Biological invasions change ecosystem functioning along secondary succession in the Inland Pampas.

YAHDJIAN, M.L.; SPIRITO, F.; TOGNETTI, P.M.; CHANETON, E.J.

Rosario

Congreso; X International Rangelands Congress; 2011

Land uses changes due to anthropogenic activities put in danger the natural ecosystems and the services they provide, allowing for biological invasions. We evaluated litter decomposition of dominant species and common litter, soil respiration, and nutrient turnover in plots that were sown by different plant assemblages and that represented different successional stages (early, intermediate, and late successional species, including native and exotic species). Litter decomposition of the dominant species significantly (P<0.05) decreased along secondary succession stages, as early species decomposed faster than intermediate and latter?s. Soil respiration rates also decreased from early to late successional stages (P<0.05). However, when the latter stages were dominated by perennial exotic grasses, litter decomposition and soil respiration rates increased and were similar to rates measured at intermediate successional stages. Biological invasions modified key ecosystem processes in successional grasslands of the Inland Pampas, giving to conditions similar to early successional stages. These impacts on biogeochemical processes as litter decomposition and soil respiration may explain the persistence of exotic perennial grasses in this ecosystem, due to change in plant-soil interactions that may promote the exotic species and hamper the recovery of native perennial grasses. In addition, plant species invasions may change the capacity of Inland Pampas grasslands to retain carbon and consequently may impact key ecosystems services in face of global changes scenarios.