2.1 | Study Species
We selected four common perennial grass species to be phytometers of soil conditioned by eastern redcedar. We selected two C3and two C4 grasses for this experiment because both photosynthetic pathways are common in North America and frequently co-occur, although they partition dominance along a gradient of temperature at the continental scale (Teeri and Stowe 1976; Stillet al. 2003). Andropogon gerardi (big bluestem) andSchizachyrium scoparium (little bluestem) are common, native warm-season C4 bunchgrasses with ranges that typically overlap in tall- or mixed-grass prairies (Weaver 1954; Wang et al. 2013). Pascopyrum smithii (western wheatgrass) is a common, native cool-season C3 rhizomatous grass that occurs in mixed-grass prairies (Dong et al. 2014). Bromus inermis(smooth brome) is a common, Eurasian cool-season C3rhizomatous grass that has rapidly spread across North American grasslands since its introduction in the late 1800s (Vogel 2004).B. inermis occurs in all contiguous states of the United States. All four grass species can co-occur with each other and with redcedar in portions of their range (Weaver 1942; Burns 1990).