Canopy conductance in a two‐storey Siberian boreal larch forest, Russia. Issue 6 (18th May 2014)

• Record Type: Journal Article
• Authors: Xue, Bao‐Lin; Li, Zhanling; Yin, Xin‐An; Zhang, Tieliang; Iida, Shin'ichi; Otsuki, Kyoichi; Ohta, Takeshi; Guo, Qinghua
• Is Part Of: Hydrological processes. Volume 29:Issue 6(2015:Mar.)
• Page Start: 1017
• Page End: 1026
• Publication Date: 2014-05-18
• Subjects: Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.10213
• Languages: English
• ISSNs: 0885-6087

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>A larch forest in eastern Siberia was characterized by the presence of two distinct storeys, the overstorey with a small leaf area index (LAI) and a dense understorey with a relatively large LAI. To understand the roles of the overstorey and understorey in forest–atmosphere water exchange, canopy conductance (<italic>G<sub>c</sub></italic>), a critical parameter used in determining the energy and mass exchange, was calculated on the basis of latent heat flux above the overstorey and understorey, measured separately. Results showed that <italic>G<sub>c</sub></italic> for the overstorey (<italic>G<sub>co</sub></italic>) and understorey (<italic>G<sub>cu</sub></italic>) experienced different seasonal fluctuations. <italic>G<sub>co</sub></italic> was smaller than <italic>G<sub>cu</sub></italic> during periods of leaf expansion and leaf fall and showed an increasing trend until 1 month after the onset of leaf expansion. In contrast, a sharp decrease in <italic>G<sub>co</sub></italic> was observed immediately before onset of leaf fall. Furthermore, <italic>G<sub>co</sub></italic> was slightly larger than <italic>G<sub>cu</sub></italic> during the fully foliated period. A simple model using solar radiation and vapour pressure deficit (<italic>D</italic>) as inputs successfully reproduced the <italic>G<sub>c</sub></italic> in fully foliated periods with acceptable accuracy. Furthermore, both the understorey and overstorey in this study have a large reference <italic>G<sub>c</sub></italic> (<italic>G<sub>c</sub></italic> at <italic>D</italic> = 1 KPa) than their counterparts of other boreal forests and would not be able to sustain a constant leaf–soil water potential difference as <italic>D</italic> increases. We speculated that this confers the forest with an advantage allowing it to be able to sustain carbon assimilation during large <italic>D</italic> days and thus provides for the survival of the ecosystem during the short growing season at this site. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>