民勤绿洲荒漠过渡带沙拐枣群落种间关联及生态位研究

基于野外样方调查资料，采用方差比率法、χ²检验、联结系数Ochiai、Spearman秩相关分析和生态位量化方法对民勤绿洲荒漠过渡带沙拐枣群落种间关系进行研究，以期为荒漠区固沙植被抚育管理提供理论支撑。结果表明：1)方差比率分析发现，沙拐枣群落总体上呈现显著正联结的关系，群落处于稳定状态。2)χ²检验正关联种对数(98)高于负关联种对数(92),正负联结种对比1.07,显著关联种对占总种对数的7.37%。3)沙拐枣与沙蓬、梭梭的正联结Ochiai指数最大分别为0.90和0.79,体现出互相促进的种间关系，但大部分种对Ochiai联结系数、Spearman秩相关系数较低，种间联结关系松散。4)沙拐枣、梭梭、沙蓬、猪毛菜生态位宽度较大，对绿洲荒漠过渡带具有较强环境适应能力。5)生态位重叠指数由高到低依次为碟果虫实和骆驼蓬(0.93)>阿拉善碱蓬和红砂(0.89)>黄花补血草与画眉草(0.68)。其均值0.16,整体上群落种间竞争较小。建议干旱区防风固沙造林树种应以种间竞争较小的林草植物种为主，构建稳定人工防护体系。

Interspecific Association and Niche of Calligonum mongolicum Community in Minqin Oasis-Desert Transition Zone

Based on the field survey,the interspecific relationship of Calligonum mongolicum community occuring in Minqin Oasis-Desert Ecotone (ODE) was studied by using variance ratio method,χ²-test,association coefficient Ochiai,Spearman correlation analysis and niche quantification to provide theoretical support for the tending management of sand-fixation vegetations in the desert areas.The results were as follows.1) The variance ratio analysis indicated that the interspecific associations within the C.mongolicum community were significantly positive as a whole and in a stable state.2) The χ²-test showed that the number of positive association species pairs (98) was higher than that of negatively correlated species pairs (92),and the ratio between positively and negatively correlated species was 1.07,accounting for 7.37% of the total species pairs.3) The Ochiai indices of positive association between Agriophyllum squarrosum,Haloxylon ammodendron and C.mongolicum were 0.90 and 0.79,respectively,indicating mutual promotion of interspecific relationship.However,the association coefficients of Ochiai and Spearman of most species pairs were low,the correlations between species pairs were weak.4) C.mongolicum,H.ammodendron,A.squarrosum and Salsola collina had larger niche width,indicating their strong adaptabilities to the environment in the oasis-desert transition zone.5) The niche overlap indices from high to low were Corispermum patelliforme and Peganum harmala (0.93),Suaeda przewalskii and Reaumuria soongarica (0.89),Limonium aureum and Eragrostis pilosa (0.68).The mean value was 0.16,indicating that interspecific competition was small.It was suggested that the species with low interspecific competition should be selected to construct a stable sand-fixation forest protection system during the species configuration of artificial vegetation construction.