SAPROXYLIC B E E T L E S (COLEOPTERA) OF THE ICKLINGHAM PLAINS, AN AREA OF SUFFOLK BRECKLAND WITH A REMARKABLE DEAD-WOOD FAUNA H . MENDEL Until recently, the conservation value of woodland has largely been determined on botanical criteria combined with recorded historical continuity, or assumed continuity based on surviving structure and species composition. The term 'ancient woodland' has b e c o m e restricted to describe woodland on a site which has never been cleared and ploughed. In Suffolk the majority of ancient woodlands, so defined, have a long history of coppice management. Although the diameters of many of the coppice stools show them to be of great age, woodland of this type may or may not have any ancient Standing timber. The term 'wildwood' was coined by R a c k h a m (1980) to describe the primeval woodland that once covered most of Britain. Some 5 , 0 0 0 years ago, Neolithic M a n started to clear the forest and the early signs of coppice management date to the same period. In East Anglia, forest on thin, light soils was most easily cleared and, in consequence, Breckland b e c a m e one of the most densely populated areas of Britain. It is gradually becoming recognised that some woodland sites which are botanically poor have a very rieh invertebrate fauna. Many of the rarest invertebrates that have survived as relicts of the wildwood are associated with the cycle of decay. T h e s e are the so called saproxylic invertebrates and their survival has depended on a continuity of specific dead-wood habitats associated with post-mature timber. Post-mature trees are a characteristic feature of pasture-woodlands originally managed both for timber and for grazing deer or livestock. This type of management is well documented for the last 1200 years but most likely began much earlier ( R a c k h a m , 1986) and remnants of pasture-woodlands often have outstanding saproxylic invertebrate faunas. Few custodians of our ancient woodlands appreciate the complexity or the diversity of the dead-wood habitat. T h e survival of invertebrate assemblages associated with decay depends on the continuity of specific conditions of micro-habitat. It is not simply a case of dead-wood invertebrates feeding on rotting logs as the Caterpillar of the cabbage white feeds on a cabbage leaf! More likely, precise conditions of humidity will be required for the development of a particular kind of fungal decay required to Support the larval development of a rare beetle on which another, even rarer, species preys. The conditions required for the survival of many dead-wood invertebrate assemblages are only maintained in Standing timber, particularly over the period between a tree's maturity and death. T h e slow decay of the heartwood provides a long succession of suitable micro-habitats. It is this succession and interdependence of species in the cycle of decay that results in the survival of invertebrate assemblages at certain key sites rather than the survival of individual species at various different sites.
Trans. Suffolk Nat. Soc. 25