Spatial variation in sap flow velocity in semiarid region trees: Its impact on stand-scale transpiration estimates

Tomonori Kume, Kyoichi Otsuki, Sheng Du, Norikazu Yamanaka, Yi Long Wang, Guo Bin Liu

Research output: Contribution to journalArticle

47 Citations (Scopus)

Abstract

In this study, we aimed to clarify spatial variations in xylem sap flow, and to determine the impacts of these variations on stand-scale transpiration (E) estimates. We examined circumferential and radial variations in sap flow velocity (F d) measured at several directions and depths in tree trunks of black locust (Robinia pseudoacacia) and native oak (Quercus liaotungensis), both of which have ring-porous wood anatomy, in forest stands on the Loess Plateau, China. We evaluated the impacts of circumferential variations in F d on stand-scale transpiration estimates using a simple scaling exercise. We found significant circumferential variations in F d in the outermost xylem in both species (coefficients of variation = 20-45%). For both species, F d measured at the inner xylem was smaller than that of the outermost xylem and the F d at the depth of > 10 mm was almost zero. The simple exercises showed that omitting circumferential variations in F d affected the E estimate by 16-21%, which was less than the effects of omitting within-tree radial and tree-to-tree variations in F d in both species. These results suggest that circumferential variations in F d can be a minor source of error for E estimates compared with within-tree radial and tree-to-tree variations in F d, regardless of the significant circumferential variations.

Original languageEnglish
Pages (from-to)1161-1168
Number of pages8
JournalHydrological Processes
Volume26
Issue number8
DOIs
Publication statusPublished - Apr 15 2012

All Science Journal Classification (ASJC) codes

  • Water Science and Technology

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