盐池县人工封育草地植物生态位动态研究

通过2007、2009和2011年的实地调查，采用Levins生态宽度指数及Pianka生态位重叠指数研究了3种不同封育措施对宁夏盐池干旱半干旱区草地植物生态位的影响。结果表明，老封育区优势种为刺沙蓬(Salsola ruthenica)和阿尔泰狗娃花(Heteropappus altaicus)，经过封育刺沙蓬的优势地位有所下降，阿尔泰狗娃花的优势地位有所上升；新封育区优势种为黑沙蒿（Artemisia ordosica）、刺沙蓬和丝叶山苦荬（Ixeris chinensis var.graminifolia），经过封育刺沙蓬的优势地位有所下降，丝叶山苦荬的优势地位明显上升；对照区的优势种为黑沙蒿、沙蓬刺、苦豆子（Sophora alopecuroides），经过封育黑沙蒿在3个时期均处于主导地位，沙蓬刺的生态位宽度稳中有所上升。老封育区优势物种之间的生态位重叠值经过封育呈下降趋势，新封育区呈上升趋势。

Vegetable niche dynamic study of the enclosed desertification rangeland in Yanchi County

Through field surveys of 2007,2009 and 2011,the effect of three different fencing measures on Yanchi arid and semi-arid grassland plant niche were studied in this paper by using the Levins niche breadth index and Pianka niche overlap index.The results showed that dominant species of the old enclosure region(E plot) were Salsola ruthenica and Heteropappus altaicus,while dominant position of S.ruthenica increased and that of H.altaicus decreased after fencing.In the new enclosure region(E1 plot),dominant species were Artemisia ordosica,Salsola ruthenica and Ixeris chinensis var.graminifolia.However,dominant position of S.ruthenica decreased and that of I.chinensis var.graminifolia increased obviously.Dominant species were A.ordosica,S.ruthenica and S.alopecuroides in the control area(E2 plot);A.ordosica was the dominant species in the three sampling periods and the niche breadth index of S.alopecuroides steady rised.The niche overlap index amone dominant species of the old enclosure region presented the downward trend through the fencing measure,while the niche overlap index amoge dominant species of the new enclosure region presented the rising trend.