高寒草原植物群落种间关系的数量分析

为了探明新疆巴音布鲁克高寒草原植物群落的物种组成和种间关系,在对其草原群落进行样方调查的基础上,利用方差比率法,χ2检验以及种间关联度指数对物种关联性和相关性进行了分析。结果表明:1)巴音布鲁克高寒草原植物群落高等植物分属16科,26属,36种;主要有14个常见植物种;2)用来检验方差比率(VR)偏离1是否显著的统计量W=61.52,说明该草原群落内物种整体关联度表现为不显著相关;表征种间关联程度的Ochiai指数(OI值),与联结系数AC值基本吻合;3)伴生种或杂类草与其它物种之间联结显著,正向或负向,在群落中表现出很强的依赖性,分布易受其它物种的影响,在群落中不能稳定存在且只占据劣势生态位;4)根据14个优势种群对环境的适应方式和主导生态因素,可将它们划分为3个生态种组,同一生态种组内,各种间具有较强的正联结,而不同组间联结较为松散,主要是由于他们具有不同的生物学特性,对生境具有不同的生态适应性和相互分离的生态位所致;5)对退化草地的恢复提出了建议。

Numerical analysis of inter-specific relationships in Alpine steppe community in Bayanbulak

Highland ecosystems are believed to be of vital importance in ecological study,partly due to the rapid climate change worldwide and the highest sensitive feature of this special system,not only its productivity and biodiversity but also its inter-specific relationship,to environmental alterations.The Bayabulak Steppe distributes in the middle part of Tianshan Mountains,and is situated at 42°18′—43°34′ N,82°27′—86°17′ E with altitude between 2460—2760 m.Climate here belongs to typical alpine cold climate with yearly mean temperature of-4.8 ℃,yearly mean precipitation here is 276.2 mm,yearly evaporation is(1 135.2±112.3) mm,the snow period in Bayabulak is about 150—180d,and there is no frost-free time in this region.Stipa purpurea and Festuca ovina grassland are the dominant vegetation types in our study site. In order to clarify the species composition and inter-specific association of the alpine grassland community of Bayanbulak in Xinjiang,China,variance ratio(VR) of the overall association,association coefficient(AC),Ochiai index(OI) and Spearman rank correlation coefficient,based on the 2 × 2 contingency table,were used in our quantitative analysis.Field data were collected in July 2009.Three parallel transect were firstly set up and the distance between each of them was 50 m,then 20 plots(0.50 m × 0.50 m for each unit) were randomly set within each transect,in so doing total of 60 plots were involved in the present work.Our results showed that: 1) There are 36 species with 14 common species of plants in Bayinbulak alpine steppe,and they belong to 26 Genus of 16 Family.W = 61.52,a statistic index to test whether the VR is significant or not,indicated that the overall correlation of all plant species was positive but not significant.2) Inter-specific associations of keystone species with others were neutral or not significant.Keystone species showed greater independence and occupied prior ecological niche in the community,and their distributions were not susceptible to other species.Values of OI were basically identical to those of association coefficient;Based on the measuring of OI,19.79% of total 91species-pairs composed by 14 common species was significant or very significant,and 72.21% of them showed positive correlation while 27.79% showed negative correlation for those significantly related species-pairs;3) Inter-specific associations of accompanying species or weeds with others were significant(negative or positive),suggesting higher dependency of accompanying species or weeds on other species,namely they were susceptible to other species and only occupied inferior ecological niche in the community.Furthermore,populations of these plant species are instability in the process of ecosystem development;4) This study provides new dimensions for the theory of species association.According to their adaptability to the environment and the relationships between plants and environment,the 14 common species were divided into three ecological species groups.Positive correlations occurred among the species in the same ecological species groups,while the negative correlations were found in the different ecological species groups.It mainly due to their different biological features induced by different adaptability to habitats or separated niches;5) Several suggestions were proposed to promote the ecological restoration of degraded steppe systems in the study region.