Synergistic Effects of Land Cover, Rain and Fog Seasonality, and Interannual Precipitation Variability
Global Change Biology (2009), doi: 10.1111/j.1365-2486.2009.01985.x Water inputs across a tropical montane landscape in Veracruz, Mexico: synergistic effects of land cover, rain and fog seasonality, and interannual precipitation variability ALEXANDRA G. PONETTE-GONZA´ LEZ*, KATHLEEN C. WEATHERSw and LISA M. CURRANz *Yale School of Forestry & Environmental Studies, 195 Prospect Street, New Haven, CT 06511, USA, wCary Institute of Ecosystem Studies, PO Box AB, Millbrook, NY 12545, USA, zStanford University, 450 Serra Mall Bldg 50, Stanford, CA 94305, USA Abstract Land-cover change can alter the spatiotemporal distribution of water inputs to mountain ecosystems, an important control on land-surface and land-atmosphere hydrologic fluxes. In eastern Mexico, we examined the influence of three widespread land-cover types, montane cloud forest, coffee agroforestry, and cleared areas, on total and net water inputs to soil. Stand structural characteristics, as well as rain, fog, stemflow, and throughfall (water that falls through the canopy) water fluxes were measured across 11 sites during wet and dry seasons from 2005 to 2008. Land-cover type had a significant effect on annual and seasonal net throughfall (NTF o0 5 canopy water retention plus canopy evapora- tion; NTF 40 5 fog water deposition). Forest canopies retained and/or lost to evaporation (i.e. NTFo0) five- to 11-fold more water than coffee agroforests. Moreover, stemflow was fourfold higher under coffee shade than forest trees. Precipitation seasonality and phenological patterns determined the magnitude of these land-cover differences, as well as their implications for the hydrologic cycle. Significant negative relationships were found between NTF and tree leaf area index (R2 5 0.38, Po0.002), NTF and stand basal area (R2 5 0.664, Po0.002), and stemflow and epiphyte loading (R2 5 0.414, Po0.001).
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