DISTRIBUTION, ECOLOGY AND CONSERVATION OF LURONIUM NATANS (L) RAF IN BRITAIN

Despite a wide ecological amplitude, Luronium natans remains a rare aq uatic plant endemic to Europe. The main populations occur in Britain, where Luronium is found in clear water lakes, navigation canals and po nds with widely ranging water chemistry and associated plant communiti es. The spread of the plant this century from upland to lowland sites via an interconnecting system of waterways is chronicled. Luronium is a permanent member of the flora in lakes where various combinations of oligotrophy and disturbance by waves produce a stable low biomass, op en-structured vegetation. It also occurs prolifically in more producti ve waters as an early colonist of recently disturbed, often artificial habitats, but in later stages of succession is out-competed by more v igorous species. Luronium is, therefore, transient or erratic in these artificial habitats, because it depends on sustained human disturbanc e to arrest hydroseral succession and maintain its niche. Dealing prim arily with canal sites, the problems of habitat management and conserv ation of Luronium are discussed.