Plant Responses to an Edaphic Gradient across an Active Sand Dune/Desert Boundary in the Great Basin Desert

Abstract

In arid ecosystems, variation in precipitation causes broad-scale spatial heterogeneity in soil moisture, but differences in soil texture, development, and plant cover can also create substantial local soil moisture heterogeneity. The boundary between inland desert sand dunes and adjacent desert habitats exhibits abrupt changes in soil and vegetation characteristics that may be associated with differences in plant-available water and nutrients. We hypothesized that differences in plant water status between habitats would mirror changes in soil texture and vegetation cover. Because the dunes have higher water availability, we predicted that plants on dunes would have higher plant water potential (C) and be less water use efficient than plants off dunes. We tested these predictions for three species-Psoralidium lanceolatum (a C 3 perennial N-fixing subshrub), Stipa hymenoides (a C 3 perennial bunchgrass), and Salsola iberica (a C 4 annual)-on actively moving desert dunes and adjacent stabilized dunes at Little Sahara Dunes, Utah. Plants on the dunes maintained higher predawn (C pd ) water potentials (>ÿ1.5 MPa) throughout the summer season, whereas off-dune plants were water stressed from July on (C pd < ÿ1:5 MPa). Midday water potential (C md ) generally mirrored C pd . As predicted, off-dune plants were more water use efficient, on the basis of leaf carbon isotope ratios (d 13 C) for the C 3 species. The observed differences in soil particle size, soil water content, and the concomitant effect on soil C likely explain the observed differences in C pd . Soil N was significantly lower on dunes, while soil P was similar across habitats. In contrast, leaf N was similar across habitats, but leaf P was significantly higher on dunes, possibly because of species-specific differences in nutrient relations or differences in habitat nutrient availability. Abrupt changes in water and nutrient availability associated with soil texture are likely to be important selective forces shaping plants' strategies in this and other desert boundary communities.

The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China

“…herbs) and increasing the dominance index of the community (Koerselman and Meuleman, 1996). Among different environmental factors, changes in water availability associated with soil properties are considered to be the most important selective forces, which shape ecosystem stability in hyperarid zones (Rosenthal et al, 2005;Ravi et al, 2010;Feng, 2015). Our study showed that spatial heterogeneity of soil properties was the major driving force for the spatial distribution of vegetation, with SWC1, SWC3 and BD contributing 59.46 % of the total explanation of vegetation variance ( Table 2).…”

Phenotypic selection on leaf water use efficiency and related ecophysiological traits for natural populations of desert sunflowers

“…Helianthus anomalus and H. deserticola are desert annual sunXowers of hybrid origin from the same ancestral parental cross (Schwarzbach and , Gross et al 2003) that diVer in phenology and are endemic to habitats diVering in water and nutrient availability (Rosenthal et al 2005a;Ludwig et al 2006). We asked the following questions: (1) is there direct and indirect selection on integrated leaf WUE, N, area and succulence and (2) is direct selection on WUE consistent with hypothesized drought/dehydration escape and avoidance strategies.…”

Re‐creating Ancient Hybrid Species’ Complex Phenotypes from Early‐Generation Synthetic Hybrids: Three Examples Using Wild Sunflowers

“…Early authors (Stebbins 1957;Grant 1958;Templeton 1980) (McCarthy et al 1995;Buerkle et al 2000). Karyotypic divergence and spatial isolation are well documented in natural hybrid species (Gallez and Gottlieb 1982;Rieseberg 1991;Rieseberg et al 1995;Hirai et al 2000), and most hybrid species occupy habitats that are different or extreme compared with the parental species (Abbott 1992; Arnold 1997;Rieseberg 1997;Schwarzbach et al 2001;Rosenthal et al 2005).…”

“…For example, three natural hybrid sunflower species, Helianthus anomalus, Helianthus deserticola, and Helianthus paradoxus have distinct multitrait phenotypes and occupy very different habitats (Heiser et al 1969;Rosenthal et al 2002Rosenthal et al , 2005Welch and Rieseberg 2002a). Many of the traits that distinguish these species are extreme relative to parental values, and phenotypic selection experiments indicate that some are favored in their native habitats (Lexer et al 2003b;Gross et al 2004;Ludwig et al 2004).…”