Low-decomposition rates of riparian litter in a North Patagonian ultraoligotrophic lake

CUASSOLO, F.;; DÍAZ VILLANUEVA, V.,; MODENUTTI, B

LIMNOLOGICA

ELSEVIER GMBH

Año: 2021 vol. 90

0075-9511

Littoral zones of lakes are important for carbon and nutrient recycling because of the accumulation anddecomposition of organic matter (OM) coming from terrestrial and aquatic plants. Here, we aimed to study OMdecomposition from the most abundant riparian trees (Nothofagus dombeyi and Myrceugenia exsucca), and anemergent macrophyte (Schoenoplectus californicus), in the littoral zone of an ultraoligotrophic North-PatagonianAndean lake. We analysed the initial 2-days leaching, and litter mass loss and litter nutrient changes after oneyear of decomposition in a litter-bag experiment. The three studied species had very slow decay rates (k < 0.005day􀀀 1), and initial nutrient release by leaching was not related to differences in decomposition rates. However,differences in leaf traits (lignin content) were related to interspecific variation in decomposition rates. Thehighest decomposition rates were observed for the macrophyte S. californicus, the species with the lower lignincontent, while the opposite was observed in the Myrtaceae M. exsucca. In the three studied species, nitrogencontent increased during decomposition. Our results indicated that in the shore of ultra-oligotrophic lakes, litterremains for long periods with net nutrient immobilization, thus OM of the riparian vegetation represents acarbon and nutrient sink.