【作者】 吴国玺；

【导师】 王林和； 张国盛；

【作者基本信息】 内蒙古农业大学 ， 水土保持与荒漠化防治， 2006， 硕士

【摘要】 毛乌素沙地是干旱向半干旱过渡的生态脆弱带,引起了国内外学者的普遍关注。臭柏、油蒿对维护该地区的景观格局和生态系统稳定发挥着重要作用,已成为研究热点,作为该系统重要组成部分的根系直到近期才受到关注,且普遍处于对根系生物量的垂直分布和水平分布的研究,对细根的季节动态变化的研究还未见报道,本文用根钻法和根系分级的方法对毛乌素沙地开发整治研究中心北实验地天然分布的臭柏、油蒿进行了调查研究,7块样地依据外貌特征进行划分,将地面植物归为臭柏群落、臭柏灌丛、油蒿群落三大类,对各样地根系进行连续取样,同时测量土壤的体积含水率,分析得到如下结果:1.各径级根系百分比组成:臭柏群落的根系生物量最大,油蒿群落根系生物量最小。不同径级的根系在根系生物总量中所占的比例相差很大:粗根在臭柏群落中所占的比例最大,油蒿群落中所占比例最小;中根所占的百分比基本相同;细根在臭柏灌丛中所占比例最大,臭柏群落中最小;死根在油蒿群落中所占比例最大,臭柏灌丛中最小。2.细根垂直分布:臭柏、油蒿细根深度特征值β在0.96左右,从年平均值来看,细根生物量最大值都在地表0～15 cm。随土壤深度的增加细根生物量在减少。50%的细根分布在地表至地下18.0～22.2 cm的范围内(即R50值),R90=59.7～73.7 cm,其中臭柏灌丛的细根分布最深。臭柏群落、臭柏灌丛和油蒿群落的细根生物量百分比垂直分布特征比较相似,相应层次上的年平均细根生物量表现为臭柏灌丛>臭柏群落>油蒿群落。细根根长密度和根面积指数在垂直面上呈现相似的规律:年平均细根最大根长密度和根面积指数都出现在表层0～15 cm,并随土层的加深而递减。0～90 cm根面积指数总和的大小顺序是:臭柏灌丛>臭柏群落>油蒿群落。3.臭柏、油蒿细根生产动态及影响因子:不同径级的细根,季节动态变化有所不同,但是臭柏群落、臭柏灌丛和油蒿群落的细根动态有共同的特征:在一个生长季内随着时间的延长,细根的生物量也在增加;雨季对细根生物量的影响很显著。臭柏群落细根季节动态变化曲线比较平稳,臭柏灌丛和油蒿群落的季节变幅较大。细根增长格局各具特色:4～5月份的细根生物量增长率最高,五月后才出现差异,臭柏灌丛的细根在整个生长季都具有增长趋势,而油蒿群落细根量在6～8月比较平稳,臭柏群落在5～6月和各8～10月都有一个回落的阶段。相关分析结果显示,臭柏群落细根生物量动态跟表层土壤含水率和空气相对湿度相关性显著,臭柏灌丛细根生物量跟空气相对湿度显著相关,油蒿群落跟气象因子和土壤水分以及地面枝条生长量相关性不显著。对臭柏根系及细根的研究可为群落演替提供参考,臭柏、油蒿细根和土壤水分更多还原

【Abstract】 Mu Us sandland is a fragile ecological band from arid zone to semi-arid zone. It attracted many scholors’attention widely. S. vulgaris and A.ordosica had important functions for keeping the landscape and the balance of ecological system. It has been focused, however, the root system, as an important section, was not valued properly until nonce. And people only noticed their vertical and horizontal distribution generally at a fixed time. But it was not reported about seasonal change of fine root. By coring and classifying the root systems, this paper mainly reported the investigation and research on dynamic characteristics of root systems of S. vulgaris and A.ordosica which grew in northern site of exploitation and research centre of Mu Us sandland. Seven sample plots were selected base on their natural appearance; the natural flora was classified into three major parts: S. vulgaris community, S. vulgaris cluster and A.ordosica community. Collecting sample from each plot, simultaneously measured the water-content in volume of the soil and analyzed the data, the results were as following:1. Diameter scale percentage: S. vulgaris community had the biggest biomass of its root systems; oppositely, A.ordosica community had the smallest. Different diameter scale root systems had different percentage in total root biomass: thick roots had maximum percentage in S. vulgaris community and the minimum happened in A.ordosica community mediate roots appeared similar percentage in three of them; fine root have the biggest percentage in S. vulgaris cluster, minimum percentage in S. vulgaris community. Dead roots had the maximum percentage in A.ordosica community, minimum in S. vulgaris cluster.2. Vertical distribution of the fine root:βof S. vulgaris and A.ordosica was around 0.96, annual average showed, the biggest biomass of fine roots appeared 0~15cm. fine roots were gradually reduced with the depth. Percentage of the fine root of S. vulgaris community , S. vulgaris cluster and A.ordosica community had similar vertical arrangement characters, annual average fine root biomass of corresponding layers show as S. vulgaris cluster>S. vulgaris community> A.ordosica community.Root Length Density (RLD) and Root Area Index (RAI) of fine root appeared similar rule on depth, and annual average maximum values happened in 0~15cm, the values reduced with the depth. The order of the total RAR of fine root was: S. vulgaris cluster>S. vulgaris community>A.ordosica community.更多还原