Modelling Canopy Actual Transpiration in the Boreal Forest with Reduced Error Propagation

Abstract

The authors have developed a scaling approach to aggregate tree sap flux with reduced error propagation in modeled estimates of actual transpiration () of three boreal species. The approach covers three scales: tree point, single tree trunk, and plot scale. Throughout the development of this approach the error propagated from one scale to the next was reduced by analyzing the main sources of error and exploring how some field and lab techniques, and mathematical modeling can potentially reduce the error on measured or estimated parameters. Field measurements of tree sap flux at the tree point scale are used to obtain canopy transpiration estimates at the plot scale in combination with allometric correlations of sapwood depth (measured microscopically and scaled to plots), sapwood area, and leaf area index. We compared the final estimates to actual evapotranspiration and actual transpiration calculated with the Penman–Monteith equation, and the modified Penman–Monteith equation, respectively, at the plot scale. The scaled canopy transpiration represented a significant fraction of the forest evapotranspiration, which was always greater than 70%. To understand climate change impacts in forested areas, more accurate actual transpiration estimates are necessary. We suggest our model as a suitable approach to obtain reliable estimates in forested areas with low tree diversity.

Plant Adaptation to Global Climate Change

“…The study also emphasized proper use of irrigation management as rainfed wheat is very sensitive to climate change. In a study, a scaling approach was used to measure the variation of scaling factors and their correlation at large scales in the estimation of actual transpiration of three boreal species in a forest [8]. The authors demonstrated that the scaled canopy transpiration signified a considerable fraction of forest evapotranspiration (>70%) and recommend the approach for the proper estimation of actual transpiration in the areas having low tree diversity.…”