Non-native earthworms in riparian soils increase nitrogen flux into adjacent aquatic ecosystems

摘要: Riparian zones are an important transition between terrestrial and aquatic ecosystems, they function in nutrient cycling removal. Non-native earthworms invading earthworm-free areas of North America can affect upland soils have the potential to it riparian soils. We examined how presence delivery streams. Two mesocosm experiments were conducted determine (1) biomass (2) earthworm species flux from nearby streams this streamwater nutrients periphyton growth. In separate experiments, soil cores amended with one four mixed biomasses (0, 4, 10, or 23 g m(-2) ash-free dry mass) three (Aporrectodea caliginosa, Lumbricus terrestris, L. rubellus) no species. coupled artificial streams, over a 36-day period, we measured leaching rates, in-stream concentrations, Ammonium increased increasing was greatest A. caliginosa treatments. Nitrate through time at greater rate higher containing caliginosa. suggest that overall response nitrate [90% total nitrogen (N)] due combination ammonium excretion burrowing by earthworms, which nitrification rates. During both but did not differ across treatments despite high inorganic N. Through time, phosphorus (P) concentration declined <5 microg l(-1), growth likely P-limited. conclude activities non-native (particularly caliginosa) alter biogeochemical zones, potentially reducing N-buffering capacity altering stoichiometric relationships adjacent ecosystems.