This report concerns the influence of automobile exhaust on certain of the organisms which function as transformers and decomposers in the trophic energy cycling of organic matter in the forest. If the rate of recycling of energy is decreased, there are important implications for decreased productivity at other levels in the food chain. A slowdown in decay of fallen leaves, branches and other organic matter of the forest floor litter conceivably could mean the accumulation of such material and eventual ecologic consequences.