TY - JOUR
T1 - Transpiration from three dominant shrub species in a desert-oasis ecotone of arid regions of Northwestern China
AU - Ji, Xibin
AU - Zhao, Wenzhi
AU - Kang, Ersi
AU - Jin, Bowen
AU - Xu, Shiqin
N1 - Publisher Copyright:
Copyright © 2016 John Wiley & Sons, Ltd.
PY - 2016/12/15
Y1 - 2016/12/15
N2 - Conservation management for the water dependent desert-oasis ecotone in arid northwest China requires information on the water use of the dominant species. However, no studies have quantified their combined water use or linked species composition to ecotone transpiration. Here, the water use of three dominant shelterbelt shrubs (Haloxylon ammodendron, Nitraria tangutorum, and Calligonum mongolicum) within an ecotone was measured throughout the full leaf-out period for three shrub species from 30 May to 16 October 2014, with sap flow gauges using the stem heat balance approach. Species-specific transpiration was estimated by scaling up sap flow velocities measured in individual stems, to stand area level, using the frequency distribution of stem diameter and assuming a constant proportionality between sap flow velocity and basal cross-sectional area for all stems. The mean peak sap flux densities (Jsn) for H. ammodendron, N. tangutorum, and C. mongolicum, were 40.12 g cm−2 h−1, 71.33 g cm−2 h−1, and 60.34 g cm−2 h−1, respectively, and the mean estimated daily area-averaged transpiration rates (Tdaily) for the same species were 0.56 mm day−1, 0.34 mm day−1, and 0.11 mm day−1. The accumulative stand transpiration was approximately 140.8 mm throughout the measurement period, exceeding precipitation by as much as 42.1 mm. Furthermore, Tdaily of these shrubs appeared to be much less sensitive to soil moisture as compared to atmospheric drivers, and the relationship between Jsn and atmospheric drivers was likely uninfluenced by soil moisture regimes in the whole profile (to 1-m depth), especially for H. ammodendron and C. mongolicum. Results indicate that these shrubs may use deep soil water recharged by capillary rise, or may directly access shallow groundwater. This study provides quantitative data offering important implications for ecotone conservation and water and land resource management.
AB - Conservation management for the water dependent desert-oasis ecotone in arid northwest China requires information on the water use of the dominant species. However, no studies have quantified their combined water use or linked species composition to ecotone transpiration. Here, the water use of three dominant shelterbelt shrubs (Haloxylon ammodendron, Nitraria tangutorum, and Calligonum mongolicum) within an ecotone was measured throughout the full leaf-out period for three shrub species from 30 May to 16 October 2014, with sap flow gauges using the stem heat balance approach. Species-specific transpiration was estimated by scaling up sap flow velocities measured in individual stems, to stand area level, using the frequency distribution of stem diameter and assuming a constant proportionality between sap flow velocity and basal cross-sectional area for all stems. The mean peak sap flux densities (Jsn) for H. ammodendron, N. tangutorum, and C. mongolicum, were 40.12 g cm−2 h−1, 71.33 g cm−2 h−1, and 60.34 g cm−2 h−1, respectively, and the mean estimated daily area-averaged transpiration rates (Tdaily) for the same species were 0.56 mm day−1, 0.34 mm day−1, and 0.11 mm day−1. The accumulative stand transpiration was approximately 140.8 mm throughout the measurement period, exceeding precipitation by as much as 42.1 mm. Furthermore, Tdaily of these shrubs appeared to be much less sensitive to soil moisture as compared to atmospheric drivers, and the relationship between Jsn and atmospheric drivers was likely uninfluenced by soil moisture regimes in the whole profile (to 1-m depth), especially for H. ammodendron and C. mongolicum. Results indicate that these shrubs may use deep soil water recharged by capillary rise, or may directly access shallow groundwater. This study provides quantitative data offering important implications for ecotone conservation and water and land resource management.
KW - arid climate
KW - ecohydrology
KW - phreatophyte shrub
KW - sap flow
KW - water use
UR - http://www.scopus.com/inward/record.url?scp=85006108603&partnerID=8YFLogxK
U2 - 10.1002/hyp.10937
DO - 10.1002/hyp.10937
M3 - Article
AN - SCOPUS:85006108603
SN - 0885-6087
VL - 30
SP - 4841
EP - 4854
JO - Hydrological Processes
JF - Hydrological Processes
IS - 25
ER -