Research Note: Alignment of ElongatedNassella pulchraPlants with Hill-Slope Contours

Abstract

On 10 sloped grassland sites, 175 Nassella pulchra plants were randomly selected and their basal geometry measured. Plants were not circular (p < 0.001) with an average elongation of 30.3% þ 20.7 and 89% of the plants had greater than 10% elongation. Sixty-six percent of the plants had the elongation oriented along the contours. Elongation was correlated with slope steepness (p ¼ 0.003, r 2 ¼ 0.06), but unrelated to the angle the long axis was deflected from the slope fall line (p ¼ 0.21, r 2 ¼ 0.02). This elongation and orientation potentially reduced overland flow compared to circular plants.Nassella pulchra (purple needlegrass), an historically dominant native perennial bunchgrass (Bartolome, Klukkert, and Barry, 1986), has been advocated over exotic annuals as having a longer grazing season (Bentley and Talbot, 1948), providing higher quality forage (Van Dyne and Heady, 1965), promoting wildlife habitat (Elstein, 2004), and resisting invasion (Reever Morghan and Rice, 2005). To decision-makers, many of these attributes have limited supporting evidence, appeal, or financial value. Yet, if N. pulchra has the potential to inhibit erosion=improve water quality (e.g., Atwill, Tate, Pereira, Bartolome, and Nader, 2006) more than its sparse cover indicates, this may offer a quantifiable reason to promote its revegetation and conservation.Hydrological models (commonly used as decision-making tools) incorporate vegetation usually as either uniform cover (e.g., Istanbulluoglu and Bras, 2005;Montaldo, Rondena, Albertson, and Mancini, 2005) or as density (e.g., Collins, Bras, and Tucker, Mancini, 2004). Inclusion of bunchgrasses using cover has been somewhat unsuccessful (Emmerich and Cox, 1992;Weltz, Frasier, and Weltz, 2000) which offers the opportunity to examine bunchgrass characteristics that could improve future models (e.g., Ludwig, Wilcox, Breshears, Tongway, and Imeson, 2005). As the path of water moving down the slope becomes more tortuous (less straight), the flow slows, and the amount of water moved sediment or contaminants

Restoration sites on the Californian coast have different ecological histories that can influence restoration success

“…At some point, its populations increased to the point of being considered a pest, especially since the populations of their predators had decreased (Gordon, 1977;Luckenbach, 1982). More recent works show its role as an ecosystem engineer, supporting the food web through its burrowing activity, and the need for a better management for this species (Lenihan, 2007;McCullough Hennessy et al, 2016) The impacts of the post-European settlement disturbances and recovery have been well studied along the California coast: Fort Baker near Bridgeville (Cooper, 1960); Angelo Preserve, UC NCCRP (Kotanen, 1996(Kotanen, , 1997(Kotanen, , 2004; UC Hopland field station (Heady, 1956); Bodega Bay (Alpert & Maron, 2000;Maron & Jefferies, 2001;Kolb et al, 2002); Tomales Bay (Reynolds et al, 2001;Corbin & D'Antonio, 2004b, a;DiVittorio et al, 2007); Marin county (Huntsinger et al, 1996); Contra Costa county and East Bay (Bartolome & Gemmill, 1981;Huntsinger et al, 1996;Bartolome et al, 2004); Jasper Ridge and Stanford (McNaughton, 1968;Dukes, 2002;Buisson et al, 2008); Santa Clara (Huenneke et al, 1990); Pomponio State Beach Park (Hatch et al, 1999;Fehmi & Bartolome, 2003); Santa Cruz (Hayes & Holl, 2003;Buisson et al, 2006); Monterey county (Robinson, 1971;Knops et al, 1995Knops et al, , 2002Stromberg & Griffin, 1996;Stromberg & Kephart, 1996;Hamilton et al, ...…”

Evaluating the effect of rainfall variability on vegetation establishment in a semidesert grassland

“…Of these categories, establishing vegetation entails the most uncertainty. Vegetation establishment is important for: reducing erosion from both wind and water (Guiterrez and Hernandez 1996 ; De Baets et al 2009 ; Fehmi et al 2008 ), improving public perception by reducing the visual impact (Hands and Brown 2002 ; Svobodova et al 2012 ), allowing for productive reuse of the land for wildlife habitat or livestock grazing (e.g., Steinke and Majak 2010 ), and otherwise reintegrating disturbed lands into the existing landscape. Uncertainty in vegetation establishment comes primarily from reliance on unpredictable rainfall for germination and establishment.…”