Functional Roles of Leaf Litter Detritus in Terrestrial Food Webs

This chapter discusses that one group of terrestrial predators responds more strongly than the two common detritivores to the removal of leaf litter-the dominant basal resource in the system. Detritus is both food and habitat for members of detrital- and plant-based compartments of food webs. Smaller forms of detritus have often been treated solely as a resource for detritivores. For example, leaf litter is a fundamental component of almost all forested ecosystems. Like coarser forms of detritus, leaf litter can also determine the relative abundance of species not dependent on litter as an energy source. Spiders were greater than four times less abundant in riparian plots in which litter was experimentally removed, than in control plots in which litter was left undisturbed. Moreover, the spider response to litter was more consistent over time than the responses of detritivores. Detritivores appeared to recruit to plots with and without litter differentially, but differences between these two treatments typically changed between dry and monsoon seasons. These results suggest that spiders rely on litter as a cover from predators at higher trophic levels through dry and monsoon seasons, and that detritivores respond to some combination of structural, thermal, and energetic attributes of leaf litter.