Hypotheses.

<p>At low rainfall levels, absolute cover and density of perennial grasses is greater in sub-canopy (solid line) than interspace (dashed line) microsites (i.e., positive grass-shrub relationship). As rainfall increases, the relationship reverses; at greater rainfall levels, absolute cover and density of perennial grasses are greater in interspace than sub-canopy microsites (i.e., negative grass-shrub relationship).</p

Type 3 fixed effects estimates for <i>P</i>. <i>secunda</i>, <i>E</i>. <i>elymoides</i>, and <i>P</i>. <i>spicata</i> analyses.

<p>F statistics (F), degrees of freedom (df), and p values (p) are given for each of the 3 main fixed effects: rainfall, sagebrush microsite (canopy, edge, interspace), and microsite*rainfall interaction.</p

Site means and predicted regression lines (with 95% confidence bands) for <i>P</i>. <i>spicata</i> for a) density (number of plants / m²), b) height (cm), and c) basal width (cm) across rainfall and shrub microsites.

<p>All regression lines were not significantly different from 0. Sites are distributed across a rainfall gradient, and at each site cover was assessed for three microsites (canopy, edge, and interspace).</p

Least square means for <i>E</i>. <i>elymoides</i> density (plants/m²) at 25^th, 50^th, 75^th, and 90^th percentile values of rainfall.

<p>Error bars represent standard error of the mean; different letters denote means that differ significantly from one another within each percentile of rainfall.</p

Least square means for <i>E</i>. <i>elymoides</i> basal width (cm) at 25^th, 50^th, 75^th, and 90^th percentile of rainfall.

<p>Error bars represent standard error of the mean; different letters denote means that differ significantly from one another within each percentile of rainfall.</p

Site means and predicted regression lines (with 95% confidence bands) for <i>E</i>. <i>elymoides</i> for a) density (number of plants / m²), b) height (cm), and c) basal width (cm) across rainfall and shrub microsites.

<p>Regression lines with slope significantly different from zero are denoted with (†). Sites are distributed across a rainfall gradient, and at each site cover was assessed for three microsites (shrub canopy, edge, and interspace).</p

Sampling sites in UT, ID, and NV.

<p>Sites were located in five major land resource areas (geographically associated land units) across the Great Basin, USA (inset). Maps were created in ArcMap v10.1. Major land resource area spatial data was obtained from the Natural Resources Conservation Service’s Geospatial Data Gateway (<a href="https://gdg.sc.egov.usda.gov/" target="_blank">https://gdg.sc.egov.usda.gov/</a>).</p

Mean percent cover and predicted regression lines (with 95% confidence bands) for a) <i>P</i>. <i>secunda</i> (n = 29 sites), b) <i>E</i>. <i>elymoides</i> (n = 27 sites) and c) <i>P</i>. <i>spicata</i> (n = 10 sites).

<p>Regression lines with slope significantly different from zero are denoted with (†). Sites are distributed across a rainfall gradient, and at each site cover was assessed for two microsites (shrub canopy and interspace). <i>E</i>. <i>elymoides</i> and <i>P</i>. <i>spicata</i> data are back-transformed.</p

Plant densities, gaps, and soil cover.

<p>Means ±1 SE for perennial grass densities by species, sagebrush (<i>Artemisia tridentata</i> ssp. <i>wyomingensis</i>) densities by size class, inter-plant gaps by total length in each gap size class, and soil cover types across three herbivore treatments: 1) Total exclosure plots that exclude both cattle and wild ungulates, 2) Cattle exclosure plots that exclude only cattle, and 3) Control plots where no large herbivores are excluded.</p><p>^a #/ha</p><p>^b total cm</p><p>^c # pin hits (of 20)</p><p>Plant densities, gaps, and soil cover.</p

NMDS results.

<p>Non-metric Multidimensional Scaling (NMDS) results depicting sample points and convex hulls for (a) three herbivore treatments and (b) three pastures in relation to plant species community composition (n = 125 frequency frames per sample point); and (c-e) treatments within individual pastures (n = 25 frequency frames per sample point). Total, Cattle, and Control treatments exclude, respectively, all large herbivores, cattle only, and no large herbivores.</p