科尔沁沙地丘间低地樟子松人工林水分利用来源的稳定同位素解析  

Stable isotopic analysis on water utilization sources of Pinus sylvestris var.mongolica plantations in inter-dune lowland in Horqin Sandy Land

作　　者：方杰[1,2] 魏雅芬[1,2] 刘帅[1,3] 赵学勇[4] 李胜功[1] 

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京100101 [2]中国科学院研究生院,北京100049 [3]农业部草原监理中心,北京100125 [4]中国科学院寒区旱区环境与工程研究所,兰州730000

出　　处：《生态学杂志》2011年第9期1894-1900,共7页Chinese Journal of Ecology

基　　金：国家自然科学基金项目(30770339)资助

摘　　要：20世纪50年代以来,樟子松(Pinus sylvestris var.mongolica)在中国北方干旱半干旱地区沙地广泛引种。近年来一些早期引种的樟子松人工林出现了早衰现象。分析生境水分条件变化、判断樟子松采取何种水分利用策略对于认识其早衰现象很有裨益。因此,本研究利用稳定同位素示踪技术,研究了科尔沁沙地东南缘固定沙丘丘间低地30年生樟子松人工林的水分来源及其利用的季节动态,分析了降水和土壤水分变化对樟子松水分利用的影响,阐明了樟子松与伴生植物(黄柳Salix gordeieril)在水分来源方面的异同。结果表明,樟子松及其主要伴生植物黄柳枝条水的稳定18O同位素组成(δ18O)存在明显的季节变化;樟子松的水分来源主要来自20～40cm或更深土层;樟子松和主要伴生植物黄柳之间存在明显的水分竞争,后者比樟子松先行利用最近较强降水(如降水量>10mm),从而影响樟子松水源的补给。本研究对于揭示沙地樟子松衰退与水分利用策略的关系具有重要意义。Mongolian pine （Pinus sylvestris var. mongolica ） has been widely planted on the sandy land in arid and semi-arid areas of North China since the 1950s, but some Mongolian pine forests planted in the 1950s are subject to decline. To examine the variations of habitat water supply and the water utilization strategies of the forests is of significance to understand the mechanisms of the decline. By means of stable isotope analysis, this paper studied the water sources and their seasonal utilization dynamics of Mongolian pine forests planted in the early 1980s in an inter-dune lowland of stabilized sand dune located in southeastern edge of Horqin Sandy Land, analyzed the effects of the variations of precipitation and soil moisture on the water utilization of the forests, and discussed the similarities and differences of Mongolian pine and its companion understory shrubs （e. g. , Salix gordejevii） in their water utilization sources. Obvious seasonal variations were observed in the water stable ^18O isotope composition （δ^18O） of the branches of Mongolian pine and its companion understory shrub S. gordejevii during the observation period from May to October 2008. The water utilization sources of Mongolian pine mainly came from 20-40 cm soil layer or even much deeper soil layers, and there existed strong competition for soil water between Mongolian pine and S. gordejevii. S. gordejevii could earlier utilize the late strong precipitation （ 〉10 mm）, giving impact on the water source supply of Mongolian pine. This study had significance for better understanding the decline of Mongolian pine in relation to its water uti- lization strategy on sandy land.

关 键 词：樟子松 水分利用来源 稳定^18O同位素 植物水分关系 

分 类 号：S791.253[农业科学—林木遗传育种]