亚热带常绿阔叶林植物叶小枝的异速生长

 植物生态学研究的重要内容之一是识别和定量刻画种间生态变异的主要维数，叶大小小枝大小维（谱）是其中之一，目前的研究相对比较薄弱，两者之间是异速还是等速生长关系仍存在着争论。亚热带常绿阔叶林植物叶大小-枝大小维的研究报道很少。该文以我国东部亚热带典型区域福建梅花山常绿阔叶林的68种常绿乔灌木植物为对象，进行了叶-小枝关系及其生态意义的研究。结果表明：1）小枝茎截面积与叶干重、总叶面积和单叶面积之间的SMA斜率分别为1.29、1.23和1.18，呈现异速生长关系，支持叶大小 小枝大小为异速生长的相关研究结论，但SMA斜率低于预期值，其原因及生态意义有待进一步研究；2）小枝总叶面积与单叶面积呈显著正相关，而与叶片数量不相关，反映了小枝总叶面积的增加主要是由单叶面积大小决定的，可能与这一地区湿润气候有关；而单叶面积与枝条长度呈正相关则可能反映了植物对常绿阔叶林内较弱光照环境的适应；3）叶干重同小枝干重、叶面积为等速生长关系，可能反映了植物与动物之间代谢方式的差异。

STUDIES ON THE LEAF SIZE-TWIG SIZE SPECTRUM OF SUBTROPICAL EVERGREEN BOARD-LEAVED WOODY SPECIES

Aims An important aim of plant ecology is to identify and quantify key dimensions of ecological variation among species and to understand the basis for them. The leaf size-twig size spectrum is an important dimension that is under development. Our aims were to determine if there is an invariant allometric scaling relationship between leaf size and twig size in subtropical evergreen broad-leaved woody species and to determine what indicates this relationship. Methods We investigated leaf and stem traits—including leaf and stem mass, individual leaf area, total leaf area, stem cross-sectional area, leaf number and stem length—at the twig level for 68 evergreen broad-leaved species on Meihuashan Mountain in the subtropical zone of East China. We determined the scaling relationships between leaf traits and stem traits at the twig level.  Important findings Twig cross-sectional area has an invariant allometric scaling relationships with leaf mass (SMA slope 1.29), total leaf area (1.23) and individual leaf area (1.18), all with common slopes being 1-1.5. Leaf mass is isometrically related to stem mass and leaf area. This suggests that there would be different metabolic ways between animal body and plant. Species with larger leaves deployed a greater total leaf area distal to the final branching point than smaller leaved species, with this leaf surface made up of fewer leaves per twig, even though the twigs were longer. This might result from the humid climate and weak light in subtropical evergreen broad-leaved forest of this region.