Foggy days and dry nights determine crown‐level water balance in a seasonal tropical montane cloud forest |
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Authors: | SYBIL G. GOTSCH HEIDI ASBJORNSEN FRISO HOLWERDA GREGORY R. GOLDSMITH ALEXIS E. WEINTRAUB TODD E. DAWSON |
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Affiliation: | 1. Department of Biology, Franklin and Marshall College, , Lancaster, PA, 17603 USA;2. Department of Natural Resources and the Environment, University of New Hampshire, , Durham, NH, 03824 USA;3. Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, , Ciudad de México, DF, 04510 México;4. Department of Integrative Biology, University of California at Berkeley, , Berkeley, CA, 94720 USA;5. School of Forestry and Environmental Studies, Yale University, , New Haven, CT, 06511 USA |
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Abstract: | The ecophysiology of tropical montane cloud forest (TMCF) trees is influenced by crown‐level microclimate factors including regular mist/fog water inputs, and large variations in evaporative demand, which in turn can significantly impact water balance. We investigated the effect of such microclimatic factors on canopy ecophysiology and branch‐level water balance in the dry season of a seasonal TMCF in Veracruz, Mexico, by quantifying both water inputs (via foliar uptake, FU) and outputs (day‐ and night‐time transpiration, NT). Measurements of sap flow, stomatal conductance, leaf water potential and pressure–volume relations were obtained in Quercus lanceifolia, a canopy‐dominant tree species. Our results indicate that FU occurred 34% of the time and led to the recovery of 9% (24 ± 9.1 L) of all the dry‐season water transpired from individual branches. Capacity for FU was independently verified for seven additional common tree species. NT accounted for approximately 17% (46 L) of dry‐season water loss. There was a strong correlation between FU and the duration of leaf wetness events (fog and/or rain), as well as between NT and the night‐time vapour pressure deficit. Our results show the clear importance of fog and NT for the canopy water relations of Q. lanceifolia. |
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Keywords: | Quercus lanceifolia canopy ecophysiology canopy microclimate environmental drivers of transpiration evaporative demand fog heat pulse technique Mexico sap flow seasonality |
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