Botanical conservation value related to origin and management of ponds

1. A botanical conservation index, derived from the national and local rari ty of aquatic macrophyte species, and also hydrophyte-species richness, wer e determined for 57 ponds in East Yorkshire, England. 2. Ponds were selected to represent diverse origins (i.e. ancient moats, vi llage ponds, gravel pits, clay pits, borrow pits and ponds of miscellaneous origin). 3. High conservation indices and species richness were found in gravel pits , clay pits and borrow pits. 4. When the ponds were grouped on the basis of water chemistry and on veget ation, using SPSS hierarchical cluster analysis and TWINSPAN respectively, the groups did not reflect conservation value or pond origin. 5. High conservation indices and species richness were, however, associated with the presence of adjacent freshwater bodies and bankside angling. Copy right (C) 2000 John Wiley & Sons, Ltd.