【作者】 刘晓春；

【导师】 洪绂曾； 龙瑞军；

【作者基本信息】 甘肃农业大学 ， 草业科学， 2008， 博士

【摘要】 民勤荒漠草地作为我国蒙新高原草原区的一部分,地处石羊河下游的干旱荒漠区,是长期适应自然和社会环境,在特定环境下自然演替的结果。对维持民勤区域生态环境稳定、抵御风沙危害、促进地方经济发展起着极其重要的作用,也是当地生态环境建设和社会经济发展的重要组成部分。因此研究该区域植被动态变化和植物群落特征,对当地生态环境建设和社会经济发展都具有十分重要的意义。本文以民勤荒漠草地主要植物群落为研究对象,通过实地调查结合“GIS”技术对民勤荒漠草地类型及其主要植物群落类型、分布特征、面积、生境条件和群落结构特征进行了分析、研究。研究的主要内容是:民勤荒漠草地类型及其植物群落类型与分布:植物群落结构特征(包括群落的物种数量组成、外貌特征、多样性、优势种群及分布格局等);通过绘制优势种的年龄结构图和静态生命曲线,分析植物群落优势种群的动态变化和发展趋势。研究结果如下:(1)根据任继周院士的草原综合顺序分类法,民勤荒漠草地归类为ⅣA4—微温极干类(温带荒漠草原)。以土壤类型和地形特征为指标,可将民勤荒漠草地划分成3个亚类,即砾质荒漠草地、沙质荒漠草地和盐渍化荒漠草地。(2)砾质荒漠草地分布在民勤北部的剥蚀低山及其周围地区,盐渍化荒漠草地主要分布在民勤盆地最低处的西大河、东大河两岸及河流尾闾的古湖盆地带,沙质荒漠草地呈条块状分布在绿洲和砾质荒漠草地之间。民勤荒漠草地的总体特征是:植被稀疏、种类少、质量差、产量低,总面积为934639.80 hm~2,其中以砾质荒漠草地和沙质荒漠草地为主,分别占民勤荒漠草地总面积的39.44%和37.66%。(3)民勤荒漠草地具有代表性的植物群落是白刺群落、红砂群落、盐爪爪群落、芦苇群落、柽柳群落、猫头刺群落、木霸王群落、柠条锦鸡儿群落、膜果麻黄群落、绵刺群落等。面积最大的群落是白刺群落,面积约为310290.20 hm~2,占民勤荒漠草地的33.20%;面积最小的群落是绵刺群落,面积约为8736.00 hm~2,占民勤荒漠草地的0.93%。(4)民勤荒漠草地植物群落的数量特征是:物种数相对少,样方调查显示:植物种最多的是猫头刺群落,只有17种,最少的是芦苇群落只有5种,民勤荒漠草地总的植物种有41种。各群落中植物种的个体数量也很少,有16.67～66.67%植物种在样方中平均出现的次数少于1次。群落中除芦苇群落以外,其它各群落以矮化的灌木、半灌木为主;从植株数量上分析,膜果麻黄群落、绵刺群落、盐爪爪群落和猫头刺群落的灌木、半灌木均在90%以上;而红砂群落、柠条群落和木霸王群落虽然灌木层在数量上不占主导优势,但草本层大多数是较小的一年生草本。(5)民勤荒漠草地植物群落中,除猫头刺群落和木霸王群落外,其它群落的优势种群的重要值均非常突出;膜果麻黄群落中膜果麻黄重要值比亚优势种群泡泡刺高出159.78;绵刺群落中绵刺种群的重要值为204.35,比亚优势种群泡泡刺高出160;红砂群落中红砂种群的重要值比亚优势种苏枸杞高出134.5;盐爪爪群落中盐爪爪种群的重要值比亚优势种泡泡刺高出179.84;柠条群落中柠条种群的重要值比亚优势种唐古特白刺、泡泡刺和猫头刺的重要值分别高出92.12、121.37和112.98;白刺群落和芦苇群落中也是白刺种群和芦苇种群的重要值占了较大比例。(6)民勤荒漠草地各植物群落的优势种群分布格局均为集群分布,这种分布格局与种群的繁殖策略、种群生物学特性以及严酷的生境条件有关。膜果麻黄、白刺、芦苇和绵刺主要以无性繁殖为主,形成以母株为中心的集群分布格局;盐爪爪、红砂、猫头刺、柠条和木霸王主要是以种子萌发和幼苗生长选择适宜的着生点进行繁殖,是由于生境条件不均匀所引起的集群分布。(7)民勤荒漠草地各植物群落多样性指数都较低。本研究选择的9种植物群落多样性从大到小的排序为:猫头刺群落＞绵刺群落＞芦苇群落＞木霸王群落＞红砂群落＞柠条群落＞膜果麻黄群落＞白刺群落＞盐爪爪群落。(8)从植物群落的外貌特征来看,民勤荒漠草地各植物群落的层片结构是由简单的灌木层和草本层组成,且植物个体矮,冠幅小,生物量低,平均高度在0.60m以下,冠幅在1.00m~2以下;生物量除了白刺、泡泡刺和柠条外,大多数植物的单株生物量鲜重都在1000 g/株以下。(9)从植物群落中优势种种群年龄结构分析,膜果麻黄、盐爪爪、柠条、甘蒙锦鸡儿和猫头刺种群在整体上表现为增长型;霸王和白刺种群表现为稳定型;泡泡刺、红砂和绵刺种群整体上呈现衰败型。更多还原

【Abstract】 Minqin desert grassland is a part of Mongolian-Xinjiang plateau of Chinese grassland region,and lies in the arid desert region of lower reaches of Shiyang River,which is the result of natural succession of long-term adaptation of natural and social environment in specific circumstances.It plays a very important role in maintaining the stability of ecological environment and resisting sand hazard as well as promoting the development of grassland agriculture.So it has the extremely important significance in studying vegetation dynamic changes and characteristics of plant communities for the local eco-environment construction and socio-economic development in the region.Based on major plant communities in Minqin desert grassland,the type of major plant communities, distribution,area,habitat conditions and community characteristics were analyzed through field investigation combined with "GIS" technology methods.The main contents of this study were the type of Minqin desert grassland,plant community types and its distribution,the characteristics of plant communities’ structure (including species quantity composition,appearance,diversity,the dominant species populations and distribution pattern,etc.).Through solving age structure curve of the dominant species and a static life curve,the dynamic changes and development trends of the dominant species of plant communities was analyzed.The results were as follows:(1) According to the comprehensive and sequential classification which was founded by academician Pen Jizhou,it classifiedⅣA4- tepid and dry type(temperate desert grassland).According to the soil,terrain features,it was divided into three types of gravelly desert grassland,sandy desert grassland and saline desert grassland.(2) Gravelly desert grassland is located in erosible low hill and surrounding areas of northern Minqin.Saline desert grassland is mainly distributed in two sides of the lowest region of the West river and the East river and the ancient lake basin areas of northern Minqin;Sandy desert grassland is distributed as strip distribution between gravelly desert grassland and Minqin oasis.The overall features of Minqin desert grassland is sparse grassland vegetation,little plant types,poor quality and low yields.A total area was 934639.8 hm~2.The gravelly desert grassland and the sandy desert grassland in Minqin mainly accounted for 39.44%and 37.66%of the total area.(3) The representative communities of Minqin desert grassland are Nitraria community, Reaumuria community,Kalidium foliatum community,Phragmites australis community, Nitraria community,Leguminose community,Zygophyllum xanthaxylum community, Caragana community,Ephedraprzewalskii community and Potaninia mongolica maxim community.The large area of community is Nitraria community,310290.20 hm~2 and is 33.20%of Minqin desert grassland;The small area of community is Potaninia mongolica maxim community,8736.00 hm~2 and is 0.93%of Minqin desert grassland.(4) The number of features of plant community in Minqin desert grassland is a relatively small species number.The survey showed that the most species was Leguminose community and only 17 species,the least species was Phragmites australis community and only 5 species.The total plant species of Minqin desert grassland are 41 species.The number of species of various communities was rarely,the average appearance number of 16.67-66.67%plant species was less than 1 in sample area.Except for Phragmites australis community,other communities were mainly the dwarf shrubs,semi-bush. Analyse from the number of plants,Ephedraprzewalskii community,Potaninia mongolica maxim community,Kalidium foliatum community and Leguminose community,all were more than 90 percent;Among Reaumuria community,Caragana community and Zygophyllum xanthoxylum community,Nitraria community,the shrub layer was not dominance in the quantity,but herb layer was most of the smaller annual herb.(5) Except for Leguminose community and Zygophyllum xanthoxylum community,the important value of the dominant populations of other community was very prominent;In Ephedraprzewalskii community,important value of Ephedraprzewalskii was 159.78 higher than subdominant community,Zygophyllaceae.In Potaninia mongolica maxim community,important value of Potaninia mongolica maxim was 204.35 and was 160 higher than subdominant community,Zygophyllaceae.In Reaumuria community, important value of Reaumuria community was 134.5 higher than subdominant community, chinese wolfberry.In Kalidium foliatum community,important value of Kalidium foliatum was 179.84 higher than subdominant community,Zygophyllaceae.In Caragana community,important value of Caragana was higher than tangutica Nitraria, Zygophyllaceae and Leguminose and were 92.12,121.37and 112.98 respectively.Among Nitraria community and Phragmites australis community,important value of Nitraria and Phragmites australis account for the greater proportion.(6) The distribution pattern of dominant community of the plant community in Minqin desert grassland was clumped.This distribution pattern was connected with the population reproductive strategies,the population biological characteristics and the harsh habitat conditions.Ephedra przewalskii,Phragmites australis and Potaninia mongolica maxim formed a cluster distribution pattern of maternal plant as centre,kalidium foliatum, Reaumuria,leguminose,Caragana,Zygophyllum xanthaxylum and Nitraria population were mainly caused by the habitat condition.(7) The diversity index of all community in Minqin desert grassland was lower.The descending order of the diversity of nine kinds of community were Leguminose Community＞Phragmites australis Community＞Potaninia mongolica maxim Community＞Zygophyllum xanthaxylum Community＞Reaumuria Community＞Caragana Community＞Ephedra przewalskii Community＞Nitraria Community＞Kalidium foliatum Community.(8) From the appearance characteristics of plant community,the synusia structure of plant community in Minqin desert grassland was composed of simple herbaceous and shrub layer,and individual plants was dwarf,small crown,low biomass,with an average altitude of 0.60 m and lower than 1.00 m~2 crown;except for Nitraria,Zygophyllaceae and Caragana,the fresh weight of per plant biomass of most plant were below 1000 g / individual.(9) Analyzing from the age structure of advantage population of various community, Ephedraprzewalskii,Kalidium foliatum,Caragana,caragana opulens and Leguminose performed overall increasing;Zygophyllum xanthaxylum and Nitraria showed stable. Zygophyllaceae,Reaumuria and Potaninia mongolica maxim appeared decreasing.更多还原