不同类型桉树人工林土壤种子库特征研究

Characteristics of Soil Seed Banks in Different Eucalyptus urophylla×E.grandis Forest Types

为揭示土壤种子库在桉树人工林可持续经营与物种多样性恢复中的潜在作用,采用野外调查取样和室内模拟试验相结合的方法,研究了不同桉林土壤种子库的物种组成、密度、垂直分布等特征。结果表明:(1)新造桉林和桉萌芽林土壤种子库储量密度分别为9 804、7 356粒/m2,显著高于对照大叶栎杂木林土壤种子库储量密度(3 614粒/m2)。(2)新造桉林土壤种子库出现物种共15种,分属于9科;桉萌芽林为8种,分属于7科;大叶栎杂木林为16种,分属于11科。不同林型土壤种子库物种组成均以草本为主,灌木次之。(3)种子库垂直分布格局表明,不同类型森林种子主要储存在枯枝落叶层和浅层土壤中。新造桉林和萌芽林土壤种子库具有较高的生态优势度指数,但丰富度指数、Simpson多样性指数、均匀度指数及土壤种子库和地上植物的相似性系数均低于对照。桉树人工林物种多样性的提高需要适度的人为干预和科学的调控措施。

To clarify the potential role of the soil seed bank in recovering species diversity and maintaining sustainable management of Eucalyptus plantation, field survey and laboratory observation experiment were conducted to study the character of soil seed banks in different Eucalyptus Forest types. The results were as follows： （1） the average seed storage of seed banks in 2-years-old new plantation and sprout forest of Eucalyptus urophylla^E.grandis was respectively 9 804 grain/m2 and 7 356 grain/m2, which was much higher than those in Castanopsis fissa mixed forest （3 614 grain/m2）. It showed Eucalyptus plantation had abundant seed storage of seed banks. （2） Speices composition of the soil seed bank in new plantation were 15 species, belonging to 9 families; 8 species were present in sprout forest of Eucalyptus, which were belonging to 7 families; 16 species were present in Castanopsis fissa mixed forest, which were belonging to 9 families. The species composition of the soil seed bank in different plantation was mainly the herb and next to the shrub. （3） Seed bank vertical distribution pattern showed that the seeds mainly stored in dead branches of leaves and 0-5 cm of soil. The ecological dominance index of soil seed banks in different Eucalyptus forest was obviously higher than that in Castanopsis fissa mixed forest, but the Margalef richness index （R）, Shannon-Wiener index （H＇）, Pielou evenness index （E）, Simpson index （D） was lower than that in Castanopsis fissa mixed forest. The improving of species diversity in Eucalyptus should be to offer scientific management.