退耕还林后陕北吴起县植物区系研究

陕西省吴起县1998年确立了封山退耕的战略,并成为名副其实的全国退耕还林第一县。实施退耕还林后，吴起现有种子植物56科160属235种。其中裸子植物3科3属3种，被子植53科157属232种。中国特有属2个，包含中国特有种2个。区系地理成分复杂，包括了种子植物科的8个分布类型和2个变型，以及种子植物属的14个分布类型和11个变型。温带成分构成了本区系的主体，本区系属于温带性质。同时本区系又有丰富的热带亚热带成分，具有明显的热带亚热带向温带过渡性

Research on Floristic Characteristics of Seed Plants After Land Conversion Implementation in Wuqi in North of Shaanxi Province

Wuqi had been implemented Land Conversion Program since 1998 in Shaanxi province,and it is the No.1 County of land conversion in China.After implementation of Land Conversion Program,there are 235 species in Wuqi,belonging to 160 genera or 56 families.Among them,3 species belonging to 3 genera or 3 families of gymnosperm and 232 species belonging to 157 genera or 53 families are included.In addition,there are 2 Chinese endemic genera including 2 Chinese endemic species.It is complex in floristic components,with 8 areal types and 2 subtypes of families of seed plants,and 14 areal types and 11 subtypes of genera of seed plants.The flora is not only dominant in North temperate components,but also related with tropic,sub tropic flora.Meanwhile,it is comparatively rich in species with obvious characteristic of crisscrossing.