干旱和湿润生境中主要优势树种叶片功能性状的比较

Comparison on leaf functional traits of main dominant woody species in wet and dry habitats

以云南南部的沟谷雨林(湿润生境)和干热河谷萨瓦纳(savanna)稀树灌丛(干旱生境)中共31种主要优势木本植物为材料,研究了叶片主要功能性状单位面积叶干重(LMA)、单位干重氮含量(Nmass)和单位干重最大净光合速率(Amass)在2个生境中的差异及各性状间的关系。结果表明:在物种水平上,干旱和湿润生境中各树种的LMA值分别为46.88～178.63和45.35～93.16g·m-2;Amass值分别为48.12～176.65和71.38～265.76nmol·g-1·s-1;Nmass值分别为11.8～36.71和12.98～31.78mg·g-1;在群落水平上,干旱生境中LMA显著高于湿润生境,而Amass显著低于湿润生境,Nmass在2个生境中差异不显著;在群落尺度上,干旱生境中LMA与Nmass和Amass均呈显著负相关;在2生境中Nmass与Amass均呈显著正相关。同一生境下不同植物对环境的适应策略有差异,但各性状间的相关关系具有趋同性;从湿润到干旱生境,植物由快速生长转向以提高资源利用效率为主的适应策略。

Three key leaf functional traits ／[leaf dry mass per area （LMA）, leaf nitrogen concentration per unit mass （Nmass）, and mass-based maximum photosynthetic rate （Amass）／] were measured in 31 woody species from tropical lowland rain forest with high rainfall and from dry-hot valley savanna with low rainfall in southern Yunnan. The results indicated that LMA was 46.88-178.63 and 45.35-93.16 g·m-2, Amass was 48.12-176.65 and 71.38-265.76 nmol·g-1·s-1, and Nmass was 11.8-36.71 and 12.98-31.78 mg·g-1 in the dry savanna and the wet rain forest, respectively. At the community level, Amass was lower but LMA was higher in the plants of dry habitat than in wet habitat. Nmass was not significantly different between the plants from the two habitats. LMA was negatively associated with Nmass and Amass in dry habitat; Amass and Nmass were positively associated in both habitats. Our results indicated that correlations among the traits of plants from the same habitat converged although adaptive strategies were different among species. The adaptive strategies of dominant species changed from faster returns on investments in dry mass in wet habitat to slower return to high resource-use efficiency in dry habitat.