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138 results for “Northwest Territories”
Terrestrial lichen data for Northwest Territories, Canada
<p>Increased fire activity due to climate change may impact the successional dynamics of boreal forests, with important consequences for caribou habitat. Early successional forests have been shown to support lower quantities of caribou forage lichens, but geographic variation in, and controls on, the rates of lichen recovery have been largely unexplored. In this study, we sampled across a broad region in northwestern Canada to compare lichen biomass accumulation in ecoprovinces, including the Saskatchewan Boreal Shield, the Northwest Territories Taiga Shield and Northwest Territories Taiga Plains, divided into North and South. We focused on the most valuable <i>Cladonia</i> species for boreal and barren ground caribou: <i>Cladonia mitis</i> and <i>C. arbuscula</i>, <i>C. rangiferina</i> and <i>C. stygia</i>, <i>C. stellaris</i> and <i>C. uncialis</i>. We developed new allometric equations to estimate lichen biomass from field measurements of lichen cover and height; allometries were consistent among ecoprovinces, suggesting generalizability. We then used estimates of lichen biomass to quantify patterns of lichen recovery in different stand types, ecoprovinces, and with time following stand-replacing fire. We used a hurdle model to account both for the heterogeneous nature of lichen presence (zero-inflation), and the range of abundance in stands where lichen was present. The first component of the hurdle model, a generalized linear model (GLM), identified stand age, stand type and ecoprovince as significant predictors of lichen presence. With a logistic growth model, a measure of lichen recovery (time to 50% asymptotic value) varied from 28 to 73 years, dependent on stand type and ecoprovince. The combined predictions of the hurdle model suggest the most rapid recovery of lichen biomass across our study region occurred in jack pine in the Boreal Shield (30 years), while stands located in the Taiga Plains (North and South) required a longer recovery period (approximately 75 years). These results provide a basis for estimating future caribou habitat that encompasses some of the large variation in fire effects on lichen abundance and vegetation types across the range of boreal and barren ground caribou in North America.</p>
Reproductive maturity in boreal trees, Northwest Territories, Canada
<p>In boreal North America, much of the landscape is covered by fire-adapted forests dominated by serotinous conifers. For these forests, reductions in fire return interval could limit reproductive success, owing to insufficient time for stands to reach reproductive maturity i.e., to initiate cone production. Improved understanding of the drivers of reproductive maturity can provide important information about the capacity of these forests to self-replace following fire. Here, we assessed the drivers of reproductive maturity in two dominant and widespread conifers, semi-serotinous black spruce and serotinous jack pine. Presence or absence of female cones were recorded in approximately 15,000 individuals within old and recently burned stands in two distinct ecozones of the Northwest Territories (NWT), Canada. Our results show that reproductive maturity was triggered by a minimum tree size threshold rather than an age threshold, with trees reaching reproductive maturity at smaller sizes where environmental conditions were more stressful. The number of reproductive trees per plot increased with stem density, basal area, and at higher latitudes (colder locations). The harsh climatic conditions present at these higher latitudes, however, limited the recruitment of jack pine at the treeline ecotone. The number of reproductive black spruce trees increased with deeper soils, whereas the number of reproductive jack pine trees increased where soils were shallower. We examined the reproductive efficiency i.e., the number of seedlings recruited per reproductive tree, linking pre-fire reproductive maturity of recently burned stands and post-fire seedling recruitment (recorded up to 4 years after the fires) and found that a reproductive jack pine can recruit on average three times more seedlings than a reproductive black spruce. We suggest that the higher reproductive efficiency of jack pine can explain the greater resilience of this species to wildfire compared with black spruce. Overall, these results help link life history characteristics such as reproductive maturity to variation in post-fire recruitment of dominant serotinous conifers.</p>
Reproductive maturity in boreal trees, Northwest Territories, Canada
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Terrestrial lichen data for Northwest Territories, Canada
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Trophic structure and mercury transfer in the subarctic fish community of Great Slave Lake, Northwest Territories, Canada
<p>In recent decades, mercury concentrations have increased in fish of Great Slave Lake (GSL), a subarctic great lake in northern Canada with important recreational, subsistence, and commercial fisheries. This study characterized habitat use and trophic position of common fish species in GSL near the City of Yellowknife (Northwest Territories, Canada), measured mercury concentrations in water and in taxa from lower trophic levels of the food web, and examined trophic and biological influences on mercury concentrations within and among fish species. Northern pike (<i>Exos lucius</i>) and lake whitefish (<i>Coregonus clupeformis</i>) fed predominantly nearshore, cisco (<i>Coregonus artedi</i>) and longnose sucker (<i>Catostomus catostomus</i>) fed predominantly offshore, and burbot (<i>Lota lota</i>) fed roughly equally in both habitats. Habitat-specific feeding did not influence mercury bioaccumulation in fish, in contrast with published studies of smaller lakes. Water concentrations of total mercury and methylmercury were low and showed little spatial variation among sites or depths. Zooplankton (>200 µm) had similarly low methylmercury concentrations to littoral and profundal amphipods, suggesting little habitat-variation of mercury exposure near the base of the food web. Age, size, and trophic position were significant explanatory variables for muscle total mercury concentrations within populations of fish species. Among fish species, size and trophic position explained 80% of the variation in muscle total mercury concentrations. This study generated the most comprehensive dataset to date on mercury bioaccumulation in the food web of GSL, which will serve as a baseline for future studies of this great lake.</p>
Vascular plant community data for Northwest Territories, Canada
<p><span><span>Climate change is altering disturbance regimes outside of historical norms, which can impact biodiversity by selecting for plants with particular traits. The relative impact of disturbance characteristics on plant traits and community structure may be mediated by environmental gradients. We aimed to understand how wildfire impacted understory plant communities and plant regeneration strategies along gradients of environmental conditions and wildfire characteristics in boreal forests. We established 207 plots (60m<sup>2</sup>) in recently burned stands and 133 plots in mature stands with no recent fire history in comparable gradients of stand type, site moisture (drainage), and soil organic layer (SOL) depth in two ecozones in Canada's Northwest Territories. <a name="_Hlk43198784">At each plot, we recorded all vascular plant taxa in the understory</a> and measured the regeneration strategy (seeder, resprouter, survivor) in burned plots, along with seedbed conditions (mineral soil and bryophyte cover). Dispersal, longevity, and growth form traits were determined for each taxon. Fire characteristics measured included proportion pre-fire SOL combusted (fire severity), date of burn (fire seasonality), and pre-fire stand age (time following fire). Results showed understory community composition was altered by fire. However, burned and mature stands had similar plant communities in wet sites with deep SOL. In the burned plots, regeneration strategies were determined by fire severity, drainage, and pre- and post-fire SOL depth. Resprouters were more common in wet sites with deeper SOL and lower fire severity, while seeders were associated with drier sites with thinner SOL and greater fire severity. This led to drier burned stands being compositionally different from their mature counterparts and seedbed conditions were important. Our study highlights the importance of environment-wildfire interactions in shaping plant regeneration strategies and patterns of understory plant community structure across landscapes, and the overriding importance of SOL depth and site drainage in mediating fire severity, plant regeneration, and community structure.</span></span></p> <p> </p>
Littoral macroinvertebrate and water quality data for 32 lakes across the boreal-tundra transition in the Northwest Territories
<p>This dataset includes macroinvertebrate and water quality data from 32 lakes sampled in the Northwest Territories, Canada, from the Dempster and Inuvik-Tuktoyaktuk Highways during July and August of 2017 and 2018. It was collected as part of a project to determine how physicochemical variables affect macroinvertebrate and fish communities in small Arctic lakes.</p>
Zooplankton and water quality data for 37 lakes in the Gwich'in and Inuvialuit regions of the Northwest Territories
<p>This dataset includes zooplankton and water quality data from 37 lakes sampled in the Northwest Territories, Canada, from the Dempster and Inuvik-Tuktoyaktuk Highways during July and August of 2017 and 2018. It was collected as part of a project to determine how physicochemical variables affect zooplankton and fish communities in small Arctic lakes.</p>
Repeated measure plant community data after fire in boreal forest, Taiga Shield, Northwest Territories, Canada, 1998-2018
<p>10 transects were established in the years following fire in boreal forest stands on the Taiga Shield, Northwest Territories, Canada in 1998-1999. These were remeasured annually. Six transects were returned to on 2018 for another measurement. At each measurement, we recorded ground covers, species identities, and counted tree stems (seedlings).</p>
Black spruce seed availability and viability after fire, Northwest Territories, Canada
<p>Context : Black spruce ( Picea mariana ) is an important conifer in boreal North American that develops a semi-serotinous, aerial seedbank and releases a pulse of seeds after fire. Variation in post-fire seed rain has important consequences for black spruce regeneration and stand composition.</p> <p>Aims : We explore the possible effects of changes in fire regime on the abundance and viability of black spruce seeds following a very large wildfire season in the Northwest Territories, Canada (NWT).</p> <p>Methods: We measured post-fire seed rain over two years at 25 black sprucedominated sites and evaluated drivers of stand characteristics and environmental conditions on total black spruce seed rain and viability.</p> <p>Results : We found a positive relationship between black spruce basal area and total seed rain. However, at high basal areas this increasing rate of seed rain was not maintained. Viable seed rain was greater in stands that were older, closer to unburned edges, and where canopy combustion was less severe. Finally, we demonstrated positive relationships between seed rain and seedling establishment, confirming our measures of seed rain were key drivers of post-fire forest regeneration.</p> <p>Conclusion: These results suggest that black spruce recruitment after fire may be reduced with projected increases in fire activity.</p>
Littoral macroinvertebrate and water quality data for 32 lakes across the boreal-tundra transition in the Northwest Territories
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Trophic structure and mercury transfer in the subarctic fish community of Great Slave Lake, Northwest Territories, Canada
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Vascular plant community data for Northwest Territories, Canada
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Repeated measure plant community data after fire in boreal forest, Taiga Shield, Northwest Territories, Canada, 1998-2018
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Zooplankton and water quality data for 37 lakes in the Gwich'in and Inuvialuit regions of the Northwest Territories
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Black spruce seed availability and viability after fire, Northwest Territories, Canada
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Data from: Paleolimnological assessment of wildfire-derived atmospheric deposition of trace metal(loid)s and major ions to subarctic lakes (Northwest Territories, Canada)
<p>Wildfires release terrestrial elements to the atmosphere as aerosols, and these events are becoming more frequent and intense in the Arctic boreal forest as the climate is warming. We quantified the impact of atmospheric deposition of aerosols from local wildfires on metal(loid) fluxes using macroscopic charcoal accumulation rates, historical fire mapping, and element concentrations in <sup>210</sup>Pb‐dated lake sediment from five subarctic lakes with small catchments. Lake sediments showed small but significant increases in fluxes (median = 5–10%) for 22 trace metals, metalloids, or major ions following fire events. The impact of wildfire aerosols on element fluxes was mostly due to short‐term (≤2 years) increasing sedimentation rate (6 ± 41% increase), whereas sediment element concentrations were not strongly impacted. Wildfire‐associated deposition to lake sediments was mainly composed of Ca, Al, Fe, Mg, K, Mn, and Na, which are major constituents of ash from burned biomass, but changes in sediment flux were greatest for Sb, As, Ni, Ba, Mn, Mo, and Sr compared to pre‐disturbance conditions. Compared to anthropogenic sources of pollution, wildfire‐associated atmospheric fluxes of metal contaminants to the lakes (e.g., Hg, Pb, As, Sb, and Cd) were low. This study provides quantitative estimates of wildfire impacts on atmospheric geochemical fluxes to subarctic lakes, which can be used for modeling larger‐scale impacts under changing fire regimes.</p>
FIGURE 8 in New olenelline trilobites from the Northwest Territories, Canada, and the phylogenetic placement of Judomia absita Fritz, 1973
FIGURE 8. The strict consensus of three most parsimonious trees of length 198 steps produced from analysis of character data in Table 1 using PAUP 4.0 (Swofford 1998). Cladogram constructed using a heuristic search with a stepwise addition sequence and 100 random replications. Bremer, bootstrap (>50%), and jackknife (>50%) support values, respectively, are given on the tree. All characters were treated as unordered. The retention index is 0.54, and the consistency index (when uninformative characters are excluded) is 0.40. Total tree support (Bremer, 1994) is at least 0.07.
FIGURE 7. Judomia absita Fritz, 1973, 1—KUMIP 320714, X3.4 in New olenelline trilobites from the Northwest Territories, Canada, and the phylogenetic placement of Judomia absita Fritz, 1973
FIGURE 7. Judomia absita Fritz, 1973, 1—KUMIP 320714, X3.4; 2—PWNHC-2009.20.23, X4.4; 3—PWNHC-2009.20.24, X3.6; 4—KUMIP 320715, X4.2; 5—KUMIP 320716, X5.3; 6—PWNHC-2009.20.25, X4.2.
FIGURE 6 in New olenelline trilobites from the Northwest Territories, Canada, and the phylogenetic placement of Judomia absita Fritz, 1973
FIGURE 6. Nevadia saupeae sp. nov., 1,2—holotype KUMIP 320711 (latex cast); 1, X0.6. Arrow indicates detached rostral plate; 2— detail of hypostome, X8.8; 4—paratype PWNHC-2009.20.21, X1.0;?Nevadia ovalis McMenamin, 1987, 3— KUMIP 320713 (latex cast), X4.1; 5—KUMIP 320712, X7.6; 6—PWNHC-2009.20.22, X6.5.
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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)
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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.