Data from: Functional diversity regulates the effects of habitat degradation on biocrust phylogenetic and taxonomic diversities

Biocrusts are major contributors to dryland diversity,
functioning and services. However, little is known about how habitat degradation
will impact multiple facets of biocrust diversity and measurable functional
traits. We evaluated changes in taxonomic, functional and phylogenetic diversity
of biocrust-forming lichens along a habitat degradation gradient related to the
presence of linear infrastructure (i.e., a road) and a profound agricultural
driven transformation. To do so, we selected 50 remnants of a Mediterranean
shrubland. We considered several surrogates of habitat quality and causal
disturbance on the various diversity facets of biocrusts by using structural
equation modelling, hypothesizing that habitat degradation primarily affects
functional diversity, which in turn regulates changes in taxonomic and
phylogenetic diversities, and also that taxonomic and phylogenetic diversities
are coupled. Fragment connectivity, distance to linear infrastructure (i.e., a
road) and, particularly, soil fertility (i.e., soil P concentration), had mostly
negative effects on biocrust functional diversity, which in turn affected both taxonomic
and phylogenetic diversities. However, we found no direct effects of habitat degradation
variables on the taxonomic and phylogenetic diversities. We also found that increases
in phylogenetic diversity had a positive effect on taxonomic diversity along
the habitat degradation gradient. Our results indicate that functional
diversity of biocrusts is strongly affected by habitat degradation, which may
profoundly alter their contribution to ecosystem functioning and services.
Furthermore, functional diversity regulates the response of biocrust taxonomic
and phylogenetic diversity to habitat degradation. These findings indicate that
habitat degradation alters and simplifies the diversity of functional traits of
biocrust-forming lichens, leading to biodiversity loss, with important
consequences for the conservation of global drylands biodiversity.