What does the changing climate hold for biocrusts?
Climate change with its many expressions threatens the stability of
ecological systems, yet difficulties arise when predicting different
ecological consequences without understanding the impacts arid
communities experience under changing conditions. Although biocrusts are
generally composed of stress tolerant species, they are still sensitive
to physical compression, frequent sub-optimal hydration periods, and
hydration periods with high temperatures (Reed et al . 2012;
Ferrenberg et al . 2015; Doherty et al . 2018). Ongoing
climate perturbations and land use practices that result in soil
disturbance will further cause habitat unsuitability and we will witness
a strong decline in the cover of biocrusts globally (RodrÃguez-Caballeroet al . 2018). Studies focused on climate disturbances, ours
included, indicate not only a decline in biocrust cover in the future,
but also the retrogression of the developmental states of these
communities. However, we demonstrated that biocrusts could broadly
maintain the integrity of their species composition after long-term
climatic disturbance, while having noticeable structural shifts with
greater impact on mosses.
The diversity of species in biocrusts has been documented to influence
productivity and multifunctionality but has not been studied with
respect to its influence on community resistance. Although we limited
our study to the diversity of lichens and mosses, more diverse
communities seem to be more susceptible to experiencing a greater change
in their composition. Press perturbations are also driving biocrusts to
less functional states, in which the decrease in richness will directly
impact the dynamics of the ecosystem. The combined impacts on
well-developed and richer biocrust communities calls for urgent
conservation actions on standing dryland biodiversity and the mitigation
of climate change impacts to assure the preservation of their ecosystem
functions and services. In addition, adding knowledge on long-term
effects of climate change on the community maturity and composition of
Southwest dryland communities will facilitate future climate projections
of ecosystem function and feedbacks to the climate system.
Acknowledgements
The project was supported by the National Science Foundation Dimensions
of Biodiversity Program grants awarded to MAB (1638966), KKC (1638955),
BDM (1638956), MJO (1638972), LRS (1638943), KMF (1638996) as well as
the US Geological Survey Ecosystems Mission Area. MCRF was also
supported by the Canyonlands Research Center Graduate Research Scholars
Programs. We thank Erika Geiger and Ed Grote for data support and L.
Bailey for her support in the field data collection. This research
comprised part of the doctoral dissertation of MCRF. Any use of trade,
product or firm names is for descriptive purposes only and does not
imply endorsement by the U.S. Government.