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Climate Change

Ground truthing
Robert Fisher and Stacey Hathaway (ARMI) ground-truthing potential desert-frog breeding sites selected using remote sensing of soil characteristics derived from known breeding site. Photo by: C. Schwalbe.

Freshwater wetlands provide critical habitat for a diverse array of organisms including many amphibians. Yet, under the continued impacts of water diversions and the newer threats of climate change, these habitats are among the most imperiled ecosystems on Earth. Climate change has the potential to alter many sources of water critical to the habitats amphibians need, especially those associated with breeding and development. Potential changes include: change in timing and availability of water from glacier melt, snow and rain timing and amount; persistence of vernal pools and seasonal wetlands; altered evapotranspiration rates; and reduced stream flows and groundwater recharge rates.

Other ecosystem components likely to change in response to climate change include the timing and frequency of fires, the spread of invasive plants and animals, and microclimates in which the animals live.

ARMI Products on Climate Change

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This is an ARMI Product. Timing of first and last calls and median calling peaks for Pseudacris crucifer, and of the first call for Hyla chrysoscelis/versicolor, at six wetlands in the St. Croix National Scenic Riverway from 2008-2012
Authors: Sadinski W, Roth M | Date: 2018-09-06 | Outlet: U.S. Geological Survey data release,
To better understand relations of annual calling phenophases for Pseudacris crucifer, and of the first calls of the season for Hyla chrysoscelis/versicolor, to the timing of the start of the calling season, we compared these dynamics for six wetlands in the St. Croix National Scenic Riverway from 2008 to 2012. We installed an acoustic recorder at each site prior to the start of each calling season and programmed it to record for five minutes at the top of every hour until late summer. We then used the Songscape option in Songscope software to generate annual summaries of all acoustic files recorded at each site. We created contour plots of the summarized median dB values across bandwidths in each recording and then assessed individual calls and calling peaks by visually examining these plots to identify first (and last) calls via the unique call signatures for these two species. We examined individual five-minute recordings aurally and visually as necessary when sound images represented on the contour plots were confounded and to ensure that the calling peaks described below were dates when calling activity was relatively intense. We also determined the daily median dB levels for frequencies across 2900 to 3200 Hz during 2100 to 2300 h, the bandwidth that typically encompassed the primary energy peak in P. crucifer calls and a time period during which P. crucifer typically called most consistently throughout their calling season. We did this for each day from the date when P. crucifer first called during each year to the date when they last called during each year. Because calling activity could vary from one hour to the next, we integrated the area under the curve for the daily median dB levels from 2900 to 3200 Hz during 2100 to 2300 h. We removed dates when overlapping sounds from storms or other sources rendered comparisons to calls of P. crucifer inaccurate. We used the resultant set of integrands to represent the relative sound intensity (as an indicator of calling activity) for P. crucifer across those hours for each date. We then used these integrands to determine the three highest peak calling dates for this species and used the median of those three dates as the overall median peak date for each site in each year.

This is an ARMI Product. The eight-day interval during which amphibians first called annually at individual study wetlands across four study areas.
Authors: Sadinski W, Roth M | Date: 2018-09-06 | Outlet: U.S. Geological Survey data release,
To help determine when winter conditions were changing to spring conditions annually in our four study areas, we determined the first eight-day interval (in accordance with the scale limitations of satellite data we used to assess the presence of snow) during which the first amphibian of the season called at each of our study wetlands in those areas. To do this, we examined contour plots of summaries of all the acoustic data we collected at that site in a given year to identify the unique call signatures of individual amphibian species by date and time. When necessary due to potential confounding on a contour plot, we also examined relevant individual five-minute recordings aurally and visually to confirm whether a call occurred. When we confirmed the date of the first call we recorded in a given season, we identified the eight-day interval in which that date fell, with the first such interval beginning on January 1 of each year.

This is an ARMI Product. Seasonal median daily water depths for study wetlands in the Tamarac National Wildlife Refuge, the St. Croix National Scenic Riverway, the North Temperate Lakes Long-term Research area, and the Upper Mississippi River study area from 2008-2012
Authors: Sadinski W, Roth M | Date: 2018-09-06 | Outlet: U.S. Geological Survey data release,
To relate water levels in our study wetlands to temperature, precipitation, wetland water depth, and amphibian calling activity, we installed one pressure logger in the deepest spot we could find in each wetland. Soon after thawing conditions allowed, we drove a plastic pipe (anchor pipe) into the sediments at the deepest location and secured another pipe to it that contained one pressure logger (Global Water Model 14 and 15 [College Station, TX, USA] or Onset Computer Corporation Model U20-001-04 [Bourne, MA, USA]) suspended approximately 2.5 cm above the sediments. We installed additional individual pressure loggers in the upper part of the logger pipes (in air) at select locations to measure barometric pressure for calibrating the submerged loggers’ readings. We measured pressure once per hour and used software supplied by the logger manufacturers to upload and convert data to depth at the end of each season.