摘要
我们对环境变量(海拔高度、支流等级、离源头距离、集水区、坡度、河宽、鱼类品种丰度)给河系范围内的真、北方须鳅和侧的同现格局产生的影响作了评估。根据7种变量采用自行组合图(神经网络)对总共474个场站进行了分类并用k-means算法检测到了3个聚类。对每个聚类各种鱼类的同现格局频率进行了计算。使用一般线性建模来说明预测每一品种出现的条件。山麓河系可能支持侧(鱼句)和真种群的共处,因为两种鱼出现有较高的或然率。上游溪流中三个品种有较高的同现频率是侧(鱼句)和真出现的频率较低的缘故。把重点放在对同现的品种有益的领域也许会增强自然保护项目的有效性。
We assessed the influence of environmental variables (elevation,stream order,distance from source,catchment area,slope,stream width,and fish species richness) on the cooccurrence patterns of the minnow,the stone loach,and the gudgeon at the stream system scale.A total of 474 sites were classified according to the seven variables using the Self-Organizing Map (neural network),and three clusters were detected (k-means algorithm). The frequency of the various fish co-occurrence patterns was calculated for each cluster, and general linear modeling was used to specify the conditions that predict the occurrence of each species.Piedmont streams were more likely to support coexisting gudgeon and minnow populations because of higher probabilities of occurrence for both species.The higher co-occurrence frequency for the three species together in headwater streams resulted from lower occurrence frequencies in gudgeon and minnow.Focusing on areas that favor the cooccurrence of species may enhance the effectiveness of conservation projects.
