The ecology of Mollusca in ancient woodland. 2 Analysis of distribution and experiments in Hayley Wood, Cambridgeshire

Analysis of distribution of molluscs in Hayley Wood shows that both abundance and diversity (number of spec1mens, and species, respectively, found in 30 minutes collecting are low in the poorly drained plateau of the wood and increase on the steeper slopes of the south and west. Slope controls drainage which, in turn, affects soil pH at the surface. Poorly drained soils are more acid to a greater depth than better drained soils. Drainage is probably the main factor directly or indirectly determining mollusc distribution.
Most species tolerate coppicing: Cepaea nemoralis and Derocerus reticulatum may actually bene6t from it. Carychium tridentatum, Cochlodina laminatum, Discus rotundatus and Euconulus fulvus probably migrated into the Triangle (recently added adjacent woodland) from the ancient wood; Arion hortensis and Oxychilus alliarius from the old railway. Trichia plebeia and Aegopinella nitidula can move overnight at least 90 and 60cm, respectively. They occur in densities of 4 and 1 per m² and the population of 4 m² changes every 6 and 5 days respectively. Cochlicopa lubrica and Cochlodina laminata occur in densities of 2.5 and 0.25 per m² and their populations in 4 m² apparently change more rapidly.