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).