作 者 ：李志波;李平衡;王权;*;徐璐;
期 刊 ：植物研究 2013年 33卷 (3)期 页码：274-281
关键词：叶大小；小枝大小；生物量分配；末端小枝；异速生长；荒漠植被；
Keywords:leaf size, twig size, biomass allocation, terminal twigs, allometry, desert plants,
摘 要 ：荒漠植被柽柳和梭梭的叶退化，以绿色的同化枝来进行光合作用，目前对于荒漠植物的小枝和其支撑的非形态学意义上的叶（即绿色同化枝）之间的关系的研究非常缺乏，本文以柽柳和梭梭的末端小枝为对象，给出了小枝尺度上的生物量和同化枝面积估算方程，并对小枝的茎、同化枝生物量分配格局以及小枝大小和同化枝面积大小之间的关系进行研究，旨在探讨2种植物适应荒漠生境的小枝-同化枝大小关系的差异。结果显示：以茎径为自变量，利用幂函数构建的枝生物量和同化枝面积估算方程具有较高的相关性，柽柳方程的幂指数要比梭梭大，表明随着茎径增大，柽柳同化枝面积和枝重的增长幅度大于梭梭。柽柳枝重与茎重、同化枝重以及茎重和同化枝重之间均呈现极显著的等速生长的关系，小枝大小对同化枝、茎的生物量分配没有影响；而梭梭枝重与同化枝重、茎重以及茎重和同化枝重间均存在极显著的异速生长关系，随着小枝增大，茎在生物量分配中更占优势，这表明梭梭对于起到支撑和水分传输作用的茎的需求更大。柽柳的同化枝面积与茎截面积、茎重分别呈现大于1和小于1的极显著的异速生长关系，表明分别以茎截面积和茎重代表小枝大小，小枝支撑的同化枝面积比例随小枝增大有两种不同的变化趋势；而梭梭同化枝面积和茎截面积、茎重间均存在小于1的极显著的异速生长关系，表明小枝越大，小枝支撑的同化枝面积的比例越小。这些结果有助于在小枝尺度上了解柽柳和梭梭这两种植被适应干旱、高温的荒漠环境的功能结构特征。
Abstract:Two representative desert plants, Tamarix ramosissima and Haloxylon ammodendron, both utilize green assimilating branches to conduct photosynthesis instead of leaves which greatly reduced. There are few studies on the relationship between twigs and the assimilating branch for these two dominant species in the central Asia up to now. In this study, regression equations of twig mass and assimilating branch area within terminal twigs were given, and biomass allocation as well as the relationship between twig size and assimilating branch area within terminal twigs of T.ramosissima and H.ammodendron have been investigated in detail with the aim of investigating the two plant’s difference in relationship of twigsize to assimilating branch size. Taking stem diameter as independent variable, the regression equations on twig mass and assimilating branch area using power function have high correlation, and the power exponent of T.ramosissima is bigger than that of H.ammodendron, indicating that the twig mass and assimilating branch area increase of T.ramosissima is bigger than that of H.ammodendron with increasing twig size. Isometric relationships were found between twig mass and stem mass, twig mass and assimilating branch mass, as well as between stem mass and assimilating branch mass of T.ramosissima, suggesting that its biomass allocation to assimilating branch or stem is independent on twig size. On the other hand, significant allometric relationships were established for twig mass and assimilating branch mass, twig mass and stem mass, as well as stem mass and assimilating branch mass of H.ammodendron, and its stem has preference to biomass allocation with increasing twig size, indicating that this species has greater demand for stem that play a role in support and water transportation. In addition, significant allometric relationships were also obtained for assimilating branch area and twig cross-sectional area (slope>1.0), and assimilating branch area with stem mass (slope<1.0) in terms of T.ramosissima, indicating that there are two different variation tendencies of the proportion of assimilating branch area with twig size which is represented by twig cross-sectional area and stem mass, respectively. As a comparison, both allometric equations for H.ammodendron have slopes significantly smaller than 1.0, indicating that the proportion of assimilating branch area decrease with increasing twig size for this species.