Surface conductance Gs is a significant parameter for indicating the evaporative and photosynthetic properties of a vegetated surface. When comparing Gs values between different observation sites, some studies have used Gsmax and others have used Ĝsmax (where Gsmax is the maximum Gs value measured during the measurement period, and Ĝ smax is the maximum Gs 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 Ĝsmax instead of Ĝsmax when comparing Gs values between different sites. We examined whether both Ĝsmax and Gsmax 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 Ĝsmax for coniferous forests with a projected leaf area index (LAI) of ≥3.0. We examined not only the relationship between h and Ĝsmax but also the relationship between h and Gsmax for coniferous forests with a projected LAI of ≥3.0. Both Ĝsmax and Gsmax decreased with increasing h. However, the relationship between h and Gsmax was less well defined than the relationship between h and Ĝ smax because of biased Gsmax data. Consequently, we conclude that Ĝsma'x is a more appropriate index than Gsmax to represent Gs for sites with different vegetation.
All Science Journal Classification (ASJC) codes
- Water Science and Technology