内蒙古阴山北麓小针茅草原的群落特征和分类

小针茅（Stipa klemenzii）草原是内蒙古阴山北麓荒漠草原的最主要的植被类型,是重要的生态安全屏障和畜牧业基地。利用2012年和2017年生长季的野外调查数据并结合已有资料,对阴山北麓的小针茅草原群落特征和分类进行了分析。结果显示,小针茅草原的群落数量特征,表现出强烈的波动性,平均物种数为9种/m²,高度（10±4） cm,总盖度（12±5）%,生物量干重（57±33）g/m²,多样性指数在0.7左右（Simpson和Shannon-Wiener指数）,平均丰富度指数为2.09,平均均匀度指数为0.55。小针茅草原共调查到种子植物79种,分属21个科,51个属,其中含种最多的科有禾本科、豆科、菊科,存在度大于60%的种有小针茅、银灰旋花（Convolvulus ammannii）、无芒隐子草（Cleistogenes songorica）、细叶葱（Allium tenuissimum）和乳白花黄芪（Astragalus galactites）;强旱生和典型旱生植物共有57种,占总物种数的72%;以多年生杂类草和一、二年生植物居多,各占48%和24%;区系地理成分以东古北极和亚洲中部成分为主,各占33%和32%。小针茅草原可划分出3个群系,7个群丛组和13个群丛,其中银灰旋花和多根葱群系为小针茅群系的退化类型。以退化指示种为亚优势种和建群种的群落,在阴山北麓广泛分布,反映出小针茅草原现阶段退化依然比较严重。

Community Characteristics and Classification of Stipa klemenzii Steppe in NorthPiedmont of Yinshan Mountain in Inner Mongolia

Stipa klemenzii steppe is the main vegetation type in north piedmont of Yinshan Mountain in Inner Mongolia. It is an important ecological security barrier and animal husbandry base. Based on the primary plots data obtained from fieldworks during the growing seasons from 2012 to 2017 as well as some earlier records, we studied the community characteristics and classifications of Stipa klemenzii steppe in north piedmont of Yinshan Mountain. The results showed that the quantitative characters of the community of Stipa Klemenzii steppe had an obvious fluctuated. The average species number, height, total coverage, biomass dry weight, diversity index （Simpson and Shannon-wiener index）, average richness index and average evenness index were separately 9 species/m², 10 cm, （12±5）%, （57±33） g/m², around 0.7, 2.09 and 0.55. A total of 79 species of seed plants, belonging to 21 families and 51 genera, were obseved in Stipa Klemenzii steppe, among which the families with the most species were Gramineae, Leguminosae and Compositae. Species with the occurrence frequency exceeding 60% included Stipa Klemenzii, Convolvulus ammannii, Cleistogenes songorica, Allium tenuissimum and Astragalus galactites. As for the ecological type of water, there were 57 species of xerophytes and typical xerophytes, accounting for 72% of the total species. In addition, perennial forbs as well as annual and biennial species were the two dominant life forms, covering 48% and 24% of the species, respectively. East Palaeo-North areal-type and middle Asian areal-type were the two major floristic elements, containing 33% and 32% of the species, respectively. Based on the life forms and dominances of the species within the community, Stipa Klemenzii steppe could be classified into 3 formations, 7 association groups and 13 associations. Convolvulus ammannii and Allium polyrhizum formation were the degraded types of Stipa klemenzii. The communities with degenerated indicator species as sub dominant species and constructive species were widely distributed in north piedmont of Yinshan Mountain, reflecting that the degradation of Stipa Klemenzii steppe was still serious at present stage.