Abstract. Understanding patterns of habitat natural recovery after
human-made disturbances is critical for the conservation of ecosystems under
high environmental stress, such as drylands. In particular, the unassisted
establishment of nonvascular plants such as biological soil crusts or
biocrust communities (e.g., soil lichens, mosses and cyanobacteria) in newly
formed habitats is not yet fully understood. However, the potential of
biocrusts to improve soil structure and function at the early stages of
succession and promote ecosystem recovery is enormous. In this study, we
evaluated the capacity of lichen biocrusts to spontaneously establish and
develop on road slopes in a Mediterranean shrubland. We also compared
taxonomic and functional diversity of biocrusts between road slopes and
natural habitats in the surroundings. Biocrust richness and cover, species
composition, and functional structure were measured in 17 road slopes (nine
roadcuts and eight embankments) along a 13 km highway stretch. Topography, soil
properties and vascular plant communities of road slopes were also
characterized. We used Kruskal–Wallis tests and applied redundancy analysis
(RDA) to test the effect of environmental scenario (road slopes vs. natural
habitat) and other local factors on biocrust features. We found that
biocrusts were common in road slopes after ∼20 years of
construction with no human assistance needed. However, species richness and
cover were still lower than in natural remnants. Also, functional structure
was quite similar between roadcuts (i.e., after soil excavation) and natural
remnants, and topography and soil properties influenced species composition
while environmental scenario type and vascular plant cover did not. These
findings further support the idea of biocrusts as promising restoration
tools in drylands and confirm the critical role of edaphic factors in
biocrust establishment and development in land-use change scenarios.
Unassisted establishment of biological soil crusts on dryland road slopes
