【作者】 奚如春；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育学， 2006， 博士

【摘要】 树体木质部导管空穴、栓塞及其组织水容特征反映了树体内水分的传输效率与存储功能。研究并阐明它们的发生规律及其与蒸腾耗水的协同关系,可以进一步探索并揭示树木的蒸腾耗水规律及其内部调节机制,为树木水分生态经济管理提供理论依据和技术指导。本文以油松、侧柏和元宝枫三个树种为研究对象,采取野外实地观测与实验室测定相结合的技术路线,采用热扩散树干边材液流测定技术、导管空穴化声发射检测技术、木质部栓塞脆弱性冲洗恢复技术和树体水容特征的含水量与水势测定技术,系统地研究了木质部空穴和栓塞的发生与恢复规律及其树体组织水容特征。研究结果表明,参试树种木质部空穴和栓塞的发生为经常性的突发型事件。油松、侧柏和元宝枫在试验期间,导管空穴化发生的最大现实枝条水势分别为-0.8 MPa、-1.0 MPa和-0.5 MPa;其木质部空穴化声发射频率集中在190 KHz～300 KHz的频谱带上;幅度集中在30～70dB的区间上,以30～50dB的中低幅度事件为主,能量以0～50mv*us的事件居多。栓塞化发生的临界水势分别为-0.85 MPa、-2.05 MPa和-0.11 MPa,一天中6:00和18:00时栓塞程度较低,10:00～14:00时栓塞程度较高。空穴和栓塞化的发生规律是,白天比夜间大;旱季(6月)比雨季(8月)大;蒸腾速率越大,空穴和栓塞发生的频度越高;枝条水势越低,空穴和栓塞越严重。枝条和顶部树干的空穴发生的频度比树体其他部位大;参试树种中元宝枫空穴和栓塞程度最大;油松次之;侧柏最小。在自然生长环境中,空穴和栓塞可以得到适度地修复。树体组织具有保持和储存水分的作用,不同组织的相对水容不尽相同。油松叶片相对含水量为80±5%,组织中自由水和束缚水的比例为1:3.5,叶比水容为0.3382 cm-2.MPa-1,枝条水容为0.2657 g.cm-3.MPa-1,树体水容为13.025 kg.MPa-1;侧柏叶片相对含水量为75±5%,组织中自由水和束缚水的比例为1:2.8,叶比水容为0.2591 cm-2.MPa-1,枝条水容为0.2899 g.cm-3.MPa-1,树体水容为17.611 kg.MPa-1;元宝枫叶片相对含水量为85±5%;组织中自由水和束缚水的比例为1:20,叶比水容为4.7074 cm-2.MPa-1,枝条水容为0.4001 g.cm-3.MPa-1,树体水容为8.955 kg.MPa-1;侧柏树体组织的保水性最好,树体水容最大,油松次之,元宝枫最差;在同一树种中,树干水容值最大,枝叶次之。树干上部茎段水容值要比下部的大;上部水容也比下部的变化明显。当蒸腾作用增强时,树体组织的储存水首先释放满足蒸腾的需求;当蒸腾作用更多还原

【Abstract】 The characteristic of xylem conduit cavitation and embolism and water capacitance reflect the efficiency of water transportation and the function of water storage in tree species. By studying on their characteristic and expounding the coordination relationship with the water consumption, we may further explore and promulgate the laws of water consumption and their internal controlling mechanisms in tree species. It was aimed at to provide a theoretical foundation and technique instructor for the water management of tree species ecological and economically in forestry.The paper was studied on the modulation mechanisms of water consumption in three tree species (Pinus tabulaeformis, Platycladus orientalis, Acer truncatum)of xylem conduits cavitation and embolism and water capacitance. The studies were carried out the technique route by experiments on-farm and in laboratory on different scales. The advanced techniques of the world have been adopted in the projects. The thermal dissipation probe method (TDP) has been used for measuring the sap flow of tree. The acoustic emission (AE) method has been adapted to check and measure the wave parameter of acoustics emission from the xylem conduits cavitation. The flashing method has been adopted for measuring the percentage loss of hydraulic conductivity (PLC) of embolism. The water content and its potential method have been adopted for measuring the water capacitance of tree tissues. The researches work has been achieved synchronization and systematization.The research result was explained the characteristics of occurrence and refills of xylem cavitation and embolism and water capacitance, and the cooperativeness controlling mechanisms on the water consumption in three tree species.The results indicated that while the xylem cavitation occurs, the maximums water potential of branch of Pinus tabulaeformis , Platycladus orientalis, and Acer truncatum are respectively as follow: -0.8MPa、-1.0MPa and -0.5MPa. The acoustic emission frequency spectrum scope of the xylem cavitation concentrates in 190 KHz ~ 300 KHz. The acoustic emission amplitude scope concentrates in 30 ~ 70dB, and the primarily events scope were in 30 ~ 50dB. The acoustic emission energy is in the majority event by 0 ~ 50mv*us.While the embolism occurs, the critical water potential of branch of Pinus tabulaeformis, Platycladus orientalis and Acer truncatum appearance respectively for -0.85 MPa、-2.05 MPa and -0.11MPa. The degree of embolism is low at the 6:00 and 18:00, and it is severity during the daytime from 10:00 to 14:00. Because of the average water potential of branch appearance frequently below -1.0MPa in trees growing under the naturally condition, the xylem cavitation and embolism occur frequently and paroxysmal in the three sample tree species.The xylem cavitation and embolism occurs more frequently during the daytime than that of during更多还原