Plant carbon isotopes were used to track assimilation of riparian resources by small mammals. Voles and shrews derived significant portions of their carbon from riparian vegetation. Deer and harvest mice were abundant in riparian habitat but assimilated little riparian vegetation indicating that the riparian corridor provided resources other than food. This is first use of stable carbon isotopes to trace riparian resources into a vertebrate community. Conifer encroachment in sagebrush ecosystems negatively affects many wildlife populations. Conifer removal is recommended across millions of hectares in the Great Basin. However the effects of conifer encroachment and conifer removal are unknown for most wildlife species. We show that the consequences of conifer encroachment, a press impact, far outweigh the pulse impact of sagebrush restoration, on small mammal diversity. Lack of demographic data limit the development of effective management, conservation and recovery goals for rattlesnakes. We used a long-term dataset and capture mark recapture models to quantify demography of four rattlesnake populations. Mean population growth indicated an overall stable population across the study, with two of the four sites declining. Survival overwhelmingly contributed to population growth relative to recruitment. No small mammals drank stream water even during periods of environmentally high water stress and high aridity, extension of the linear regression equation for small mammal body water towards the meteoric waterline, captures stream water, the weighted mean average for regional meteoric waters. Similar regression of fossilized small mammal tissues would also capture local meteoric waters. Even in arid regions, small mammal fossils are a suitable proxy for climate reconstructions. In the Great Basin, snowmelt overwhelmingly contributes to local precipitation, plant production, and stream flows. Snowmelt supports riparian and upland plants, and small mammals. Rattlesnakes prey primarily on small mammals, indirectly depending on snow melt for survival and reproduction. Climate models and rattlesnake emergence strongly indicate an earlier onset of spring and reduced ratio of snow to rain. Declining snowpack will have major impacts on biodiversity and management such as riparian vegetation, native plant restoration, trophic interactions, and ecological goods and services.

In recent decades, there has been increased global concern about observed climate change; however for future climatic impacts and anthropogenic forcings of climate change to be realistically predicted, natural climate variability in the past needs to be better understood. The aim of this research is to develop quantifiable proxy records of past climate change through the calibration of isotope values in modern surface waters and tree ring cellulose with meteorological and atmospheric records. Terrestrial proxy records that utilize oxygen and hydrogen isotope values to reconstruct paleoclimatic and paleohydrologic conditions are limited by a paucity of data on the modification of surface water isotope values prior to sequestration into proxy material. To address this gap in our knowledge and determine the most appropriate study sites, this research focuses on isotopic records preserved in surface water reservoirs, precipitation, and tree-ring cellulose. In the first study, δD, δ18O, and deuterium-excess values were determined for lakes and rivers from Tasmania, southeastern Australia. <p> The second focus of this research was to calibrate the δ18O, δD, and δ13C values of tree-ring cellulose from North America with instrumental records. A new high-resolution sampling procedure that uses a robotic micromilling device to very precisely map and sample along growth rings in trees is discussed. Additionally, a seasonally resolved (early/late wood) 110-year record of δ18O values from tree-ring α-cellulose from spruce species (<i>Picea mariana</i> and <i>P. glauca</i>) from east-central Saskatchewan, Canada is compared to growing season precipitation δ18O values, temperature, and relative humidity. The δ18O time series from α-cellulose display a high correlation with growing season precipitation isotope values (r = 0.86). δ18O α-cellulose time series from a white spruce (<i>Picea glauca</i>) also records seasonal changes in atmospheric circulation associated with the position of the circumpolar vortex and dominate modes of atmospheric variability such as the North Atlantic Oscillation and Pacific Decadal Oscillation.

In recent decades, there has been increased global concern about observed climate change; however for future climatic impacts and anthropogenic forcings of climate change to be realistically predicted, natural climate variability in the past needs to be better understood. The aim of this research is to develop quantifiable proxy records of past climate change through the calibration of isotope values in modern surface waters and tree ring cellulose with meteorological and atmospheric records. Terrestrial proxy records that utilize oxygen and hydrogen isotope values to reconstruct paleoclimatic and paleohydrologic conditions are limited by a paucity of data on the modification of surface water isotope values prior to sequestration into proxy material. To address this gap in our knowledge and determine the most appropriate study sites, this research focuses on isotopic records preserved in surface water reservoirs, precipitation, and tree-ring cellulose. In the first study, δD, δ18O, and deuterium-excess values were determined for lakes and rivers from Tasmania, southeastern Australia. <p> The second focus of this research was to calibrate the δ18O, δD, and δ13C values of tree-ring cellulose from North America with instrumental records. A new high-resolution sampling procedure that uses a robotic micromilling device to very precisely map and sample along growth rings in trees is discussed. Additionally, a seasonally resolved (early/late wood) 110-year record of δ18O values from tree-ring α-cellulose from spruce species (<i>Picea mariana</i> and <i>P. glauca</i>) from east-central Saskatchewan, Canada is compared to growing season precipitation δ18O values, temperature, and relative humidity. The δ18O time series from α-cellulose display a high correlation with growing season precipitation isotope values (r = 0.86). δ18O α-cellulose time series from a white spruce (<i>Picea glauca</i>) also records seasonal changes in atmospheric circulation associated with the position of the circumpolar vortex and dominate modes of atmospheric variability such as the North Atlantic Oscillation and Pacific Decadal Oscillation.