铜尾矿废弃地与相邻生境土壤种子库特征的比较

土壤种子库是植被群落的重要组成部分,其特征决定了群落的演替方向。对铜陵杨山冲尾矿库6个植被群落及相邻两处生境的土壤种子库进行了研究。结果表明,尾矿内各植被群落种子库的种子密度间存在较大差异,变化范围为57—593粒/m2,平均种子密度为370粒/m2,尾矿坝体和周围山体种子库种子密度分别为999和121粒/m2,各样地土壤中种子均主要集中在0—5 cm范围内。尾矿种子库与坝体种子库间的相似性指数大于其与周围山体种子库的相似性指数,但尾矿内各植被群落种子库间的相似性较差,相似性指数的变化范围为0.308—0.636。可见,群落微生境对土壤种子库的种子密度和物种组成产生了较大的影响。尾矿种子库种类与地上植被的平均相似指数为0.355,低于坝体种子库种类与地上植被相似性系数。3处样地土壤种子库的物种多样性、丰富度和均匀度指数均表现为坝体>尾矿>山体。尾矿种子库在农田土壤中萌发并正常生长的幼苗为16科44属53种,而在尾矿基质中仅为9科36属45种,均以禾本科、菊科和豆科植物萌发和生长状况较好,这3科构成了尾矿地上植被的主要类型。尾矿种子库在尾矿基质中萌发成活率为62.2%—91.2%,约为坝体和山体土壤种子库在尾矿基质中萌发成活率的2倍。说明,组成尾矿种子库的种子大部分已经适应了尾矿的极端恶劣环境或者其本身就是耐性极强的植物类型。

Characters of soil seed bank in copper tailings and its adjacent habitat

Soil seed bank is an important part of plant community, which dominates the development of community succession. Soil seed bank characteristics of copper tailings and its adjacent habitat were investigated. The results showed that the seed density of the seed bank between different community microhabitats in the copper tailings were different, the range of which was 57-593 grains/m². The average seed density of the seed bank in the tailings was 370 grains/m², and that in the tailings dam and the mountains was 999 and 121 grains/m², respectively. The difference of the sorensen's coefficients on species between the seed banks in the tailings was greater, the range of which was 0.308-0.636. These showed that the effects of microhabitat on seed density and species of soil seed bank was huge. The seeds of the soil seed banks in all the plots concentrated in 0-5 cm layer. The sorensen's coefficient of species between the tailings seed bank and the vegetation was 0.355, and lower than the coefficient of species between the tailings dam and the vegetation. The species diversity, abundance and evenness index of the soil seed banks all displayed the followed trend: the tailings dam > the tailings > the mountains. The seedling of 16 families 44 genera 53 species from the tailings seed bank were germinated and survived in the farmland soil substrates, and only 9 families 36 genera 45 species in the tailings substrates survived. The plants germinated and grow well all belonged to Gramineae, Composite and Leguminosae, and the three families were also constituted the main vegetation types of the tailings. The seedling germination and survival rate of the tailings seed bank in the tailings substrates was 62.2%-91.2%, which was about 2 times of the dam soil seed bank and the mountains soil seed bank. This indicated that the seeds of the tailings seed bank already adapted to the extreme environment of the tailing, or they were tolerant plants. The study suggested that the microhabitat affected the seed density and the species composition of the copper tailings seed bank, through human activities changing microhabitat conditions could improve seed density and species diversity of soil seed bank, thus would speed up the process of succession and recovery of the tailings vegetation.