02539nas a2200217   4500008004100000245010700041210006900148300001200217490000800229520184000237653001802077653002002095653001902115653002602134653001802160653002302178100001502201700001602216700002302232856006602255       2016                        eng d00aComparative ecohydrology between Cornus drummondii and Solidago canadensis in upland tallgrass prairie0 aComparative ecohydrology between Cornus drummondii and Solidago   a267-2760 v2173 a<p>Woody species expansion threatens to transform mesic North American grasslands. In many tallgrass prairies of the central Great Plains with deep soil, Cornus drummondii develops large shrub islands that exhibit non-linear increases in cover through time. Reliance on soil moisture from deeper soil depths facilitates constant gas exchange rates and minimizes competition with coexisting herbaceous species. Conversely, C. drummondii growth and expansion in thin-soil locations is stochastic and these locations are typically free of large shrub islands. At the Konza Prairie in northeast Kansas, USA, we compared the ecohydrology of C. drummondii individuals to a similar-sized forb (Solidago canadensis) in thin-soil locations with varying fire frequency (4-, 20-year) and grazer abundance (bison present or absent). Gas exchange rates were relatively constant for C. drummondii, while S. canadensis declined across the growing season. For S. canadensis, maximum photosynthesis (Amax), daytime transpiration (E), and stomatal conductance (gs) were higher on ungrazed than grazed treatments. Nighttime E rates were higher in C. drummondii, accounting for over 10 % of the daytime E rates. The water source used did not vary among contrasts, with the majority of water uptake occurring from 30 cm depth for both species. These results highlight a unique ecohydrology of C. drummondii (static water flux, and high rates of nighttime E) compared to a similar-sized, co-occurring forb. Whereas C. drummondii is infrequent in thin-soil locations, the climate conditions occurring during measurements were not a likely filter restricting persistence. Rather, drier conditions or interactions with other grassland disturbances are likely required to restrict C. drummondii encroachment in the thins-soil locations of tallgrass prairie.</p>10aKonza Prairie10aMesic grassland10aphotosynthesis10aStable water isotopes10aTranspiration10awoody encroachment1 aMuench, A.1 aO'Keefe, K.1 aNippert, Jesse, B.  uhttps://link.springer.com/article/10.1007%2Fs11258-016-0567-z