Given the expansion of plantation forests in Ireland over recent years, there is a need to assess their impact on biodiversity and to identify how sustainable forest management strategies can incorporate biodiversity. We aimed to assess the impact of plantation forests on spider communities and identify structural indicators of their diversity. Pitfall traps were used to sample spiders in Sitka spruce (Picea sitchensis) and ash (Fraxinus excelsior) plantations at different stages of the forest cycle and cover of vegetation, dead wood and soil organic content were measured within each site. Ordinations revealed that spider assemblages were separated by both forest development and canopy species across the forest cycle. The pre-thicket ash and spruce assemblages were similar, whereas canopy species had a greater effect in the more structurally developed stands. The mature ash plots formed a distinct group from the other stands. Overall species richness was highest in the spruce and ash pre-thicket stands, and in the mature spruce stands with a more open canopy.Mature ash stands had the lowest species richness. Lower field layer vegetation was positively correlated with total spider species richness and open habitat specialist species richness whereas canopy closure had a negative effect on these species variables. Forest spider species were positively correlated with litter cover, depth and twig cover. To enhance the diversity of open and forest spider species within a stand, the growth of lower field layer vegetation should be encouraged at all stages of the forest cycle, whilst retaining features typical of a mature forest. Within a plantation, a mosaic of different aged stands will sustain both open and forest specialists to enhance diversity. The distinct assemblages found in the mature plantations indicate that on a landscape scale, the establishment of both ash and spruce plantations will enhance overall diversity.

In order to examine the degree of resource selectivity in a north temperate dung beetle assemblage und to identify major parameters that influence such selectivity, the occurrence of adult dung beetles (Aphodius. Geotrupes and Sphaeridium) in up to five different types of dung over a period of up to 25 d was examined in a series of field experiments using standardised dung pats. There were significant physical and chemical differences in dung quality between dung types and over time during succession. Dung beetle species showed distinct preferences for particular types of dung which were generally similar in data sets from both pitfall traps and dung pat samples. Species also showed distinct patterns of successional occurrence. Ordinations produced by Canonical Correspondence Analysis, based on species occurrences in dung types and over time, usually selected dung pat age as the most important environmental variable influencing dung beetle assemblages. Dung quality parameters contributed a significant element of structure to the species ordinations but ordinations using dung types or dung quality parameter values as the environmental variables were very similar in terms of sample and species placement within the ordination for each data set. Most importantly the CCA ordinations clearly grouped species according to their breeding behaviour. Early‐successional species laid eggs in the soil, or in silken egg cocoons, which allowed them to exploit wet dung. Mid and late‐successional species laid eggs in the dung pat: late‐successional species could exploit normally wetter dung types than mid‐successional species, probably due to increased crust formation and drying as the dung pat ages. Thus, species appear to be differentially adapted to exploit varying types of dung microhabitats. Therefore, where two or more species of large herbivores are present, dung quality preferences probably constitute an important niche dimension.

Gittings, T and Giller, P S 1997 Life history traits and resource utilisation in an assemblage of nonh temperate Aphodius dung beetles (Coleoptera Scarabaeidae) -Ecography 20 55-66To help understand and interpret the structure and function of Aphodius dung beetle assemblages, life history traits and resource utilisation were studied for the ten species compnsing the local assemblage of intensively grazed pastures in southem Ireland Most species were univoltine but one species (A ftmetarttis) was at least panly bivoltme However, temporal overlap in adult flight penods does not necessanly imply overlap in resource use Three different strategies of ovanan development were distinguished and were related to the preferred oviposition site and successional occurrence of the vanous species Evidence suggested that absence of mature eggs in a female's ovanes did not necessanly imply that a female was in a non-reproductive state Two species (A prodromus and A sphatelatus) did not breed in dung, in the laboratory larvae were reared in decaying vegetation One species (A errattcus) developed m brood masses beneath the dung pat Larvae of all the other species developed within the dung pat There were consistent lnterspeciflc differences in the larval development rates, with two species {A rujipes and A rufus) overwintenng mainly as prepupae and the other species mainly as adults Previous studies have considered Aphodtus assemblages as single guilds but the detailed natural histones of these species may affect guild designation

Abstract. 1. Studies of north temperate dung beetle communities frequently invoke competition as an influential ecological process. In this review, the evidence for competition in north temperate dung beetle communities is evaluated and the role of competition as a factor affecting community structure is assessed.2. Resource limitation and the evidence for interspecific competition are assessed by collating the available experimental and observational evidence for both the adult and larval stages of the dung beetle life cycle. The role of competition as a structuring force in dung beetle communities is discussed under the following headings: niche dynamics, migration to and from individual pats, the aggregation model of co-existence, and metapopulations.3. Some of the main conclusions are that competition for space is much more likely to occur than competition for food; the effects of competition on community structure are poorly understood; several of the influential studies of competition in north temperate dung beetle communities need to be evaluated carefully. The differences in ecology between tropical and temperate dung beetle communities are clarified.4. As priorities for future research, resource utilisation and competition should be researched experimentally: density-dependent relationships should be investigated, particularly for the larval stages, as should competitive interactions with other dung fauna. If such experimental approaches establish convincingly the occurrence of competition, then the extent of competition in the field and under real world conditions needs to be established. A functional group classification of dung beetles and other dung fauna is described, which may improve the generality of interpretation from individual, site-specific results.

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