格氏栲天然林林窗和林下种子散布及幼苗更新研究

Studies on the Seeds Dispersal and Seedlings Regeneration in Gaps and Understory of Castanopsis kawakamii Natural Forest

摘要:

以格氏栲(Castanopsis kawakamii)天然林为研究对象,探讨了林窗和林下格氏栲种子雨、种子库的分布特征及幼苗更新状况。结果表明:林窗种子雨总量和完好种子密度高于林下,未成熟种子比例低于林下;林窗和林下种子雨高峰期掉落数量分别占种子雨总量的77.13% 和74.5%;林窗种子库储量低于林下,种子库中以全食或捡拾种子比例最高,其中种子库储量垂直分布表现为枯落物层(约占2/3) > 腐殖质层(0~5 cm)(约占1/3) > 心土层(5~10 cm)(小于1%),以格氏栲种子占绝对优势;格氏栲从种子到幼苗的转化率低,林窗中格氏栲完好种子密度与幼苗密度均高于林下。林窗微生境提高了种子散布过程中格氏栲成熟种子的密度和比例,有利于促进格氏栲的幼苗更新,表明林窗在格氏栲种群恢复过程中扮演着重要角色。

Abstract:

Seed rain and seed bank distribution and seedlings regeneration status in forest gaps and understory of Castanopsis kawakamii natural forest were studied in Fujian Province. The results showed that the amount of total seeds and intact seeds in forest gaps were higher than those in understory, whereas immature seed rate in gaps was lower than that in understory. The falling seed rain at peak stage accounted for 77.13% and 74.5% of total seeds in forest gaps and understory, respectively. Seed reserve in forest gaps was lower than that in understory, which the most in seed bank were totally eaten by animals or picked up seeds in soil seed bank. The seed vertical distribution in soil seed bank was in order as litter layer (about 2/3) > humus layer (about 1/3) > subsoil layer (less than 1%), which dominated by C. kawakamii seeds. The convention rates from seed to seedlings were low in forest gaps and understory. The densities of intact seed and seedlings of C. kawakamii in forest gaps were higher than those in understory. It suggested that the microhabitat of forest gap improved the density and proportion of mature seeds in seeds dispersal and seedlings regenerated. Therefore, forest gaps play important roles in restoration of C. kawakamii population.