Sap flow measurements to estimate overstory transpiration of Pinus patula plantations within a seasonally dry montane cloud belt in central Veracruz, Mexico (2008-2010)

Data collected to study transpiration rates of Pinus patula (Mexican weeping pine). Datapackages available: whole-tree and stand level sap flow (units: liters per unit of time and liter per square meter of ground per unit of time) at 60 min resolution, from Nov 2008 to May 2010. Sap flow was measured at breast height in the main stem using heat pulse sensors (Heat Ratio Method) encompassing two dry seasons and a wet season. Two stands at different developmental stage were under study: a young reforestation (YREF; 10-year-old) near canopy closure (n = 8 trees) and a mature heterogeneous stand (MREF) dominated by P. patula with the age of canopy trees ranging from 17 to >60 years (n = 10 trees). Sap flow was scaled to the whole tree level from measurements at three depths into the sapwood and a characterization of the radial profile of sap velocity (see for details: Alvarado-Barrientos et al. (2013), Agricultural and Forest Meteorology 168:108-119). Whole-tree level sap flow was subsequently scaled to the stand for YREF by averaging across all sample trees and multiplying by stand density as the stand was even-aged and tree spacing was fairly homogeneous. Given the more complex structure of MREF, scaling up to the stand was based on quantifying sapflow for trees representing the distribution in DBH classes in the stand. Stand level sap flow data were analyzed for different specific questions including quantification of stand level annual transpiration rates, and the effect of fog and high nighttime VPD on transpiration rates (see knb-enchilada.meteo1 for corresponding meteorological data). Reserach articles derived from these and related data are presented in the PhD Dissertation by M. Susana Alvarado-Barrientos ("Plant water use and canopy-fog interactions across a land use change trajectory of pasture to pine reforestation in a seasonally dry tropical montane cloud belt" 2013. Earth and Environmental Sciences, University of New Hampshire).