This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.
Comparison of microbial processing of Brachiaria brizantha, a C4 invasive species and a rainforest specie in tropical streams of the Atlantic Forest of Southeast Brazil
The breakdown of allochthonous organic matter is considered the main source of energy and nutrients to the majority of first order streams. Thus, changes in riparian vegetation will lead to disturbances in the structure and function of aquatic ecosystems by modifying the organic matter supply. The C4 grasses are poorly studied as important sources of allochthonous material as they are usually considered a poor source of nutrients. Because the effects of land use change on ecosystem functions are not fully known, we aimed to evaluate how such changes can affect nutrient cycles by measuring the decomposition rate of an abundant native C3 species, Mollinedia schottiana, and the exotic C4 grass, Brachiaria brizantha, in first order streams of the Atlantic Forest. Our results showed that B. brizantha detritus decomposed faster than C3, despite its lower nutrient concentration. This finding can likely be explained by the lower lignin content of the grass specie when compared to the native specie. Lignin also influenced the dynamic of nutrient losses, as it can interact with other cellular constituents and prevent the decomposition of most labile compounds. Our results support the observation that the replacement of riparian vegetation alters decomposition rates and nutrient distributions with the potential to disrupt aquatic food webs.
MF17080 Accepted 06 February 2018
© CSIRO 2018