FUNCTIONAL ROLE OF MOSS BIOCRUST IN DISTURBED SEMIARID SHRUBLANDS OF NORTH-EASTERN PATAGONIA, ARGENTINA.

Biocrusts are key biotic components of arid and semi-arid ecosystems worldwide. In the semi-arid ecosystems of north-eastern Patagonia, the moss biocrust is present both beneath shrubs and in intershrub spaces. In this study we ran a series of field and greenhouse trials aimed at quantifying the moss biocrust cover at sites that differed in grazing and/or shrub mechanical (chaining) disturbance and evaluating its seed entrapping capacity, and its effect on the superficial water balance and grass seedling growth. Grazing or the combined effect of grazing and chaining impacted negatively on the moss biocrust cover. The presence of moss biocrust facilitated seed entrapment and increased the seed density of perennial grasses in the soil seed bank, improved the superficial water balance, and enhanced grass seedling growth. In conclusion, in the semi-arid shrublands in north-eastern Patagonia, the moss biocrust appeared vulnerable to grazing and shrub mechanical disturbance, and it showed functional roles that may facilitate seedling establishment for perennial grasses. [ABSTRACT FROM AUTHOR]