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913 results for “Niwot Ridge”
Pika habitat occupancy survey data for Niwot Ridge and Green Lakes Valley, 2016 - ongoing
Long-term monitoring of habitat occupancy can reveal patterns of habitat use, population dynamics, and factors controlling species distribution. The American pika (Ochotona princeps), a small mammal found in rocky habitats throughout western North America, has been targeted for occupancy studies due to its relatively conspicuous behavior and its unusual adaptations for surviving long, cold winters without hibernation. These adaptations include an unusually high resting metabolic rate and maintenance of body temperatures near the lethal maximum for this species, which would appear to compromise the pika's ability to survive warmer summers. Recent monitoring as well as projections based on future climate scenarios have suggested this species is experiencing a period of range retraction due to warming summers and/or loss of insulating winter snow cover. Niwot Ridge is situated ideally to test competing hypotheses about the trajectory and drivers of pika range shift. The pika is still common throughout the Colorado Rockies, but published models differ markedly regarding projections of the pika’s future distribution in this region. Niwot Ridge has experienced warmer summers as well as shorter periods of insulating snow cover in recent years, and there is evidence that pikas are now less common than they once were in at least one area on the ridge. This study is designed to provide robust data on pika population trends through long-term monitoring of occupancy in a spatially balanced random sample of pika habitat patches centered on Niwot Ridge. Survey plots (n = 72) were selected according to a Generalized Random-Tessellation Stratified (GRTS) algorithm, stratified dichotomously by elevation, average annual snow accumulation (SWE), and probabilities of pika occurrence based on previous data. Each plot extends 12 m in radius from a GRTS point. To ensure that each plot contains at least 10% cover of talus, plot coordinates were adjusted (usually less than 50 m) or replaced
Snowbed experiment species composition and hobo data for Niwot Ridge, 2012 - ongoing.
Niwot Ridge climate records indicate a trend of warmer spring and summer temperatures and earlier timing of snowmelt. In alpine tundra plant communities where snow cover limits growing season length, the current climatic trend is conducive to a longer growing season. The snowbed experiment was established in order to monitor changes in plant cover and community composition in the alpine tundra in response to extended summer growing season conditions. Of particular interest are late-melting snowbed areas where plant colonization and survival are most restricted or entirely prevented by a limited number of snow-free days with the sunlight and temperature necessary for plant establishment and growth. In 2012, fifteen 1 x 1 m plots were established at 5 sites where there are persistent, late-melting snowbeds. Plots were placed along (1) an elevation gradient and (2) a snow-cover gradient from persistent snowbeds, where snowpack is greatest and melt-out dates latest in the season, to wind-scoured dry meadows, where snow pack is least and melt-out dates earliest. In 2015 the one site was dropped from the experiment because the snowbed there was quite different from the other four.
Mercury in soil, vegetation, and organisms across Niwot Ridge, Saddle Catchment, and Green Lakes Valley, 2020 - 2023.
This dataset includes soil, vegetation, water, atmospheric deposition, litterfall, incubation, and organism data from the Niwot Ridge, Saddle Catchment, and Green Lakes Valley collected during 2020 and 2021 to investigate the storage, transformation, and mobilization of mercury in the Colorado Rocky Mountains. During Summer 2020, we collected soil cores (10cm x 3cm) across vegetation plant functional groups in wet meadows, moist meadows, dry meadows, krummholz, subalpine forest, shrub areas, as well as at the inlet and outlet of the Green Lakes in Green Lakes Valley. At each of these sites, we collected leaves from forbs, graminoids, and shrubs, as well as litter (and moss if present). For organisms, we sampled pika hairs from nine different pika trapped on the West Knoll, in addition to caddisfly pupae found in wet meadows in the Saddle Catchment. We analyzed hairs from weasel specimens at the CU Boulder Natural History Museum that were trapped either on, or near, Niwot Ridge. Finally, we analyzed dust samples collected by Dr. Ruth Heindel in 2018 and 2019 on Niwot Ridge. We analyzed soil samples for organic matter; pH; water content; percent carbon, nitrogen, and sulfur; stable carbon, nitrogen, and sulfur isotopes; total mercury; and methylmercury. We analyzed vegetation samples for percent carbon, nitrogen, and sulfur; stable carbon, nitrogen, and sulfur isotopes; total mercury; and methylmercury. We analyzed organism and dust samples for total mercury and methylmercury. During Spring 2021, we collected composite snow cores from 4 sites in the Saddle region and 3 sites in the subalpine forest. We measured snow depth and density to calculate snow water equivalent and then analyzed these samples for sulfate, nitrate, chloride, dissolved organic carbon, dissolved organic nitrogen, total mercury, and methylmercury concentrations. During Summer 2021, we collected soil cores (10cm x 3cm) every other week from June through September from a solifluction lobe, alpine wet
Plant species list for Niwot Ridge and Green Lakes Valley, 1970 - ongoing.
A plant species list was created for Niwot Ridge and Green Lakes Valley from species identified in those areas by NWT scientists, working primarily at the Saddle and Martinelli sites. Additions to this list included species identified by Komarkova (1979) in the Indian Peaks Wilderness area but not on Niwot Ridge or in the Green Lakes Valley because of the likelihood that those species might exist within the LTER research area. Additions to the list were also provided by Terry Theodose, Leeanne Lestak, Teresa Nettleton, Susan Sherrod, Laura Mujica-Crapanzano (2004), Hope Humphries (2006), and Jane G. Smith (2019-2025). The list was revised to remove duplicate entries, correct typos, and resolve synonymy problems. Species and non-species categories received USDA PLANTS database names and codes.
Subalpine tree seed availability and germination at Niwot Ridge, 2015 - ongoing.
These data were collected to assess how seed availability and site limitations affect conifer germination across species distributions. Our study focused on areas above alpine treeline where subalpine tree species must migrate to track movement of suitable climate, but we also included sites in the core and at the lower ecotone of subalpine forests. We monitored seed availability and germination of new seedlings for four subalpine tree species from 2015-present at Niwot Ridge, Colorado, USA. Seed availability was collected in 66-95 seed traps in 14-17 sites (6-12 traps per site; see data for count per site), depending on year. In the lab, seeds were counted by species. In the field, new germinants were counted by species 3-5 weeks after snow disappearance (i.e., peak germination) and again in late September from 2015 to 2018 only. Only one census of new germinants was conducted from 2019 to 2023. New germinants from prior years were censused in subsequent summers.
Small mammal species composition data for Niwot Ridge, 1981 - 1990.
Small mammals were live trapped during the summer of each year at various locations on Niwot Ridge. Species trapped included pikas (Ochotona princeps), marmots (Marmota flaviventris), deer mice (Peromyscus maniculatus), voles (Microtus longicaudus, Microtus montanus, and Phenacomys intermedius), and pocket gophers (Thomomys talpoides). Pocket gophers were only trapped through the summer of 1983. Mice and voles were trapped using Sherman traps, while Tomahawk traps were used to trap both the pikas and marmots. Sherman gopher traps were used to trap gophers. The mice and vole traps were placed 10 meters apart in parallel rows in grids containing from 25 to 100 traps; weather permitting, these traps were placed for 3 consecutive nights every 1 or 2 weeks from June to August. The pikas, marmots, and gophers were trapped during late summer of each year; consult Halfpenny et al. (1984; 1987) for a general description of these trap locations, as well as descriptions of baiting and handling techniques and surrounding vegetation communities. Pika and marmot traps were selectively placed in areas where evidence of these animals existed. In the case of the pocket gophers, traps were placed below ground in active mounds. For pikas, marmots and pocket gophers, traps were set during the day and were checked every 2 hours. After determining and recording species, sex, age, reproductive status, weight, health, and trap location, trapped animals were permanently tagged and released. An additional quality-controlled, derived data-table (pikas_no_recap.cr.data.csv) was added to the original dataset in 2022. This data table is derived from the original capture data, but includes only year-unique captures, where each year-unique capture is the "best" one for comparison with other year-unique captures. For comparability among years, the best capture for comparability among years is usually the first capture of the year, representing the animal's baseline weight for the year (weight appea
Snow water equivalent data for Niwot Ridge and Green Lakes Valley, 1993 - ongoing.
Snow pits were excavated at various locations on Niwot Ridge and within the Green Lakes Valley. Temperature and snow density were measured at various depths throughout the snow cover profiles to characterize the temperature and snow water equivalent (SWE) of the snowpack throughout the year. Snow density was measured at 10-cm intervals using a 1000-ml cutter. This dataset contains derived values of SWE from snow profile measurements.
Snow grain data for Niwot Ridge and Green Lakes Valley, 1995 - ongoing.
Snow pits were excavated at various locations on Niwot Ridge and within the Green Lakes Valley. Temperature and snow density were measured at various depths throughout the snow cover profiles to characterize the temperature and snow water equivalent (SWE) of the snowpack throughout the year. Snow density was measured at 10-cm intervals using a 1000-ml cutter. Data on snow grain qualities were collected beginning in the 1994-95 snow season.
Snow cover profile data for Niwot Ridge and Green Lakes Valley, 1993 - ongoing.
Snow pits were excavated at various locations on Niwot Ridge and within the Green Lakes Valley. Temperature and snow density were measured at various depths throughout the snow cover profiles to characterize the temperature and snow water equivalent (SWE) of the snowpack throughout the year. Snow density was measured at 10-cm intervals using a 1000-ml cutter. Data on snow grain qualities were collected beginning in the 1994-95 snow season.
Soil nitrous oxide and carbon dioxide concentration data for Niwot Ridge and Loch Vale watershed, 1994.
Concentrations of carbon dioxide and nitrous oxide from snow-covered alpine soil surfaces were measured at Niwot Ridge. Six sites characterized by relatively shallow snowpacks were sampled in 1993. A total of 27 sites were sampled in 1994. Nine of the 1994 sites were located in the naturally shallow snowfield sampled in 1993, 9 sites were located in a formerly shallow snowpack site where snow depth was augmented by the construction of a 2.8-m high, 60-m long snowfence, and the 9 remaining sites were located in a naturally deep snowpack. Concentrations of N2O and CO2 at the soil surface were measured monthly from January until March, biweekly through April, and weekly until snowmelt was complete. Elevated levels of CO2 under the snowpack, suggesting microbial activity, were first observed under the shallow snowpacks in early March of 1993. N2O production under snow was first observed in April 1993, when soil temperatures had warmed above -3 degrees C. In 1994 shallow snowpack sites exhibited diminished and sporadic production of both CO2 and N2O, apparently due to the inconsistent snow cover compared to 1993. The snowfence sites exhibited elevated CO2 and N2O levels beginning in February 1994. Both CO2 and N2O fluxes from the snowfence site were similar to those measured under the naturally deep snowpack. These data suggest that the timing and depth of snow cover during the alpine winter control microbial activity by insulating soils from extreme air temperatures. To obtain a regional perspective on subnivean trace gas fluxes, both CO2 and N2O samples were determined at sites below treeline on Niwot Ridge and at Loch Vale in Rocky Mountain National Park.
Soil nitrous oxide and carbon dioxide flux data for Niwot Ridge and Loch Vale watershed, 1994.
Fluxes of carbon dioxide and nitrous oxide from snow-covered alpine soils were measured at Niwot Ridge. Six sites characterized by relatively shallow snowpacks were sampled in 1993. A total of 27 sites were sampled in 1994. Nine of the 1994 sites were located in the naturally shallow snowfield sampled in 1993, 9 sites were located in a formerly shallow snowpack site where snow depth was augmented by the construction of a 2.8-m high, 60-m long snowfence, and the 9 remaining sites were located in a naturally deep snowpack. Concentrations of N2O and CO2 at the soil surface were measured monthly from January until March, biweekly through April, and weekly until snowmelt was complete. Elevated levels of CO2 under the snowpack, suggesting microbial activity, were first observed under the shallow snowpacks in early March of 1993. N2O production under snow was first observed in April 1993, when soil temperatures had warmed above -3 degrees C. In 1994 shallow snowpack sites exhibited diminished and sporadic production of both CO2 and N2O, apparently due to the inconsistent snow cover compared to 1993. The snowfence sites exhibited increased CO2 and N2O fluxes beginning in February 1994. Both CO2 and N2O fluxes from the snowfence site were similar to those measured under the naturally deep snowpack. These data suggest that the timing and depth of snow cover during the alpine winter control microbial activity by insulating soils from extreme air temperatures. To obtain a regional perspective on subnivean trace gas fluxes, both CO2 and N2O samples were determined at sites below treeline on Niwot Ridge and at Loch Vale in Rocky Mountain National Park.
Tree ring data from the Niwot Ridge subalpine zone, 2017 - 2018.
Tree cores were collected across a range of diverse stand types and topographic positions in 2017 and 2018 to examine changes in tree growth as a response to changing climate in the subalpine forest of the Colorado Front Range, USA. Tree cores were collected for all present species in the subalpine zones; Engelmann spruce (Picea engelmannii), subalpine fir (Abies lasiocarpa), lodgepole pine (Pinus contorta) and limber pine (Pinus flexilis). We extracted core from ~180 trees from 3 large permanent plots across a range of species and sizes classes within each plot. The cores were then processed using WinDENDRO software. This dataset includes field data taken on each tree from which a core was extracted, the original WinDENDRO files for each coree.g. bark thickness, height, etc.), 2) MRS4 .txt fil output from WinDENDRO, 3) MRS5 .txt fil output from WinDENDRO, 4) MRS7.txt fil output from WinDENDRO, The WinDENDRO, outputs will be used to reconstruct a time series of radial growth for each tree in each plot to examine whether the topoclimatic position affects tree growth (by species and stand types) and whether tree growth has changed with warming temperatures.
25-meter elevation lattice grid, Niwot Ridge LTER Project Area, Colorado
25-meter lattice made from the Niwot Ridge LTER TIN model (ltertin). This dataset was made to support hierarchical GIS databases at the Niwot Ridge LTER. Additional information concerning the Niwot Ridge LTER hierarchical GIS can be found in Walker et al. (1993).
3.23-meter elevation lattice grid, Martinelli Snowfield, Niwot Ridge LTER, Colorado
Martinelli snow field lattice. This dataset is part of the Martinelli grid geographic information system (GIS). Additional information concerning the Niwot Ridge LTER hierarchical GIS can be found in Walker et al. (1993).
1-meter elevation lattice grid, Martinelli Snowfield, Niwot Ridge LTER, Colorado
Resampled version of Martinelli snow field lattice grid (martlat) with finer resolution. This dataset is part of the Martinelli grid geographic information system (GIS). Additional information concerning the Niwot Ridge LTER hierarchical GIS can be found in Walker et al. (1993).
5-meter elevation contours, Martinelli Snowfield, Niwot Ridge LTER, Colorado
Martinelli snow field contour lines. This dataset is part of the Martinelli grid geographic information system (GIS). Additional information concerning the Niwot Ridge LTER hierarchical GIS can be found in Walker et al. (1993).
Annual snow survey, Green Lakes Valley, Niwot Ridge, Colorado, 2013 - ongoing.
Yearly snow surveys were conducted in the Green Lakes Valley in the City of Boulder Watershed at the estimated peak of snowpack in late spring. Over a period of several days, surveying teams (1 to several people) traversed valley slopes measuring snow depth with avalanche probes. Locations of each depth measurement were recorded as waypoints in Garmin hand-held GPS units. Snow depths were recorded on standardized field sheets along with dates, recorder names, waypoint numbers, and comments.
Multi-year measurements of tree motion from an accelerometer on a spruce tree near Niwot Ridge, Colorado
<p>This repository includes 12 Hz three-axis acceleration data from an accelerometer mounted to the bole of a <em>Picea engelmannii</em> (engelmann spruce) next to the C-1 Ameriflux tower at Niwot Ridge LTER, Colorado, USA. The data were recorded from November 2014 through August 2020. More information on the installation can be found in Raleigh et al. (in review, Water Resources Research).</p> <p>The data are stored in netCDF files, chunked based on the collection date when the data were downloaded from the accelerometer.</p> <p><strong>File metadata:</strong></p> <p>Filename</p> <p>GCDC_L01_Raw_Data_Niwot_TreeXX_collection_YYYYMMDD.nc</p> <p>where</p> <p>XX = tree number (01 = spruce, 02 = fir)</p> <p>YYYYMMDD = year (YYYY), month (MM), and day (DD) of data collection</p> <p> </p> <p>Each netCDF includes four variables:</p> <p>1. serial_date = time increment (fractional days), as defined by Matlab: "A serial date number represents the whole and fractional number of days from a fixed, preset date (January 0, 0000) in the proleptic ISO calendar." The serial dates are in mountain standard time (MST) with no adjustments for daylight savings.</p> <p>2. Ax = acceleration in the vertical direction (counts)</p> <p>3. Ay = acceleration in the east-west direction (counts)</p> <p>4. Az = acceleration in the north-south direction (counts)</p> <p>To convert the "counts" unit to gravitational units (g), divide Ax, Ay, and Az each by 2048, as explained in the manufacturer's user manual.</p> <p> </p> <p> </p>
Multi-year measurements of tree motion from an accelerometer on a fir tree near Niwot Ridge, Colorado
<p>This repository includes 12 Hz three-axis acceleration data from an accelerometer mounted to the bole of an <em>Abies lasiocarpa</em> (subalpine fir) next to the C-1 Ameriflux tower at Niwot Ridge LTER, Colorado, USA. The data were recorded from November 2014 through August 2020. More information on the installation can be found in Raleigh et al. (in review, Water Resources Research).</p> <p>The data are stored in netCDF files, chunked based on the collection date when the data were downloaded from the accelerometer.</p> <p><strong>File metadata:</strong></p> <p>Filename</p> <p>GCDC_L01_Raw_Data_Niwot_TreeXX_collection_YYYYMMDD.nc</p> <p>where</p> <p>XX = tree number (01 = spruce, 02 = fir)</p> <p>YYYYMMDD = year (YYYY), month (MM), and day (DD) of data collection</p> <p> </p> <p>Each netCDF includes four variables:</p> <p>1. serial_date = time increment (fractional days), as defined by Matlab: "A serial date number represents the whole and fractional number of days from a fixed, preset date (January 0, 0000) in the proleptic ISO calendar." The serial dates are in mountain standard time (MST) with no adjustments for daylight savings.</p> <p>2. Ax = acceleration in the vertical direction (counts)</p> <p>3. Ay = acceleration in the east-west direction (counts)</p> <p>4. Az = acceleration in the north-south direction (counts)</p> <p>To convert the "counts" unit to gravitational units (g), divide Ax, Ay, and Az each by 2048, as explained in the manufacturer's user manual.</p> <p> </p>
Ground water well elevation for Niwot Ridge Saddle, 2012 - 2018.
Water level of Saddle Ground Water Wells. Ground Water Well locations, depths, and design were determined by Niwot Ridge LTER lead researchers, Mark Williams and Nel Caine, to monitor groundwater chemistry and water levels. Well locations were selected based on proximity to the headwater region of the Saddle stream channel. Ground Water Wells are located along an east-west transect at the Saddle site, each pair consisting of a deep well to a depth between 6.3 and 8.8 m, and a shallow well to a depth of 1.5 m. Ground surface elevations at the Saddle wells range from about 3522 m at the eastern wells to 3532 m at the western wells. The transect is roughly 170 m from east to west, has an average slope of 0.06, and is perpendicular to the Saddle stream. Saddle pair 3 was installed very close to the channel. Saddle pairs 2 and 4 were installed on opposite sides of the channel. Saddle pair 1 was installed furthest from the channel (King, 2012). Ground water wells were installed in October 2005 by Bandimere Geothermal Drilling Systems. Wells are cased with 2-inch nominal pipe size, Schedule 40 polyvinyl chloride (PVC), flush-threaded pipe. Well screens were constructed from 0.020-inch continuous slot PVC and installed in 5-ft (1.52 m) intervals. All of the wells have 1.52 m screens at the bottom of the well. The bottoms of the wells were capped with a PVC flush-threaded point cap. The annular space around each screen and pipe was backfilled with #10-20 silica sand to act as a filter (King, 2012). The Niwot Ridge LTER monitoring of these Ground Water Wells has varied over the years since the wells were installed. Prior to 2014, all wells were sampled weekly in summer and monthly in winter for chemistry, and alternating wells were monitored for water level with pressure transducers and a weighted tape measure. From 2015 through present, Saddle Deep 3 (SD3) and Saddle Deep 4 (SD4)- those located closest to the Saddle Stream headwaters- are being monitored for water level, wat
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