A STUDY ON THE SOIL SEED BANKS AT THE DIFFERENT SUCCESSION STAGES OF SOUTH SUBTROPICAL FORESTS
南亚热带森林不同演替阶段土壤种子库的初步研究

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.