Ecological Responses of Bryophytes to Changing Climate
Brinda, John C. , Stark, Lloyd R. .
Global change and biological soil crusts in the Mojave Desert.
PROJECTED climate change patterns for the Mojave Desert include increases in temperature as well as increased frequency of summer (monsoon) precipitation. These changes are in addition to elevated atmospheric CO2 levels and increases in N deposition due to environmental pollution. In combination, these changes may influence the health and composition of the biological soil crust, which performs several valuable ecosystem functions in arid regions. At the Nevada Desert Research Center (NDRC) intact patches of Mojave desert scrub have been exposed for several years to experimental treatments designed to simulate predicted future conditions. Field treatments at the NDRC include a FACE (Free Air Carbon dioxide Enrichment) site where plants are exposed to elevated CO2 (550 ppm) as well as a separate site where treatments of N supplementation and summer irrigation are carried out. To estimate the responses of the moss component of the crust to these anticipated conditions, patches of the dominant Mojave Desert moss Syntrichia caninervis Mitten were sampled from these experimental treatments. Contrary to expectations, field-collected shoots exhibited lower productivity (length and biomass) after exposure to elevated CO2 compared to shoots grown under ambient CO2 levels. However, shoots grown under elevated CO2 expressed sex more frequently and tolerated repeated cycles of desiccation better than their ambient counterparts. A tradeoff is therefore apparent between productivity and expression/stress tolerance. Under increased monsoon precipitation events, sex expression and regenerational vigor were suppressed relative to control plants. Sex expression was also stimulated by the addition of N in moderate amounts. Increased monsoonal frequency as forecast for the northern Mojave Desert may therefore result in declines in sexual and asexual vigor in Syntrichia. However, this effect may be buffered by the effects of CO2 and N fertilization.
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1 - University of Nevada, Las Vegas, Department of Biological Sciences, 4505 Maryland Parkway, Las Vegas, Nevada, 89154-4004, USA
biological soil crust
Presentation Type: Symposium or Colloquium Presentation
Date: Monday, July 31st, 2006
Time: 10:45 AM