Molluscs in coppice woodland

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A coppice woodland in Sussex has been surveyed for molluscs (quantitatively for snails and qualitatively for slugs) and measurements taken of pH, free chalk, litter and vegetation, with the aim of determining whether coppicing has an effect on snails. The fauna and population structure are described. No direct correlations have been found between age of coppice compartment and either diversity or abundance of snails, although significant relationships were obtained between age and litter depth and between age and percentage vegetation cover. However, two species of snail were found mainly in the earlier or later stages (Vitrina pellucida, Oxychilus alliarius). A negative relationship exists between snail diversity and abundance, and may reflect, in this particular woodland, the increased dominance of Carychium tridentatum. However, comparison with other studies indicates that a positive relationship between diversity and abundance is also possible.

The pH has a significant, positive relationship with snail species richness and abundance in the community as a whole. A number of individual species (Carychiurn tridentatam, Discus rotundatus, Aegopmella pura, Vitrea contracta, Pomatias elegans and Vitrina pellucida) show strong positive relationships with pH, and others (Nesovitrea hammonis and Punctum pygmaeum) show pronounced negative relationships. Litter depth and litter percentage cover appear to play an important role, with several species achieving peak numbers at 2 cm depth of litter. Soil particle size may also be a factor affecting richness and abundance. It is suggested that the main effects of coppicing on snails could be caused by the assoclated initial reduction in litter. This would affect litter dwelling species most. The arboreal and dead-wood favouring species are likely to be at a relatively low level of abundance because of the removal of dead wood associated with coppicing.

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