Shoot Population Dynamics of Beaked Sedge following Cattle Grazing

Abstract

We studied the effect of cattle grazing on shoot density and flux in 4 southwest Montana beaked sedge (Carex rostrato ex With.) stands for 2 years. Forty plots were protected and 40 plots were grazed by cattle in June and September of 1989 and 1990. The effect of grazing vs. no grazing on mean shoot density and emergence varied over time (treatment by time interactionP<O.OOl and P = 0.003, respectively). About 90% of the time by treatment interaction for shoot density occurred from September 1989 through July 1990. Mean shoot density increased more in grazed plots than in ungrazed plots in spring 1990, and remained 12-16% higher during the last 6 months of the study. Mean shoot emergence was 20% greater (P q 0.006) in the grazed than in the ungrazed plots, with the greatest monthly differences occurring after 3 of the 4 grazing treatments. Mean shoot height declined similarly from June 1989 to June 1990 in the grazed and ungrazed plots (6 and 5%, respectively), indicating that productivity per shoot was similar between treatments. Beaked sedge in our study site was tolerant of light to moderate grazing, given adequate regrowth between spring and fall treatments.

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

“…Although some tall montane sedges are relatively unaffected by grazing (Allen and Marlow 1994;McIlroy and Allen-Diaz 2012), our findings better align with results obtained by Clary (1995) and Sørensen et al (2009) who found high elevation and/or high latitude sedges to demonstrate more grazing effects than other vegetation. Stohlgren et al (1989), also working in Sequoia and using experimental clipping, determined that assemblages dominated in part by sedge were more affected than assemblages dominated in part by reed grass.…”

“…Reed grass forms a dense root mat (Botti and Sydoriak 2001), which, in combination with a shoot density six times greater than sedge, should confer some protection from trampling via higher shear strength (Morrocco and Ballantyne 2008;Monz et al 2010). The greater effects of grazing on sedge relative to reed grass in our study were likely also driven in part by soil moisture (Jensen 1985;Marlow et al 1987;Allen and Marlow 1994), which is two to fourteen times greater in sedge than in reed grass in the Sierra (Neuman 1996; Holmquist and Schmidt-Gengenbach unpublished). Higher soil moisture and silt content may have contributed to the observed lower soil strength in sedge, which, coupled with a morphology that may be more easily penetrated, probably influences the observed patterns of hoof punching: conservatively twice as deep in sedge as in reed grass (Neuman 1996).…”

“…Assemblages in these wetter patches may be more easily damaged by grazing, because trampling impacts can be facilitated by moist, less firm substrata (Jensen 1985;Marlow et al 1987;Willat and Sulistyaningsih 1990;Allen and Marlow 1994;Cole 2004;see also Turner 1987;McClaran 1989;Eckrich and Holmquist 2000). Differing responses as a function of vegetation type (Cole 1995a;Cole and Spildie 1998) may be amplified in mountain wetlands as a result of the short growing season, high soil moisture (Nagy and Grabherr 2009) and high level of aquatic-terrestrial connectivity, with many ecological flows passing through the arthropod assemblage (Yi et al 2006;Epanchin et al 2010;Holmquist et al 2011a).…”

“…Bailey (Benedict 1983;Allen and Marlow 1994;Neuman 1996), which provides a structurally distinct habitat: a taller canopy (up to 70 cm vs. ~9 cm, Holmquist et al 2010;2013), broader blades (2-12 mm vs. 1 mm, Botti and Sydoriak 2001), up to twice the productivity of reed grass (Stohlgren et al 1989), lower shoot density, and higher soil silt content (400 vs. 2900 shoots/m 2 , 60 vs. 10% silt, Holmquist and Schmidt-Gengenbach unpublished). Stock graze both sedge and reed grass habitats intensively (Ballenger et al 2012 unpublished report).…”

Use of a Wetland Index to Evaluate Changes in Riparian Vegetation After Livestock Exclusion1

“…Limitations of livestock exclosures include their small size (relative to the larger watershed which influences runoff and sediment yield), haphazard placement, and variable or unknown site histories in terms of livestock activity, which can lead to inconsistent results (Sarr, 2002). Another limitation of many riparian exclosure studies is that the data are from sites on the same stream (Kauffman et al, 1983;Schultz and Leininger, 1990;Allen and Marlow, 1994;Green and Kauffman, 1995;Case and Kauffman, 1997;Dobkin et al, 1998;Clary, 1999;Brookshire et al, 2002) or from adjacent watersheds (Leege et al, 1981), leading to small sample sizes, questions of pseudoreplication, and an inability to extrapolate results to other areas.…”