Bryological and Lichenological Section/ABLS
Coe, Kirsten K , Sparks, Jed P .
What’s the frequency, Syntrichia? Quantifying desert moss response to changes in precipitation regime.
Due to the delicate hydrological balance of arid regions, shifts in precipitation regime (including changes to rainfall frequency and intensity) may play a large role in determining desert plant growth, distribution, and survival under future climate scenarios. In arid zones of the Southwest US, some of the most ecologically important organisms are found in biological soil crusts (BSCs), soil-surface communities consisting of cyanobacteria, lichens, and moss. BSCs increase water-holding capacity of soil, prevent erosion, aid in seedling establishment, and often are the primary nitrogen source for plants. Ascertaining the vulnerability and response of BSC organisms to potential changes in precipitation regime is therefore essential in predicting arid ecosystem response to global change. Crust moss may be particularly sensitive to changes in water availability since they are dependent on hydration for carbon (C) acquisition and growth, and because the rehydration phase of each wet-dry cycle is associated with significant respiratory losses. The present study sought to 1) examine the physiological response (in terms of net C gain or loss) of the common BSC moss Syntrichia caninervis to an array of rainfall event sizes; then 2) determine the degree to which rainfall frequency affects C gain per event. Rainfall size had a significant effect on net C gain (P<0.05). Specifically, moss receiving 1/4 average rainfall amount suffered net loss of C per event because respiratory losses during the rehydration phase were not compensated for during the wet, photosynthetically active phase. In all other precipitation amounts (up to 4x average), moss achieved a net positive C balance, though this affect plateaued following exceptionally large rainfall amounts. Overall, current data suggest that future climate scenarios involving smaller, high frequency events may cause moss decline due to a progressively negative seasonal C balance, and larger events interspersed by drought may be more favorable.
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1 - Cornell University, Ecology and Evolutionary Biology, E146 Corson Hall, Ithaca, NY, 14850, USA
2 - Cornell University, Ecology and Evolutionary Biology, E409 Corson Hall, Ithaca, NY, 14850, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Magpie B/Cliff Lodge - Level B
Date: Monday, July 27th, 2009
Time: 1:30 PM