中文摘要：

枝条大小和数量关系反映了植物适应环境胁迫的构型和生物量分配策略。该研究以浙江天童木本植物为对象，通过对小枝大小（横截面积）与数量（稠密度）关系的研究发现：1）小枝稠密度与枝截面积显著负相关（斜率为-1．32，CI=-1．48--1．17；P〈0．05）；2）在相同曝光度，在Ⅱ级曝光环境（植株40％-80％暴露在直射光中）中常绿植物比落叶植物单位小枝截面积的小枝稠密度高，而在Ⅰ级（植株〈40％暴露在直射光中）和Ⅲ级（〉80％暴露在直射光中）曝光环境中，小枝稠密度在两种生活型间无显著差异；3）在不同曝光度下，常绿植物单位枝条在Ⅰ和Ⅱ级比Ⅲ级曝光水平具有更高的小枝稠密度；但落叶植物单位枝条的小枝稠密度在3个曝光水平相同；4）相同枝条大小下，4m以下灌木比4m以上的亚乔木和乔木具有更高的小枝稠密度。总之，天童地区木本植物的小枝“大小-数量”关系符合Comer法则（描述枝叶“大小-数量”关系的法则），且在不同生活型间存在差异，常绿植物相对于落叶植物，灌木相对于乔木具有较高的小枝稠密度，从而有利于它们适应光资源的限制。

英文摘要：

Aims The branch size-number trade-off among woody plants has implications for both the formation of plant architecture and biomass allocation in response to environment stresses. Our objective was to examine how the twig size-number relationship varies among woody plants in subtropical broad-leaved evergreen forests in southeastern China. Methods The study site is located in Tiantong National Forest Park （29°52＇ N, 121°39＇ E）, Zhejiang Province, in Eastern China. We measured twig length, twig diameter, number of twigs and length and diameter of branches from which the twigs were sampled for 76 woody species in a 1-hm^-2 plot. Standardized major axis （SMA） analysis was conducted to examine the quantitative relationship between twig size （cross-sectional area） and the number of twigs at a given twig size （twig intensity）. Important findings A significantly negative allometric scaling relationship was found between twig intensity and its cross-sectional area. Under level-II light exposure （LE-Ⅱ, 40%-80% of the plant under direct light）, evergreen species had a much higher twig intensity than deciduous species. However, there was no difference in twig intensity between these two life forms under LE-Ⅰ （〈40% exposure） or LE-Ⅲ （〉80% exposure）. Higher twig intensity was found in evergreen species under LⅠ-Ⅲ than under both LE-Ⅰ and LE-Ⅱ. In contrast, twig intensity of deciduous species was not different among any of the light exposure levels. Shrubs 〈4 m height had higher twig intensity than sub-trees and trees 〉4 m at a given twig size. We conclude that the twig size-number trade-off across woody plants in Tiantong was consistent with the Corner＇s rule （that describes the relationship between twig size and the number of twigs）, but might differ among different life forms. Both evergreen species and shrubs are inclined to develop higher twig intensity, which indicates their adaptation to environment stress caused by limitations in light availability.