The Community of Invertebrates in Decaying Oak Wood

Abstract

This paper reports a study of the invertebrate fauna of pieces of decaying oak wood taken from the floor of a mixed deciduous woodland in the Wytham Woods Estate, Berkshire, a property used for field studies by Oxford University (Elton 1966). In order to reduce variability due to differences between localities, all samples were taken from a small area in Marleywood Plantation-approximately 100 m wide by 150 m long. Emphasis has been placed on information obtained from four types of synthetic logs (boxes of compressed oak sawdust) that were placed on the forest floor in this area for various lengths of time. As the initial differences between the types of logs were controlled and there were exact replicates for each of two seasons and at each of three locations, it has been possible to examine the effects of log characteristics, season and locality separately and also to obtain some idea of the interaction between these environmental factors. Interspecific relationships have been looked at using the concept of recurrent groups outlined in a previous paper (Fager 1957). A total of 182 species were found in the fifty-one samples that were examined completely (thirty-six synthetic logs and fifteen natural logs taken for comparison). The distribution of these species among major taxonomic groups is shown in Table 1. This does not, of course, represent a complete list of the fauna of decaying oak wood; approximately fifty additional species were found in a small number of logs that were examined during preliminary work, and records inthe survey of Wytham, beingdone by Elton (Elton M Elton 1966) and others would add more. It does, however, appear to give a satisfactory representation of the organisms that were abundant in this habitat at this locality. The analyses in this paper are based solely on the 108 species that occurred in five or more samples (middle three columns in Table 1). This division is arbitrary but seems justified because what is wanted is a knowledge of the processes that affect the numerically more important species. The full names of these species and details of determinations are given in the Summary List of Species (Appendix A). The animals found in small pieces of decaying oak wood have been treated as an ecological unit, the components of which influence each other directly and indirectly and are variously affected by the environment. A complete, detailed picture of the workings of this unit will require much more study, but it has been possible to make a start at untangling the complex of factors and processes that operate in this habitat and determine the composition and structure of the animal groupings found in it.