Browsing by Author "Harper, Joel T."

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Key rules of life and the fading cryosphere: Impacts in alpine lakes and streams
(Wiley, 2020-10) Elser, James J.; Wu, Chenxi; González, Angélica L.; Shain, Daniel H.; Smith, Heidi J.; Sommaruga, Ruben; Williamson, Craig E.; Brahney, Janice; Hotaling, Scott; Vanderwall, Joseph; Yu, Jinlei; Aizen, Vladimir; Aixen, Elena; Battin, Tom J.; Camassa, Roberto; Feng, Xiu; Jiang, Hongchen; Lu, Lixin; Qu, John L.; Ren, Ze; Wen, Jun; Wen, Lijuan; Woods, H. Author; Xiong, Xiong; Xu, Jun; Yu, Gongliang; Harper, Joel T.; Saros, Jasmine E.
Alpine regions are changing rapidly due to loss of snow and ice in response to ongoing climate change. While studies have documented ecological responses in alpine lakes and streams to these changes, our ability to predict such outcomes is limited. We propose that the application of fundamental rules of life can help develop necessary predictive frameworks. We focus on four key rules of life and their interactions: the temperature dependence of biotic processes from enzymes to evolution; the wavelength dependence of the effects of solar radiation on biological and ecological processes; the ramifications of the non-arbitrary elemental stoichiometry of life; and maximization of limiting resource use efficiency across scales. As the cryosphere melts and thaws, alpine lakes and streams will experience major changes in temperature regimes, absolute and relative inputs of solar radiation in ultraviolet and photosynthetically active radiation, and relative supplies of resources (e.g., carbon, nitrogen, and phosphorus), leading to nonlinear and interactive effects on particular biota, as well as on community and ecosystem properties. We propose that applying these key rules of life to cryosphere-influenced ecosystems will reduce uncertainties about the impacts of global change and help develop an integrated global view of rapidly changing alpine environments. However, doing so will require intensive interdisciplinary collaboration and international cooperation. More broadly, the alpine cryosphere is an example of a system where improving our understanding of mechanistic underpinnings of living systems might transform our ability to predict and mitigate the impacts of ongoing global change across the daunting scope of diversity in Earth's biota and environments.
Significance of trends toward earlier snowmelt runoff, Columbia and Missouri Basin headwaters, western United States
(American Geophysical Union, 2007-08) Moore, Johnnie N.; Harper, Joel T.; Greenwood, Mark C.
We assess changes in runoff timing over the last 55 years at 21 gages unaffected by human influences, in the headwaters of the Columbia-Missouri Rivers. Linear regression models and tests for significance that control for “false discoveries” of many tests, combined with a conceptual runoff response model, were used to examine the detailed structure of spring runoff timing. We conclude that only about one third of the gages exhibit significant trends with time but over half of the gages tested show significant relationships with discharge. Therefore, runoff timing is more significantly correlated with annual discharge than with time. This result differs from previous studies of runoff in the western USA that equate linear time trends to a response to global warming. Our results imply that predicting future snowmelt runoff in the northern Rockies will require linking climate mechanisms controlling precipitation, rather than projecting response to simple linear increases in temperature.
Supporting Information for "Significance of trends toward earlier snowmelt runoff, Columbia and Missouri Basin headwaters, western United States"
(American Geophysical Union, 2007-08) Moore, Johnnie N.; Harper, Joel T.; Greenwood, Mark C.
This is auxiliary material for this article contains one text file, four tables, and three figures from the article "Significance of trends toward earlier snowmelt runoff, Columbia and Missouri Basin headwaters, western United States" from Geophysical Research Letters on the 28 August 2007. http://onlinelibrary.wiley.com/doi/10.1029/2007GL031022/full