黔西北喀斯特土壤种子库季节动态及种子库对策

Seasonal dynamics and strategies of soil seed banks in karst region of northwest Guizhou

采用野外样线取样与温室萌发相结合的方法,研究了贵州省西北部喀斯特区域处于不同演替阶段群落的土壤种子库季节动态与种子库对策。实验共检测出130个物种,种子库密度变动于541-11180粒·m^-2,草本种子的密度和物种数远大于木本种子。采样时间和地点对土壤种子库平均物种数和密度有显著影响。各群落类型的土壤种子库平均物种数都在4月达到最高,除草地外在12月下降到最低,草地在8月下降到最低。各群落类型土壤种子库密度都在4月达到最高,8月、12月以及次年5月的密度差异不显著。至少两种种子仅存在于1年中某些时段的短暂性土壤种子库类型和两种种子在全年的土壤种子库中都存在的持久性土壤种子库类型。植物的种子库对策是物种本身固有的生活史对策,但某些物种的种子库对策可能受干扰历史及微环境因素的影响,使其在种子数量上表现出不同的季节动态。

In this paper,0-10 cm soil samples were collected four times（April, August and December of 2008,and May 2009） from five sites with plant communities at different succession stages in karst region of northwest Guizhou,and germinated in a greenhouse,aimed to understand the seasonal dynamics and strategies of the soil seed banks.In the soil seed banks,a total of 130 species were identified,and the seed density varied from 541 to 11180 ind·m-2.Herbaceous plants seed density and species number were far greater than woody plants＇,and sampling time and sites had significant effects on the mean values of the seed density and species number in the soil seed banks.At all five sites,the mean species number in the seed banks was the highest in April and the lowest in December,with an exception in grassland where the species number in soil seed bank was the lowest in August.The seed density peaked in April,and had no significant differences in August,December,and next May.The peaks of the seed density and species number in April could be due to the seed input/output pattern,which highly related to phenology,and to the persistence of seeds from previous years.Four seasonal soil seed bank strategies were identified,two transient and two persistent.Soil seed-bank strategy is a life-history trait of plant species,but the disturbance history and microenvironmental factors also have effects on the seasonal variations in seed quantity of some species.