Previous Grazing or Clipping Affects Seed of Indian Ricegrass

Abstract

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Differing Effects of Cattle Grazing on Native and Alien Plants

“…Although the historical importance of bunchgrasses in the California grasslands of pre‐European settlement has been a subject of debate (Wester 1981; Heady 1988; Hamilton 1997; Schiffman 2000), the negative effects of simulated grazing on P. secunda suggest this species was more abundant in California's arid grasslands prior to the initiation of cattle grazing. Other native bunchgrasses, such as Nassella pulchra and Achnatherum hymenoides ( Oryzopsis hymenoides ), are sometimes negatively affected by grazing (Huntsinger et al 1996; Orodho et al 1998) and compete poorly with European grasses (Nelson & Allen 1993; Dyer & Rice 1997; Gerlach et al 1998). Native forbs are also often excluded by invasive European grasses, partially because the European species reduce soil moisture levels (Welker & Menke 1990).…”

“…There were 10 blocks of five treatments: controls (unclipped with mulch left intact), clipped once (late February), clipped twice (late February and early March), clipped three times (late February, early March, and early April), and mulch removed (late February, no clipping of live plants). We applied the treatments in the spring of 1999, 2000, and 2001, and clipping was done 1 cm above ground level (Orodho et al 1998; Kotanen & Bergelson 2000).…”

Defoliation Effects on Reproductive Biomass: Importance of Scale and Timing

“…However, to answer this, one must assess whether or not grazing affects seed viability in addition to numerical production as was done in our study. There is evidence that defoliation history does not influence seed viability (Orodho et al 1998), but whether seeds produced by grazed and ungrazed Yellowstone grasses exhibit similar viability is not known. We suggest that early spring defoliation in Yellowstone National Park's northern winter range has played a role in the persistence of grazed plant communities by maintaining community level seed production.…”

Journal of Range Management, Volume 53, Number 5 (September 2000)

“…However, protection from livestock grazing for more than 50 years did not result in altered seed production in Indian ricegrass (A c h n a t h e r u m hymenoides (Roemer & J.A. Schultes) Barkworth) genotypes taken from grazed or ungrazed sites when these genotypes were grown in a common environment (Orodho et al 1998). A lack of additional data on seed reproduction and the evolution of grazing morphotypes prevents a more integrated understanding of demographic processes that may be affected by the presence of grazing animals.…”