六盘山森林土壤种子库与植被演替过程

以六盘山森林植被为研究对象,通过20多年的森林土壤种子库变化与植被演替过程的试验研究,分析了8种森林群落类型的不同生长年限、生长坡位、枯枝落叶层和土壤深度对土壤种子库形成过程的影响。结果表明:六盘山森林群落不同生长坡位,土壤种子库的储量坡中部>坡下部>坡上部;不同层次土壤种子库,枯枝落叶层远高于0-15 cm深土层,8种森林群落类型排序为华北落叶松林>油松林>华山松林>辽东栎林>山杨林>白桦林>灌丛>草地;土壤种子库储量高峰期,不同群落有显著差异,华山松林和油松林在林龄的30~40年,华北落叶松林在20年,辽东栎林、山杨林、白桦林在15~20年,灌丛和草地在10~20年,其森林群落生长年限与土壤种子库储量变化趋势呈拟合曲线,符合指数方程,相关性极为显著;土壤种子库物种组成丰富,草本和灌木植物远高于乔木树种,乔木树种仅有3~5种,但多数为外来入侵种,而在每一类型中出现频率最高的草地植物多为蒿类,灌木植物为柔毛绣线菊和沙棘,乔木为辽东栎树种。因此,在六盘山林区植被自然更新与合理演替的驱动种和先锋种草地植物为蒿类,灌木植物为柔毛绣线菊和沙棘,乔木为辽东栎,其次是华北落叶松、油松和华山松。

Soil Seed Banks and Vegetation Succession of Different Forest Communities in Liupan Mountain

To analyze the effect of forest growth years,litter and soil depth at different slope positions to the formation of seed banks,soil seed banks changes and vegetation succession of 8 forest communities in 20 years were studied in Liupan mountain.The results indicated that seed reserves followed the order of mid-slope>underside slope>upside slope for different layers.Seed bank reserves in litter layer was larger than that in 0-15 cm soils.The seed reserves in soils of 8 forest communities presented the order of Larix principis-rupprechtii forest>Pinus armandii forest>Quercus liaotungensis forest>Populus davidiana forest>Betula platyphylla forest>shrubbery land>grass land.The maximum accumulation age of seed reserves varied greatly with vegetation communitites.The times for the approach of the maximum seed reserves was about 30 to 40 years for Pinus armandii and P.tabulaeformis communities,20 years for Larix principis-rupprechtii community,15 to 20 years for Quercus liaotungensis,Populus davidiana,and Betula platyphylla communities,and 10 to 20years for shrubbery and grass communities..The relationship between forest growth times and seed bank reserves changes followed an exponential equation and the relation was significant at p<0.05.Soil seed banks at different vegetation communities were rich in species composition,and that was higher in grass and shrubbery species than that in arbor species.Only 3 to 5 species of seed banks were arbor species and the majority of arbor species were invasive species.The frequently occurred species of grass,shrub,and arbor species are Artemisia,Spiraea pubescens and Hippophae reamnoides,and Quercus liaotungensis,respectively.Therefore,these species are the driving and pioneering species during the succession and natural renovation course.