Jeff Welker’s US Network for Isotopes in Precipitation (USNIP) was featured in a presentation at the famous Goldschimdt (http://goldschmidt.info/2013/index) international conference this past week in Florence, Italy. The presentation occurred in the session titled: “Reconstructing Terrestrial Hydrology: Proxies, Mechanisms, and Records”. The title of the study was “Variations in Triple Oxygen Isotopes in Precipitation and River Waters in the Continental U.S.”: N Levin, S Li, R Brooks and JM Welker. Naomi Levin (Assistant Professor at John Hopkins University) was the presenter while the PhD student, Shuning Li and EPA Scientist Renee Brooks were contributors and participants.
- Ph.D. Department of Rangeland Ecology and Management, Texas A&M, University, College Station, TX, 1985. Carbon and nitrogen cycling in native bunchgrass plants.
- M.S. Range Science, Range and Animal Science Department, Montana State University, Bozeman, MT,1982. Climate change affects on prairie vegetation.
- B.S. Agriculture-Range Science Major, Range and Animal Science Department, Montana State University, Bozeman, MT, 1980.
The Welker lab is dedicated to understanding the ecophysiological processes governing the functional and structural traits of Arctic/Alpine tundra, boreal forests and temperate grasslands under current and future conditions. Welker’s research program centers on four main themes:
1) Experimental and observational studies that examine how carbon and nitrogen cycling in Low and High Arctic ecosystems respond to deeper snow in winter and warmer temperatures in summer;
2) Continental-scale processes and patterns of the isotope geochemistry of precipitation as a means to understand the ecohydrology of landscapes and the recording of climate records in proxies such as ice cores, tree rings and speleothems;
3) The food web and migratory ecology of ecosystems in Alaska involving gray wolves, moose, salmon, caribou, polar bears, white-fronted geese, and seabirds; and
4) Climate-plant-animal interactions in Arctic and temperate landscapes using experimental and observational studies.
Selected Publications (2011-2010):
- Cable, J. Ogle, K., Welker, J.M. and 10 additional authors. (2011) The temperature response of soil respiration: A 7 desert synthesis. Biogeochemistry. 103: 71-90.
- Cahoon, S., Sullivan, P.F., Post, E., and Welker, J.M. Herbivores constrain Arctic CO2 uptake and surpress C cycling responses to warming. Global Change Biology. (In Press)
- Chimner, R., and Welker, J.M. Influence of grazing and precipitation on ecosystem carbon cycling in a mixedgrass prairie. Pastorial Science. (In Press)
- Ives, S., Sullivan, P.F., Dail, R., Berg, E. and Welker, J.M. Seasonal and inter-annual patterns in the magnitudes of CO2 exchange along a hydrologic gradient in the Kenai Lowlands, AK: Feedback implications of wetland drying and vegetation succession. Ecohydrology. (In Press)
- Rogers, M., Sullivan, P. and Welker, J.M. (2011) Experimental increases in snow depth delays the seasonality but enhances the magnitudes of vegetation traits and trace gas exchanges in the High Arctic of NW Greenland. Arctic, Antarctic and Alpine Research. 43: 95-106.
- Tape, K. D., Verbyla, D. and Welker, J.M. Erosion decline in Arctic Alaska uplands since 1980: the influence of shrubs, runoff, and permafrost . JGR Biogeosciences. (In Press)
- Werner, C., Welker, J.M., et al. (2011) Linking carbon and water cycles using stable isotopes across scales: Progress and challenges. Biogeosciences Discussions. 8: 2659-2719. (On-line Journal)
- Wilgenberg, S. L., Hobson, K. A., Brewster, K, and Welker, J.M. Addressing uncertainty in assessing dispersal in threatened migratory species using stable hydrogen (?D) analysis of feathers. Conservation Biology. (In Press)
- Chimner, R., Welker, J.M., Morgan, J., LeCain, D. and Reader, J. (2010) Experimental manipulations of winter snow cover and summer rain influence ecoystem C cycling in a Mixedgrass Prairie. Ecohydrology. 3: 284-297.
- Czimczik, C., and Welker, J.M. (2010) Age and sources of soil respiration from High Arctic tundra in NW Greenland. Arctic, Antarctic and Alpine Research. 42: 342-350.
- Liu, Z., Bowen, G., and Welker, J.M. (2010) Precipitation isotope (?18O) gradients depict modern atmospheric circulation over the conterminous United States. Journal of Geophysical Research. 115: D22120, doi:10.1029/2010JD014175.
- Nowinski, N., Taneva, L., Trumbore, S., and Welker, J.M. (2010) Decomposition of old organic matter as a result of a deeper active layer in a snow manipulation experiment. Oecologia 163: 785-792.
- Stevenson, B.A., Kelly, E., McDonald, E., Busacca. A., and Welker, J.M. (2010) Oxygen isotope ratios in Holocene carbonates across a climatic gradient eastern Washington State, USA: Evidence for seasonal effects on pedogenic mineral isotopic composition. The Holocene. 20: 575-583.
- Sullivan, P.F., Arens, S., Sveinbjörnsson, B. and Welker, J.M. (2010) Modeling the seasonality of belowground respiration along an elevational gradient in the Chugach Mountains, south central Alaska. Biogeochemistry. 101: 61-75.
- Vachon, R.W., Welker, J.M., White, J.W.C., and Vaughn, B.H. (2010) Monthly precipitation isoscapes (?18O) of the United States: Connections with surface temperatures, moisture source conditions, and air mass trajectories. Journal of Geophysical Research. 115: D21126. doi:10.1029/2010JD014105.
- Vachon, R.W., Welker, J.M., White, J.W., and Vaughn, B.H. (2010) Moisture source temperatures and precipitation ?18O-temperature relationships across the US. Water Resources Research. 46: W07523.