Browsing by Author "Sherwood, Jill A."

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Effects of experimentally reduced snowpack and passive warming on montane meadow plant phenology and floral resources.
(2017-03) Sherwood, Jill A.; Debinski, Diane M.; Caragea, P. C.; Germino, Matthew J.
Climate change can have a broad range of effects on ecosystems and organisms, and early responses may include shifts in vegetation phenology and productivity that may not coincide with the energetics and forage timing of higher trophic levels. We evaluated phenology, annual height growth, and foliar frost responses of forbs to a factorial experiment of snow removal (SR) and warming in a high-elevation meadow over two years in the Rocky Mountains, United States. Species included arrowleaf balsamroot (Balsamorhiza sagittata, early-season emergence and flowering) and buckwheat (Eriogonum umbellatum, semi-woody and late-season flowering), key forbs for pollinator and nectar-using animal communities that are widely distributed and locally abundant in western North America. Snow removal exerted stronger effects than did warming, and advanced phenology differently for each species. Specifically, SR advanced green-up by a few days for B. sagittata to >2 wk in E. umbellatum, and led to 5- to 11-d advances in flowering of B. sagittata in one year and advances in bud break in 3 of 4 species/yr combinations. Snow removal increased height of E. umbellatum appreciably (~5 cm added to ~22.8 cm in control), but led to substantial increases in frost damage to flowers of B. sagittata. Whereas warming had no effects on E. umbellatum, it increased heights of B. sagittata by >6 cm (compared to 30.7 cm in control plots) and moreover led to appreciable reductions in frost damage to flowers. These data suggest that timing of snowmelt, which is highly variable from year to year but is advancing in recent decades, has a greater impact on these critical phenological, growth, and floral survival traits and floral/nectar resources than warming per se, although warming mitigated early effects of SR on frost kill of flowers. Given the short growing season of these species, the shifts could cause uncoupling in nectar availability and timing of foraging.
An Examination of Interannual Population Variation in Parnassius Clodius Butterflies
(2011-01) Sherwood, Jill A.; Debinski, Diane M.
Examining how population size and structure vary over time is an important part of understanding how environmental factors influence a particular species. Organisms in which multiple generations can be studied in a short period of time are useful when attempting to predict the consequences of such changes. Insects, and in particular butterflies, have a short generation time, which makes them ideal for studying the effects of environmental change on demographics. In this study, we examine the population dynamics of a butterfly common in the Teton area, Clodius Parnassian (Parnassius clodius). This area was initially studied starting in 1998-2000 (Auckland et al. 2004) and surveys were continued in 2009 – 2011. Emergence date varied between years by as much as three weeks. In addition, peak flight and end of flight dates also varied. Preliminary examination of the population data reveals similar patterns across years, where male emergence occurred prior to female emergence. In addition, sex ratios were also fairly consistent between years. Variation among years is observed primarily in the total number of butterflies marked and recaptured. Further data analyses comparing demographic parameters such as survival and population size need to be performed before any additional conclusions can be made. This study will add additional data to an ongoing study of the potential effects of environmental change on a common species of butterfly (Parnassius clodius).
Testing the Effects of Simulated Climate Change Effects Using Open Sided Warming Chambers
(2010-01) Sherwood, Jill A.; Debinski, Diane M.; Germino, Matthew J.
Regional models of global climate change for the northern Rocky Mountains predict warmer temperatures, and some of the main implications of these changes at a local level involve decreased snowpack, earlier snowmelt, and decreased soil moisture during the growing season. In order to mimic the anticipated effects of climate change, and test the responses from a soil microclimate and plant physiology perspective, open-sided warming chambers and snow removal treatments were applied to 2.44 X 2.44 m plots in a sagebrush steppe meadow within Grand Teton National Park, WY. Four treatments included: (1) control, (2) reduced snowpack, (3) increased temperature, and (4) reduced snowpack with increased temperature. Snow was removed using shovels in early May, and chambers were placed at the same time. The chambers were left on the plots through mid-October. Soil moisture and temperature were measured and recorded at 5 cm, and 25 cm depths using dataloggers set up at the time of snow removal and chamber placement. In addition, surface temperature was measured under each plot and within the study area. Plant physiological data on four plant species, including leaf temperature at dawn and mid-afternoon and water potential, were collected for all of the plots in July. Data are being analyzed to determine whether differences existed between the plots for soil moisture, soil and air temperature, and the plant physiological traits measured.