Effects of earthworms and the salamander Ambystoma maculatum on detrital community structure and function in a mixed deciduous forest

Decomposition is essential to the function of an ecosystem. In forests the decomposition of litter cycles nutrients, contributes to soil formation, and provides an energy base for the detrital food web. The productivity of an ecosystem depends on the rate at which the matter is broken down and circulated through the system. In forests large quantities of litter fall to the forest floor where the organic matter is reduced and returned to the soil. The integral role of the forest floor community in maintaining ecosystem function has long been recognized but they have been neglected in food web and community studies. Interactions among members of the forest floor community are poorly understood and there have been few studies of the effects of changing species composition on community structure and function. Such information becomes more relevant as natural systems undergo changes in species composition.; This study investigated ecosystem level questions under more natural conditions than previous studies by using field enclosures on the Edmund Niles Huyck Preserve in Eastern New York State. Species densities were altered in two trophic levels to investigate what factors regulate detrital communities. A two by two factorial design was used with two levels of earthworm densities and two levels of salalamders. Litter invertebrates were sampled to detect changes in community structure and litter decomposition was used as a measure of community function.; Results indicate that there was an effect of salamanders and earthworms on invertebrate abundance and litter decomposition but responses varied over space and time and were not always as predicted. There was a strong relationship between site variability and aspect. This research expands our knowledge of the functional significance of earthworms on the decomposition of leaf litter, and how amphibians in the terrestrial stage influence the dynamics of detrital systems. The study also aids in understanding our ability to predict how future species introductions and extirpations may affect terrestrial systems.