EVIDENCE AND ECOLOGICAL EFFECTS OF HYDRAULIC LIFT IN POPULUS EUPHRATICA

doi:10.3773/j.issn.1005-264x.2009.06.012

Abstract

Abstract:

Aims In the Tarim River Basin of China, desert riparian forest vegetation grows despite the stresses of high temperature and aridity. The species have deep roots that absorb soil water, but a more important reason may be the hydraulic lift (HL) of species. Our aims are to explore whether HL exists in desert riparian vegetation and to determine its ecological impacts.
Methods We studied the HL of Populus euphratica, an important species of desert riparian forest, in September 2008. We used heat ration method (HRM) sap-flow monitoring sensors to measure sap velocity in roots of three trees during four days. Meteorological factors, including wind speed, air relative humidity, leaf temperature and surface temperature, were monitored by a recording weather station. We concurrently sampled and analyzed soil water content by the drying method at six soil depths.
Important findings The sap velocity of tap roots was positive day and night. In contrast, sap flows of lateral roots reversed at night. Soil water content in the subsoil was higher than topsoil in 0-120 cm soil depth and increased with reversed sap flow of lateral roots at night, especially in the 60-120 cm soil depth (soil water content was 28%-38% greater at 4:00 than that at 16:00. Leaf surface vapor pressure deficit can critically affect sap velocity in lateral roots. Hydraulic redistribution has commonly been associated with arid or strongly seasonal environments; our findings prove it also occurs in an extremely arid region of middle Asia.

Key words: Tarim River, hydraulic lift, root sap flow, soil water content

HAO Xing-Ming, CHEN Ya-Ning, LI Wei-Hong, Guo Bin, ZHAO Rui-Feng. EVIDENCE AND ECOLOGICAL EFFECTS OF HYDRAULIC LIFT IN POPULUS EUPHRATICA[J]. Chin J Plant Ecol, 2009, 33(6): 1125-1131.

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URL: https://www.plant-ecology.com/EN/10.3773/j.issn.1005-264x.2009.06.012

https://www.plant-ecology.com/EN/Y2009/V33/I6/1125

Figures/Tables 5

Fig. 1 Sap flow velocity (Vh) in the tap root of Populus euphraticaduring 10 Sept. to 22 Sept. a, b and c respresent the diurnal and nocturnal variation of three trees in four days, respectively

Fig. 2 Sap flow velocity (Vh) in the lateral root of Populus euphraticaduring 10 Sept. to 22 Sept. a, b and c respresent the diurnal and nocturnal variation of three trees in four days, respectively. Data O, S, a, y is the address of sensors that were installed in the lateral roots of the tree

Fig. 3 Average soil water content in six soil depth of three soil profile (n=48) The soil water content was monitored during four days in every soil profile

Fig. 4 The average soil water content at different time and soil depth of three soil profile (n=12) The soil water content was monitored during four days in every soil profile

Table 1 Correlation analysis between root sap velocity of Populus euphraticaand meteorological factors

		风速 Wind speed (m·s^-1)	相对湿度 Air relative Humidity (%)	叶面温度 Leaf temperature (℃)	地表温度 Surface temperature (℃)	水汽压亏缺Vapor pressure deficit (kPa)
主根 Tap root	相关系数	0.462^**	-0.614^**	0.624^**	0.655^**	0.610^**
	Pearson correlation	0.000	0.000	0.000	0.000	0.000
	n	288	288	288	288	288
侧根 Lateral root(O)	相关系数	0.112	-0.648^**	0.653^**	0.646^**	0.692^**
	Pearson correlation	0.057	0.000	0.000	0.000	0.000
	n	288	288	288	288	288
侧根 Lateral root (S)	相关系数	0.559^**	-0.643^**	0.635^**	0.606^**	0.679^**
	Pearson correlation	0.000	0.000	0.000	0.000	0.000
	n	288	288	288	288	288
侧根 Lateral root (a)	相关系数	0.028	-0.553^**	0.619^**	0.637^**	0.680^**
	Pearson correlation	0.636	0.000	0.000	0.000	0.000
	n	287	287	287	287	288
侧根 Lateral root (y)	相关系数	0.234^**	-0.477^**	0.456^**	0.442^**	0.481^**
	Pearson correlation	0	0	0	0	0.000
	n	288	288	288	288	288

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