@article {KNZ001783,
	title = {Pushing precipitation to the extremes in distributed experiments: recommendations for simulating wet and dry years},
	journal = {Global Change Biology},
	volume = {23},
	year = {2017},
	pages = {1774-1782},
	abstract = {<p>Intensification of the global hydrological cycle, ranging from larger individual precipitation events to more extreme multiyear droughts, has the potential to cause widespread alterations in ecosystem structure and function. With evidence that the incidence of extreme precipitation years (defined statistically from historical precipitation records) is increasing, there is a clear need to identify ecosystems that are most vulnerable to these changes and understand why some ecosystems are more sensitive to extremes than others. To date, opportunistic studies of naturally occurring extreme precipitation years, combined with results from a relatively small number of experiments, have provided limited mechanistic understanding of differences in ecosystem sensitivity, suggesting that new approaches are needed. Coordinated distributed experiments (CDEs) arrayed across multiple ecosystem types and focused on water can enhance our understanding of differential ecosystem sensitivity to precipitation extremes, but there are many design challenges to overcome (e.g., cost, comparability, standardization). Here, we evaluate contemporary experimental approaches for manipulating precipitation under field conditions to inform the design of \&lsquo;Drought-Net\&rsquo;, a relatively low-cost CDE that simulates extreme precipitation years. A common method for imposing both dry and wet years is to alter each ambient precipitation event. We endorse this approach for imposing extreme precipitation years because it simultaneously alters other precipitation characteristics (i.e., event size) consistent with natural precipitation patterns. However, we do not advocate applying identical treatment levels at all sites \&ndash; a common approach to standardization in CDEs. This is because precipitation variability varies \&gt;fivefold globally resulting in a wide range of ecosystem-specific thresholds for defining extreme precipitation years. For CDEs focused on precipitation extremes, treatments should be based on each site\&$\#$39;s past climatic characteristics. This approach, though not often used by ecologists, allows ecological responses to be directly compared across disparate ecosystems and climates, facilitating process-level understanding of ecosystem sensitivity to precipitation extremes.</p>},
	keywords = {LTER-KNZ},
	doi = {10.1111/gcb.13504},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13504},
	author = {Alan K. Knapp and M.L. Avolio and Beier, C. and Carroll, C.J.W. and Scott. L. Collins and Dukes, J.S. and Fraser, L.H. and Griffin-Nolan, R.J. and Hoover, D.L. and Jentsch, A. and Loik, M.E. and Phillips, R.P. and Post, A.K. and Sala, O.E. and Slette, I.J. and Yahdjian, L. and M.D. Smith}
}
@article {KNZ001684,
	title = {Characterizing differences in precipitation regimes of extreme wet and dry years: Implications for climate change experiments},
	journal = {Global Change Biology},
	volume = {21},
	year = {2015},
	pages = {2624 -2633},
	abstract = {<p>Climate change is intensifying the hydrologic cycle and is expected to increase the frequency of extreme wet and dry years. Beyond precipitation amount, extreme wet and dry years may differ in other ways, such as the number of precipitation events, event size, and the time between events. We assessed 1614 long-term (100 year) precipitation records from around the world to identify key attributes of precipitation regimes, besides amount, that distinguish statistically extreme wet from extreme dry years. In general, in regions where mean annual precipitation (MAP) exceeded 1000 mm, precipitation amounts in extreme wet and dry years differed from average years by ~40\% and 30\%, respectively. The magnitude of these deviations increased to \&gt;60\% for dry years and to \&gt;150\% for wet years in arid regions (MAP\&lt;500 mm). Extreme wet years were primarily distinguished from average and extreme dry years by the presence of multiple extreme (large) daily precipitation events (events \&gt;99th percentile of all events); these occurred twice as often in extreme wet years compared to average years. In contrast, these large precipitation events were rare in extreme dry years. Less important for distinguishing extreme wet from dry years were mean event size and frequency, or the number of dry days between events. However, extreme dry years were distinguished from average years by an increase in the number of dry days between events. These precipitation regime attributes consistently differed between extreme wet and dry years across 12 major terrestrial ecoregions from around the world, from deserts to the tropics. Thus, we recommend that climate change experiments and model simulations incorporate these differences in key precipitation regime attributes, as well as amount into treatments. This will allow experiments to more realistically simulate extreme precipitation years and more accurately assess the ecological consequences.</p>},
	keywords = {LTER-KNZ, rainfall patterns},
	doi = {10.1111/gcb.12888},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.12888},
	author = {Alan K. Knapp and D.L. Hoover and K.R. Wilcox and M.L. Avolio and Koerner, S.E. and Kimberly J. La Pierre and Loik, M.E. and Luo, Y. and Sala, O.E. and M.D. Smith}
}
@article {KNZ00917,
	title = {Convergence across biomes to a common rain-use efficiency},
	journal = {Nature},
	volume = {429},
	year = {2004},
	pages = {651 -654},
	keywords = {LTER-KNZ},
	doi = {10.1038/nature02561},
	author = {Huxman, T.E. and M.D. Smith and Fay, P.A. and Alan K. Knapp and Shaw, M.R. and Loik, M.E. and Smith, S.D. and Tissue, D.T. and Zak, J.C. and Weltzin, J.F. and Pockman, W.T. and Sala, O.E. and Haddad, B.M. and Harte, J. and Koch, G.W. and Schwinning, S. and Small, E.E. and Williams, D.G.}
}
@article {KNZ00881,
	title = {Assessing the response of terrestrial ecosystems to potential changes in precipitation},
	journal = {BioScience},
	volume = {53},
	year = {2003},
	pages = {941 -952},
	abstract = {Changes in Earth{\textquoteright}s surface temperatures caused by anthropogenic emissions of greenhouse gases are expected to affect global and regional precipitation regimes. Interactions between changing precipitation regimes and other aspects of global change are likely to affect natural and managed terrestrial ecosystems as well as human society. Although much recent research has focused on assessing the responses of terrestrial ecosystems to rising carbon dioxide or temperature, relatively little research has focused on understanding how ecosystems respond to changes in precipitation regimes. Here we review predicted changes in global and regional precipitation regimes, outline the consequences of precipitation change for natural ecosystems and human activities, and discuss approaches to improving understanding of ecosystem responses to changing precipitation. Further, we introduce the Precipitation and Ecosystem Change Research Network (PrecipNet), a new interdisciplinary research network assembled to encourage and foster communication and collaboration across research groups with common interests in the impacts of global change on precipitation regimes, ecosystem structure and function, and the human enterprise.},
	keywords = {LTER-KNZ, Community, ecosystem, global change, Precipitation, soil moisture},
	doi = {doi: 10.1641/0006-3568(2003)053[0941:ATROTE]2.0.CO;2},
	author = {Weltzin, J.F. and Loik, M.E. and Schwinning, S. and Williams, D.G. and Fay, P.A. and Haddad, B. and Harte, J. and Huxman, T.E. and Alan K. Knapp and Lin, G. and Pockman, W.T. and Shaw, M.R. and Small, E. and M.D. Smith and Tissue, D.T. and Zak, J.C.}
}
