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6,175 results for “Composite”
Distribution and Composition of the Seed Bank at the Kellogg Biological Station, Hickory Corners, MI (1990 to 2008)
Dataset Abstract The distribution and composition of the weed seed bank in treatments 1-7 of the LTER main site is periodically (every 3-6 years) evaluated using elutriation and seed counting methods. The goal is to determine: how well the seed bank predicts weed abundances and composition in subsequent years, and how changes in disturbance (tillage) and plant species (cropping systems) affect the bank. Composite soil samples to two depths are periodically elutriated to determine seed densities, species composition, and viabilities of seven target species which are dominant on the site. original data source http://lter.kbs.msu.edu/datasets/9
McMurdo Dry Valleys Halogen chemistry and isotopic composition in McMurdo lake waters and pore fluids
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file are the dissolved halogens :chloride, bromide, and total iodine in lake waters and pore waters. The isotopic composition of I-129 and Cl-36 are also presented for these same samples, as are the molar ratios of I-129/I-127, and Cl-36/Cl-37.  Alkalinity was also determined in order to subsequently investigate the relationship between the oxidation of organic matter and the release of iodine into the lake waters.
McMurdo Dry Valleys Iodine content and I-129 isotopic composition in McMurdo lake-bottom sediments
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and the pore waters were collected by centrifuging the wet sediment.  Presented  in this file is the total iodine content and I-129 isotopic composition of lake-bottom sediments from Lakes Joyce and Fryxell. An attempt was made to determine the  iodine and chlorine isotopic content  of gypsum cored from the bottom of Lake Vanda, but the total iodine content was below detection.       Â
McMurdo Dry Valleys Mineralogic composition of cryogenic evaporites determined by low-temperature X-ray diffactometry
As part of a collaborative investigation between researchers at Rice University, Arkansas State University, University of Rochester, and Ohio State University, lakes of the McMurdo Dry Valleys were sampled at discreet depth intervals during the 2005-2006 field season.  Sample splits were subsequently analyzed for chemical and isotopic composition of both gases and dissolved  ions, as well as dissolved organic carbon. In addition, cryogenic salts were sampled in the surrounding lake shores in order to determine the salt sources. Gravity cores were also obtained and in the case of Lake Vanda, a white precipitate was recovered from the lake bottom.        Presented  in this file is the mineralogic composition of salt crusts that were collected on the surface of sediment and rocks surrounding the lakes, as well as the lake-bottom precipitate from Lake Vanda.  The results are based on low-temperature XRD determinations, and Rietveld refinement of whole peaks.       Â
MCR LTER: Coral Reef: Water Column: Zooplankton Composition and Abundance
This data package contains zooplankton abundance and taxonomic composition measured at 5 stations on the north shore of Moorea, French Polynesia: Forereef, Backreef, Fringing Reef, Cooks Bay, and Oceanic (5 km due north) from 2005 to 2010. Day time measurements over the reef were taken with a 30 cm, 200 μm mesh plankton net equipped with a slow speed General Oceanics Model 2030 flow meter. Nets were swum horizontally by a diver 1 m above the bottom at Forereef, Backreef and Fringing Reef sites. Daytime sampling at the Oceanic and Cooks Bay sites consisted of 0-50 m, 0-100 or 0-30 m vertical tows with a 30 cm, 200 μm mesh plankton net equipped with a standard General Oceanics Model 2030 flow meter. Nighttime sampling and some daytime sampling was done at the Forereef, Backreef and Fringing Reef sites using automated plankton pumps equipped with flow meters and 200 μm internal nets (described in Alldredge and King, 2009). These pumps sampled 75 cm above the bottom for 1 to 1.5 hours beginning at 11 pm local time. Nocturnal zooplankton abundance was sensitive to lunar phase. On some sampling dates pump samples were taken at the same depth in duplicate, or at several different depths simultaneously. The zooplankton time series was terminated when it became clear that the variability in zooplankton abundance over just 50 cm difference in depth over the reef was greater than the variability seasonally or even day to night (Alldredge and King, 2009). Alldredge AL and J M King 2009. Near-surface enrichment of zooplankton over a shallow back reef: Implications for coral reef planktivores. Coral Reefs 28:895-908. DOI: 10.1007/s00338-009-0534-4
MCR LTER: Coral Reef: Demersal Zooplankton Composition and Abundance
This data package contains demersal zooplankton abundance and taxonomic composition measured at 3 stations on the north shore of Moorea, French Polynesia: Forereef, Backreef and Fringing Reef from 2005 to 2010. Demersal zooplankton emerging from sand or rubble substrates on the reef during the night were captured in 8 inverted funnel traps placed on the substrate in the late afternoon and retrieved the following morning. Traps were made of 200 μm mesh netting with the opening to the cod end located 18 cm above the bottom. Four traps, each covering 0.0615 m2 of substrate, were combined to obtain one sample for counting. The table reports means of 2 replicates each containing 4 combined traps. Traps placed over sand were pushed into the substrate. However, traps over rubble had numerous gaps along their bases allowing some contamination from the water column. Data are expressed as number of animals emerging per square meter of bottom.
N and P fertilization experiment plant species composition and diversity data for South of saddle, 1990 - 2000.
The effects of nitrogen, phosphorus, and nitrogen+phosphorus fertilization on alpine plant species composition and diversity in a dry and a wet meadow community were examined. A point-quadrat system was used to estimate the cover frequencies for each species in plots in the 2 communities on the south slope of Niwot Ridge. Treatments were N, P, N+P, and control. Observations were made once per year per plot over a period of several years. Diversity (Shannon-Weaver) indices were also calculated.
Warming and snow experiment plant species composition data for Saddle snowfence, 1993 - 2000.
The International Tundra Experiment (ITEX) is a consortium of research sites seeking to understand the response of tundra plant populations to changes in growing season temperatures through a simple temperature manipulation and transplant experiment. The research goal is to examine the phenologic and reproductive responses of a set of species to experimentally-induced warming at a network of sites. The ITEX design is hierarchical, with sites participating at whatever level they are able. At the minimum, participation in ITEX requires climate monitoring (using the LTER MSR standards), a temperature manipulation using one of three possible designs, and monitoring phenologic and reproductive variables for at least one designated ITEX species or two other species. The temperature manipulation is achieved through use of conical or hexagonal open-top chambers of solar fiberglass, which have been shown to increase the air temperature at the surface approximately 3 degrees C. ITEX studies at Niwot Ridge, a logical outgrowth of the long-term phenology studies there, uses a factorial design based around the long-term snowfence experiment. Twenty cones are placed behind the snowfence, distributed at 10, 25, 45, and 75 m from the fence; each cone is paired with an adjacent plot. Beginning with the 1995 season, 24 additional plots were implemented outside of the snowfence influence. Twelve cones are distributed beyond both the north and south edges of the snowfence area, at 10, 25, 45, and 75 m behind the line of the snowfence; each cone is paired with an adjacent plot. This results in the following treatments: increased winter snow, increased summer temperature, increased snow and increased temperature, and control. Key phenologic, growth, and reproductive traits are being followed on marked individuals of Acomastylis (Geum) rossii and Bistorta (Polygonum) bistortoides, and complete species composition is being monitored. The point-quadrat technique used was identical to that d
Con-mod species composition in the Black Sand experiment for East Knoll, Audubon, Lefty, Soddie and Trough, 2019 - ongoing.
In the alpine tundra, shrubs modify wind distribution of snow, increasing snowpack on the leeward side of shrubs, and they provide shading, which modifies temperatures. In order to mimic these abiotic effect of shrubs, structures called connectivity modifiers, hereafter referred to as con-mods, were deployed in Black Band experiment plots in September 2018. Briefly, the Black Sand experiment was initiated in May 2018 to measure the effects of an extended growing season, by initiating earlier snow melt through the application of black sand, on plants and biogeochemistry. Together, this experimental framework allows us to ask how biotic effects influence climate exposure and ecological responsiveness.
Microscope-based phytoplankton community composition for Green Lake 4, 2000 - 2007.
These data represent phytoplankton community composition in Green Lake 4 observed during bi-weekly sampling events following ice-off during the 2000-2007 field seasons. Samples were collected from the deepest part of the lake using a Van Dorn sampler from depths of 0, 3, and 9 m. Samples from the inlet and outlet are grab samples. Phytoplankton samples were preserved in 1% Lugol’s solution. Cell counts for each taxonomic group were conducted using an inverted microscope with 1000x magnification. Taxonomic resolution was based on the imaging capabilities of the instrument and varies based on the size and distinguishing characteristics of the cells in a given taxonomic group. Please see details in Methods.
The Effect of Kangaroo-Rat Activity on Plant Species Composition at the Sevilleta National Wildlife Refuge, New Mexico (1999)
Our objective was to evaluate the effects of kangaroo rat mounds on species diversity and composition at a semiarid-arid grassland ecotone. We expected that source populations of plants occurring on kangaroo rat mounds have important influences on the species composition of vegetation at the landscape scale, and that these influences differ by grassland type. Our study was conducted at the Sevilleta LTER in New Mexico, where a grassland type dominated by Bouteloua gracilis, a shortgrass steppe species, and a grassland type dominated by B. eriopoda, a desert grassland species, meet to form patches across the landscape. Four 0.4 ha plots were sampled for species diversity and composition in a regular 7m x 7m grid in each grassland type. Kangaroo rat mounds were also mapped and sampled for vegetation measures in four areas of 1.6 ha in each type. The landscape scale abundance of many subordinate species was increased significantly by populations occurring on kangaroo rat mounds in both grassland types. However, the area affected by the burrowing activity of kangaroo rats was twice as large in the B. eriopoda dominated grassland type. Furthermore, dominant plants on mounds in the B. eriopoda type were also abundant in off-mound areas whereas dominant plants on mounds in the B. gracilis type were not as abundant off-mound. These results indicate that the presence of mounds in the B. gracilis dominated type is creating islands of plant communities that are distinct from the rest of the grassland. Therefore, the occurrence of certain plant species in this grassland type may be intimately associated with the disturbance regime at this ecotone. This study demonstrates that effects of small burrowing animals may facilitate the coexistence of species at this ecotone.
Livestock Exclosure Study: Plant Species Composition in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico (2004-2007)
Grazing in grasslands creates changes in plant community structure. The magnitude of these changes depends on the productivity and the intensity of grazing. Low productivity grasslands coupled with high grazing intensity may lead to shrub encroachment in some aridland ecosystems. We examined the effects of cattle grazing in arid grassland at the Sevilleta LTER site in central New Mexico USA where cattle were removed in 1973 and an area just north of the Sevilleta LTER where grazing by cattle still occurs. At each site we measured plant species composition and cover in permanent plots in the spring and fall from 2004 to 2007. Quadrats were clipped annually to quantify aboveground standing crop to answer the following questions: 1) Does cattle grazing affect plant species composition and standing crop? 2) Does grazing alter community response to inter-annual climate variability? and 3) How does grazing impact the abundance of native grasses?
South Bay, VA, seagrass sediment and autotroph source stable isotope compositions, 2014
Abstract text from Oreska et al. (2017): Non-seagrass sources account for 50% of the sediment organic carbon (SOC) in many seagrass beds, a fraction that may derive from external organic matter (OM) advected into the meadow and trapped by the seagrass canopy or produced in situ. If allochthonous carbon fluxes are responsible for the non-seagrass SOC in a given seagrass bed, this fraction should decrease with distance from the meadow perimeter. Identifying the spatial origin of SOC is important for closing seagrass carbon budgets and "blue carbon" offset-credit accounting, but studies have yet to quantify and map seagrass SOC stocks by carbon source. We measured sediment d13C, d15N, and d34S throughout a large (6 km2), restored Zostera marina (eelgrass) meadow and applied Bayesian mixing models to quantify total SOC contributions from possible autotroph sources, Z. marina, Spartina alterniflora, and benthic microalgae (BMA). Z. marina accounted for <40% of total meadow SOC, but we did not find evidence for outwelling from the fringing S. alterniflora salt-marsh or OM advection from bare subtidal areas. S. alterniflora SOC contributions averaged 10% at sites both inside and outside of the meadow. The BMA fraction accounted for 51% of total meadow SOC and was highest at sites furthest from the bare subtidal-meadow edge, indicative of in situ production.
Species composition and plant functional traits on Hog and Metompkin Islands, VA 2016-2017
Physical characteristics (soil salinity, elevation, distance from shoreline) and biological parameters (species composition, cover, biomass, and functional traits) were measured for plants on Hog Island (Northampton Co. VA) and Metompkin Island (Accomack County, VA). Physical parameters were measured during 2016. Plant biomass, species composition, percent cover, and functional traits were measured in 2017. Data Table 1: Environmental and geographic data on Hog and Metompkin Islands, VA 2016 Data Table 2: Species composition and aboveground plant functional traits on Hog and Metompkin Islands, VA 2017 Data Table 3: Vegetative biomass on Hog and Metompkin Islands, VA 2017 Data Table 4: Plot-level root functional traits on Hog and Metompkin Islands, VA 2017 Data Table 5: Latitude-longitude coordinates of plots on Hog and Metompkin Islands, VA 2016-2017
Settlement-Era Gridded Tree Composition, Northeastern US: Level 2
This is a data product of the estimated composition of tree taxa at the time of European and Euro-American settlement of the northeastern United States. Composition is defined as the proportion of stems larger than approximately 20 cm diameter at breast height in 22 taxonomic groupings, generally at the genus level. The data come from settlement survey records that provide raw data that are transcribed and then aggregated spatially, giving count data. The domain is divided into two regions, eastern (Maine to Ohio) and western (Indiana to Minnesota). Public Land Survey point data in the western region are aggregated to a regular 8 km grid, while data in the eastern region, from Town Proprietor Surveys, are aggregated at the township level in irregularly-shaped local administrative units. The product is based on a Bayesian statistical model fit to the count data that estimates composition on a regular 8 km grid. The statistical model allows us to estimate composition at locations with no data and to smooth over noise caused by limited counts in locations with data. Critically, it also allows us to quantify uncertainty in our composition estimates. We expect this data product to be useful for understanding the state of vegetation in the northeastern United States prior to large-scale European settlement. In addition to specific regional questions, the data product can also serve as a baseline against which to investigate how forests and ecosystems change after intensive settlement. This material is based upon work supported by the National Science Foundation under grants #DEB-1241874, 1241868, 1241870, 1241851, 1241891, 1241846, 1241856, 1241930.
Settlement-Era Gridded Tree Composition, Midwestern US: Level 1
Gridded forest composition data for Minnesota, Wisconsin, Michigan, and portions of Illinois and Indiana from survey notes from the Public Land Survey System (PLSS), prior to widespread land use conversion by EuroAmerican settlers. The Public Land Survey System in this region was carried out from approx. 1800 - 1904, in a time transgressive manner from east to west. Trees identified at section and quartersection points within the PLSS are aggregated to a regular 8km grid on a Great Lakes St. Lawrence Albers projection (EPSG:3175). For all points only the closest two trees are used in estimating composition and then summed within the 8km grid cell. The raw count of trees is reported, including "No trees" where surveyors found no trees within 300 links of the point. Methods and data are described in Goring et al., 2015 (http://biorxiv.org/content/early/2015/10/24/026575), except for data from Illinois and Indiana which are described in the methods below. This material is based upon work supported by the National Science Foundation under grants #DEB-1241874, 1241868, 1241870, 1241851, 1241891, 1241846, 1241856, 1241930.
STEPPS 2000 Year Forest Composition Estimates, Upper Midwest US, Level 2
Forest ecosystems in eastern North America have been in flux for the last several thousand years, well before Euro-American land clearance and the 20th-century onset of anthropogenic climate change. However, the magnitude and uncertainty of prehistoric vegetation change have been difficult to quantify because of the multiple ecological, dispersal, and sedimentary processes that govern the relationship between forest composition and fossil pollen assemblages. Here we extend STEPPS, a Bayesian hierarchical spatio-temporal pollen-vegetation model, to estimate changes in forest composition in the upper Midwestern United States from about 2,100 to 300 years ago. Using this approach, we find evidence for large changes in the relative abundance of some species, and significant changes in community composition. However, these changes took place against a regional background of changes that were small in magnitude or not statistically significant, suggesting complexity in the spatio-temporal patterns of forest dynamics. The single largest change is the infilling of Tsuga canadensis in northern Wisconsin over the past 2000 years. Despite range in-filling, the range limit of T. canadensis was largely stable, with modest expansion westward. The regional ecotone between temperate hardwood forests and northern mixed hardwood/conifer forests shifted southwestward by 15-20 km in Minnesota and northwestern Wisconsin. Fraxinus, Ulmus, and other mesic hardwoods expanded in the Big Woods region of southern Minnesota. The increasing density of paleoecological data networks and advances in statistical modeling approaches now enables the confident detection of subtle but significant changes in forest composition over the last 2,000 years.This material is based upon work supported by the National Science Foundation under grants #DEB-1241874, 1241868, 1241870, 1241851, 1241891, 1241846, 1241856, 1241930.
STEPPS 8000 Year Forest Composition Estimates, Northeastern US, Level 2
These reconstructions of forest composition in the northeastern US for the last 8,000 years help establish natural baselines, variability, and trajectories of forest dynamics before and during the emergence of intensive anthropogenic land use. These reconstructions are based on 1) the pollen–vegetation model (PVM) STEPPS, 2) a network of fossil and modern pollen data mostly drawn from the Neotoma Paleoecology Database (www.neotomadb.org), and 3) a vegetation calibration dataset based on a spatial statistical model of relative tree abundances from the Township Proprietor Survey (TPS) from the early EuroAmerican settlement period. STEPPS is a process-based Bayesian Hierarchical Model that is run in two stages: a parameterization stage based upon spatial data layers of forest composition and pollen assemblages, and a prediction stage based on fossil pollen assemblages. The statistical modeling of the TPS forest data and relative abundances is described by Paciorek et al. (2016, PLoS One, doi: 10.1371/journal.pone.0150087) and is available at EDI as PalEON Products msb.paleon.1 (doi: 10.6073/pasta/8544e091b64db26fdbbbafd0699fa4f9) and msb.paleon.4 (doi: 10.6073/pasta/3c4844cfe8beff6b173b62034d1cb5d8). The parameterization of STEPPS and comparison to REVEALS, a different widely used PVM, is described by Trachsel et al. (2020, Quaternary Research, doi:10.1017/qua.2019.81). Both PVMs predict the observed macroscale patterns of vegetation composition in the NEUS; however, reconstructions of minor taxa are less accurate and predictions for some taxa differ between PVMs. These differences can be attributed to intermodel differences in structure and parameter estimates. STEPPS parameter estimates are similar between the UMW and NEUS, suggesting that STEPPS parameter estimates are transferable between floristically similar regions and scales. The parameterized STEPPS model was then run for a network of fossil pollen records from the Neotoma Paleoecology Database to produce post
Arsenic adsorption modelling: TiO2, Fe2O3 and composite TiO2-Fe2O3 sorbents - detailed characterisation and adsorption data sets
<p>Raw data, example files and templates for the research paper provisionally titled 'Improved Accuracy in the Surface Complexation Modelling of Arsenic on Multicomponent Sorbents Using Low Energy Ion Scattering'</p> <p>Included is</p> <ul> <li>materials characterisation data (TiO2, Fe2O3 and a TiO2-Fe2O3 composite)</li> <li>arsenic(III) and arsenic(V) adsorption data (both adsorption isotherms and pH adsorption edges)</li> <li>potentiometric titration data</li> <li>templates for preparing FITEQL input files from titration data and pH adsorption edges</li> <li>examples of FITEQL input and output files</li> </ul> <p>Characterisation techniques used include BET, XRD, FTIR, zeta potential, DLS, low energy ion scattering (LEIS), XPS and XRF. Data was primarily collected by Jay Bullen between 2016 and 2019, with assistance from named collaborators.</p>
Figure 5 in Winter species composition, diversity and abundance of macrozoobenthos in Kuwait's waters, Arabian Gulf
Figure 5. Changes in the abundance A and the number of species B in relevance with depth.
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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.