The effects of temperature and moisture on the efflux of CO2 from leaf litter.

Abstract

Soil respiration represents an enormous output of carbon dioxide to the atmosphere. The possibility of a positive feedback effect between global climate change and soil respiration makes it important to understand how future climatic changes will affect soil respiration in forest ecosystems. One important component of soil respiration is the highly labile leaf litter. In a forest ecosystem the leaf litter carbon pool is closely tied to the net primary productivity, and it is subjected to greater variation over short periods of time in the main drivers of soil respiration, temperature and moisture, than the rest of the soil. Leaf litter samples were collected from four plots and on two dates in a temperate forest in northern lower Michigan. The litter samples were subjected to laboratory experiments to determine the relationship between temperature, moisture, and the rate of CO2 efflux from leaf litter. This study presents a predictive model of the efflux of CO2 from leaf litter based on the experimentally generated data. The model was used to estimate the contribution of the previous year's leaf litter to the total soil respiration in the same region. Both temperature and moisture are significantly correlated with leaf litter respiration, and the previous year's leaf litter was found to be a significant contributor (0-8% over a two week period, depending on conditions) to total soil respiration, with the proportional contribution of leaf litter varying under different environmental conditions. The results are consistent with other studies that have named primary production as an important factor in variation in soil respiration between ecosystems.