作 者 ：陈宝瑞,杨桂霞,张宏斌,段庆伟,辛晓平*
期 刊 ：生态学报 2010年 30卷 21期 页码：5868~5874
Keywords:Hulunber, point pattern, grazing, cutting, fencing,
摘 要 ：生态系统各层次的空间格局与生态学过程的相互关系一直是生态学的研究热点之一，这一问题的关键是选取合适的观察尺度。羊草（Leymus chinensis）作为呼伦贝尔草原的地带性植被，研究其种群空间格局对理解种群生态过程和草地资源可持续利用具有重要意义。利用Ripley’s K函数和Monte Carlo随机模拟方法，对两块样地3种干扰下的羊草种群格局进行定量分析。结果表明：(1)刈割、围封、放牧3种干扰对羊草草甸草原恢复改良样地（LM）和贝加尔针茅试验样地（SM）的羊草种群空间格局具有显著影响，空间格局在不同尺度上存在差异。(2)在较小的空间尺度内，羊草种群倾向于非随机分布，在LM样地、SM样地分别为均匀分布和聚集分布；当空间尺度大于临界值后，羊草种群在围封（30—100cm）、放牧干扰（84—100cm）下倾向于随机分布，刈割干扰下仍为聚集分布。这主要与羊草的繁殖对策、群落地位以及各种干扰下对资源的竞争能力有关。(3)空间结构的规律性表面上取决于观察尺度，但更小尺度的数据对局域空间结构的生物学解释可能更有效。
Abstract:Grassland degradation is one of the important environment and resource issues in North China. Different degrees of grassland degradation in Hulunber grassland are mainly caused by global climate change, overexploitation and other reasons, which threats to the sustainable development of grassland animal husbandry and improvement of living standards of farmers. The relationship between spatial patterns and ecological processes at different scales is one of the hottest research topics, the key point of which is to select an appropriate observation scale. Disturbance as part of the process, is the main sources of spatial heterogeneity, which can significantly change the ecological pattern and processes at different scales, causing apparently shift of the structure and function of ecological systems. Small-scale spatial structure of plant species was important in plant ecology as it affected the dynamics of plant populations, communities and ecosystem processes. Hulunber steppe with a plateau landscape is a component of the Mongolian Plateau in central Asia and located in the eastern part of Inner Mongolian, which with the unique ecosystem characteristics, relatively well-preserved natural environment, abundant landscape types and biodiversity, relatively advanced and intensive production mode, is the optimal object for researching the natural ecological patterns and process in steppe ecosystems, and its responses to human-caused disturbances. Leymus chinensis, the zonal vegetation in Hulunber grassland, has a great significance for understanding ecological processes and sustainable utilization of grassland resources with studies on population patterns of Leymus chinensis. We recorded fine-scale (0-100cm) spatial patterns of this species as presence/absence maps from 2m×2m grids (2cm×2cm quadrats) in two plots under three kinds of disturbances: cutting, fencing and grazing. Ripley′s K function and Monte Carlo stochastic simulation method were used to quantitatively analyze Lemus chinensis population patterns. Based on life history characteristics, strategies of ecological adaptation of Leymus chinensis population and interspecific interaction in the community under different disturbances, the mechanism generating and maintaining these patterns was discussed. The results showed that: First, there were significant effects on spatial patterns of Lemus chinensis populations under the disturbances of cutting, fencing and grazing in the Restoration Succession Sample of Leymus chinensis Meadow Steppe(abbr. LM) and Long-term Observation Sample of Stipa baicalensis Meadow Steppe(abbr. SM). The density of Leymus chinensis population in LM was significantly greater than SM, but its L(h) value in LM was lower than SM, which indicated the aggregation level of SM was greater than LM. Second, there is a difference at virous scales. On the scales less than certain critical points with the population usually characterized by non-random distribution, is being regular in LM and clumped in SM respectively; In contrast, if the scales enlarge beyond these critical points, the plants will disperse randomly but without disturbances of cutting which is clumped. It is mainly related to Leymus chinensis′s reproductive responses community′s position, and competition ability for resources under different disturbances. Third, the nature of spatial structure seemingly depends on the scale of observation, but the smaller-scale data are likely to provide a more powerful biologically explanation for local spatial structure in this community.
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