraxinus americana) were located in Harvard Forest. At a later date, plots were also established in a red oak (Quercus rubra) stand on Prospect Hill in the MES tower footprint. At each site we located six replicate, 8 m radius, monodominant plots that were based on the following criteria: (1) more than 80% of the standing basal area was composed of the targ
Regional and Historical Variation in Garlic Mustard Distribution in Western Massachusetts 2006-2007
The susceptibility of a site to invasion by nonnative species depends on its current ecological features and its historical land use. Certain environments might be more conducive to an invasive plant’s success, and several recent studies have shown that former agricultural sites are more susceptible to invasion than sites that have been continuously wooded. We studied the invasive herb garlic mustard (Alliaria petiolata), at roadside forested edges. Site selection was stratified by two regions with distinct ecological characteristics (the Connecticut River Valley and the Berkshire Valley in Massachusetts), and two historical land uses (wooded versus cleared in 1830).
Bayesian Analysis of Tree Distributions Across Space and Time in Eastern North America 2010-2011
The distributions of many organisms are spatially autocorrelated, but it is unclear whether including spatial terms in species distribution models (SDMs) improves projections of future species distributions. We provide the first comparative test of a purely spatial SDM, a purely non-spatial SDM, and an SDM that combines spatial and environmental information. Spatial SDMs provided better fits to the calibration data, more accurate predictions of a hold-out validation data set of modern trees, and lower false positive rates at all time periods than non-spatial SDMs. Hindcasted projection of spatial SDMs had higher variance than those of non-spatial SDMs. Overall predictive performance of non-spatial and spatial SDMs varied temporally and as a function of niche overlap. Ecological modelers should include spatial terms in SDMs used for projecting future distributions of species.
Lake Sediment Pollen from Berry Pond in North Andover MA from 15000 BP to Present
Aim We analyzed lake-sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post-glacial climatic changes, (2) landscape-scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north-central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yr BP). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yr BP; by Pinus strobus from 11,500 to 10,500 cal yr BP; and by P. strobus and Tsuga between 10,500 and 9500 cal yr BP. At 9500-8000 cal yr BP, however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yr BP, when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid-Holocene Tsuga decline (5500-3500 cal yr BP), but the pattern weakened during the late-Holocene (3500-300 cal yr BP) and European-settlement intervals. Within-group similarity declined in response to the uneven late-Holocene expansion of Castanea, while between-group similarity increase
Lake Sediment Pollen from Blood Pond in Dudley MA from 15000 BP to Present
Aim We analysed lake-sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post-glacial climatic changes, (2) landscape-scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north-central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yr BP). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yr BP; by Pinus strobus from 11,500 to 10,500 cal yr BP; and by P. strobus and Tsuga between 10,500 and 9500 cal yr BP. At 9500-8000 cal yr BP, however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yr BP, when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid-Holocene Tsuga decline (5500-3500 cal yr BP), but the pattern weakened during the late-Holocene (3500-300 cal yr BP) and European-settlement intervals. Within-group similarity declined in response to the uneven late-Holocene expansion of Castanea, while between-group similarity increase
Lake Sediment Pollen from Little Pond in Royalston MA from 15000 BP to Present
Aim We analysed lake-sediment pollen records from eight sites in southern New England to address: (1) regional variation in ecological responses to post-glacial climatic changes, (2) landscape-scale vegetational heterogeneity at different times in the past, and (3) environmental and ecological controls on spatial patterns of vegetation. Location The eight study sites are located in southern New England in the states of Massachusetts and Connecticut. The sites span a climatic and vegetational gradient from the lowland areas of eastern Massachusetts and Connecticut to the uplands of north-central and western Massachusetts. Tsuga canadensis and Fagus grandifolia are abundant in the upland area, while Quercus, Carya and Pinus species have higher abundances in the lowlands. Results Our analyses revealed a sequence of vegetational responses to climate changes occurring across southern New England during the past 14,000 calibrated radiocarbon years before present (cal yr BP). Pollen assemblages at all sites were dominated by Picea and Pinus banksiana between 14,000 and 11,500 cal yr BP; by Pinus strobus from 11,500 to 10,500 cal yr BP; and by P. strobus and Tsuga between 10,500 and 9500 cal yr BP. At 9500-8000 cal yr BP, however, vegetation composition began to differentiate between lowland and upland sites. Lowland sites had higher percentages of Quercus pollen, whereas Tsuga abundance was higher at the upland sites. This spatial heterogeneity strengthened between 8000 and 5500 cal yr BP, when Fagus became abundant in the uplands and Quercus pollen percentages increased further in the lowland records. The differentiation of upland and lowland vegetation zones remained strong during the mid-Holocene Tsuga decline (5500-3500 cal yr BP), but the pattern weakened during the late-Holocene (3500-300 cal yr BP) and European-settlement intervals. Within-group similarity declined in response to the uneven late-Holocene expansion of Castanea, while between-group similarity increase
Lake Sediment Pollen from Wildwood Lake in Long Island NY from 4500 BP to Present
Analyses of pollen, charcoal, and organic content in a lake-sediment core from Wildwood Lake, Long Island, New York, provide insights into the ecological and environmental history of this region. The early-Holocene interval of the record (~9800-8800 cal. a BP) indicates the presence of Pinus rigida-Quercus ilicifolia woodlands with high fire activity. A layer of sandy sediment dating to 9200 cal. a BP may reflect a brief period of reduced water depth, consistent with widespread evidence for cold, dry conditions at that time. Two other sandy layers, bracketed by 14C dates, represent a sedimentary hiatus from ~8800 to 4500 cal. a BP. This discontinuity may reflect the removal of some sediment during brief periods of reduced water depth at 5300 and 4600 cal. a BP. In the upper portion of the record (before 4500 cal. a BP), subtle changes at ~3000 cal. a BP indicate declining prevalence of Quercus-Fagus-Carya forests and increasing abundance of Pinus rigida, perhaps due to reduced summer precipitation. Elevated percentages of herbaceous taxa in the uppermost sediments represent European agricultural activities. However, unlike charcoal records from southern New England, fire activity does not increase dramatically with European settlement. These findings indicate that present-day Pinus rigida-Quercus ilicifolia woodlands on eastern Long Island are not a legacy of recent, anthropogenic disturbances.
Demography and Morphology of Ericaceous Species on a Sand Plain in Montague MA 1994-1996
The study was a demographic analysis of Gaultheria procumbens conducted on the Montague Sand Plain. It compared the demographic parameters of above-ground stems between plowed and unplowed areas within scrub oak and hardwood sites. Past land use can have long-term effects on plant species distributional patterns if alterations in resources and environmental conditions have persistent effects on population demography ("environmental change") and/or if plants are intrinsically limited in their colonisation ability ("historical factors"). We evaluated the role of environmental alteration versus historical factors in controlling distributional patterns in Gaultheria procumbens (L.), a woody, clonal, understorey species with a pronounced restriction to areas that have never been ploughed and near absence from adjoining areas that were ploughed in the 19th century. The demographic study was conducted in scrub oak and hardwood plant communities on an extensive sand plain where it was possible to control for the effect of variation in environment prior to land use.
Modeling Range Expansion of Hemlock Woolly Adelgid in Eastern North America 1951-2009
Range expansion by native and non-native species will continue to be a major component of global change. Anticipating the potential effects of changes in species distributions requires models capable of forecasting population spread across realistic, heterogeneous landscapes and subject to spatiotemporal variability in habitat suitability. Several decades of theory and model development, as well as increased computing power and availability of fine-resolution GIS data, now make such models possible. This R code allows simulation of the spread of the hemlock woolly adelgid (HWA, Adelges tsugae) under climatic conditions experienced from December of 1951 until March of 2009. The code describes a spatially explicit stochastic model that combines dynamic dispersal and population processes with fine-resolution maps characterizing spatiotemporal heterogeneity in winter temperature and hemlock abundance to model range expansion of HWA. The model is parameterized using multi-year datasets describing population and dispersal dynamics of HWA and is applied to eastern North America.
Regional Distribution and Abundance of Eastern Hemlock in Eastern North America 2010
We developed comprehensive maps on the distribution and abundance of hemlock for the purposes of mapping the host distribution, and modeling the spread, of the hemlock woolly adelgid. Multiple statistical models were used to map the distribution of hemlock. Hemlock occurrence data were taken from the FIA database and multiple environmental predictors were gathered from various databases as described in methods. The raster map depicts the predicted abundance of hemlock m2 basal area per hectare) across its range in eastern North America.
Annual Maps of Mean Winter Temperature for Eastern North America 1951-2009
We developed annual raster maps depicting spatiotemporal variation in mean winter temperature for the purposes of modeling the spread of the hemlock woolly adelgid. The maps are based on the PRISM and WorldClim datasets as described in methods.
CO2 Profile at Harvard Forest HEM and LPH Towers since 2009
Carbon dioxide profile measurements are designed to supplement eddy flux measurements in calculating the carbon exchange of a forest. In the case of the Harvard Forest flux towers, the change in CO2 storage between the ground and the height of the eddy flux system during each half hour must be added to the eddy flux measured above the forest to determine the total carbon exchange. The profile measurements are also necessary in order to calculate CO2 movement by advection, or horizontal air transport. The amount of CO2 removed from a particular site by advection is the product of the total CO2 within the air a given range of height above the ground, and the average velocity of airflow parallel to the ground surface within that height range.
Simulating Intrastand Movement of Hemlock Woolly Adelgid at Harvard Forest 2009
The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), has spread rapidly across the eastern USA since its introduction from Japan 60 years ago, causing widespread mortality of both eastern hemlock [Tsuga canadensis (L.) Carriere] and Carolina hemlock [Tsuga caroliniana Engelm. (Pinaceae)]. Although HWA spread patterns have been repeatedly analyzed at regional scales, comparatively little is known about its dispersal potential within and between hemlock stands. As the small size and clonal nature of HWA make it nearly impossible to identify the source populations of dispersing individuals, we simulated intrastand HWA movement in the field by monitoring the movement of clumps of fluorescent powder that are slightly larger than HWA, but much easier to detect in the forest understory. Using three hemlock trees with three colors of fluorescent powder as source populations, we detected dispersal events at the farthest distances within our trapping array (400 m). However, more than 90% of dispersal events were less than 25 m. Dispersal patterns were similar from all three source trees and the distribution of dispersal distances in all cases could be described by lognormal probability density functions with mean dispersal distance of 12-14 m, suggesting that dispersal was relatively independent of location of source trees. In general, we documented tens of thousands of passive dispersal events in the forest understory despite the presence of a dense forest canopy. Thus, even under relatively light-wind conditions, particles of similar dimensions to HWA are capable of intra-stand movement, suggesting that a large population of HWA could rapidly infest other trees within several hundred meter radius, or beyond.
Effects of Warming on Tree Species Recruitment at Harvard Forest and Duke Forest since 2009
Climate change is restructuring forests of the United States, although the details of this restructuring are currently uncertain. Rising temperatures of 2 to 8 deg C and associated changes in soil moisture will shift the competitive balance between species that compete for light and water, changing their abilities to produce seed, germinate, grow, and survive. We are using large scale experiments 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, we are exposing seedlings 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. We focus on tree species common to both Harvard and Duke Forests (such as red, black, and white oaks), those near northern range limits (black oak, tulip poplar), and those near southern range limits (yellow birch, sugar maple). At each site, we plant seeds in common gardens established in temperature-controlled, open-top chambers. The experimental design is replicated and fully factorial and involves three temperature regimes (ambient, +3 deg C and +5 deg C) and two light regimes (closed forest canopy (low light) and gap conditions (high light)). Measured variables include Fall/Spring responses to temperature and mid-Summer responses to low soil moisture. This research will advance our understanding of how the abu
Vegetation Response in Simulated Hurricane Experiment at Harvard Forest since 1990
Wind disturbance profoundly shapes temperate forests but few studies have evaluated patterns and mechanisms of long-term forest dynamics following major windthrows. In 1990, we initiated a large hurricane simulation experiment in a 0.8 ha manipulation (pulldown) and 0.6 ha control area of a maturing Quercus rubra-Acer rubrum forest in New England. We toppled 276 trees 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. We used twenty years of measurements 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. The first decade of analyses emphasized tree seedling establishment and sprouting by damaged trees as the dominant mechanisms of forest recovery in this extensive damaged area. However, despite 80% canopy damage and 8000 m2 patch size, surviving overstory and advance regeneration controlled longer-term forest development. Residual oaks make up 42% of stand basal area after 20 years. The new cohort of trees, dominated by black birch advance regeneration, contributes 30% of stand basal area. There were shifts in understory vegetation composition and cover, but few species were gained or lost after 20 years. Stand productivity rebounded quickly (litterfall recovered to pre-disturbance levels in six years), but we predict that basal area in the pulldown will lag behind the control (which gained 6 m2/ha over 20 years) for decades to come. This controlled experiment showed that although the scale and intensity of damage were great, abundant advance regeneration, understory vegetation, and damaged trees remained, allowing the forest to resist changes in ecosystem processes and invasion by new species.
Landscape-Scale Forest Dynamics in the Luquillo Experimental Forest in Puerto Rico 1936-1989
This study examined landscape-scale forest dynamics in the Luquillo Experimental Forest (Puerto Rico). The analysis was based on vegetation maps created from aerial photographs taken in 1936 and 1989. For details on methods and results, please see the published paper (Foster, D. R., M. Fluet and E. R. Boose. 1999. Human or natural disturbance: landscape-scale dynamics of the tropical forests of Puerto Rico. Ecological Applications 9: 555-572). The Abstract from the paper is reproduced below. "Increasingly ecologists are recognizing that human disturbance has played an important role in tropical forest history and that many assumptions concerning the relative importance of natural processes warrant re-examination. To assess the historical role of broad-scale human versus natural disturbance on an intensively studied tropical forest we undertook a landscape-level analysis of forest dynamics in the Luquillo Experimental Forest (LEF; 10,871 ha) in eastern Puerto Rico. Using aerial photographs (1936 and 1989), GIS, a model of topographic exposure to hurricane winds, and historical data, we sought to: (1) document historical changes in extent, cover and type of forest vegetation, (2) evaluate the distribution of land-use and hurricane impacts, (3) assess the contributions of these processes in controlling current vegetation patterns, and (4) relate these results to ongoing ecological, conservation and natural resource discussions. "With over 1000 m of relief in the LEF, the broad vegetation zones of Tabonuco (below 600 m a.s.l.), Colorado (600-900 m), Dwarf (above 900 m), and Palm forest are determined by environmental gradients. However, over the past 60-100 years forest extent, cover, and type have been transformed: in 1936, 40% of the LEF was unforested or secondary forest and less than 50% had continuous canopy (more than 80% cover); in 1989, less than 97% was continuous forest. Secondary forest and agricultural lands in 1936 were replaced largely by Tabonuco and Colo
Carbon and Nitrogen Across Two ULTRA-Ex Urban to Rural Gradients in Massachusetts 2010
As part of the Boston University-led, Urban Long-Term Research Area - Exploratory Award (ULTRA-Ex), we established 135 circular, 15 m radius biometric plots extending across two Boston urban-to-rural gradients (Boston MA to Petersham MA and Boston MA to Worcester MA). The plots were stratified based on neighborhood (1 km2 surrounding area) characteristics for population density, impervious surface area fraction, and land cover. Within each plot we measured aboveground live and dead biomass, species characteristics, ground cover characteristics, and soil properties.
Ungulate-Forest Interactions in Partially Harvested Oak-Pine Stands in Central Massachusetts 2009
Ungulates are attracted to forest openings created by natural disturbance and timber harvesting due to the abundance of high quality browse in these openings. Despite the increased activity 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 are the foundation hardwood taxon and predominant timber tree in the region and are in decline. 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.
Ungulate-Disturbance Interactions in Hemlock Ecosystems at Harvard Forest 2012-2013
Densities of ungulates are often associated with recent forest disturbances such as fire, logging and insect outbreaks, as increased resources stimulate tree regeneration, leading to abundant available browse. Despite the often significant role that ungulates play in disturbed forests, surprisingly little is known about ungulate-disturbance interactions, and 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. Our objectives are twofold: to determine (1) the response of ungulates to varying disturbance types and intensities and (2) the influence of ungulate interactions with canopy disturbance on vegetation, other biota, and ecosystem processes. We will examine 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. We will also monitor the response of vegetation to ungulate browsing by sampling woody and herbaceous vegetation in fenced exclosures and paired controls in disturbed and undisturbed plots.
Regional Conservation Partnerships in New England 2009-2012
Across New England, a new model of regional collaboration is increasingly being used by land conservation trusts, watershed associations, state agencies and others. Regional conservation partnerships (RCPs) serve multiple purposes, such as coordinating among the various active groups in the region and allowing them to leverage funding and staff capacity. However, their essential missions are the same--protect more land from development. We use interviews, geographic information systems (GIS), and statistical analysis on 20 case studies to document RCP growth and characteristics and to analyze which attributes most contribute to their ability to conserve land. Along with well-known factors of organizational development, we find that the RCPs that match the size of the partnership region with the territory and capacity of the host partner organization are better able to achieve measurable conservation gains.
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Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.