Abstract Detail

Bryology and Lichenology

Brencher, George [1], Rengifo Faiffer, Cristina [2], Antoninka, Anita [2], Bowker, Matthew [2], Stark, Lloyd [3], Coe, Kirsten [1].

Effects of increased aridity on recovery from desiccation in the biocrust moss Syntrichia caninervis.

Dryland ecosystems constitute 41% of the global land area and are inhabited by two billion people. Climate change is predicted to strongly affect drylands through changes in precipitation regime and events like severe heat-waves and extreme storms; therefore, it is important to understand how dryland organisms will respond to such changes. Biocrusts are soil communities of mosses, fungi, lichens, and cyanobacteria found in nearly all drylands that possess important and diverse ecosystem functions. In North American drylands, mosses of the genus Syntrichia are keystone organisms that live in biocrust communities. Syntrichia mosses exhibit desiccation-tolerance (DT), a set of traits that allows them to lose all cellular water, then resume metabolism and photosynthesis once hydrated. In the face of increasing aridity, DT in Syntrichia is likely determine patterns of physiological performance and survival. In this study, populations of Syntrichia caninervis in intact biocrust communities on the Colorado Plateau were exposed to a 30% rainfall reduction treatment for 8 years, and photosynthetic recovery following desiccation was compared to populations grown in ambient conditions. In the first phase of our analysis, moss desiccated in the field was rehydrated in the lab, and its photosynthetic recovery was assessed using chlorophyll fluorescence. Then, the same shoots were dehydrated again at a relative humidity of either 75% or 35% (above and below a hypothesized physiological threshold for recovery of 50%), and their photosynthetic recovery was assessed a second time. Compared to control mosses, field-dried mosses exposed to the rainfall reduction recovered at a faster rate, and exhibited higher efficiency of photosystem II following 24 hours of rehydration. On average, lab-dried mosses recovered to pre-dry photosystem II efficiency levels very quickly, irrespective of relative humidity treatment, and rainfall reduction had no distinguishable effect on their recovery. Overall, our results suggest that Syntrichia may be able to acclimate its DT to drought conditions, which could improve its ability to survive changing Southwestern precipitation regimes.

1 - Middlebury College, Biology
2 - Northern Arizona University
3 - University Of Nevada, Las Vegas, School Of Life Sciences, Las Vegas, NV, 89154, United States

Keywords:
bryophyte
climate change
Precipitation
Dryland
photosynthesis.

Presentation Type: Oral Paper
Session: BRY1, Bryology
Location: Tucson G/Starr Pass
Date: Tuesday, July 30th, 2019
Time: 10:30 AM
Number: BRY1008
Abstract ID:837
Candidate for Awards:A. J. Sharp Award