【作者】 孙丹丹；

【导师】 王德利； 曹勇宏；

【作者基本信息】 东北师范大学 ， 生态学， 2006， 硕士

【摘要】 本实验运用种群生态学及景观生态学的原理和方法,研究不同刈割强度对羊草(Leymus chinensis)种群动态、种群空间分布、群落特征以及草地微景观和土壤环境的影响,由此解释植被对环境干扰(刈割)的反应及适应机制,为草地景观的有效分析与利用提供一定的理论依据。实验选择羊草分布相对均匀、以羊草为单优种群且地势比较平坦的样地,样地大小为6m×6m,共10块。干扰处理采用刈割方式,处理强度分别为M(中度刈割,留茬高度为植株高度的50%),H(重度刈割,留茬高度为植株高度的75%),HH(过度刈割,留茬高度为0cm),每个处理强度3次重复,另设CK(对照样地,不刈割)一个。实验方法主要采用网格法测量羊草种群分布格局规模及强度,并将获得的数据进行克立格插值得到羊草分布的空间格局图,将图形导入Arcgis9.0中进行矢量化数据分析。通过两年的刈割干扰,结果表明:(1)羊草种群特征随刈割强度增大发生不同程度的变化。首先,种群高度随刈割强度增加而降低,各刈割处理之间(M、H、HH)高度差异显著(P<0.05);其次,种群密度随着刈割强度增大而降低,但处理间的差异不显著;最后,刈割降低羊草单株生物量,2005与2006年各处理组羊草单株生物量与对照样地相比,分别下降了:41.61、54.14、61.30%和58.98、67.36、75.26%,且处理间的差异达到显著水平(P<0.05);刈割也使羊草种群地上生物量降低。(2)羊草种群的分布格局类型在各处理组均为集聚分布;种群聚集强度随刈割强度的增大而增强,且次年羊草种群的集聚强度高于第一年;种群的最大聚集规模未随刈割干扰强度增加发生明显变化,聚集面积维持在1.28m2,但连续的刈割使羊草种群聚集的小斑块数目增多。(3)刈割提高了羊草群落的物种多样性,物种多样性随着刈割强度的增大呈现上升趋势。(4)刈割对羊草微格局的影响体现在斑块数量、面积和周长上。随着刈割强度的增大,斑块数量增加,斑块面积缩小,周长减少,景观呈现破碎化;刈割增加了景观的边界密度,第二年与第一年相比景观边界密度有所升高,破碎化程度有所减轻;刈割增加了景观的破碎度指数;刈割同时也使羊草微斑块的形状指数发生变化,即刈割使斑块形状趋向规则化。(5)刈割对样地土壤有机质含量和pH值没有显著影响,即短期内的干扰不足以使土壤系统立即作出反应。更多还原

【Abstract】 To explain the vegetable’s response and adaptive mechanism when suffered disturbance such as environmental interruption (defoliation) and provide the theoretical base for making the valid programming and using of grassland, one experiment was conducted to investigate the population dynamics, spatial distribution pattern, community characteristics, microlandscape and soil environment for the grassland of Leymus chinensis with different cutting intensities by applying the theory and method of population ecology and landscape ecology. In the experiment, we choose the area where the topography is smooth and the distribution of L. chinensis is relatively even. The defoliation experiment design was three treatments (medium cutting-M, heavy cutting-H and over-cutting-HH) with three paddocks per treatment and there was also a contrast (CK). We use gridding to measure the population distribution pattern and intensity, in the same time, using Kriging Spatial interpolating to obtain the figure of spatial pattern of L. chinensis and make vector analysis of data to explain the influence on the micropattern of L. chinensis under different cutting intensities. The results showed that:(1) The population characteristics varied with the increasing of cutting intensities. Firstly, the population height fell with the increasing of cutting intensities and differed significantly among treatments of medium (M), heavily (H) and over defoliation (HH) in the scale of P<0.05. Secondly, the population density decreased with increasing of defoliation intensity, but the difference is not significantly. Lastly, cutting made the biomass of L. chinensis per tiller fewer than CK significantly (p<0.05) and the biomass reduced by 41.61, 54.14, 61.30% and 58.98, 67.36, 75.26% respectively compared to contrast in 2005 and 2006; Cutting also reduced the population biomss in aboveground.(2) The spatial distribution patterns of L. chinensis in the treatments were aggregation after the last cutting; the aggregation intensity of population for L. chinensis enhanced with increasing of cutting intensities and the effects of continuous disturbance were embodied; the largest population aggregation pattern haven’t change distinctly with the aggregation area of 1.28m2, but small clumping patterns appeared with increasing of cutting intensities. Cutting also improved biodiversity of community.(3) Defoliation as a way of disturbance has an important influence on micro-patch of L. chinensis. In the same year, numbers of patch increased with cutting intensities enhanced, the area of patch reduced and the landscape appeared fragmentation. Degree of fragmentation had a little drop in the second year. The edge density in landscape and fragmentation index both have increased with the increasing of clipping intensities, that is to say, the landscape更多还原