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Abstract Detail


Limm, Emily [1], Simonin, Kevin [2], Dawson, Todd [3].

Foliar uptake of fog prevents water deficit and induces hydraulic redistribution from fern crowns to the soil in Polystichum munitum.

Fog presence changes ecosystem water balance by altering the direction and magnitude of water flux between the soil and vegetation. In the coast redwood forest ecosystem of Northern California, maritime fog provides a direct water subsidy during summer when soil water deficit and plant demand for water are highest. Using glasshouse experiments, we evaluated the effects of both increased humidity and leaf wetting from nocturnal fog exposure on the physiology and the directionality of water movement within the crown of the dominant understory fern, Polystichum munitum. We found that nocturnal leaf wetness provides sufficient hydration to increase leaf water potential by approximately 0.3 MPa following fog exposure even as soil water deficit increases. This improved plant water status can double stomatal conductance to water vapor, allowing the maintenance of carbon gain during soil drought. Polystichum munitum exhibits foliar uptake at an average rate of 0.12 mmol H2O m-2 s-1 ± 0.04 SD and if plant crowns experience sustained leaf wetness overnight, the fog water absorbed exceeds the internal water storage capacity of the fern and hydraulic redistribution causes shoot-to-root water efflux into the soil of 35.4 g H2O per m-2 24 hr-1 ± 18.4 SD. When this empirical efflux rate was scaled to the P. munitum canopy across the latitudinal gradient throughout the redwood forest ecosystem, we found that the high leaf area present in the most northern P. munitum populations has the potential to redistribute up to 100 g H2O m-2 of ground surface area following a single nocturnal fog event. Shoot-to-root water efflux by P. munitum not only increases soil water availability locally for its own re-acquisition when fog abates, but may also affect other soil-related processes like plant-plant interactions and plant-microbe interactions in the fern rhizosphere.

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1 - University of California, Santa Cruz, Ecology and Evolutionary Biology, 1156 High Street, A308 Earth and Marine Sciences Bldg., Santa Cruz, CA, 95064, USA
2 - University of California, Berkeley, Integrative Biology, 3060 Valley Life Sciences Bldg. #3140, Berkeley, CA, 94720, USA
3 - University of California, Berkeley, Department of Integrative Biology, 3060 Valley Life Sciences Bldg #3140, Berkeley, California, 94720, USA

redwood forest
water relations
hydraulic transport
Western sword fern
Polystichum munitum.

Presentation Type: Oral Paper:Papers for Topics
Session: 30
Location: 551B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 9:15 AM
Number: 30004
Abstract ID:370

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