Flora in Songshu Mountains in Inner Mongolia and community characteristics of Pinus tabulaeformis forest

Based on the investigations of the flora in Songshu Mountains in Inner Mongolia and the study of the community characteristics of Pinus tabulaeformis forest, the following results were obtained: (1) From the viewpoint of flora, Songshu Mountains located at the transitional area of Mongolia flora, North China flora, Changbai flora, and Darhurica flora. There were plenty of plant species, including 394 spermatophytes. The numbers of the family, genus, and species of the plants occupied 61.1%, 58.1%, and 41.1% of those on the Horqin sandy lands, respectively. (2) The geographic components of the flora in Songshu Mountains were dominated by temperate ones, occupying 90.61% of the total, among which, temperate Asia component, Old World temperate component, and Sino-Japan component occupied 16.8%, 14.0% and 13.7%, respectively. (3) P. tabulaeformis forest was the only coniferous broadleaved mixed forest in Songshu Mountains and Horqin sandy lands. As for the life form of community, hemicryptophyte was plenty, being 40.7%, followed by phaenerophytes (22.2%) and geocryptophyte (25.5%). (4) The P. tabulaeforinis forest in the sandy lands could be divided into two types, i. e., Ass. Lespedeza bicolor-Quercus mongolica + P. tabulaeformis and Ass. Prunus sibirica-P. tabulaeformis. The former distributed on lithoid dune, while the latter mainly located on the shadow slope of fixed dune. The community succession series was sandy pioneer community stage →rhizome herb-grass community stage→sandy shrub community stage→sandy P. tabulaeformis forest stage.