Dune Blowouts as Microbial Hotspots and the Changes of Overall Microbial Activity and Photosynthetic Biomass Along with Succession of Biological Soil Crusts.

Biological soil crust (BSC) constitutes a consortium of cyanobacteria, algae, lichen, mosses, and heterotrophic microorganisms, forming a miniature ecosystem within the uppermost soil layer. The biomass of different organisms forming BSC and their activity changes along with succession. Previous studies focused primarily on BSC in hyper-arid/arid regions, whereas the ecophysiology of BSC in temperate climates is still not well recognized. In order to determine changes in overall microbial activity and photosynthetic biomass in BSC at different stages of the succession of inland sandy grasslands, we analyzed dehydrogenase activity and determined the content of photosynthetic pigments. We also compared these parameters between BSC developed on the dune ridges and aeolian blowouts in the initial stage of succession. Our study revealed a significant increase in both photosynthetic biomass and overall microbial activity in BSC as the succession of inland shifting sands progresses. We found that chl a concentration in BSC could be considered a useful quantitative indicator of both the presence of photoautotrophs and the degree of soil crust development in warm-summer humid continental climates. The photosynthetic biomass was closely related to increased microbial activity in BSC, which suggests that photoautotrophs constitute a major BSC component. Dune blowouts constitute environmental niches facilitating the development of BSC, compared to dune ridges. High biomass of microorganisms in the dune blowouts may be associated with a high amount of organic material and more favorable moisture conditions. We conclude that deflation fields are key places for keeping a mosaic of habitats in the area of shifting sands and can be a reservoir of microorganisms supporting further settlement of dune slopes by BSC.

Clonal integration helps Psammochloa villosa survive sand burial in an inland dune.

• Rhizomatous clonal plants frequently colonize and stabilize dunes on sea and lake shores, and in inland deserts and desertified areas, where sand burial is common. To date, little attention has been paid to how clonal integration affects their ability to withstand sand burial. • In an inland dune Psammochloa villosa ramets were buried under 0, 20, 40 and 60 cm of sand, and the rhizomes at the edges of the 50 × 50 cm2 treatment quadrats were either severed or left connected. • With increasing burial depth the surviving ramets of P. villosa decreased markedly both in number and in size (number of leaves and above-ground biomass). In the connected quadrats, however, sand burial resulted in significantly smaller decreases than in the severed quadrats of the number, but not in size, of the surviving P. villosa ramets. • We conclude that clonal integration increased the ability of P. villosa to withstand sand burial, and that P. villosa could emerge from deep burial probably by elongating vertical structures with the help of the energy imported from the connected, unburied ramets.