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1,985 results for “2003”
Zooplankton density for all samples collected from Toolik Lake and lakes near the Toolik Field Station, Arctic LTER 2003-2022.
Zooplankton samples were taken on lakes with a 30 cm diameter plankton net with a 256 micron mesh netting from 2018-2022. Prior years used a 156 micron mesh netting. Density was calculated based on the number of each taxa counted in a subsample or whole sample and expanded to the volume sampled to determine the number of each zooplankton taxa per liter. All samples were collected from Toolik Lake and lakes near the University of Alaska Toolik Field Station, Fairbanks, Arctic LTER from 2003-2022.
Soil Characteristics and Nutrient Data from the Shark River Slough, within Everglades National Park (FCE), from March 2003 to March 2004
Three random soil cores are collected once a year from SRS1b, SRS2, and SRS3. The collection of these soil cores is in the dry season (Dec.-May). The top 10cm of soil is collected using a soil core. The soil is then analyzed to obtain its bulk density, organic matter content, TC, TN, and TP.
Abundance of the planthopper Prokelisia at GCE LTER sampling sites in October, 2003-2019
The abundance of the planthopper Prokelisia spp was estimated each year during the fall monitoring at each zone of each GCE site that was dominated by Spartina alterniflora. N Observations were made in the vicinity of the permanent vegetation plots and Prokelisia abundance was scored on a 5 point scale.
Adult Population Survey of Hemlock Woolly Adelgid in Massachusetts 2003-2005
To effectively document insect presence and abundance a statistically based sampling plan is necessary. No such plan for the hemlock woolly adelgid is currently available in the published literature. Two interrelated sampling strategies allow a researcher to enter a site and determine with a given level of probability whether or not an HWA infestation is present and the level of infestation. A ground based sampling plan is also critical to the ‘ground truthing’ of aerial survey systems. A fully developed sampling plan requires relatively extensive datasets obtained over time, and may include the use of computer-generated data obtained through re-sampling techniques. The results obtained through the Harvard Forest Summer Research Program should provide a firm foundation for further development of an HWA sampling program. Data collection is on-going.
Understory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003
Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock, and widespread harvesting 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.
Light Environment in Hemlock Removal Experiment at Harvard Forest since 2003
The impending loss of hemlock trees due to hemlock woolly adelgid (Adelges tsugae) infestation is expected to lead to changes in the light environment of the forest understory. These changes will both drive succession and will themselves be altered by successional processes. The light reaching the forest floor is measured using hemispherical canopy photographs. Photographs were taken in summer of 2003 and in December 2004 and May 2005 (both deciduous-tree leaf-off condition), prior to the application of the logging and girdling treatments, and then in September 2005 (deciduous tree leaf-on condition) after logging and girdling. Subsequent photographic series will be taken annually in spring (leaf-off) and summer/fall (leaf-on).
Overstory Vegetation in Hemlock Removal Experiment at Harvard Forest since 2003
Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock. Widespread harvesting 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 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.
Impacts of Hemlock Harvesting in Central Massachusetts 2003-2009
The recent unimpeded infestation of the hemlock woolly adelgid (HWA; Adelges tsugae) across the northeastern U.S. is driving large-scale hemlock decline and mortality. HWA has already infested over 40% 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, we 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. Forty-two to ninety-seven percent of hemlock stems and basal area were removed from the harvested sites. Sapling densities of 10,500 to 24,000 stems ha-1 dominated the vegetation at older cuts and consisted primarily of black birch (Betula lenta), red maple (Acer rubrum), and white pine (Pinus strobus). Seedling densities averaged 5 m-2 across sites, peaked at 20 m-2 at 6 to 9 year old sites, and consisted of hemlock, white pine, black birch, and red maple. Additional understory species that were common in cuts sites included various raspberry (Rubus) species, often averaging 30% cover, hay-scented fern (Dennstaedtia punctilobula), and various sedge (Carex) species. Harvesting resulted in soils that were 3 to 5 (deg C) warmer and tended to be drier in recent vs. older cuts. Net nitrogen mineralization rates in organic soils averaged just over 10 kg N ha-1yr-1 in recent cuts and approx. 5 kg N ha-1yr-1 in older cuts. Mineral soil net mineralization rates were lower among all cuts, ranging from 2.1 to 3.5 kg N ha-1yr-1. Nitrification rates were low in both soil horizons at all harvest ages. Recent cuts had much higher nitrogen capture (NH4- + NO3+) on resin bags averaging around 1200 μg N g resin-1 vs. 300 to 600 μg N g resin-1 captured in older cuts. Nitrification rates and nitrate capture on resin bags were lower in Massachusetts sites than those reported on sites with a long history o
Linking Xylem Diameter Variations with Sap Flow Measurements at Harvard Forest 2003-2006
Measurements of variation in the diameter of tree stems provide a rapid response, high resolution tool for detecting changes in water tension inside the xylem. Water movement inside the xylem is caused by changes in the water tension and theoretically, the sap flow rate should be directly proportional to the water tension gradient and, therefore, also linearly linked to the xylem diameter variations. The coefficient of proportionality describes the water conductivity and elasticity of the conducting tissue. Xylem diameter variation measurements could thus provide an alternative approach for estimating sap flow rates, but currently we lack means for calibration. On the other hand, xylem diameter variation measurements could also be used as a tool for studying xylem structure and function. If we knew both the water tension in the xylem and the sap flow rate, xylem conductivity and/or elasticity could be calculated from the slope of their relationship. In this study we measured diurnal xylem diameter variation simultaneously with sap flow rates (Granier-type thermal method) in six deciduous species (Acer rubrum L., Alnus glutinosa Miller, Betula lenta L., Fagus Sylvatica L. Quercus rubra L., and Tilia vulgaris L.) for 7-91 day periods during summers 2003, 2005 and 2006 and analyzed the relationship between these two measurements. We found that in all species xylem diameter variations and sap flow rate were linearly related in daily scale (daily average R 2 = 0.61-0.87) but there was a significant variation in the daily slopes of the linear regressions. The largest variance in the slopes, however, was found between species, which is encouraging for finding a species specific calibration method for measuring sap flow rates using xylem diameter variations. At a daily timescale, xylem diameter variation and sap flow rate were related to each other via a hysteresis loop. The slopes during the morning and afternoon did not differ statistically significantly from each other,
Canopy Phenology and Greenness Indices at 13 Sites across North America 2003-2012
This data set contains camera-derived color index data, which serve as a proxy for canopy phenology. The data set spans 13 geographically distinct research sites, including 17 different cameras it total, each of which was mounted on a eddy flux tower for intercomparison of canopy and photosynthesis phenology. Each site was dominated by one of three PFTs: deciduous broadleaf forest, evergreen needleleaf forest, and grassland/crops (see HF215-01 for details). On each eddy covariance tower, a digital camera was installed in a fixed position, with a view across the top of the canopy. Most cameras collected photos, which were saved in 24-bit JPEG format, at 30-60 minute intervals, 12-24 hours a day. Time series were first visually inspected for camera shifts and changes in field of view. Noting these changes, we processed the image archives to extract regions of interest (ROI) that encompassed all portions of the full canopy within the foreground. To quantify canopy greenness, we calculated the green chromatic coordinate (GCC), which is widely used to monitor canopy development and identify phenological phase changes, as follows: GCC = DNG / (DNR + DNG + DNB) where DN is the digital number and R, G and B denote the red, green and blue channels, respectively. The Excess Green (ExG) index was then calclated as follows: ExG = 2 * DNG - (DNR + DNB) To characterize canopy coloration in fall, the red chromatic coordinate (RCC) was calculated using the same form as GCC, substituting DNR in the numerator. Indices have been smoothed along a 3-day interval, using a 90th percentile filter (Sonnentag et al. 2012). For each deciduous broadleaf site, there are three files – one each for GCC, ExG and RCC. For the grassland and evergreen needleleaf sites, there are two files, one each for GCC and ExG.
Longitudinal Streamflow in Headwater Streams on Prospect Hill Tract at Harvard Forest 2003
We have initiated long-term monitoring of streamflow in headwater streams on the Prospect Hill Tract at the Harvard Forest. In addition, we have periodically recorded summer flow conditions longitudinally along the length of headwaters within Harvard Forest to obtain information about spatial heterogeneity of flow and of availability of aquatic habitat within these headwaters. In summer of 2003, we recorded streamflow each week at 20-m intervals along the length of two tributaries of Nelson Brook, Tributary A, from Route 32 to its outlet from the Black Gum Swamp, and Tributary B, from its junction with Tributary A to its origin in wetlands north of Prospect Hill Road.
Salamander Response in Hemlock Removal Experiment at Harvard Forest 2003-2005
Despite reductions in prices, pre-emptive salvage logging of eastern hemlock stands has increased since the arrival of eastern hemlock woolly adelgid (Adelges tsugae, HWA) into this region. The microenvironmental changes associated with eastern hemlock loss have been found to be even more severe than when stands are lost to logging due to HWA infestation. This study assessed the effects of a commercial logging operation on two 90m x 90m (0.8 ha) plots, conducted in the winter of 2004-2005, on eastern redback salamander (Plethodon cinereus) relative abundance within the Simes tract at Harvard Forest. Over the past seven seasons (fall 2003 - fall 2005; excluding winter) I have been monitoring eastern redback salamander relative abundance using artificial cover objects (ACOs). The objectives of this study were 1) to assess whether logging has an impact on redback relative abundance at a plot level 2) to assess whether logging in isolated plots has an impact on relative abundance throughout the entire Simes tract 3) to assess whether redback relative abundance is stable over two years. Redback relative abundance in spring 2005 was 660% lower than in spring 2004 in logged plots, while in unlogged plots there was a 4% increase in redback relative abundance in spring 2005 versus spring 2004 (one-way ANOVA; df = 7, F = 6.21, p less than 0.05). Between fall 2004 and spring 2005 redback relative abundance decreased by 727% in the logged plots, compared to only a 29% decrease in unlogged plots (one-way ANOVA; df = 7, F = 10.51, p less than 0.05). Plots adjacent to logged plots had a significantly higher increase in redback relative abundance in spring 2005 versus spring 2004 than those not adjacent to the logged plots (one-way ANOVA; df = 5, F = 8.64, p less than 0.05). There was no significant difference in redback relative abundance in all plots in spring 2004 versus spring 2005 (one-way ANOVA; df = 15, F = 0.20, p = 0.665), or in fall 2004 versus spring 2005 (one-way ANOVA;
Synthesis of Hemlock Removal Experiment at Harvard Forest 2003-2019
In 2023, we synthesized the data from 6 Harvard Forest Hemlock Removal Experiment datasets (HF054, HF106, HF107, HF125, HF126 and HF161) to discern differences between the girdling and logging treatments from 2004-2019. Forest insect outbreaks cause large changes in ecosystem structure, composition, and function. Humans often respond to insect outbreaks by conducting salvage logging, which can amplify the immediate effects, but it is unclear whether logging will result in lasting differences in forest structure and dynamics when compared with forests affected only by insect outbreak. We used 15 years of data from an experimental removal of Tsuga canadensis (L.) Carr. (Eastern hemlock), a foundation tree species within eastern North American forests, and contrasted the rate, magnitude, and persistence of response trajectories between girdling (emulating mortality from insect outbreak) and timber harvest treatments.
Community and Ecosystem Impacts in Hemlock Removal Experiment at Harvard Forest 2003-2020
Hemlock decline in New England is caused by direct and indirect effects of invasion of the hemlock woolly adelgid. Direct damage from the insect is causing gradual mortality of hemlock, and widespread harvesting of hemlock in advance of mortality creates a contrasting disturbance. 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 have designed an experiment to simulate the impact of both in order to contrast them. To simulate some of the effects of the adelgid (e.g., progressive mortality, retention of the wood on the site) we are girdling all hemlocks in a hemlock-dominated stand. In the adjacent area we are conducting a commercial harvesting of hemlock. Results from both 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.
Soil Respiration Along a Hydrological Gradient at Harvard Forest EMS Tower 2003-2006
Soil respiration is an important component of the terrestrial carbon budget. Spatial variation of organic matter and plant cover induce temperature and moisture gradations that obscure direct response of soil respiration to radiative forcing. Separation of spatial patterns from microclimate and substrate availability is vital to predict the response to global change. We are measuring temporal and spatial patterns of soil CO2 flux across a hydrological gradient from wetland to upland soils. A system of 8 automated opaque chambers were installed in 2003 along a hydrological gradient on the northeast margin of the "Beaver Swamp" north of the EMS tower (+42.537755,-72.171478). Two additional clear chambers were installed in the wetland in 2006. Each automated chamber closes for a measurement every four hours. The resulting semi-continuous data has been providing a high-temporal density characterization of soil flux during the growing season since 2003. Soil temperature and moisture were recorded in the litter, organic, and mineral soils during 2004 at three locations along the slope. These structures will provide a database of soil respiration flux, temperature, and soil moisture with both high spatial and temporal resolution, across multiple cover types and ground water levels. The analysis will seek to determine the appropriate spatial scale of soil respiration measurement in eastern hardwood forests.
Salamander Abundance at Harvard Forest 2003-2004
1. Eastern redback salamander relative abundance Eastern hemlock (Tsuga canadensis), an important late successional tree species, is currently threatened in this region by the hemlock woolly adelgid (Adelges tsugae), a small aphid-like invasive insect from Japan. While many species of birds and mammals have found to be associated with eastern hemlock dominated stands, there have been very few studies examining amphibian relative abundance in this forest type. Eastern redback salamanders (Plethodon cinereus) are important components of the forest ecosystem as they are extremely abundant with a biomass found to be twice that of breeding birds and equal to small mammals in the Hubbard Brook Experimental Forest. In addition, redbacks are positioned in the middle of the food web where they are important predators of soil invertebrates, potentially impacting soil respiration rates, and prey for larger vertebrates such as birds, reptiles, and small mammals. Redbacks have been cited as excellent indicators of forest health due to these characteristics as well as their low annual variation in abundance compared to other forest fauna. The objectives of this study was to 1) establish baseline data on eastern redback salamander relative abundance in eastern hemlock dominated stands and mixed deciduous stands in the Harvard Forest in Petersham, MA using artificial cover objects (ACOs) 2) test for differences in redback relative abundance based on forest type, 3) test for correlations between redback relative abundance and soil pH and forest floor temperature. 2. Juvenile eastern red-spotted newt minimum density This study provides baseline estimates of juvenile eastern red-spotted newt (Notophthalmus viridescens viridescens) or "red eft" minimum density through visual surveys of transects in ten forest stands, five eastern hemlock (Tsuga canadensis) dominated and five mixed deciduous, located in the Prospect Hill, Slab City, Simes, and Tom Swamp tracts of Harvard Forest. The obj
Massachusetts Growing Degree Day and Precipitation Maps 2003
A regression model that estimates monthly temperature and precipitation as a function of latitude, longitude, and elevation for the New England area was used to estimate annual growing degree days and precipitation for the state of Massachusetts. For details of the regression model please see the published paper (Ollinger, S.V., Aber, J.D., Federer, C.A., Lovett, G.M., Ellis, J.M., 1995. Modeling Physical and Chemical Climate of the Northeastern United States for a Geographic Information System. US Dept of Agriculture, Forest Service, Radnor, PA, USA).
City of Seattle, Seattle Public Utilities, Riparian Permanent Sample Plots 2003-current, Cedar River Municipal Watershed, King County, WA
The City of Seattle’s Cedar River Municipal Watershed is managed to support and supply clean drinking water to the greater Seattle area. The watershed covers 91,000 acres, hosts a rich diversity of plants, animals, and habitats, and is owned by the City of Seattle. From 2003 to 2005, Seattle Public Utilities established 61 permanent sample plots (PSP) in riparian habitats of the Cedar River Municipal Watershed. 31 of these plots (plot #s 1-31) were established in 2003 upstream of Chester Morse Lake, the drinking water reservoir for the City of Seattle. 30 additional plots (plot #s 32-61) were established in 2005 downstream of Chester Morse Lake. In 2012, 6 of the 61 total plots (plot #s 4, 11, 12, 27, 28, 29) were resampled and the sampling methods were simplified. Each sampling year had different surveyors. The riparian permanent sample plots were limited to low gradient, moderately to unconfined reaches along the Cedar River and its tributaries because they typically show the most variability in riparian condition, stream-riparian interactions are greatest, and fish use is highest. Sites were randomly selected along these reaches, with two plots located at each site, one on each side of the stream. Sites were stratified into four stand types: deciduous dominated, mixed deciduous/conifer, conifer dominated in stem exclusion phase with little understory, and conifer dominated differentiated with well-developed understory, with at least five plots in each type. Each plot was measured for tree species and diameter, snag diameter and height, shrub species and cover, herb species and cover, sapling species and cover, percent canopy cover, and other species found in the plots but not previously recorded in the tree, shrub, and herb sampling. Selection of riparian plots for resampling in 2012 was designed to include plots in second and old growth forests and with medium and large stream sizes. Future resampling is expected to occur at an approximately ten-year interval. T
Data associated with the FLooded Upland Dynamics EXperiment (FLUDEX), conducted at the IISD Experimental Lakes Area 1997 to 2003, investigating reservoir flooding impacts on ecosystems, particularly the release of mercury and greenhouse gases.
The data included in this repository were collected over the course of the FLooded Upland Dynamics Experiment (FLUDEX) conducted at the IISD Experimental Lakes Area (IISD-ELA) from 1997 to 2003. A plethora of data was collected over five years of flooding three upland reservoir sites, in order to examine the relationship between the amount of flooded, and thus decomposed, terrestrial organic matter and the production of methylmercury (MeHg), total mercury (THg), and greenhouse gases (GHGs) in the reservoirs. Findings from this experiment suggest that the amount of organic carbon stored in a flooded site does not directly influence the amount of THg, MeHg, and GHGs produced, but it does affect the persistence of mercury in the reservoir and food web. This version of the repository contains data collected on water chemistry, benthic invertebrate (chironomid) emergence, mercury and methylmercury concentrations in the water and food web, stable isotopes of carbon and nitrogen in emerging insects and zooplankton, and abundance and biomass of zooplankton, phytoplankton, and bacteria. This data package contains only some of the data from the FLUDEX project. IISD-ELA hopes to add more data in subsequent versions.
Macrophyte and microbial mat biomass co-variation along a hydrologic gradient and response to a removal experiment in temporary wetlands Everglades, FL, USA, February 2003 – November 2006
This data package encompasses hydrologic variables, soil depth, hydrologically-regulated macrophyte community types, macrophyte biomass and community structure, and microbial mat biomass that was collected in two observational surveys and one in-situ experimental manipulation in six temporary wetland regions located in the Everglades, FL, USA. The goal of this project was to examine the co-variation in macrophyte and microbial mat biomass along the hydrologic gradient present across wetland regions and to determine the type and strength of interactions occurring between the two communities, which was tested using a biomass (macrophyte or microbial mat) removal experiment. The census observational survey took place at 140 sites from 2003-04-09 to 2004-05-26, which were randomly distributed across the hydrologic gradient present across the six temporary wetland regions. The transect observational survey occurred along six transects and each was deliberately established along the present hydrologic gradient within each region; a total of 254 sites were sampled from 2003-02-19 to 2005-03-04. The experiment took place at three temporary wetland sites with contrasting hydroperiods (3 – 6 months), and four transects were established per site with 24 pairs of control and treatment plots per transect. The removal treatment occurred one year before data collection, and data collection occurred from 2004-06-20 to 2006-11-25. The package includes six datasets, one R code file, and two shape files associated with the R code. Data collection for all datasets is complete. FCE1274_Census_Survey includes hydrologically-regulated macrophyte community type classifications, macrophyte biomass, microbial mat ash-free dry mass, mean soil depth, water depth, mean annual hydroperiod, and vegetation-inferred hydroperiod; each site was sampled once during the survey period and a subset of sites were sampled each year. FCE1274_Transect_Survey includes macrophyte community type classifications
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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.