Species-specific transpiration responses to intermediate disturbance in a northern hardwood forest

TitleSpecies-specific transpiration responses to intermediate disturbance in a northern hardwood forest
Publication TypeJournal Article
Year of Publication2014
AuthorsMatheny AM, Bohrer G, Vogel CS, Morin TH, He L, Frasson RPrata de M, Mirfenderesgi G, Schäfer KVR, Gough CM, Ivanov VY, Curtis PS
JournalJournal of Geophysical Research: Biogeosciences
Paginationn/a - n/a
Date Published12/2014

Intermediate disturbances shape forest structure and composition, which may in turn alter carbon, nitrogen, and water cycling. We used a large-scale experiment in a forest in northern lower Michigan where we prescribed an intermediate disturbance by stem-girdling all canopy-dominant early successional trees to simulate an accelerated age-related senescence associated with natural succession. Using three years of eddy covariance and sap flux measurements in the disturbed area and an adjacent control plot, we analyzed disturbance induced changes to plot level and species-specific transpiration and stomatal conductance. We found transpiration to be ~15% lower in disturbed plots than in unmanipulated control plots. However, species-specific responses to changes in microclimate varied. While red oak and white pine showed increases in stomatal conductance during post-disturbance (62.5 and 132.2%, respectively), red maple reduced stomatal conductance by 36.8%. We used the hysteresis between sap flux and vapor pressure deficit to quantify diurnal hydraulic stress incurred by each species in both plots. Red oak, a ring porous anisohydric species, demonstrated the largest mean relative hysteresis, while red maple, bigtooth aspen, and paper birch, all diffuse porous isohydric species, had the lowest relative hysteresis. We employed the Penman-Monteith model for LE to demonstrate that these species-specific responses to disturbance are not well captured using current modeling strategies, and that accounting for changes to leaf area index (LAI) and plot microclimate are insufficient to fully describe the effects of disturbance on transpiration.