title: Foggy days and dry nights determine crown-level water balance in a seasonal tropical Montane cloud forest.
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.
authors.affiliation: Department of Biology, Franklin and Marshall College, PO Box 3003, Lancaster, PA, 17603, USA.
authors.forename: Sybil G
authors.initials: SG
authors.lastname: Gotsch
authors.forename: Heidi
authors.initials: H
authors.lastname: Asbjornsen
authors.forename: Friso
authors.initials: F
authors.lastname: Holwerda
authors.forename: Gregory R
authors.initials: GR
authors.lastname: Goldsmith
authors.forename: Alexis E
authors.initials: AE
authors.lastname: Weintraub
authors.forename: Todd E
authors.initials: TE
authors.lastname: Dawson
mesh_terms: D017753:Ecosystem; D008800:Mexico; D008834:Microclimate; D018515:Plant Leaves / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D029963:Quercus / Q000502:physiology*; D012621:Seasons; D014197:Trees; D014329:Tropical Climate; D014867:Water / Q000502:physiology*; D014887:Weather
chemical_list: D014867:Water
keywords: Mexico; Quercus lanceifolia; canopy ecophysiology; canopy microclimate; environmental drivers of transpiration; evaporative demand; fog; heat pulse technique; sap flow; seasonality