不同放牧强度下冷蒿种群小尺度空间格局  

Fine-scale spatial pattern of Artemisia frigida population under different grazing intensities

作　　者：刘振国[1] 李镇清[1] 

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

出　　处：《生态学报》2004年第2期227-234,共8页Acta Ecologica Sinica

基　　金：国家自然科学基金资助项目 (3 0 2 70 2 49) ;中国科学院知识创新工程资助项目 (KSCX2 -SW-10 7;KSCX-1-0 8)~~

摘　　要：时间、空间格局的发展和维持及其对种群和生态系统的影响一直是生态学研究的中心议题 ,这些问题的核心是观察的尺度怎样影响格局的描述。冷蒿 (Artemisia frigida)种群伴随着典型草原退化演替的各个阶段 ,对其所在群落的结构和功能具有重要的影响。应用 Ripley's K函数以及蒙特卡罗 (Monte Carlo)随机模拟方法 ,定量分析了 4种放牧强度下冷蒿种群在 0～10 0 cm尺度上的空间格局及其随尺度的变化规律 ;研究了放牧对冷蒿种群空间格局的影响以及冷蒿在放牧胁迫下的生态适应对策。并以放牧条件下冷蒿的生活史特征、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放牧对冷蒿种群空间格局有显著影响。同一放牧强度下冷蒿种群在不同尺度 (0～ 10 0 cm)上的空间格局存在显著差异 ;2在 0～ 10 0 cm尺度上 ,无牧、轻牧条件下冷蒿种群的空间格局为聚集分布 ;中牧条件下在 0～ 6 0 cm尺度上冷蒿种群的空间格局为聚集分布 ,而在 6 0～ 10 0 cm尺度上为均匀分布 ;重牧条件下在 0～ 72 cm尺度上冷蒿种群的空间格局为聚集分布 ,而在 72～ 10 0 cm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 ;Two fundamental and interconnected themes in ecology are the creation and maintenance of spatial and temporal pattern, and their consequences for population and ecosystem dynamics. Central to these questions is how the scale of observation influences the description of pattern. Artemisia frigida populations are present in every stage of degraded succession of Chinese Inner Mongolia steppe. They have important effects on community structure and function, but spatial pattern of Artemisia frigida populations are poorly understood. We recorded fine-scale (0～100cm) spatial patterns of this species as presence/absence maps from 2m×2m grids (2cm×2cm quadrats) under four grazing intensities: no grazing (0 sheep/hm^(2)), light grazing (1.33 sheep/hm^(2)), medium grazing (4.00 sheep/hm^(2)) and heavy grazing (6.67 sheep/hm^(2)). Local spatial structure and its scaling principles in these patterns were quantified using the Ripley's K function and Monte-Carlo random simulation methods, and the effect of grazing on spatial pattern of Artemisia frigida populations was studied. Based on life history traits, strategies of ecological adaptation of Artemisia frigida populations and interspecific interaction in the community under the grazing regime, the mechanisms generating and maintaining these patterns were discussed. The results showed that: (1) Grazing had obvious effects on spatial patterns of Artemisia frigida populations. Under the same grazing intensity, the spatial patterns at different scales (0～100cm) were significantly different. (2) Under non-grazing and light-grazing conditions, the spatial patterns of Artemisia frigida populations were aggregated at 0～100cm scales; under medium-grazing conditions they were aggregated at 0～60cm scales, but regular at 60～100cm scales; under heavy-grazing conditions, the spatial distributions of Artemisia frigida populations were aggregated at 0～72cm scales, but regular at 72～100cm scales. (3) The relative strength of the various ecological processes that drive communi

关 键 词：冷蒿 放牧强度 小尺度 空间格局 生态适应对策 

分 类 号：S812.6[农业科学—草业科学]