宁夏荒漠草原不同群落蒙古冰草种群空间格局及种间关联性

Spatial distribution patterns and interspecific relationships of Agropyron mongolicum populations in different desert steppe communities in Ningxia

为探讨蒙古冰草种群对环境的适应对策,以宁夏盐池县荒漠草原短花针茅+蒙古冰草群落、蒙古冰草+牛枝子群落、蒙古冰草+牛心朴子群落为研究对象,采用点格局分析中的O-ring函数统计方法,分析了不同群落中蒙古冰草种群的数量特征、分布类型及优势种群的种间关联性。结果表明:不同群落生境条件下,蒙古冰草+牛枝子群落中蒙古冰草种群的密度、盖度和地上生物量显著高于短花针茅+蒙古冰草群落和蒙古冰草+牛心朴子群落(P<0.05),3个群落之间蒙古冰草种群的高度差异不显著(P<0.05)。不同群落生境蒙古冰草种群在<4 m尺度范围内主要表现为聚集分布,随尺度增大,聚集强度减弱,逐渐过渡到随机分布和均匀分布。蒙古冰草种群与短花针茅种群、蒙古冰草种群与牛枝子种群在小于4 m尺度上呈显著负关联,随尺度的增大趋于无关联;蒙古冰草种群与牛心朴子种群在整个研究尺度上无关联。

Population characteristics and interspecies relationships are important in the study of population ecology.To investigate the environmental plasticity mechanisms of Agropyron mongolicum populations,three 10 m×10 m plots dominated by communities of Stipa breviflora+A.mongolicum,A.mongolicum+Lespedeza potaninii and A.mongolicum+Cynanchum komarovii were studied in desert steppe grassland in Yanchi County.The spatial coordinates and quantitative characteristics,including height and above ground biomass of A.mongolicum were measured in the study plots.The spatial distribution pattern of the A.mongolicum populations and the interspecific relationships between the A.mongolicum populations and other dominant species in the studied plant communities were analyzed by‘point pattern analysis’and‘O-ring function statistic’methods.It was found that the density,ground cover and above-ground biomass of A.mongolicum populations in A.mongolicum+L.potaninii communities were significantly higher than those in S.breviflora+A.mongolicum and A.mongolicum+C.komarovii communities(P<0.05),and the height did not differ significantly among the three communities(P<0.05).The spatial pattern of A.mongolicum populations mainly displayed an aggregated distribution,with an aggregation scale of less than 4 m.When spatial distribution was evaluated at larger scale,the aggregation degree decreased with increasing scale and gradually transformed to random and uniform distribution.The associations between A.mongolicum and S.breviflora populations,and A.mongolicum and L.potaninii populations showed a negative relationship at a scale of less than 4 m and tended to show no association with increase in the evaluation scale.No association between A.mongolicum and C.komarovii populations was detected at the 0-5 m evaluation scale.