Sand movement and vegetation interactions at Mono Lake, California

An improved understanding of the ecological relationships between sand movement and vegetation is needed in arid lands. Across a 96 ha study site encompassing the dune and playa system of Mono Lake, California, I studied the role of vegetation in naturally stabilizing sand, the effect of sand mobility on the plant community, and the mechanisms by which plants tolerate sand burial. Major sand deposition patterns at this site are explained by wind and precipitation patterns and large-scale topography dominated by the presence of a transverse berm. Local measurements of sand movement did not correlate with vegetation cover; instead, dimensionless parameters quantifying plant shape provided the best description of plant characteristics that reduce erosion and sand mobility. Plants associated with regions of low sand movement had a profile area at least 0.75 times as large as their surface area and were shorter than they were wide. Ordination analysis indicated that sand mobility find a moderate effect on the distribution of shrub and herbaceous species in this community, while net levels of sand deposition were less important. Some species clearly tolerated high levels of sand movement. I conducted a field and pot experiment with three of the dominant species of this dune system to examine their survival, patterns of resource allocation, and growth responses to four levels of sand burial. Individuals of Sarcobatus vermiculatus and Distichlis spicata were more tolerant of extreme and repeated levels of burial than were those of Chrysothamnus nauseosus. Plants of all species shifted both biomass and nitrogen resources from belowground to aboveground components in response to burial but only S. vermiculatus altered (reduced) its growth rate. Many of the responses of plants that survived burial, including a high correlation between relative growth rate and new assimilation rate, were consistent with the responses of plants grown in responses of plants that survived burial, including a high correlation between relative growth rate and new assimilation rate, were consistent with the responses of plants grown in conditions of low light. These experiments suggest that despite the harsher environment in deserts, dune plants of arid regions respond to burial in much the same manner as do coastal dune plants. This examination of vegetation that naturally stabilizes sand has produced a template of plant species and shape to guide ecological restoration and sand-dune stabilization efforts in the Great Basin.