<abstract xmlns="http://www.w3.org/1999/xhtml"><p>Rainfall pulses can significantly drive the evolution of the structure and function of semiarid ecosystems, and understanding the mechanisms that underlie the response of semiarid plants to rainfall is the key to understanding the responses of semi–arid ecosystems to global climatic change. We measured sap flow in the branches and stems of shrubs (<italic>Caragana korshinskii</italic> Kom. and <italic>Hippophae rhamnoides</italic> Linn.) using sap flow gauges, and studied the response of sap flow density to rainfall pulses using the “threshold–delay” model in the Chinese Loess Plateau. The results showed that the sap flow began about 1 h earlier, and increased twofold after rainfall, compared to its pre-rainfall value. The sap flow increased significantly with increasing rainfall classes, then gradually decreased. The response of sap flow was different among rainfall, species, position (branch and stem) during the pulse period, and the interactive effects also differed significantly (<italic>P</italic> &lt; 0.0001). The response pattern followed the threshold–delay model, with lower rainfall thresholds of 5.2, 5.5 mm and 0.7, 0.8 mm of stem and branch for <italic>C. korshinskii</italic> and <italic>H. rhamnoides</italic>, demonstrating the importance of small rainfall events for plant growth and survival in semi–arid regions.</p></abstract>

Rainfall pulses can significantly drive the evolution of the structure and function of semiarid ecosystems, and understanding the mechanisms that underlie the response of semiarid plants to rainfall is the key to understanding the responses of semi–arid ecosystems to global climatic change. We measured sap flow in the branches and stems of shrubs (Caragana korshinskii Kom. and Hippophae rhamnoides Linn.) using sap flow gauges, and studied the response of sap flow density to rainfall pulses using the “threshold–delay” model in the Chinese Loess Plateau. The results showed that the sap flow began about 1 h earlier, and increased twofold after rainfall, compared to its pre-rainfall value. The sap flow increased significantly with increasing rainfall classes, then gradually decreased. The response of sap flow was different among rainfall, species, position (branch and stem) during the pulse period, and the interactive effects also differed significantly (P < 0.0001). The response pattern followed the threshold–delay model, with lower rainfall thresholds of 5.2, 5.5 mm and 0.7, 0.8 mm of stem and branch for C. korshinskii and H. rhamnoides, demonstrating the importance of small rainfall events for plant growth and survival in semi–arid regions.

Sap flow in response to rainfall pulses for two shrub species in the semiarid Chinese Loess Plateau

College of Water Conservancy & Environmental, Zhengzhou University, Science road 100, Zhengzhou, China.

Journal of Hydrology and Hydromechanics

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Rainfall pulses can significantly drive the evolution of the structure and function of semiarid ecosystems, and understanding the mechanisms that underlie the...

Sap flow in response to rainfall pulses for two shrub species in the semiarid Chinese Loess Plateau

Published Online: May 12, 2016

Page range: 121 - 132

Received: Dec 09, 2015

Accepted: Apr 12, 2016

DOI: https://doi.org/10.1515/johh-2016-0023

Keywords
Rainfall pulses, Sap flow, Meteorological factors, Loess Plateau,

© 2016 Shengqi Jian et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Sap flow in response to rainfall pulses for two shrub species in the semiarid Chinese Loess Plateau

Published Online: May 12, 2016

Page range: 121 - 132

Received: Dec 09, 2015

Accepted: Apr 12, 2016

DOI: https://doi.org/10.1515/johh-2016-0023

KeywordsRainfall pulses, Sap flow, Meteorological factors, Loess Plateau,

© 2016 Shengqi Jian et al., published by De Gruyter Open

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
Rainfall pulses, Sap flow, Meteorological factors, Loess Plateau,