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

生物多样性与生态系统功能之间的关系在生态学中越来越重要。增加多样性被认为通过选择[也称为“抽样”效应]和互补性效应影响生态系统功能，互补性效应将性能优越的物种的效应与协同物种混合物的效应区分开来。关键的生态系统功能，如北方森林中碎屑生物量的分解，进一步受到地上和地下群落之间相互作用的调节。我将比较地表和地下CWM中腐木节肢动物和真菌的多样性，1)混合木和黑云杉占主导的时间序列[跨越100 - 300年]，2)管理的jackpine林分，其中CWM的数量通过森林采伐而实验性地改变。然后，我将进行一系列对照实验，在三个营养水平（木材腐烂真菌、食真菌动物和食肉动物）上依次增加物种和功能群的多样性，并测量对木材分解率的总体影响。这些实验将辅以一个额外的实验，旨在在每个营养水平上分离选择和互补效应。综上所述，这些研究将清楚地了解物种多样性和地上地下食物网如何相互作用，以控制北方土壤中碎屑生物量的积累。了解地下碎屑动态是很重要的，因为在碳平衡模型中，地下碎屑C储量往往被忽略，并且可能比地上碎屑C储量更大。通过比较不同林龄和经营活动的多样性和组成的变化，我将能够进一步概括出森林经营在什么时候对生态系统功能产生最大的影响。通过划分选择和互补效应，我还将能够确定何时需要额外的细过滤器保护策略[由相对较强的选择效应表明]来维持管理森林的生态系统功能。

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.