植物水分利用策略研究进展

Advances in studies on plant water use strategy

关键词:  水分利用策略  稳定同位素  水分来源  水分再分配  植物功能型  二元或三元线性混合模型

Key words:  water use strategy  stable isotope  water resource  hydraulic redistribution  plant functional type  two-or three-compartment linear mixing model

摘要:

水分是影响植物生长发育的重要因子之一。地球上大多数生态系统中的植物都会经历一个降水相对稀少的干旱季节,植物在不同的季节与不同的生态系统中究竟如何利用水分,利用哪些水分去获得生存,成为一个人们关注的问题。在过去的20年,稳定同位素技术在植物生态学中的应用得到了稳定长足的发展。因为陆地植物(少数排盐种类除外)在水分吸收过程中不发生同位素分馏,因此可以利用δD与δ¹⁸O数据进行水分获取方式的研究。对植物木质部水分以及其潜在水源的稳定同位素进行分析,并参考土壤水势、叶片水势、土壤含水量等数据,同时运用二元或三元混合模型,可以定量确定植物的水分利用来源。大量的研究表明,不同功能型、生长阶段、季节的植物以及不同物种往往具有不同的水分利用策略。

Abstract:

Water is one of the most important factors for plants'growth. Plant would undergo a dry season which precipitation was less than wet reason in almost ecosystems in the world. How to use water and what water to use for plants to survive in different seasons and ecosystems became a matter of people concerns. The use of stable isotope techniques in plant ecological research had grown steadily during the past decades. It was easy to apply δD and δ¹⁸O data to water acquisition studies because there was no isotopic fractionation during water uptake by terrestrial plants except some salt-excluding plant species. By analyzing hydrogen and oxygen isotope composition of plant xylem water and available plant water sources,the contributions of the sources to plant could be determined quantitatively using two-or three-compartment linear mixing model. Applying isotope techniques,coupled with other ecological or physiological measurements became a useful way to link the water sources used by plants to other aspects of their water relation. Mixing model had many disadvantages when the sources were more than three. Recently,a set of papers had provided guidelines for the issue. For many species,the water sources varied with seasons,and plants with different functional types and life stages had different water use strategies. Also,different species had different water use strategies.