沙区人工固沙植物的种间生态位关系与系统模拟研究

在沙坡头沙区人工植被群落区,采用空间序列代替时间序列,并以演替时间为生态位维度,通过定量分析物种的生态位体积和生态位重叠,研究沙区人工植物群落演替过程中群落各组分种对资源的利用能力、种间生态相似性及竞争机制。基于干扰作用的机理分析,组建具有干扰作用的竞争系统模型,并进行数值模拟研究。结果表明:人工栽植的灌木花棒、柠条和半灌木油蒿的生态位体积值在时间尺度上呈现先增加而后减少的变化趋势;天然1年生草本各植物种则呈现持续增加的趋势。灌木、半灌木种之间、草本植物与草本植物之间的生态位重叠值较大,其中花棒与油蒿、虎尾草与雾冰藜之间的生态位重叠值分别为0.719 2和0.862 2,这表明二者之间有较大的生态相似性,从而在演替过程中具有较强的竞争作用;而半灌木油蒿与各草本植物之间的生态位重叠值很小,它们能够实现稳定共存。系统模拟结果表明:在群落竞争系统中,干扰强度适中时,弱竞争种具有较强侵占率,可以排斥强竞争者,不同干扰强度下系统可以产生多个可能的竞争结果,即诱发出群落不同的稳定状态,这与样区调查结果是一致的。

Interspecific Niche Relations and Dynamical System Simulation of Artificial Sand-fixation Plants Employed in Sand Regions

With spatial sequence taking the place of temporal sequence and succession time as ecological dimension,the niche volumes and overlaps of various species were quantitatively investigated in the manmade florae of Shapotou Area to study the resource-exploiting capacities,interspecific similarities and competition mechanisms of various community components of manmade florae in sand areas in community succession.A competition-system model of interference was established on the basis of the analysis of interference mechanism and its numerical simulation was carried out.It was shown that planted Caragana korshinskii and Hedysarum scoparium and Artemisia ordosica present a niche volume that tends to increase initially and then decline with time,and natural herbaceous annuals have a niche volume that tends to increase at all times.There are large niche overlaps between the shrub and semi-shrub species and among the herbaceous plants of which the overlap between H.scoparium and A.ordosica and between Chloris virgata and Bassia dasyphylla were 0.719 2 and 0.862 2,respectively,and this indicates that they have greater ecological similarity thus possessing strong competitive capacities in community succession;there are smaller niche overlaps between A.ordosica and various herbaceous plants and thus they can stably co-existed.System simulation reveals that in the system of community competition the species with weak competitiveness have strong colonizing capacity thus excluding the species with strong competitiveness given an intermediate interference,and the system can produce many competition results at different interference intensities,i.e.the interferences at different intensities can induce different stable states,which is in agreement with the results of the quadrat investigation.