秦岭北坡不同生境栓皮栎种子雨和土壤种子库动态

Dynamics of Quercus variabilis seed rain and soil seed bank in different habitats on the north slope of Qinling Mountains.

为了阐明栓皮栎种子雨和种子库动态,以秦岭北坡林下、林窗、林缘3种生境栓皮栎天然林为对象,采用离地和地面收集种子的方法,连续定位观测了栓皮栎种子雨、种子库的数量、质量动态,以及幼苗发育过程.结果表明:栓皮栎种子雨从8月中旬开始,9月中旬到10月上旬达到高峰期,11月上旬结束;3种生境种子雨降落历程、发生时间和组成不同;林下种子雨强度最大,为(39.55±5.56)粒·m-2,林窗种子雨降落时间最早,持续时间最长,种子活力最高,而林缘成熟种子占其种子雨的比例最大,达58.7%.从种子雨降落结束到翌年8月,土壤种子库总储量均以林下最大,林缘最小;各生境的土壤种子库中成熟、未成熟、被啃食种子数量和种子活力均随时间变化呈递减趋势,而霉烂种子数量则相反.各生境的土壤种子库中的种子均主要集中在枯落物层,其次为0～2cm土层,2～5cm土层中只有极少量种子存在.3种生境中栓皮栎幼苗的密度差异显著,林窗幼苗最多,林缘次之,林下最少.说明林窗更适合栓皮栎种子的萌发和幼苗生长.在栓皮栎林的经营中,通过适当间伐、增加林窗数量,可以促进栓皮栎林的天然更新.

In order to explore the dynamics of Quercus variabilis seed rain and soil seed bank in different habitats on the north slope of Qinling Mountains,three kinds of micro-habitats（understory,forest gap,and forest edge） were selected,with the seed rain quantity and quality of Q.variabilis,seed amount and viability in soil seed bank,as well as the seedling development of Q.variabilis studied.The seed rain of Q.variabilis started from mid August,reached the peak in mid September-early October,and ended at the beginning of November,and there existed differences in the dissemination process,occurrence time,and composition of the seed rain among the three micro-habitats.The seed rain had the maximum intensity（39.55±5.56 seeds·m-2） in understory,the seeds had the earliest landing time,the longest lasting duration,and the highest viability in forest gap,and the mature seeds had the largest proportion in forest edge,accounting for 58.7% of the total.From the ending time of seed rain to next August,the total reserve of soil seed bank was the largest in understory and the smallest in forest edge.In the three habitats,the amount of mature and immature seeds,that of seeds eaten by animals,and the seed viability in soil seed bank all decreased with time.In contrast,the number of moldy seeds increased.The seeds were mainly concentrated in litter layer,a few of them were in 0-2 cm soil layer,and few were in 2-5 cm soil layer.The density of the seedlings varied with habitats,being the largest in forest gap,followed by in forest edge,and the least in understory,which suggested that forest gap was more suitable for the seed germination and seedling growth of Q.variabilis,and thus,appropriate thinning should be taken to increase forest gap to provide favorable conditions for the natural regeneration of Q.variabilis forest.