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Drought and freezing are both known to limit desert plant distributions, but the interaction of these stressors is poorly understood. Drought may increase freezing tolerance in leaves while decreasing it in the xylem, potentially creating a mismatch between water supply and demand. To test this hypothesis, we subjected Larrea tridentata juveniles grown in a greenhouse under well-watered or drought conditions to minimum temperatures ranging from -8 to -24 �C. We measured survival, leaf retention, gas exchange, cell death, freezing point depression and leaf-specific xylem hydraulic conductance (k?). Drought-exposed plants exhibited smaller decreases in gas exchange after exposure to -8 �C compared to well-watered...
These data are associated with an article published in Global Ecology and Conservation (https://doi.org/10.1016/j.gecco.2020.e01173) that describes climate's cascading effects on disease, predation, and hatching sucess in the Yosemite toad (Anaxyrus canorus). The Yosemite toad currently is federally listed as threatened under the U.S. Endanered Species Act based upon reported population declines and vulnerability to climate and other global-change factors. The species occurs only in California’s central Sierra Nevada at medium to sub-alpine elevations. Lands throughout its range largely are protected from development, but climate and other global-change factors potentially can limit populations.
Amino acids have been shown to be a potentially significant N source for the alpine sedge, Kobresia myosuroides. We hypothesised that freeze-thaw and dry-rewet events allow this plant species increased access to amino acids by disrupting microbial cells, which decreases the size of competing microbial populations, but increases soil amino acid concentrations. To test this hypothesis, we characterized freeze-thaw and dry-rewet events in the field and simulated them in laboratory experiments on plant-soil microcosms. In one experiment, 15N,13C-[2]-glycine was added to microcosms that had previously been subjected to a freeze-thaw or dry-rewet event, and isotopic concentrations in the plant and microbial fractions...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. To assess and document the depths to the tops of individual A. canorus and Pseudacris regilla egg masses and to the sediments, we measured water depths at masses of both species. We used a meter stick to measure the depth (nearest mm) where female A. canorus deposited individual egg masses, and the distance from the water’s surface to the tops of those masses, at several breeding sites across 1996, 1998, 1999, and 2000. We did the same for egg masses of P. regilla...
In northern peatlands, subsurface ice formation is an important process that can control heat transport, groundwater flow, and biological activity. Temperature was measured over one and a half years in a vertical profile in the Red Lake Bog, Minnesota. To successfully simulate the transport of heat within the peat profile, the U.S. Geological Survey’s SUTRA computer code was modified. The modified code simulates fully saturated, coupled porewater-energy transport, with freezing and melting porewater, and includes proportional heat capacity and thermal conductivity of water and ice, decreasing matrix permeability due to ice formation, and latent heat. The model is verified by correctly simulating the Lunardini analytical...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. ENCLOSURES We used field enclosures to test the hypothesis that exposure to ambient UV-B caused embryo mortality in 1996 and 1998. We covered the top of each enclosure with one or two types of thin plastic sheeting. One type was transparent to the solar spectrum. The other type filtered UV-B below 314 nm (UV-B<314) but was otherwise transparent to solar radiation. Laying both types together over the top of an enclosure did not alter the transmission characteristics...
? This research tested the hypothesis that experimental infrared warming will reduce photosynthesis for the evergreen shrub Artemisia tridentata and the subalpine, herbaceous Erythronium grandiflorum exposed to an in situ experimental freezing event during the spring snowmelt period. ? Photosynthetic tolerance of freezing was measured for plants growing under infrared (IR) warming at 3050 m in the Rocky Mountains, Colorado, USA. In situ freezing was imposed using cold nitrogen gas (from a pressurized container of liquid nitrogen) passed through a heat exchanger placed on top of stems and leaves. ? Plant water potential, photosynthetic CO2 assimilation, and stomatal conductance to water vapor were higher for both...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. From 1999 to 2001, we deployed Optic StowAway Temperature loggers (Onset Computer Corporation; Bourne, Massachusetts, USA) to measure minimum daily air temperatures at various breeding sites during embryogenesis for A. canorus. These measurements enabled us to determine relations between air temperatures at individual breeding sites relative to air temperatures measured at the automated weather station in Dana Meadows (DAN) in the heart of our study area. We measured...
Dust deposition to mountain snow cover, which has increased since the late 19(th) century, accelerates the rate of snowmelt by increasing the solar radiation absorbed by the snowpack. Snowmelt occurs earlier, but is decoupled from seasonal warming. Climate warming advances the timing of snowmelt and early season phenological events (e.g., the onset of greening and flowering); however, earlier snowmelt without warmer temperatures may have a different effect on phenology. Here, we report the results of a set of snowmelt manipulations in which radiation-absorbing fabric and the addition and removal of dust from the surface of the snowpack advanced or delayed snowmelt in the alpine tundra. These changes in the timing...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. We assessed the extent of annual mortality among embryos of A. canorus and Pseudacris regilla variously among breeding sites and years by measuring hatching success in as many individual egg masses as possible, given logistical constraints, at sites we surveyed annually from 1996 to 2000. We visually evaluated each individual embryo in an egg mass in situ while kneeling alongside it immediately before, at, or very soon after hatching (when individual capsules remained...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. We assessed the three general categories (early, mid, and late) for the developmental stage at which embryos of A. canorus died among various breeding sites from 1999 to 2001. We visually evaluated each individual embryo in an egg mass in situ while kneeling alongside it immediately before, at, or very soon after hatching (when individual capsules remained from hatched embryos and when any remnants of dead embryos typically still were visible). We did not assess...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. To assess embryo mortality, we visually evaluated each individual embryo in an egg mass in situ while kneeling alongside it immediately before, at, or very soon after hatching (when individual capsules remained from hatched embryos and when any remnants of dead embryos typically still were visible). We did not assess mortality in any egg masses that had deteriorated too far to evaluate embryos. In 2001, a limited number of field personnel caused us to estimate...
We produced this data set as part of a larger, integrated study to assess the statuses of populations of Anaxyrus canorus and the causes of observed effects on fitness at field sites, primarily in Yosemite National Park near Tioga Pass, from 1996 to 2001. We conducted a field experiment in 1999 to test for effects of enclosing embryos of A. canorus and moving them to slightly deeper water, thereby reducing the potential for exposure to ice and freezing temperatures, on hatching success at five breeding sites. We split freshly laid egg masses approximately into halves. We left one indiscriminately chosen half of each mass where it was deposited originally (replicates of which were scattered among the shallow waters)...


    map background search result map search result map Yosemite Toad (Anaxyrus canorus) project datasets; climate, disease, predation, and hatching success data Minimum daily air temperatures (1999 to 2001) and minimum and maximum daily water temperatures next to egg masses (2001) during embryogenesis for Anaxyrus canorus at various breeding sites near Tioga Pass Effects of exposure to ambient UV-B on embryos of Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, in 1996 and 1998 Egg-mass depths for Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, in 1996, 1998, 1999, and 2000 Developmental stage at Anaxyrus canorus embryos died at various breeding sites Embryo mortality for Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, from 1996 to 2001 Embryo mortality relative to the abundance category of the water mold, Saprolegnia diclina, and an unidentified predatory flatworm (Turbellaria spp.) for egg masses of Anaxyrus canorus at various breeding sites near Tioga Pass, California, USA, in 2001 Mortality resulting from two field experiments regarding freezing potential for embryos of Anaxyrus canorus at various breeding sites near Tioga Pass, California, USA, in 1999 and 2000 and for one laboratory experiment in 2000 at the Sierra Nevada Aquatic Research Laboratory in Mammoth Lakes, California, USA Yosemite Toad (Anaxyrus canorus) project datasets; climate, disease, predation, and hatching success data Minimum daily air temperatures (1999 to 2001) and minimum and maximum daily water temperatures next to egg masses (2001) during embryogenesis for Anaxyrus canorus at various breeding sites near Tioga Pass Effects of exposure to ambient UV-B on embryos of Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, in 1996 and 1998 Egg-mass depths for Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, in 1996, 1998, 1999, and 2000 Developmental stage at Anaxyrus canorus embryos died at various breeding sites Embryo mortality for Anaxyrus canorus and Pseudacris regilla at various breeding sites near Tioga Pass, California, USA, from 1996 to 2001 Embryo mortality relative to the abundance category of the water mold, Saprolegnia diclina, and an unidentified predatory flatworm (Turbellaria spp.) for egg masses of Anaxyrus canorus at various breeding sites near Tioga Pass, California, USA, in 2001 Mortality resulting from two field experiments regarding freezing potential for embryos of Anaxyrus canorus at various breeding sites near Tioga Pass, California, USA, in 1999 and 2000 and for one laboratory experiment in 2000 at the Sierra Nevada Aquatic Research Laboratory in Mammoth Lakes, California, USA