糙隐子草草原3个放牧演替阶段的种间联结对比分析

COMPARATIVE ANALYSIS OF INTERSPECIFIC ASSOCIATION FOR THREE GRAZING SUCCESSIONAL STAGES OF CLEISTOGENES SQUARROSA STEPPE

种间联结分析是研究植物群落演替的一种有效方法。应用方差检验法和基于 2× 2列联表的分析手段对糙隐子草 (Cleistogenes squarrosa)草原的重度放牧、过度放牧和极度放牧 3个放牧演替阶段的主要植物的种间联结动态进行了定量分析。结果表明 :1)随着逆行演替进程 ,群落主要植物总体的种间联结由显著的正关联过渡到无关联 ;2 )在过牧阶段 ,生活型、生长型和水分生态类型十分相近的白花黄芪 (Astragarus galactites)、糙叶黄芪 (A.scaberrimus)和阿氏旋花 (Convolvulusammanii)相互构成的种对正关联极显著。此结果为种对正关联理论提供了有力证据 ;3)同一种对的联结性质 (正关联或负关联 )

Interspecific association analysis is an efficient method to study the succession of plant communities. Variance tests and 2×2 contingency table analyses were used in quantitative analysis of the dynamics of interspecific association among the main plant species of the three grazing successional stages (heavy, over and extreme grazing) on a Cleistogenes squarrosa steppe. With the progress of the retrogressive succession, the overall interspecific association among main plant species of the community transformed from significant positive to none. In the overgrazing stages, species pairs composed of any two of the following three plant species, Astragalus galactites, A. scaberrimus and Convolvulus ammanii , which were rather similar in life form, growth form and hydro ecological type showed positive association. This result provides powerful evidence for the theory of species pair positive association. Finaly we note that the association status (positive or negative) or association degree (Ochiai indices) varied according to successional stage.