干旱胁迫对油松和侧柏水分运输安全性和有效性的影响  

Influences of drought stress on hydraulic safety and efficiency in the saplings of Pinus tabulaeformis and Platycladus orientalis

作　　者：刘娟娟[1,2] 李吉跃[3,2] 张建国[1] 

机构地区：[1]中国林业科学研究院林业研究所,北京100091 [2]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 [3]华南农业大学林学院,广州51064232

出　　处：《生态学报》2010年第9期2507-2514,共8页Acta Ecologica Sinica

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

摘　　要：通过采用改良的冲洗法测定5年生苗木油松(Pinus tabulaeformis)和侧柏(Platycladus orientalis)在不同干旱胁迫时期的水力结构参数,结果表明随着干旱胁迫增加,不同分枝级和茎段所在区域的导水率损失(PLC)增加,比导率(Ks)减少。油松和侧柏在0级,1级和2级分枝级的发生栓塞的水势阈值分别为-0.55、-0.49、-0.43和-0.90、-0.78、-0.74MPa。随着相对分枝级的增加,油松和侧柏的水势阈值增大,栓塞脆弱性变大。非限速区PLC大而Ks小,限速区PLC小而Ks大。油松和侧柏相对分枝级和茎段所在区域的栓塞脆弱性大小为2级>1级>0级,限速区>非限速区,且油松大于侧柏。油松和侧柏在不同干旱胁迫,不同相对分枝级,不同茎段所在区域采取不同的方式来适应由水势降低而引起的栓塞变化。其采取的生态策略包括:保持较高的水分安全性;减轻安全性而对有效性的折衷;同时降低有效性和安全性但不终止任何生产力或树高的组织生长所需水的限制。Hydraulic architecture parameters of 5-year-old saplings of Pinus tabulaeformis and Platycladus orientalis under drought stress were measured using the improved flushing method.The hydraulic architecture of trees is based on differences in the hydraulic properties of the xylem and is characterized by two important functional aspects,hydraulic safety and hydraulic efficiency.The hydraulic efficiency is proportional to the specific conductivity（Ks） of the xylem,while the hydraulic safety describes the resistance of the xylem against embolism formation,which quantized through the percent loss of conductivity（PLC）.The aims were to study the compromises between hydraulic safety and hydraulic efficiency and adaptations by determining the hydraulic architecture parameters changed with drought stress of P.tabulaeformis and P.orientalis,which have different leaf types and ecological strategies,and to search the mechanism influenced the trade-offs.The results showed that PLC increased and Ks decreased in all the ramification and stem segments with increasing drought stress.The water potential thresholds were-0.55,-0.49,-0.43 MPa for P.tabulaeformis and-0.90,-0.78,-0.74 MPa for P.orientalis respectively,in the three categories of branches 0,1 and 2.As the water thresholds increased,embolisms vulnerability was highest in branch 2,followed by branch 1 and branch 0 in both species,and higher in P.tabulaeformis than that in P.orientalis.This may relate to the number of water transportation tissues in different branches or the ability of resistance to the embolism.PLC increased and Ks decreased in non-restrict area stem segment,visa versa in the restrict area.As the PLC reached the maximum,the water potential were-5.08,-4.62,-4.07 and-6.79,-6.40,-6.21 MPa respectively in the three different branches.Therefore,the ecological strategy of P.tabulaeformis and P.orientalis were as much as possible to serve the trunk or lower ramification branch in this phase.The vulnerability was higher in non-restrict area stem segment than

关 键 词：干旱胁迫 水分运输 安全性 有效性 油松 侧柏 

分 类 号：S791[农业科学—林木遗传育种]