Distribution and environmental regulation of species of Ranunculus subgenus Batrachium in British rivers

A. J. Spink, K. J. Murphy and D. F. Westlake (1997) Arch. Hydrobiol.  139 (4) 509-525


An extensive survey of river vegetation was carried out at sites where spe­cies of Batrachian Ranunculus occurred. 57 sites in England and Wales were visited four times each and environmental measurements were made. Plants, sediments and waters were analysed for nutrients. The sites were classified by TWINSPAN, and ordination and correlation were carried out using Detrended Canonical Correspond-ence Analysis. The communities and Rananculus species distributions were most strongly correlated with the following environmental variables: water pH; sediment calcium, nitrogen and potassium concentrations; management and land-use categories. Particular species and sub-species were associated with certain combinations of envi­ronmental variables. Tissue phosphorus concentrations in the Ranunculus leaves were positively correlated with phosphorus concentrations in the water, phosphorus in the sediment and nitrate in Ihe water. Tissue nutrient concentrations in Ranunculus leaves of all species was greater than critical values for nutrient limitation. In general, Ra­nunculus was associated with moderately eutrophic conditions.

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