糙隐子草种群在不同放牧强度下的小尺度空间格局  

Fine-scale spatial pattern of Cleistogenes squarrosa population under different grazing intensities

作　　者：刘振国[1] 李镇清[1] Ivan Nijs Jan Bogaert 

机构地区：[1]中国科学院植物研究所植被数量生态学重点实验室,北京100093 [2]比利时安特卫普大学生物系 [3]比利时布鲁塞尔自由大学景观生态学实验室

出　　处：《草业学报》2005年第1期11-17,共7页Acta Prataculturae Sinica

基　　金：中国科学院知识创新项目(KSCX2 SW 107;KSCX 1 08);国家自然科学基金项目(30270249)资助。

摘　　要：利用Ripley'sK函数,在0～100cm的空间尺度域上定量分析了4种放牧强度———无牧(0只/hm2羊)、轻牧(1.33只/hm2羊)、中牧(4.00只/hm2羊)、重牧(6.67只/hm2羊)下糙隐子草种群的空间格局及其随尺度的变化规律;用蒙特卡罗(MonteCarlo)随机模拟方法估计了^L(t)的置信限。研究了放牧对糙隐子草种群空间格局的影响以及糙隐子草在不同放牧条件下的斑块大小,并进一步以放牧条件下糙隐子草的生活史特征、生态适应对策以及群落内植物种间的相互作用为基础,探讨产生和维持这些格局的机理。研究结果表明:1)放牧显著影响糙隐子草种群空间格局,即使在同一放牧强度下在不同尺度(0～100cm)上糙隐子草种群的空间格局也显著不同;2)在0～100cm尺度上,糙隐子草种群的空间格局在无牧条件下为均匀分布,在轻牧和中牧条件下为集聚分布。重牧条件下,糙隐子草种群的空间分布在0～42cm尺度上为集聚分布,而在42～100cm尺度上为均匀分布,这与其自身的生物学特性和种群对放牧压力的生态适应对策密切相关;3)不同放牧条件下,糙隐子草种群的斑块大小不同;4)放牧活动的加剧改变了群落中的各种过程,并最终代替群落中的种间竞争过程而成为决定群落内物种分布的主导过程,这为在放牧活动的干预下,退化草原群落演替规律的研究提供了理论依据。The fine-scale spatial patterns of Cleistogenes squarrosa (Trin.) Keng) were recorded in the Inner Mongolia steppe of China as presence/absence maps from 2 m×2 m grid (2 cm×2 cm) quadrats under four grazing intensities: no-grazing (0 sheep/hm^2), light-grazing (1.33 sheep/hm^2), medial-grazing (4.00 sheep/hm^2) and heavy-grazing (6.67 sheep/hm^2) . Local spatial structure and its scale law in these patterns were quantified using the Ripley's K function and Monte-Carlo random simulation methods, and studied the effects of grazing on spatial pattern and size of patches of Cleistogenes squarrosa population. Based on life history characteristics and strategies of ecological adaptation of Cleistogenes squarrosa population and interspecific interaction in the community in the grazing condition, the mechanism generating and maintaining these patterns was discussed. The results showed that: 1) Grazing has significant effects on spatial pattern of Cleistogenes squarrosa population. The spatial patterns of Cleistogenes squarrosa population changed with scale changing (0-100 cm) even if the same grazing intensity had been experienced; 2) At 0-100 cm scales, the spatial distribution of Cleistogenes squarrosa population was regular under no-grazing condition but aggregate under light- grazing and medial-grazing conditions; however, under heavy-grazing condition, the spatial distribution of Cleistogenes squarrosa population was aggregate at 0-42 cm scales, but regular at 42-100 cm scales, which depend on its biological properties and of adaptive strategies to the grazing pressure; 3) The size of Cleistogenes squarrosa population patches was different under different grazing intensities; 4) The various ecological processes would been changed as increasing of grazing intensity, and grazing would replaced the interspecific competition as the dominant process determined species abundance and distribution in the community, which would provided an insight into the mechanism of community succession under the disturbance of grazing

关 键 词：放牧强度 糙隐子草 小尺度 空间格局 生态适应策略 

分 类 号：S812.8[农业科学—草业科学]