Search Results - "J. M. Welker"

Quantifying global soil carbon losses in response to warming by Crowther, T. W., Todd-Brown, K. E. O., Rowe, C. W., Wieder, W. R., Carey, J. C., Machmuller, M. B., Snoek, B. L., Fang, S., Zhou, G., Allison, S. D., Blair, J. M., Bridgham, S. D., Burton, A. J., Carrillo, Y., Reich, P. B., Clark, J. S., Classen, A. T., Dijkstra, F. A., Elberling, B., Emmett, B. A., Estiarte, M., Frey, S. D., Guo, J., Harte, J., Jiang, L., Johnson, B. R., Kröel-Dulay, G., Larsen, K. S., Laudon, H., Lavallee, J. M., Luo, Y., Lupascu, M., Ma, L. N., Marhan, S., Michelsen, A., Mohan, J., Niu, S., Pendall, E., Peñuelas, J., Pfeifer-Meister, L., Poll, C., Reinsch, S., Reynolds, L. L., Schmidt, I. K., Sistla, S., Sokol, N. W., Templer, P. H., Treseder, K. K., Welker, J. M., Bradford, M. A.

“…A compilation of global soil carbon data from field experiments provides empirical evidence that warming-induced net losses of soil carbon could accelerate…”
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NDVI changes in the Arctic: Functional significance in the moist acidic tundra of Northern Alaska by Jespersen, R Gus, Anderson-Smith, M, Sullivan, P F, Dial, R J, Welker, J M

“…The Normalized Difference Vegetation Index (NDVI), derived from reflected visible and infrared radiation, has been critical to understanding change across the…”
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Role of Land-Surface Changes in Arctic Summer Warming by Chapin, F. S, Sturm, M, Serreze, M. C, McFadden, J. P, Key, J. R, Lloyd, A. H, McGuire, A. D, Rupp, T. S, Lynch, A. H, Schimel, J. P, Beringer, J, Chapman, W. L, Epstein, H. E, Euskirchen, E. S, Hinzman, L. D, Jia, G, Ping, C.-L, Tape, K. D, Thompson, C. D. C, Walker, D. A, Welker, J. M

“…A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from…”
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The role of topography on catchment-scale water residence time by McGuire, K.J, McDonnell, J.J, Weiler, M, Kendall, C, McGlynn, B.L, Welker, J.M, Seibert, J

“…The age, or residence time, of water is a fundamental descriptor of catchment hydrology, revealing information about the storage, flow pathways, and source of…”
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Diet of female polar bears in the southern Beaufort Sea of Alaska: evidence for an emerging alternative foraging strategy in response to environmental change by Rogers, M. C., Peacock, E., Simac, K., O’Dell, M. B., Welker, J. M.

“…Polar bear ( Ursus maritimus ) diet may become more variable in some Arctic regions due to climate warming and altered sea ice habitat. We surveyed carbon and…”
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High Arctic wetting reduces permafrost carbon feedbacks to climate warming by Lupascu, M., Welker, J. M., Seibt, U., Maseyk, K., Xu, X., Czimczik, C. I.

“…The combination of climatic warming and wetting can increase the CO 2 sink strength of High Arctic semi-deserts by an order of magnitude, according to a…”
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Snowier winters extend autumn availability of high‐quality forage for caribou in Arctic Alaska by Richert, J. C., Leffler, A. J., Spalinger, D. E., Welker, J. M.

“…Caribou (Rangifer tarandus) rely on the short Arctic growing season to restore body condition, support the demands of lactation, and prepare for the long…”
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Monthly precipitation isoscapes (δ18O) of the United States: Connections with surface temperatures, moisture source conditions, and air mass trajectories by Vachon, R. W., Welker, J. M., White, J. W. C., Vaughn, B. H.

“…This research presents the most spatially complete data set depicting average monthly δ18O precipitation values across the United States (isoscapes). Average…”
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Distribution and drivers of ectomycorrhizal fungal communities across the North American Arctic by Timling, I, Dahlberg, A, Walker, D. A, Gardes, M, Charcosset, J. Y, Welker, J. M, Taylor, D. L

“…Ectomycorrhizal fungi (EMF) form symbioses with a few plant species that comprise a large fraction of the arctic vegetation. Despite their importance, the…”
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The amount and timing of precipitation control the magnitude, seasonality and sources ( 14 C) of ecosystem respiration in a polar semi-desert, northwestern Greenland by Lupascu, M, Welker, J. M, Seibt, U, Xu, X, Velicogna, I, Lindsey, D. S, Czimczik, C. I

“…This study investigates how warming and changes in precipitation may affect the cycling of carbon (C) in tundra soils, and between high Arctic tundra and the…”
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Grazing Impacts on Soil Carbon and Microbial Communities in a Mixed-Grass Ecosystem by Ingram, L.J, Stahl, P.D, Schuman, G.E, Buyer, J.S, Vance, G.F, Ganjegunte, G.K, Welker, J.M, Derner, J.D

“…Good management of rangelands promotes C sequestration and reduces the likelihood of these ecosystems becoming net sources of CO2. As part of an ongoing study,…”
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More Snow Accelerates Legacy Carbon Emissions From Arctic Permafrost by Pedron, S. A., Jespersen, R. G., Xu, X., Khazindar, Y., Welker, J. M., Czimczik, C. I.

“…Snow is critically important to the energy budget, biogeochemistry, ecology, and people of the Arctic. While climate change continues to shorten the duration…”
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Leaf mineral nutrition of Arctic plants in response to warming and deeper snow in northern Alaska by Welker, J. M., Fahnestock, J. T., Sullivan, P. F., Chimner, R. A.

“…Articulating the consequences of global climate change on terrestrial ecosystem biogeochemistry is a critical component of Arctic system studies. Leaf mineral…”
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Isotopic (δ18O) characteristics of weekly precipitation collected across the USA: an initial analysis with application to water source studies by Welker, J. M

“…A portion of the precipitation samples collected and stored by the National Atmospheric Deposition Program (NADP) are shown to be useful for analysis of…”
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Spatially telescoping measurements for improved characterization of ground water–surface water interactions by Kikuchi, C.P., Ferré, T.P.A., Welker, J.M.

“…► Characterizing GW–SW interactions with spatially telescoping measurements. ► Catchment-scale surveys indicated areas of significant groundwater contribution…”
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Stable isotopic evidence of El Niño-like atmospheric circulation in the Pliocene western United States by Winnick, M. J., Welker, J. M., Chamberlain, C. P.

“…Understanding how the hydrologic cycle has responded to warmer global temperatures in the past is especially important today as concentrations of CO2 in the…”
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Annual CO2 flux in dry and moist arctic tundra : Field responses to increases in summer temperatures and winter snow depth by WELKER, J. M, FAHNESTOCK, J. T, JONES, M. H

“…Welker et al examined the annual exchange of carbon dioxide between the atmosphere and moist tussock and dry heath tundra ecosystems under ambient field…”
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Amount-weighted annual isotopic (δ18O) values are affected by the seasonality of precipitation: A sensitivity study by Vachon, R. W., White, J. W. C., Gutmann, E., Welker, J. M.

“…Year to year differences in the isotopes of precipitation (δ18O) are typically attributed to corresponding interannual changes in mean annual temperature…”
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Differential water resource use by herbaceous and woody plant life-forms in a shortgrass steppe community by Dodd, M.B, Lauenroth, W.K, Welker, J.M

“…We conducted a study to test the predictions of Walter's two-layer model in the shortgrass steppe of northeastern Colorado. The model suggests that grasses and…”
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Long-term experimental manipulation of winter snow regime and summer temperature in arctic and alpine tundra by Walker, M. D., Walker, D. A., Welker, J. M., Arft, A. M., Bardsley, T., Brooks, P. D., Fahnestock, J. T., Jones, M. H., Losleben, M., Parsons, A. N., Seastedt, T. R., Turner, P. L.

“…Three 60 m long, 2·8 m high snowfences have been erected to study long‐term effects of changing winter snow conditions on arctic and alpine tundra. This paper…”
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