Abundance, biomass and functional structure of the saprophagous macrofauna in the litter and soil of Mediterranean oak forests

The saprophagous macrofauna (macroarthropods, gastropods, earthworms)was sampled in five Mediterranean forests of southern France: two helmoak (Quercus ilex) sites on limestone, two downy oak (Q. pubescens)sites on limestone and a helm oak site on schist. The total biomass washigh, ranging from 52.1 to 113.1 g fresh mass m(-2). Classification ofspecies into functional groups (epigeic, epi-anecic, anecic andendogeic) showed that the four groups were well represented in thisregion. However, the density and biomass of epigeic macroarthropods(mainly millipedes) were significantly higher at the helm oak sites onlimestone (186 ind. m(-2); 9.6 g m(-2)) than at the other sites. Incontrast, the density and biomass of epi-anecic earthworms (Lumbricusspp.) were higher at the downy oak: sites on limestone (13 ind. m(-2);16.7 g m(-2)). Anecic earthworms (Aporrectodea and Scherotheca spp.)were dominant in terms of biomass at all sites (overall mean 56.6 gm(-2)). Although the results are consistent with possible competitiveinteractions between epigeic macroarthropods and epi-anecic earthworms,they also show a high degree of coexistence between both of these groupsand anecic earthworms. The study provides an insight into the possibleresponses of the macrofauna of N-W Europe to climate change towardswarmer and drier conditions. There is potential for maintenance of allthe functional groups that take part in the formation of forest mull.