Variations in the coverage of biological soil crusts along an aridity gradient in the central-west Argentina

Abstract

Biological soil crusts (biocrusts) play a fundamental role in arid and semiarid areas of South America. Nevertheless, little attention has been paid to the distribution and coverage of them, and studies about biocrusts are still scarce especially in Argentina. The goal of this contribution was to analyze the coverage of biocrusts and their main biological components along an aridity gradient in the central-west Argentina. The coverage percentage of each component was recorded using the point-quadrat method in transects along a gradient consisting of three bioclimatic sites: semiarid, arid, and hyperarid. The diversity of components in biocrusts was recorded in each studied site. The semiarid site had the highest record of species followed by the arid and hyperarid site. The hyperarid site had the highest record of cyanobacteria species and the semiarid site of lichens. The arid site was the system with the highest coverage of biocrusts followed by the hyperarid site. The semiarid site presented the lowest value of coverage. Cyanobacteria were the dominant group in the hyperarid site. Additionally, cyanobacteria together with lichens were dominant in the arid site. The coverage of the studied organisms showed variations in the semiarid site. Results found in this contribution supported the idea that the coverage and organisms in biocrusts showed changes along an aridity gradient. Differences about the dominance of species and the coverage of biocrusts could be reflected in the functioning role of them in the different sites.