Biocrust structure responds to soil variables along a tropical scrubland elevation gradient

Abstract

Biocrusts are composed of diverse organisms including bryophytes, lichens, archaea, bacteria, cyanobacteria, microfungi, and green algae. While biocrusts are distributed worldwide, most of our knowledge comes from temperate regions, and scarce information is available from tropical regions. We aimed to: i) generate the first map of potential areas of occurrence of biocrust in Ecuador, ii) describe the structure of biocrust components along an elevation gradient predicted by our map analysis to support biocrusts. Our maps identified 9145 km2 as potential area for the occurrence of biocrusts, which represents 18% of Ecuadorian drylands. Our study site was located in mountain shrubland in southeastern Ecuador. Species richness increased with elevation and species composition was significantly different among elevation levels. The abundance of species forming biocrusts was related to several soil variables, including pH and fine texture. Our results provide insights into the importance of soil variables as drivers of biocrust composition and abundance in the tropics. Moreover, the information generated in this study could be useful in assigning conservation priorities to Ecuadorian drylands. Thus, our results help fill current gaps in our knowledge of biocrusts and add to the scant literature dealing with these organisms in tropical drylands.