科尔沁草甸草地放牧和割草条件下土壤种子库研究

研究了科尔沁沙地草甸草地在放牧、割草两种利用方式下的土壤种子库的大小、组成及其与地上植被的关系．结果表明，在自由放牧下，土壤种子库密度为6158±1647粒·m^-2，在割草利用下，土壤种子库密度为8312±2540粒·m^-2．放牧干扰下，种子库组成以矮小、短命的一年生植物为主，其中一二年生植物占81．66％，占比例最大的前4种植物分别为虎尾草(38．55％)、灰绿藜(15．42％)、毛马唐(14．95％)和狗尾草(9．83％)，多年生植物种子密度仅为1129±302粒·m^-2；割草干扰下，一二年生植物占68．08％，其中狗尾草占52．7％；而割草地多年生植物种子密度为2653±811粒·m^-2．放牧地土壤种子库密度与地上植物相关不显著；割草地土壤种子库密度与地上植物多度显著相关(r=0．76，P<0．01)．放牧地种子库的Shannon—Wiener指数、丰富度指数分别为2．96和2．98，明显小于割草地的3．10和5．09，表明自由放牧更易使物种多样性下降．

Soil seed bank in Keerqin meadow grassland under grazing and harvesting

This study on the size and composition of seed bank and its relationship with vegetation showed in Keerqin meadow grassland, the density of soil seed bank was 6158 +/- 1647 grains x m(-2) under grazing and 8312 +/- 2540 grains m(-2) under harvesting. Under grazing, the seed bank was mainly composed of some dwarf and short-life annuals. The seeds of the annuals and biennials accounted for 81.66% of the seeds in seed bank. The four species with largest proportion of seed bank were Chloris virgata, Chenopodium glaucum, Digitaria cilliaris and Setaria viridis, and the proportions were 38.55%, 15.42%, 14.95%, and 9.83%, respectively. The density of perennials in soil seed bank was 1129 +/- 302 grains x m(-2). Under harvesting, the seeds of annuals and biennials accounted for 68.08% of the seed in seed bank, and the proportion of Setaria viridis was 52.7%. In the harvesting meadow grassland, the seed density of perennials was 2653 +/- 811 grains x m(-2). There was no significant correlation between the seed density in soil and the vegetation under grazing, but a significant correlation between the seed density in soil and the species abundance of vegetation under harvesting (r = 0.76, P < 0.01). The index of Shannon-Wiener and richness of grazing meadow grassland were 2.96 and 2.98, respectively, distinctly smaller than 3.10 and 5.09 of harvesting meadow, which showed that free grazing made the diversity of seed bank decrease easily.