南亚热带森林不同演替阶段土壤种子库的初步研究

本文对鼎湖山不同演替阶段的森林（马尾松林、针阔叶混交林、季风常绿阔叶林）的土壤种子库进行了初步研究．分别从各个阶段的样地内抽取４或８个１×１ｍ的小样地，分三层（共１０ｃｍ厚）采集土样，带回实验室，通过萌发法观察记录其土壤种子库状况．通过统计分析，其结果如下：１．种子数量和物种多样性一般随演替发展而减少，种子数目以３—５ｃｍ厚土层为最多．２．各演替阶段土壤种子库的种类组成均以草本植物为主．３．在光照和湿度基本一致的情况下，萌发种子数与温度成正相关．４．雨季取的种子数目较旱季多，且种类组成有所不同．这是因为南亚热带森林内植物种子的休眠期短，在旱季采集土样时许多种的种子尚未下落．５．种子库组成与地上植物相关性不明显，但演替早期阶段的相关性比演替后期更密切。

A STUDY ON THE SOIL SEED BANKS AT THE DIFFERENT SUCCESSION STAGES OF SOUTH SUBTROPICAL FORESTS

Soil seed banks at four succession stages of southsubtropical forests (Pine forest,Pine and broad-leaf mixed forest, young monsoon evergreen broad-leaf forest and mature monsoon evergreen broad-leaf forest) in Dinghushan Nature Reserve, Guangdong Province,were investigated. Four quadrates (1m× 1m each) were measured three times (one was in dry, one in rainy season, another was before rainy season) for each stages, and three soil stratifications were sampled for each quadrate. The soil samples were set in laboratory under sufficient humidity and nature sunlight, and seed gendnation was noted daily. The results showed that the number of seeds in the soil seed banks decreased with the development of forest succession, but the species diversity increased. The number of seeds and the species diversity were both higher in rainy season than in dry season. The number of seeds in the stratification at 3-5cm depth was almost the highest as compared with other stratifications.According to a regression analysis, species composition in the soil seed banks was less related to that on the ground vegetation. The seeds of herb species were dominant, but a few dominant species of ground vegetation were not found in the soil seed banks because of the short life of some seeds and eating by animals. The germination of seeds in the soil seed banks was more closely related to temperature than to humidity. The roles of soil seed banks in forest succession were discussed.