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Canopy Phenology, Remote Sensing and Microclimate at Harvard Forest 2006-2011
Our research at the Harvard Forest walk-up tower site examines how seasonality of canopy leaf area, or canopy phenology, influences, and is influenced by, local climate. As part of this activity we are studying methods for (and limits to) remote sensing of canopy phenology. To address this research topic, we have initiated measurements to quantify how radiation fluxes through a deciduous forest canopy are modified by seasonal canopy leaf dynamics. We continuously measure above- and below-canopy radiation fluxes at a variety of spectral bands (shortwave, photosynthetic) and with digital photography. These measurements provide a surrogate measures of canopy leaf area dynamics, and directly represent the radiation component of the surface energy balance. These measurements complement ongoing microclimate and eddy covariance measurements of water and carbon exchange at the EMS flux tower.
Lake Sediment Pollen from Knob Hill Pond in Marshfield VT from 14000 BP to Present
The abrupt, range-wide decline of Tsuga canadensis ~5500 calibrated years before present (cal. yr BP) is one of the most-studied events in North American paleoecology. Little attention, however, has been given to an earlier Tsuga decline, dated to ~6000 cal. yr BP in southern Ontario, Canada. To investigate whether this event occurred elsewhere in eastern North America, we analyzed the middle-Holocene interval of a lake-sediment record from Knob Hill Pond, located in northern Vermont, USA, an area of historically high Tsuga abundance. A dramatic, short-lived drop in Tsuga pollen abundance does occur at ~6000 cal. yr BP in the Knob Hill Pond record, indicating that Tsuga populations declined in various parts of its range. We hypothesize that both middle-Holocene declines of Tsuga were caused by the deleterious effects of pronounced droughts on this moisture-sensitive tree. Close examination of pollen data from a transect of sites across New England reveals that the earlier decline of Tsuga is present in other records, although some aspects of the event appear to have varied geographically. While northern and higher-elevation sites exhibit a nearly full recovery of Tsuga populations between the two declines, records further to the south are characterized by a stair-step pattern of progressive decline. At sites near its southern range limit, relatively warm conditions between ~6000 and 5500 cal. yr BP were apparently not conducive to the reestablishment and survival of Tsuga, and thus it was unable to recover between the drought events.
Lake Sediment Pollen from Little Pond in Bolton MA from 3000 BP to Present
Analyses of a sediment core from Little Pond, located in the town of Bolton, Massachusetts, provide new insights into the history of environmental and ecological changes in southern New England during the late Holocene. Declines in organic content and peaks in the abundance of Isoetes spores indicate reduced water depth at 2900-2600, 2200-1800, and 1200-800 calibrated years before present (cal yr BP), generally consistent with the timing of dry conditions in records from elsewhere in the northeastern United States. The Little Pond pollen record features little change over the last 3000 yr, indicating that the surrounding vegetation was relatively insensitive to these periods of drought. The 1200-800 cal yr BP dry interval, however, coincides with increased abundance of Castanea pollen, suggesting that the expansion of Castanea in southern New England may have been influenced by late-Holocene climatic variability.
History and Dynamics of American Beech in Coastal New England 1620-2006
Variation in forest response to hurricane disturbance in coastal New England Research on disturbance in forest ecosystems has generally focused on either catastrophic disturbances generating stand-replacing successional sequences, or small-scale disturbances (e.g. individual tree-fall gaps) resulting in tree-by-tree replacement. The role of moderate disturbances in forest development, in contrast, is poorly understood. While the most severe hurricanes can cause catastrophic disturbance, the vast majority of hurricanes that affect forests from the Caribbean to the northeastern United States are moderate in intensity. In this study we examine both individual and population level responses of beech (Fagus grandifolia) and oak species (Quercus spp.) to hurricanes of varying intensity in coastal Massachusetts. We characterize growth response to disturbance using a novel approach that explicitly compares the range of growth responses observed following known disturbances to the range of growth responses in non-event years. The tree species exhibited a wide range of growth and regeneration responses to hurricanes; however, only a single storm caused dramatic increases in growth and new establishment for beech. The results of this study highlight the importance of wind disturbance in the establishment and persistence of beech, and suggest that while some moderate disturbances have little or no effect on species growth and regeneration dynamics, individual storms may have substantial impacts. Forest response to wind storms of varying, but moderate intensities, depended on local site conditions, including environmental, meteorological, topographical, historical and biological factors. Beech dominance in a coastal New England forest Monodominant forests occur in a wide range of tropical and temperate ecosystems, but the mechanisms enabling their development are not well understood. This study examines the history and dynamics of beech-dominated forests in coastal New England i
Impacts of Land Use on Japanese Barberry Invasion in Central Massachusetts 2005
Despite the recognized importance of historical factors in controlling many native species distributions, few studies have incorporated historical landscape changes into models of invasive species distribution and abundance. We explore the possibility that the current distribution of invasive species may reflect legacies of historical land use despite nearly a century of forest succession and subsequent disturbances. We evaluated the modern distribution and abundance of Berberis thunbergii DC. (Japanese barberry), a problematic non-native shrub in forests of the northeastern U.S., relative to two distinct periods of historical land use, modern forest harvesting activity, and environmental and edaphic characteristics. Species questions addressed in this study include: (1) Do patterns of historical land use influence modern barberry distribution and abundance? (2) What is the influence of disturbance type and timing relative to the timing of introduction on current barberry distribution and abundance? (3) Which disturbance, environmental and edaphic variables best predict modern barberry distribution and abundance? Japanese barberry occurred more frequently and was more abundant in sites historically cleared for agriculture than in historically wooded sites. This relationship was strongest for areas in agriculture in the early 20th century after barberry was introduced to the region. The strong relationship between modern distribution patterns and prior land use suggests historical colonization of abandoned agricultural lands and persistence through subsequent reforestation. Contrary to our expectations, recent forest harvesting did not influence the occurrence or abundance of barberry. Our results indicate that interpretations of both native community composition and modern plant invasions must consider the importance of historical landscape changes and the timing of species introduction along with current environmental and edaphic conditions.
Demography of Sarracenia Purpurea in Massachusetts and Vermont 1997-2021
The northern pitcher plant Sarracenia purpurea is a model system for forecasting extinction risk in the face of environmental change. We have monitored demographic variables of two mapped cohorts of S. purpurea in ombrotrophic bogs of northern New England from 1997-2005 (Hawley Bog, Massachusetts) and 1997-present (Molly Bog, Vermont). Growth, survivorship, and reproduction are in close balance, and matrix-models with four life stages (seeds, seedlings/juvenile plants, non-flowering adult plants, flowering adults) predicted population growth rates close to zero, with long doubling times. To further assess seed-to-seedling transitions, we measured and weighed Sarracenia seeds, and conducted a greenhouse experiment on density-dependent dynamics of newly germinated seedlings of S. purpurea.
Stand and Community Response to Hemlock Woolly Adelgid in Southern New England since 1995
Hemlock woolly adelgid (HWA), Adelges tsugae, an introduced aphid-like insect from Asia, is expanding its range across the northeastern United States through the range of Tsuga canadensis (eastern hemlock) and can severely reduce or eliminate this important late-successional species. As part of a study investigating stand- and landscape-level forest dynamics resulting from HWA infestation, we examined initial community response of eight T. canadensis stands in south-central Connecticut and then continued to monitor these stands every other year. Our major objectives were to assess mortality patterns in T. canadensis, evaluate subsequent changes in stand microenvironment, and relate these and stand composition to initial patterns of regeneration, understory response, and community reorganization. Tsuga canadensis damage varied broadly across the study area ranging from near zero to greater than 95 % mortality. All size and age classes sampled were attacked by HWA, although smaller trees exhibited higher mortality rates than larger trees. All remaining T. canadensis sampled in seven of the eight stands were infested with HWA and over 90 % suffered at least 50 % foliar loss. Since 1995, overstory and understory mortality has risen 5 to 15 % per year to overall values of 50 to 99%. There has been no sign of tree recovery and the health and vigor of remaining trees deteriorated in all infested stands. Results suggest that trees on some sites can remain alive for over 10 years following initial infestation and remain standing for 6 to 8 years following mortality. Substantial accumulations of downed woody debris have developed in stands with severe HWA damage. Canopy gaps created by HWA damage significantly increased the amount of light reaching the forest floor and resulted in rapid understory vegetation responses. Prolific Betula lenta (black birch) establishment occurred in stands with moderate to severe T. canadensis mortality. In addition, opportunistic herbaceous spe
Pre-Colonial and Modern Tree Data from Nine Northeastern States 1620-2008
The northeastern United States is a predominately-forested region that, like most of the eastern U.S., has undergone a 400-year history of intense logging, land clearance for agriculture, and natural reforestation. This setting affords the opportunity to address a major ecological question: How similar are today’s forests to those existing prior to European colonization? Working throughout a nine-state region spanning Maine to Pennsylvania, we assembled a comprehensive database of archival land-survey records describing the forests at the time of European colonization. We compared these records to modern forest inventory data and described: (1) the magnitude and attributes of forest compositional change, (2) the geography of change and (3) the relationships between change and environmental factors and historical land use. We found that with few exceptions, notably the American chestnut, the same taxa that made up the pre-colonial forest still comprise the forest today, despite ample opportunities for species invasion and loss. Nonetheless, there have been dramatic shifts in the relative abundance of forest taxa. The magnitude of change is spatially clustered at local scales (less than 125-km) but exhibits little evidence of regional-scale gradients. Compositional change is most strongly associated with the historical extent of agricultural clearing. Throughout the region, there has been a broad ecological shift away from late successional taxa, such as beech and hemlock, in favor of early- and mid-successional taxa, such as red maple and poplar. Additionally, the modern forest composition is more homogeneous and less coupled to local climatic controls.
Modeling Foundation Species in Food Webs
Foundation species are basal species that play an important role in determining community composition by physically structuring ecosystems and modulating ecosystem processes. Foundation species largely operate via non-trophic interactions, presenting a challenge to incorporating them into food-web models. Here, we used non-linear, bioenergetic predator-prey models to explore the role of foundation species and their non-trophic effects. We explored four types of models in which the foundation species reduced the metabolic rates of species in a specific trophic position. We examined the outcomes of each of these models for six metabolic rate “treatments” in which the foundation species altered the metabolic rates of associated species by one-tenth to ten times their allometric baseline metabolic rates. For each model simulation, we looked at how foundation species influenced food-web structure during community assembly and the subsequent change in food-web structure when the foundation species was removed. When a foundation species lowered the metabolic rate of only basal species the resultant webs were complex, species-rich, and robust to foundation species removals. On the other hand, when a foundation species lowered the metabolic rate of only consumer species, all species, or no species the resultant webs were species poor and the subsequent removal of the foundation species webs resulted in the further loss of species and complexity. This suggests that in nature we should look for foundation species to predominantly facilitate basal species.
Forest Inventory for Tree Demography and Carbohydrate Reserves at Harvard Forest 2009-2011
The objective of this study is to establish a network of forest plots spanning the eastern U.S. focused on understanding how regional scale climate patterns affect patterns of tree demography (e.g. growth, mortality, dieback). Within each research site we also aim to understand the landscape-scale variability in demographic rates and how these rates are affected by edaphic variables by aligning plots along primary environmental gradients (elevation, soils, hydrology, fire return interval). The demographic data obtained will also be compared to regional and landscape-scale patterns in carbon reserves in adults and sapling by sampling root and stem concentrations of nonstructural carbohydrates (TNC) and relate these to demographic patterns, life-history traits, and plant C:N ratios. Besides addressing important ecological questions directly, this study is designed to improve the representations of vegetation dynamics and carbohydrate reserves in regional and landscape-scale forest ecosystem models--two of the least data-constrained processes in such models--by parameterizing and validating the modules for these processes in the Ecosystem Demography model (ED v2.1). This data set contains two years of census data for eight mapped plots distributed across Harvard Forest along the aforementioned primary environmental gradients.
Fluxes of Carbonyl Sulfide at Harvard Forest EMS Tower 2010-2013
Carbonyl sulfide (OCS), the most abundant sulfur compound in the atmosphere, controls the sulfur budget and aerosol loading of the stratosphere in times of low volcanic activity. OCS is also closely tied to the vegetative carbon cycle and may provide an independent measure of the photosynthetic uptake of carbon. However, the detailed nature of the biogeochemical cycling of OCS throughout the seasons in terrestrial ecosystems has not been thoroughly explored. We measured the seasonal response of the ecosystem flux of OCS above a deciduous temperate forest using an infrared laser absorption spectrometer at Harvard Forest (MA, USA) in 2011. Fluxes were calculated using two complementary approaches: gradient – flux (also known as flux – gradient; January – July, 2011) and eddy covariance flux (August – December, 2011), which agreed within the combined error for a period with both measurements. Strong uptake of OCS by the forest was observed during most of the growing season, but significant uptake also occurred when the deciduous leaves were not present. A strong diel cycle of mid-day OCS uptake was observed in May/June and August/September, consistent with OCS uptake by processes parallel to CO2 photosynthetic uptake, at the ecosystem scale, for these months. The results show that while overall OCS and CO2 both show evidence of vegetative uptake, the OCS flux cannot be explained by this process alone and the relationship between OCS and CO2 changes throughout the year above this mixed deciduous forest. The data imply that terrestrial uptake of OCS, and hence the stratospheric sulfur cycle, are potentially quite sensitive to extremes in temperature and soil moisture.
Impacts of Nutrient Availability on Calystegia Spithamaea at Harvard Forest 2013
Low bindweed (Calystegia spithamaea (L.) Pursh ssp. spithamaea, Convolvulaceae), is a low-growing perennial plant of the morning glory family that ranges from Georgia north to Nova Scotia. It is recorded from 3 extant and 8 historic stations in Massachusetts, and 18 total extant populations across New England, where it inhabits dry, open sites with sandy to rocky soils, including sandy roadsides and path edges, inland sandplains, power line rights-of-way, loose talus slopes, and gravel pits. Massachusetts lists the species as S1, Endangered. Factors promoting reproduction in this rare species are largely unknown. Although Calystegia spithamaea has been noted to produce short rhizomes, its ability to spread vegetatively had not been determined as of 2013. Sexual reproduction is very rare in extant New England populations; although herbarium specimens show flowers, fruits are rare and seeds have not been collected at any population. Field studies have been conducted since 2007 of a population of several thousand ramets of Calystegia spithamaea in a minimally managed field on the Army Corps of Engineers Birch Hill Dam property, Royalston, Massachusetts. The population occurs on excessively drained, sandy loam, which supports otherwise low plant diversity and appears to be nutrient-poor. We tested the hypothesis that nutrient limitation may hinder sexual reproduction and ramet growth in this species. From May to August 2013, a greenhouse study was conducted at Harvard Forest to determine the effects of nutrient availability on Calystegia spithamaea growth and reproduction: Ramets were excavated from the field and were found to be propagating on long rhizomes, confirming for the first time that the species is capable of at least limited asexual reproduction. Forty-eight ramets of Calystegia spithamaea were planted in pots in the greenhouse and randomly allocated to one of two treatments: control and nutrient-amendment with 20:20:20 N:P:K fertilizer. Five ramets from a ne
Growth Rates of Xanthoparmelia Lichens in North Cemetery, Petersham MA 2005-2011
Lichens fix carbon dioxide from the air to build biomass. Crustose and foliose lichens grow as nearly flat, circular disks. While smaller lichens grow slowly, but with small, steady increases in radial growth rates, larger lichens grow more quickly, with radial velocities that remain roughly constant over the lifetime of an individual. These basic features follow directly from a novel mathematical model based on the diffusion of carbon dioxide around a lichen, and its absorption by the thallus. Smaller lichens fix carbon dioxide across the entire thallus, but larger lichens fix carbon dioxide disproportionately at edges. Because local edges remain the primary source of carbon as a lichen grows ever larger, radial growth rates remain constant. Predicted growth dynamics depend on four measurable parameters, and tests of the model against data suggest the model provides an accurate, robust, and universal framework for understanding the growth dynamics of lichens in nature.
Ant Functional Diversity in Temperate Zone Forests: A Comparison with Neotropical Ants 2010
Predicted impacts of climatic change on ant functional diversity and distributions in eastern North American forests Aims--Climatic change is expected to rearrange species assemblages and ultimately affect organism-mediated ecosystem processes. We focus on identifying patterns and relationships between common ant species (representing 99% of total ant records) richness and functional diversity; modelling how these patterns may change at local and regional scales in future climatic conditions; and interpreting how these changes might influence ant-mediated ecosystem processes. Location--Forested ecosystems of eastern North America. Methods--We used a previously published dataset to evaluate functional diversity at 67 sites in the eastern U.S. and quantified 14 taxonomic, morphometric and natural history traits for 70 common ant species in the region. We used functional diversity metrics, functional groups and species distribution modelling methods to address our aims. We used stacked species distribution models and stacked functional group models to predict species assemblages and functional richness at the 67 sites and at a regional scale for current and future climatic conditions. Results--Species richness and functional diversity are positively correlated throughout the region. Under future climate scenarios, species richness and functional group richness were predicted to decrease in southern ecoregions and increase in northern ecoregions. This may be due to increased thermal stress for species in the southern extent of their ranges and increased habitat suitability in the northern ecoregions. Decomposers, arthropod community regulators and seed dispersers are forecast to be the most threatened ant functional groups. Main Conclusions--Climate change will likely lead to major changes in ant species richness and functional group richness in the forests of the north-eastern United States, and this may substantially alter ant-mediated ecosystem processes and services
Coarse Woody Debris in the Clearcut Site at Harvard Forest 2010
The woody debris survey was designed to quantify the baseline amount of woody debris within the clearcut site, including coarse and fine woody debris and stumps. Coarse woody debris and stumps were measured using the plot method, while fine woody debris was measured using the line intercept method. Our woody debris survey methods are detailed below. An initial or baseline survey was completed in 2010.
Respiration of Coarse Woody Debris in the Clearcut Site at Harvard Forest in 2011
This study explored the effects of log position and microclimate variability on the rates of coarse woody debris (CWD) respiration. The rates of respiration of downed Norway spruce (Picea abies) logs were repeatedly measured in-situ using an LI-6200 gas analyzer. Treatments included native logs in the clearcut site, native logs in a neighboring mature spruce stand, and logs transferred from the clearcut site to the mature spruce stand.
Nonstructural Carbohydrates in Red Maple at Harvard Forest and Bartlett Forest 2011-2012
Nonstructural carbohydrates (NSC) are the primary products of photosynthesis, composed mostly of sugars and starch. Recent studies show that NSC pools in mature trees can be quite large and on average a decade old. Thus, NSC pools integrate years of carbon assimilation and represent significant ecological memory at the whole plant and ecosystem level. However, we know very little about how older stored NSC versus newly assimilated NSC are used to support growth and metabolism, or how available older NSC are to trees during stress or following disturbance. To better understand these potential lags in NSC allocation, we studied mature red maple (Acer rubrum) trees in two New England temperate forests. We determined stemwood concentrations of stored sugars and starch of five trees at each site. Applying the radiocarbon (14C) “bomb spike” approach, we estimated the age of carbon in stemwood NSC, ring cellulose, and bole respiration. We also collected stump sprouts regrowing from a separate set of recently harvested red maple trees at each site, and determined the radiocarbon age of this tissue. Our data show that younger NSC is preferentially used for growth and day-to-day metabolic demands. More recently stored NSC contributes to annual ring growth and metabolism in the dormant season. Older reserves are available to the tree after disturbance (e.g. harvesting).
Concentration and Age of Nonstructural Carbon Reserves in Two Trees at Harvard Forest 2012
We know surprisingly little about whole-tree nonstructural carbon (NSC; primarily sugars and starch) budgets. Even less well understood is the mixing between recent photosynthetic assimilates (new NSC) and previously stored reserves. And, NSC turnover times are poorly constrained. We characterized the distribution of NSC in the stemwood, branches, and roots of two temperate trees, and we used the continuous label offered by the radiocarbon (14C) bomb spike to estimate the mean age of NSC in different tissues. NSC in branches and outermost stemwood growth rings had the 14C signature of the current growing season. However, NSC in older above- and below-ground tissues was enriched in 14C, indicating that it was produced from older assimilates. Radial patterns of 14C in stemwood NSC showed strong mixing of NSC across the youngest growth rings, with limited.
INTERPNT Software for Mapping Trees Using Distance Measurements
The INTERPNT method can be used to produce accurate maps of trees based solely on tree diameter and tree-to-tree distance measurements. For additional details on the technique please see the published paper (Boose, E. R., E. F. Boose and A. L. Lezberg. 1998. A practical method for mapping trees using distance measurements. Ecology 79: 819-827). Additional information is contained in the documentation that accompanies the program. The Abstract from the paper is reproduced below. "Accurate maps of the locations of trees are useful for many ecological studies but are often difficult to obtain with traditional surveying methods because the trees hinder line of sight measurements. An alternative method, inspired by earlier work of F. Rohlf and J. Archie, is presented. This "Interpoint method" is based solely on tree diameter and tree-to-tree distance measurements. A computer performs the necessary triangulation and detects gross errors. The Interpoint method was used to map trees in seven long-term study plots at the Harvard Forest, ranging from 0.25 ha (200 trees) to 0.80 ha (889 trees). The question of accumulation of error was addressed though a computer simulation designed to model field conditions as closely as possible. The simulation showed that the technique is highly accurate and that errors accumulate quite slowly if measurements are made with reasonable care (e.g., average predicted location errors after 1,000 trees and after 10,000 trees were 9 cm and 15 cm, respectively, for measurement errors comparable to field conditions; similar values were obtained in an independent survey of one of the field plots). The technique requires only measuring tapes, a computer, and two or three field personnel. Previous field experience is not required. The Interpoint method is a good choice for mapping trees where a high level of accuracy is desired, especially where expensive surveying equipment and trained personnel are not available."
Seedlings and Saplings in the Clearcut Site at Harvard Forest 2010-2013
The aim of this dataset is to quantify the changes over time in woody seedling and sapling abundances and sizes at a site that was clearcut in the fall of 2008, followed by natural regeneration. It evidences successional changes in recruitment, survival, and associated self-thinning, and can be used to quantify accumulation of aboveground live biomass post-clearing with corresponding allometric relationships.
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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.