珍稀植物狭果秤锤树群落木本植物种间联结性及群落稳定性研究

Analysis on community stability and inter-specific correlations among dominant woody populations of the endangered plant Sinojackia rehderiana communities

关键词:  狭果秤锤树, 2×2联列表, 种群联结性, 群落稳定性

Key words:  Sinojackia rehderiana, 2×2 contingency table, population associativity, community stability

摘要:

在珍稀植物狭果秤锤树集中分布地设置0.5 hm²的固定样地,采用相邻格子法进行野外调查,在2×2联列表基础上,运用x²和W检验,联结系数(AC)、共同出现百分率(PC)的种间联结性分析和M. Godron群落稳定性测定方法,对狭果秤锤树群落中频度较高的24个木本植物优势种,276个种对间的联结性及群落稳定性进行了研究,以评价狭果秤锤树这一稀有种群的种间关系及群落稳定性。联结性分析表明,群落总体联结性VR(方差比率)>1,检验统计量W≤x²_0.05(50),显示群落木本种群间表现出净的正关联,但未达到显著水平。联结性测定指标显示,狭果秤锤树与大多种群关联不显著,表现出相对独立性和随机性,关系松散。群落稳定性比值为35/65,远离20/80,表明群落总体不稳定。狭果秤锤树群落尚未达到稳定阶段,急需加强保护。在物种就地保护和回归实践中,可选择和保护与之正联结的物种,建立适宜的生存环境以达到更好的保护效果。

Abstract:

Populations of Sinojackia rehderiana are highly threatened and have small and scattered distribution due to habitat fragmentation and human activities. In the present study, we selected 24 dominant species according to frequency and studied interspecific associations and correlations usingvariance ratio(VR)analysis of the overall association, x² and W tests, association coefficient, and percentage co-occurrence based on 2×2 contingency tables of species presence/absence data. In addition, we tested the level of community stability by using the Godron stability analysis. The results showed that the total community association of variance ratio was greater than one; the test satistic W was lower than x²_0.05(50), indicating that the species in the overall community were positively associated, but this association was not significant. When species pairs were analyzed, the associations of S. rehderiana with other plant species had no significant inter-specific associations and inter-specific correlations tended to be independent and random. Godron stability analysis showed that the ratios of cumulative inverse of species number to cumulated relative frequency was 35/65, distinctly different from 20/80. The ratios was far from the stability point, indicating that the whole community was unstable. The results indicated that the S. rehderiana community was not stable, and stronger protective measures were required. Therefore, species with positive associations should be chosen in situ and ex situ conservations in order to establish a suitable environment for S. rehderiana, and make its populations more stable.