胡杨根系水力提升作用的证据及其生态学意义

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

摘要/Abstract

摘要：

生长在塔里木河流域的荒漠河岸林植被虽长期忍受着高温和干旱的威胁, 然而它们却能够一直延续并保存至今。除了植物深根系吸水作用外, 另一个更主要的原因可能就是荒漠河岸林植被存在水力提升的效应。该文采用HRM热比率法茎流仪对3株胡杨(Populus euphratica)主根和侧根的液流速率分别进行了为期4 d的连续监测; 利用自动气象站对微气象因子：风速、空气相对湿度、叶面温度和地表温度进行连续监测; 同时采用了烘干法对不同深度土层在不同时刻的土壤含水率进行了取样分析。试验结果表明：胡杨主根液流在白天和夜间均表现为正值, 相反的, 胡杨侧根液流速率则出现了明显的夜间负向流动。胡杨根系0~120 cm土层土壤水分含量具有下湿上干的变化趋势; 胡杨侧根在夜间发生负向流动后, 土壤含水率显著升高, 尤其在60~120 cm土层中, 4:00土壤含水率上升幅度达到4:00时刻土壤含水率的22%~26%。影响胡杨侧根液流速率的主要气象因子主要是叶面水汽压亏缺。

关键词: 塔里木河, 水力提升, 根系液流, 土壤含水率

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

郝兴明, 陈亚宁, 李卫红, 郭斌, 赵锐锋. 胡杨根系水力提升作用的证据及其生态学意义. 植物生态学报, 2009, 33(6): 1125-1131. DOI: 10.3773/j.issn.1005-264x.2009.06.012

HAO Xing-Ming, CHEN Ya-Ning, LI Wei-Hong, Guo Bin, ZHAO Rui-Feng. EVIDENCE AND ECOLOGICAL EFFECTS OF HYDRAULIC LIFT IN POPULUS EUPHRATICA. Chinese Journal of Plant Ecology, 2009, 33(6): 1125-1131. DOI: 10.3773/j.issn.1005-264x.2009.06.012

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链接本文: https://www.plant-ecology.com/CN/10.3773/j.issn.1005-264x.2009.06.012

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

图/表 5

图1 胡杨主根液流速率(Vh) a、b和c分别代表3棵胡杨各自在4 d时间内的液流速率日变化

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

图2 胡杨侧根液流速率(Vh) a、b和c分别代表3株胡杨各自在4 d时间内的液流速率日变化; 数据系列O, S, a, y则分别表示安装在胡杨侧根的4套传感器

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

图3 不同深度土层中土壤含水率均值变化(n=48) 数据来自3个土壤剖面各自4 d的动态监测

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

图4 不同时间不同土层中土壤含水率均值变化(n=12) 数据来自3个土壤剖面各自4 d的动态监测

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

表1 胡杨根系液流速率(Vh)与主要气象因子的相关分析

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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