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- Title
Gas-exchange and sap flow measurements of Salix viminalis trees in short-rotation forest.
- Authors
Cienciala, Emil; Lindroth, Anders
- Abstract
Water use efficiency was estimated for Salix viminalis (L.) trees growing in the field under non-limiting nutrient and soil water conditions. Gas exchange measurements were used to calculate conductances to water vapour and CO fluxes. Sap flow was measured using a tree-trunk heat balance technique. Transpiration and CO uptake were estimated using an open-top ventilated chamber enclosing the whole foliage of a tree. Mesophyll conductance to CO (gm ′) was modelled as a non-linear function of global radiation ( R) and air temperature. Stomatal conductance (gs) was modelled as a function of R and vapour pressure deficit (δe). The models explained 92 and 88% of the variation of gm′ and gs, respectively. The net photosynthetic capacity of S. viminalis was high compared to a number of broad-leaved species. The optimum temperature for photosynthesis was found to be 20.5 °C. The instantaneous water use efficiency (WUE) was high: it reached a maximum of 15 g (CO) kg (HO) for small rates of E, and decreased down to 9 g kg for peak rates of E. Water use efficiency calculated from above-ground biomass measurements and from net carbon assimilation revealed a specific carbon allocation pattern during the season. The combination of gas exchange and dendrometric measurements was found to be a promising approach of non-destructive estimation of root/shoot allocation of carbon.
- Publication
Trees: Structure & Function, 1995, Vol 9, Issue 5, p295
- ISSN
0931-1890
- Publication type
Article
- DOI
10.1007/BF00202020