Succession, Diversity and Trophic Relationships of Some Soil Animals in Decomposing Leaf Litter

Abstract

Soil systems contain some of the most species-rich communities in existence. Well developed temperate woodland soils may contain up to a thousand species of soil animals alone, including several hundred species of mites and Collembola, in populations exceeding 1 to 2 millions per square metre. Investigations of the interand intra-specific relationships within these immensely complex communities has proved to be one of the most intractable ecological problems. The study of microhabitat development and successional changes in soil organism communities during the breakdown and decomposition of organic materials in the soil could provide useful information towards an understanding of the larger system. Unfortunately few studies of this kind have been carried out. Succession of the soil microflora on leaves has been demonstrated in a number of studies (notably, Hogg & Hudson 1966; Frankland 1966; Hudson 1968, Parkinson & Balasooriya 1969; Jensen 1971) but there have been few investigations of the soil fauna associated with decomposing leaf litter. One major problem in studies of this type is in maintaining the identity of the experimental material without altering the soil environment. Crossley & Hoglund (1962) suggested that the use of litter bags would overcome this difficulty and this method has been used by Stevanovic (1968) to study general arthropod succession and by Metz & Farrier (1969) to study succession of the Mesotigmata (Acari) in leaf litter. Anderson (1973a, b) investigated the breakdown and decomposition of beech (Fagus sylvatica L.) and sweet chestnut (Castenea sativa Mill) litter using litter bags and found that beech leaves were less palatable to soil animals and more resistant to microbial decomposition than chestnut leaves. The present study is an analysis of the soil animal populations extracted from these litter bags over a 20-month period to investigate the successional development, structure and trophic relationships of soil organism communities in beech and chestnut leaves.