胡杨根系水力提升作用的证据及其生态学意义  

EVIDENCE AND ECOLOGICAL EFFECTS OF HYDRAULIC LIFT IN POPULUS EUPHRATICA

作　　者：郝兴明[1,2] 陈亚宁[1,2] 李卫红[1,2] 郭斌[1,2] 赵锐锋[1,2] 

机构地区：[1]中国科学院新疆生态与地理研究所,乌鲁木齐830011 [2]中国科学院绿洲生态与荒漠环境重点实验室,乌鲁木齐830011

出　　处：《植物生态学报》2009年第6期1125-1131,共7页Chinese Journal of Plant Ecology

基　　金：中国科学院知识创新工程重要方向项目(KZCX2-YW-Q10-3-3);国家自然科学基金(40701011和40871059)

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4d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0～120cm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60～120cm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。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.

关 键 词：塔里木河 水力提升 根系液流 土壤含水率 

分 类 号：Q948[生物学—植物学]