Canopy transpiration (E_c) of a 150-year-old Pinus sylvestris L. stand in an inner Alpine dry valley, Tyrol, Austria was estimated throughout two growing seasons 2011 and 2012 by means of xylem sap flow measurements. Although there were prolonged periods of limited soil water availability, E_c did not show a clear trend with respect to soil water availability and averaged 0.4 ± 0.19 mm day⁻¹ under conditions of non-limiting soil water availability and 0.37 ± 0.17 mm day⁻¹ when soil water availability was limited. This is because canopy conductance declined significantly with increasing evaporative demand and thus significantly reduced tree water loss. The growing season total of E_c was 74 mm and 88 mm in 2011 and 2012, respectively, which is significantly below the values estimated for other P. sylvestris forest ecosystems in Central Europe, and thus reflecting a strong adaptation to soil drought during periods of high evaporative demands.

© 2014 Elsevier GmbH

通过木质部汁液流量测量，在 2011 年和 2012 年两个生长季节估计了奥地利蒂罗尔州内阿尔卑斯干旱山谷中一株150 年树龄的樟子松林的冠层蒸腾量 ( E _{c )。}尽管土壤水分可用性有限的时期很长，但在土壤水分可用性非限制条件和 0.37 ± 0.17^毫米/_天^{- 1}当土壤水分供应有限时。这是因为冠层导度随着蒸发需求的增加而显着下降，从而显着减少了树木的水分流失。生长期总计2011 年和 2012 年E _c分别为 74 毫米和 88 毫米，显着低于中欧其他樟子松森林生态系统的估计值，因此反映了在高蒸发需求期间对土壤干旱的强烈适应。

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