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.