宁夏云雾山典型草原半灌木扩张过程中植物种间联结性研究

Interspecific Association of Plants in the Process of the Subshrub Expansion in Typical Steppe of Yunwu Mountain,Ningxia

灌木、半灌木的分布面积在干旱半干旱区持续增加,显著改变了原有植被景观及生态学过程。本研究以宁夏云雾山典型草原为研究对象,采用基于2×2列联表的方差比率法(VR)、χ^(2)检验、物种联结系数等计算物种间关联性,从而揭示灌木扩张过程中群落内物种总体间及种对间的联结性变化规律。结果表明:物种总体关联性在轻度扩张强度下表现为正联结,其它扩张强度下表现为负联结;随扩张强度的增大,半灌木-草本间正联结物种对逐渐增加,草本-草本间负联结物种对表现为先增加后减小的趋势,白莲蒿(Artemisia sacrorum)-百里香(Thymus mongolicus)间的种间联结性趋于无关联,白莲蒿-甘肃蒿(A.gansuensis)间的种间联结性趋于负联结;白莲蒿-草本间的正联结物种对随扩张强度增大而增加。综上,灌木扩张强度和物种自身属性会改变物种间联结性,这种改变是种间竞争、种间互利以及物种对周围环境趋同或分异的结果。

The distribution area of shrubs,subshrubs continues to increase in arid and semi-arid areas,which is significantly changing the original vegetation landscape and ecological process.In this study,the Steppe of Yunwu Mountain in Ningxia was taken as the research object.The variance ratio method(VR),χ^(2) test corrected by Yate’s,species association coefficient(AC)and species association degree(JI)based on 2×2 contingency table were used to calculate the interspecific association of plants,so as to reveal the pattern of interspecific association of plants in the process of shrub and subshrub expansion.The results showed that the overall association of species was positive under mild expansion intensity and negative under other expansion intensity.With the increase of expansion intensity,the positive association species pairs between subshrubs and herbs gradually increased,and the negative association species pairs between herbs and herbs showed a trend of first increasing and then decreasing.The interspecific association between Artemsia sacrorum and Thymus mongolicus tended to be unrelated,and the interspecific association between A.sacrorum and Artenisia gansuensis tended to be negative;The positive species pairs between A.sacrorum and herbs increased with the expansion intensity.Thus,the expansion intensity of shrubs and the attributes of species themselves will change the connectivity between species,which is the result of interspecific competition,interspecific mutual benefit and species convergence or differentiation to the surrounding environment.