What is the best way to represent surface conductance for a range of vegetated sites?

✍ Scribed by Hikaru Komatsu; Norifumi Hotta; Tomonori Kume

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 109 KB
• Volume: 21
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/hyp.6674

✦ Synopsis

Abstract

Surface conductance G~s~ is a significant parameter for indicating the evaporative and photosynthetic properties of a vegetated surface. When comparing G~s~ values between different observation sites, some studies have used G~smax~ and others have used Ĝ~smax~ (where G~smax~ is the maximum G~s~ value measured during the measurement period, and Ĝ~smax~ is the maximum G~s~ value obtained with a vapour pressure deficit (VPD) of ≥ 1·0 kPa during the measurement period).

In this study, we demonstrate a clear justification for using Ĝ~smax~ instead of G~smax~ when comparing G~s~ values between different sites. We examined whether both Ĝ~smax~ and G~smax~ lead to the same conclusions in classifying vegetated sites. Komatsu (2003b) [Hydrological Processes 17: 2503–2512] reported a clear relationship between canopy height h and Ĝ~smax~ for coniferous forests with a projected leaf area index (LAI) of ≥ 3·0. We examined not only the relationship between h and Ĝ~smax~ but also the relationship between h and G~smax~ for coniferous forests with a projected LAI of ≥ 3·0.

Both Ĝ~smax~ and G~smax~ decreased with increasing h. However, the relationship between h and G~smax~ was less well defined than the relationship between h and Ĝ~smax~ because of biased G~smax~ data. Consequently, we conclude that Ĝ~smax~ is a more appropriate index than G~smax~ to represent G~s~ for sites with different vegetation. Copyright © 2007 John Wiley & Sons, Ltd.