中国西北针茅草原的基本群落特征

西北针茅(Stipa sareptana var. krylovii)群系是亚洲中部地区特有的典型草原之一, 也是生态适应性最广的草原类型, 向东可以在呼伦贝尔高原与草甸草原重叠分布, 向西可以在乌兰察布高原、天山等地区与荒漠草原形成复合分布, 向南可分布至黄土高原与暖温带草原镶嵌分布, 还可在青藏高原的东缘与高寒草原混生。该研究调查了中国西北针茅群系的主要植被类型, 通过对117个样地的调查数据分析, 量化描述了该群系的基本群落特征。结果表明, 中国西北针茅群系共有种子植物336种, 分属于36科131属, 物种数大于15的科有禾本科、菊科、豆科、蔷薇科、藜科和百合科; 物种存在度等级划分中, I级(0-20%)植物占比91.67%, 多为群落中的偶见种或稀有种, 最为常见的植物除西北针茅外, 也有糙隐子草(Cleistogenes squarrosa)、阿尔泰狗娃花(Heteropappus altaicus)、冰草(Agropyron cristatum)、 草(Koeleria cristata)、二裂委陵菜(Potentilla bifurca)、猪毛菜(Salsola collina)、细叶韭(Allium tenuissimum)和羊草(Leymus chinensis)等; 生活型组成上以地面芽植物最多, 占66.37%; 水分生态类型以旱生植物最多, 占61.19%; 区系地理成分以东古北极植物占优势, 占33.33%。基于群落学-生态学分类原则, 将西北针茅群系划分为6个群丛组, 45个群丛。

Basic characteristics of Stipa sareptana var. krylovii communities in China

Stipa sareptana var. krylovii alliance is one of the typical steppes endemic to Central Asia. The eastern border of its distribution is adjacent to the meadow steppes on the Hulunbeir Plateau, the western border extends to the desert steppes on the Ulanqabu Plateau and Tianshan Mountains, and the southern border lies among the warm temperate steppes on the Loess Plateau. The distribution of this alliance also spreads into the alpine steppes on the eastern margin of the Qinghai-Xizang Plateau. The broad its distribution suggests that S. sareptana var. krylovii alliance has wide ecological adaptability. In this study, we described and analyzed the eco-geographical distribution, community characteristics and classification of S. sareptana var. krylovii alliance based on data from 117 plots. The results showed that there are 336 seed plants belonging to 36 families and 131 genera in these plots. The families with more than 15 species are Gramineae, Compositae, Leguminosae, Rosaceae, Chenopodiaceae and Liliaceae. Among all species in these plots, 91.67% are rare species with occurrence frequency smaller than 20%. Besides S. sareptana var. krylovii, the most common species in this alliance include Cleistogenes squarrosa, Heteropappus altaicus, Agropyron cristatum, Koeleria cristata, Potentilla bifurca, Salsola collina, Allium tenuissimum and Leymus chinensis. In addition, hemicryptophytes are the most common life form within the surveyed plots, accounting for 66.37% of all species. Xerophytes are the most common water ecological type, accounting for 61.19% of all species. East Palearctic element was the major floristic geographical element, accounting for 33.33% of all species. Based on the China Vegetation Classification System, S. sareptana var. krylovii alliance could be classified into 6 association groups and further into 45 associations.