摘要
本文根据多年的植被调查和沙层水分动态的观测资料,对沙坡头地区无灌溉条件下人工植被33年演变过程中的组成进行分析。结果表明:(1)目前,人工植被已经演变为以油蒿为主的灌木半灌木+一年生草本+孢子植物占优势的人工——天然植被。(2)人工植被的生活型以高位芽植物和一年生植物为主,辅以少量的地面芽植物,没有地上芽和隐芽植物,生活型谱不完整。与天然油蒿群落比较,人工植被种类少、投影盖度低、根栖层水分严重亏缺。(3)投影盖度是荒漠半荒漠植被最重要的特征之一。人工植被演变初期投影盖度波动性上升。7—16龄为鼎盛时期,投影盖度为30%左右。随后又波动性下降。这种波动性变化规律在判断沙漠化程度时有意义。(4)人工植被演变过程中Shannon-Wiener多样性指数的变化规律近似“∩”型。种优势度指数的变化规律与其成负相关,近似“U”型。(5)流沙群落、3—33龄的人工植被的种多度分布模式为几何级数型。天然油蒿群落和红砂—珍珠群落为对数正态分布。1—2龄的人工植被种多度分布模式完全受人为因素的制约。
This paper focuses on the analysis of ommunity composition in the 33years succession of artificial vegetation under no-irrigation condition inShapotou area,Ningxia Hui Autonomous Region.The8years experimental dataare discussed and analysed. The results show (1) The artificial communityhas evolved into shrubs (dominated by Artemisia crdosica)+annual plants+sporophytes community, which is still dominated by r-strategists. (2) Inthe life form spectrum, dominant types are phanerophytesand therophytes.There are a little hemicrytophytes and no chamaephytes and geophytes.Compared with natural community, the composition, structure and arrange-ment of species of artificial vegetation should be improved. (3) Coverdegree is the most important feature for studying the plant community inarid and semiarid region. Cover degree -- succession curve of artificialvegetation roughly likes a'∩'. At the early succession stage the cover de-gree increases and gradually approach to the maximum cover degree (about30%) at the age of 7-16 years. Then cover degree decreases gradually.This irregular pattern has a great significance for determining the degreeof desertification. (4) Shannon--Wiener index--succession curve of arti-ficial vegetation roughly likes a'∩' and dominance index--succession cur-ve of artificial vegetation roughly likes a 'U'. (5) The dominance di-versity curves are roughly geometric distribution for 3-33 years old arti-ficial vegetation and community on shifting sand dune, lognormal distribu-tion for Artemisia oraosica community and Reaumuria scongorica+Salsolapasserina community. The distribution of dominance diversity are controlled by anthropic factor for 1-2 years old artificial vegetation.
出处
《干旱区资源与环境》
CSCD
1991年第1期22-32,共11页
Journal of Arid Land Resources and Environment
关键词
人工植被
组成分析
沙坡头
Artificial vegetation
Analysis of composition
Shapotou
