Grazing or Not Grazing: Implications for Ecosystem Services Provided by Biocrusts in Mediterranean Cork Oak Woodlands

Abstract

AbstractLivestock grazing is one of the most common practices in managed woodlands affecting the abundance and diversity of plant and soil communities. While grazing effects have been studied thoroughly in vascular plants, little is known about grazing consequences for soil lichens and mosses (“biocrusts”) in managed woodlands. However, these complex communities have critical contributions to soil functioning in drylands. We evaluated grazing effects on biocrust abundance and functional composition in Mediterranean cork‐oak woodlands under long‐term grazing and after 7 and 17 years of grazing exclusion. We found four main groups in the region regarding the functional trait ‘growth form’: fruticose and foliose lichens, and short and tall mosses. Each group presented different water absorption and retention capacity, and showed group‐specific effects on soil water and temperature. Fruticose lichens were the most sensitive group to grazing, decreasing dramatically in cover with grazing (~7 times). Also, this group presented higher water retention capacity (~19 h), together with a consistent reducing effect on soil temperature along the grazing gradient (up to 0·9 °C). The shift in biocrust abundance and functional composition under grazing pressure has direct consequences in microclimate regulation, and is likely to influence other ecosystem processes such as CO2 fixation, soil surface protection and habitat provision. In particular, microclimate regulation may affect cork‐oak regeneration processes, which is one of the main concerns in managed woodlands. Copyright © 2016 John Wiley & Sons, Ltd.