Preprint Article Version 1 NOT YET PEER-REVIEWED

Response of Leaf-Level Gas Exchange and Hydraulic Conductance on a Typical Subtropical Tree Species (Osmanthus fragrans) to a Severe Summer Drought

Version 1 : Received: 7 March 2017 / Approved: 8 March 2017 / Online: 8 March 2017 (05:31:31 CET)

How to cite: Zhang, C.; Guan, H.; Li, X.; Han, G.; Zhang, X. Response of Leaf-Level Gas Exchange and Hydraulic Conductance on a Typical Subtropical Tree Species (Osmanthus fragrans) to a Severe Summer Drought. Preprints 2017, 2017030046 (doi: 10.20944/preprints201703.0046.v1). Zhang, C.; Guan, H.; Li, X.; Han, G.; Zhang, X. Response of Leaf-Level Gas Exchange and Hydraulic Conductance on a Typical Subtropical Tree Species (Osmanthus fragrans) to a Severe Summer Drought. Preprints 2017, 2017030046 (doi: 10.20944/preprints201703.0046.v1).

Abstract

Increasing drought frequency and intensity are considered to be a driven factor for recent declines in terrestrial ecosystem productivity. Therefore, knowledge of how tree species respond to drought is critical for modeling and predicting the impacts of climate change on forest and woodland ecosystems. The aim of this study was to evaluate the effects of a severe summer drought on the performance of a subtropical evergreen tree species (Osmanthus fragrans) based on field measurements, including stem water potential, sap flow, and leaf gas exchange. The results show that drought stress posed a significant consequence on leaf gas exchange, and this influence come from combined effect of decreased soil water potential and enhanced vapor pressure deficit (VPD) during the drought period. Leaf transpiration shows a similar behavior to the carbon assimilation in terms of its response to soil moisture condition, but effect of VPD are opposite. Daily maximum water use efficiency shows a parabolic curve in response to soil water potential Ψpd. The threshold of Ψpd for the daily maximum WUE is around -1.5 MPa for WUE. These results provide useful information for understanding ecosystem responses to seasonal droughts in humid climate zones.

Subject Areas

droughts; subtropical humid climate; soil water potential; leaf carbon assimilation; stomatal conductance; water use efficiency; plant hydraulic conductance

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