Linking arthropod biodiversity and food webs with changes in surface and below-ground detritus

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Relating between biodiversity to ecosystem function continues to gain relevance in ecology. Increasing diversity is thought to affect ecosystem functions through both selection [also termed 'sampling' effects] and complementarity effects which partition the effects of species with superior performance from those of synergistic species mixtures. Critical ecosystem functions such as decomposition of detrital biomass in boreal forests are further regulated by interactions between above- and below-ground communities. I will compare diversity of saproxylic arthropods and fungi between surface and buried CWM across 1) mixedwood and black-spruce dominated chronosequences [spanning >300 years] and 2) managed jack-pine stands where CWM volume has been experimentally altered through forest harvesting. I will then perform a series of controlled experiments where species and functional group diversity is increased sequentially at three trophic levels [wood decaying fungi, fungivores and predators] and overall effects on wood decomposition rate are measured. These experiments will be complemented by an additional experiment designed to separate selection and complementarity effects at each trophic level. Taken together these studies will provide clear understanding of how species diversity and above- and below-ground food webs interact to control the accumulation of detrital biomass in boreal soils. Understanding below-ground detrital dynamics is important as below-ground stocks of detrital C are often neglected in carbon balance models and can be greater than those found above-ground. By comparing changes in diversity and composition across a range of stand ages and management activities I will be able to further generalize when forest management will have greatest effects on ecosystem functions. By partitioning selection and complementarity effects, I will also be able determine when additional fine filter conservation strategies [as indicated by relatively strong selection effects] will be required to maintain ecosystem functions in managed forests.