中文摘要：

对松嫩草原沙地蒙古黄榆（Ulmus macrocarpa var．mongolica）群落的种类组成及其生态类型结构进行了调查．结果表明：研究区蒙古黄榆群落不存在灌木层；乔木层高度5．83～9．33m，郁闭度40％～60％．林下草本层种类组成丰富，总计有33种，隶属17科28属、11种分布区型、3个水分生态类型和6个生活型．其中常见科有禾本科、豆科和菊科．生活型以一年生植物最多，占45．45％；其次为地面芽植物．分布区型以蒙古-东北-兴安-华北种类最多，占36．36％，具有4个分布区型相汇聚的特征．水分生态类型以中生种类为主，其余为旱生和中旱生种类，旱化趋势明显．

英文摘要：

The species composition and ecological structure of Ulmus macrocarpa var. rnongolica community in sandy land of Songnen grassland were investigated. The results showed that there was not shrubs in U. macrocarpa var. mongolica forest and the height of arbor layers was 5.83 -- 9.33 m, canopy closure was 40 % --60 %. The total number of herbal species were 32 and belonged to 13 families and 27 geneses, 11 areal type, 3 ecological type of water and 6 life forms. The main families embraced Poaceae, Fabaceae and Compositae. The life forms of most of the plants belonged to the therophytes which accounted for 45.45 %, followed by hemicryptophytes. Most areal type were Mongolian-Northeastern China-Dahuricia-China north which accounted for 36.36 %. The area has the influx characteristic of 4 areal type. The species of mesophyte dominated three ecological type of water, making up 59.37 %, the rest was xerophyte and mesoxerophyte, which had the trends of dried habitat condition.