Abstract Detail



Bryology and Lichenology

Bowker, Matthew [1], Rengifo Faiffer, Maria [1], Antoninka, Anita [1], Belnap, Jayne [2], Duniway, Michael [3], Reed, Sasha C. [3].

Biocrust biodiversity does not provide resistance to perturbation caused by persistent rainfall reduction.

Many drylands of the world are experiencing warming temperatures and increasingly severe droughts. Biological soil crusts (biocrusts) – soil surface-aggregating communities composed of lichens, mosses, and cyanobacteria, among other organisms – are a widespread community type in the world’s drylands and are key contributors to ecosystem function. Although biocrusts tolerate desiccation, biocrust organisms are only active when the soil surface is hydrated, suggesting that their productivity and composition may be sensitive to decreasing duration of soil surface hydration. The biodiversity of biocrusts may also be a factor in their resistance to change, as biodiversity has been hypothesized to confer stability to ecosystems confronted with perturbations such as climate change. We investigated the cumulative effects of eight years of an experimental rainfall reduction that eliminated 30% of the rainfall received using passive rainfall interception shelters. We sampled and characterized the cover of the biocrust community in 25 rainfall interception shelters, each paired with a control plot. The 25 pairs were in turn superimposed on a natural aridity gradient ranging from semi-arid to arid in southeast Utah. Biocrust communities in arid and semiarid regions experienced shifts of similar magnitude and trajectory towards similarity with biocrusts of the most arid climates in the sample. This pattern generally expressed as a decrease in relative abundance of mosses, and an increase in relative abundance of cyanobacterial biocrusts. We found no evidence that greater diversity (Shannon’s index) stabilizes these communities against the perturbation of rainfall reduction. Rather, the more diverse samples were more likely to lose diversity than were less diverse sites, suggesting a movement toward homogenization of the diversity of biocrusts across natural diversity gradients. The rate of species loss was more precipitous in semi-arid samples, which initially had more species, but a negative relationship between initial diversity and diversity loss was also observed in arid climates. These results suggest that biodiversity did not favor resistance to perturbation. Rather initial biodiversity is a predictor of the degree of biodiversity loss that a community might experience when the climate changes.


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1 - Northern Arizona University, School of Forestry, 200 E. Pine Knoll, Box 15018, Flagstaff, AZ, 86011, United States
2 - US Geological Survey, 2290 SW Resource Blvd, Moab, UT, 84532, USA
3 - US Geological Survey, 2290 SW Resource Blvd, Moab, UT, 84532, United States

Keywords:
biological soil crust
Syntrichia
climate change
drought
ecosystem stability.

Presentation Type: Oral Paper
Number: 0001
Abstract ID:381
Candidate for Awards:None


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