J. For. Sci., 2018, 64(7):319-329 | DOI: 10.17221/49/2018-JFS

Soil water potential determines the presence of hydraulic lift of Populus euphratica Olivier across growing seasons in an arid desert regionOriginal Paper

Fei WANG^1,2, Yilu XU³, Xiaodong YANG^*,1,2, Yanju LIU³, Guang-Hui LV^1,4, Shengtian YANG²

¹ Key Laboratory of Oasis Ecology, Urumqi, China

² Institute of Resources and Environment Science, Xinjiang University, Urumqi, China

³ Global Centre for Environmental Remediation, University of Newcastle, Newcastle, Australia

⁴ Institute of Arid Ecology and Environment, Xinjiang University, Urumqi, China

Hydraulic lift (HL) of deep-rooted plants is a water adaptation phenomenon to extreme drought conditions which would subsequently improve the survival of shallow-rooted plants in an arid desert area. There is an ongoing debate on whether the difference in water potential between plant roots and soils determine the presence of HL, thus considerable research efforts are needed to improve our understanding. In this study, we used the Ryel model and comparative analysis to determine the changes in soil water potential (SWP), the soil layer of obtaining water from plant roots (SLOW), the amount water released from plant roots into soils, and the total amount of release water of HL (H_T) of five stratified soil layers at different depths (i.e. 0-10, 10-40, 40-70, 70-100 and 100-150 cm) across plant growing season (i.e. June, August and October). The results showed that SLOW always appeared in the lowest SWP soil layer, and that lowest SWP differed among soil layers. The lowest SWP soil layer and SLOW shifted from shallow to deep soil layers across the growing seasons. Additionally, H_T decreased across the growing seasons. Fine root biomass decreased in shallow whereas increased in deep soil layers across growing seasons. Our results proved the water potential difference among soil layers determined the presence of HL in an arid desert region. The changes in water potential difference among soil layers might shift the lowest SWP soil layer from shallow to deep soil layers, and as a consequent decrease H_T across plant growing seasons.

Keywords: deep-rooted plants; extreme drought environment; fine roots distribution; soil layers

Published: July 31, 2018  Show citation