Litter decomposition of the invasive Potentilla anserina in an invaded and non-invaded freshwater environment of North Patagonia

Abstract

Potentilla anserina is a common invasive species of Patagonian wetlands. Although this species is commonly found in temporary habitats, where it establishes during the dry phase, the littoral zones of lakes are also susceptible, as water fluctuations make this habitat extremely variable in terms of water availability. Decay rates and nutrient release of P. anserina were compared with two native macrophyte species, Eleocharis pachycarpa and Schoenoplectus californicus, in two different freshwater environments: a temporary wetland, where P. anserina develops important stands, and the littoral zone of a lake not yet colonized by the invasive plant. Our results showed that both environments differed in nutrient concentrations, being higher in the temporary wetland. However, the invasive species decomposed faster in the littoral zone of the lake, due to the presence of the amphipod Hyallela patagonica in the litter bags. The invasive plant litter decomposed twice faster than the native species. The species with highest N content, E. pachycarpa, released more N in leachates. After 71 days of decomposition, P. anserina loss more C and gained more N than the native species, while the P content remained constant across the three species. Our results demonstrated that the introduction of an invasive species as P. anserina into new habitats would contribute with dissolved and particulate organic matter impacting nutrient cycling and invertebrate assemblages with consequences to the entire ecosystem.