CO_2浓度倍增与干旱胁迫对油松(Pinus tabulaeformis)相对分枝级水力结构的影响  

Influences of doubled CO_2 concentration and drought stress on branch hydraulic traits in Pinus tabulaeformis saplings

作　　者：刘娟娟[1] 李吉跃[2] 庞静[1] 

机构地区：[1]北京林业大学省部共建森林培育与保护教育部重点实验室,北京100083 [2]华南农业大学林学院,广州510642

出　　处：《生态学报》2008年第9期4136-4143,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目(30471370);国家教育部博士点基金资助项目(20050022003)~~

摘　　要：在密闭式生长箱内经过13个月高CO2浓度培养的5年生油松(Pinus tabulaeformis)为实验对象,采用改良冲洗法研究了CO2浓度倍增(720μmolmol-1)与干旱胁迫交互作用对油松相对分枝级水力结构参数的影响。通过测定油松不同分枝级的水力结构参数分别在720μmolmol-1CO2和380μmolmol-1CO2(大气现有CO2浓度)浓度下随着干旱胁迫的变化,得出不同分枝级的导水率(Kh)、比导率(Ks)和胡伯尔值(Hv)在2个CO2浓度下均随着干旱胁迫的增加而逐渐下降,叶比导率(Lsc)在720μmolmol-1CO2浓度下随着干旱胁迫的增加非线性变化(0级>2级>1级)不同于380μmolmol-1CO2(0级>1级>2级)。同期干旱胁迫条件下,720μmolmol-1CO2浓度下的Kh、Ks、Lsc和Hv均大于380μmolmol-1CO2且差异显著。根据整株苗木的水势将苗木的水分状况分为4个梯度,在正常水分(-0.45^-0.65MPa)、轻度干旱(-1.15^-0.75MPa)和中度干旱(-1.95^-1.35MPa)胁迫时,3个分枝级均在720μmolmol-1CO2条件下的Kh和Ks较380μmolmol-1CO2增加,说明交互作用能提高导水能力,同时加快水分运输效率。在重度干旱(<-2.80MPa)胁迫时Kh比380μmolmol-1CO2增加,而Ks比380μmolmol-1CO2减小,即交互作用提高了水分运输的安全性,却减少了有效性。Branch hydraulic traits under 720μmolmol^-1CO2 and drought stress were measured by improved flushing method after 5 years Pinus tabulaeformis saplings have been exposed to 720μmolmol^-1 CO2 for 13 months. The results show that hydraulic conductivity （ Kh）, specific conductivity （Ks） and huber value （Hv） in their branch under 720μmolmol^-1 CO2 and 380μmolmol^-1 CO2 concentrations reduce along drought stress, while leaf specific conductivity （Lsc） under 720μmolmol^-1 CO2 declines non-linearly along drought stress. In the same drought stress, Kh, Ks, Lsc and Hv under 720μmolmol^-1CO2 are respectively larger than that under the lower CO2eoneentration and their differences between the two treatments are significant. According to the water potential, the water condition of the trees was divided into four grades. During the normal water（ - 0.45 -- - 0.65MPa）, light drought condition （ - 1. 15 -- - 0.75MPa） and middle drought condition（ - 1.95 -- - 1.35MPa） , the Kh and Ks increase which compared with the plants in the control chamber, which show that the interaction of doubled CO2 concentration and drought stress improve the hydraulic conductivity ability else the water transport efficiency. While in the heavy drought condition（ 〈 -2.80MPa）, Kh increase but Ks decrease compared with the control, which show that the interaction improve the water transport security whereas reduce water transport efficiency. It suggests that the present study focusing on the variation of the hydraulic traits and the key effect of water transport security under elevated CO2 concentration and drought stress would benefit to afforestation in different water condition soil as increasing CO2 concentration.

关 键 词：CO2浓度倍增 干旱胁迫 水势 油松(Pinus tabulaeformis) 相对分枝级 水力结构 

分 类 号：Q945[生物学—植物学]