Restauração de áreas florestais próximas a corpos hídricos: uma visão microcósmica dos efeitos da diversidade de folhas sobre o funcionamento de um ecossistema aquático

Abstract

Biodiversity is essential for the maintenance of ecological processes and biogeochemical cycles. With the excessive exploitation of natural resources and the consequent loss of biodiversity globally, studies on BEF (Biodiversity and Ecosystem Functioning) seek to understand how the loss of biodiversity affects ecosystem processes, also considering the restoration of degraded areas. The restoration of degraded areas positively affects the functioning of such ecosystems, via the increase of sources of organic matter when compared to degraded areas. This study aimed at evaluating the effects of the diversity of trees on the decomposition of organic matter and nutrient release from terrestrial to aquatic ecosystems. For this, a microcosms decomposition experiment was carried out with native trees leaves from the Brazilian Atlantic Forest, simulating a gradient of species diversity (1, 3, 6 and 12 species; all with 4 replicates). The leaves of each species were collected from young individuals, then dried, ground and leached for 72 hours in a flask with water from the Chapéu D'uvas reservoir (Ewbank da Camara, MG). Afterwards, the leachate was incubated with a bacterial inoculum from the reservoir for 72 hours. Then, we evaluated carbon and nitrogen release rates, optical characteristics of dissolved organic matter (DOM) and bacterial respiration by inorganic carbon release. There was no effect of species richness on DOM leaching and nutrient release, but there was a significant difference in dissolved organic carbon (DOC) leaching rates amongst the different plant species. Additionally, we observed significant differences on DOM quality between the different species combinations. A significant negative correlation between species richness and bacterial respiration was also observed. In conclusion, the DOM quality had a greater influence on bacterial mineralization than the amount of leached DOC, and higher species diversity resulted in lower mineralization rates of DOM.