Will competitiveness of resulting plants of persistent soil seed bank decline? Example from Eupatorium adenophorum Density-Dependence of Calamagrostis epigejos in Songnen Grassland Sprouting propagation characteristics of Cleyera pachyphylla in the Baishanzu subtropical evergreen forest Density-dependent regulation of above- and below-ground modules in Allium cepa var. proliferum populations Composition and temporal dynamics of tree seedlings at different successional stages of conifer and broad-leaved mixed forests in Jiaohe, Jilin Province, China