Leaf litter decomposition in an ephemeral karst lake (Chaney Lake, Kentucky, U.S.A.)

摘要

Litter decomposition in temporary aquatic environments has not been experimentally studied as much as it has in perennial systems. However, litter is likely a critical resource for organisms inhabiting ephemeral aquatic habitats. In this study, we used litterbags under differnt conditions of submergence and water physical and chemical properties/characteristics to study mass and nutrient losses of terrestrial materials in an ephemeral karst lake in south-central Kentucky (USA). In the first experiment, which was designed top compare decomposition rates in submerged and dry sites, total mass and carbon declined more rapidly in the litter at fully submerged sites than in dry sites. In the second experiment, which was designed to compare decomposition rates in two different submerged environments, total mass and carbon showed similar decomposition trends between the two submerged areas with different seasonal tmperature patterns. Nitrogen patterns were variable but in general nitrogen levels increased in the litter in both experiments over a period of several months. These results are similar to those found in some perennially inundated systems and indicate that litter decomposition dynamics in ths temporary lake can be greatly affected by lake hydrology. Year-to-year variations in hydrology may thus have strong impacts on untrient and energy release within this system, which may affect the organisms within this karst lake and in other areas of the karst ecosystem that are ecologically connected to it.