Species richness of aquatic macrophytes in ponds related to number of species in neighbouring water bodies

The number of species of aquatic macrophytes and the number of neighbouring water bodies (within 500m) were counted for three botanically rich ponds and three botanically poor ponds in north-east England. The number of species and the sum of records of aquatic macrophytes in the neighbouring water bodies were also determined. The linear regression model of number of species in the ponds against number of species in neighbouring water bodies closely fitted the data. This model suggested that ponds contain both a baseline number of taxa representing long-distance migrants and/or introductions, and a number of species which have come from neighbouring water bodies.