Effects of the invasive plant Lupinus polyphyllus on vertical accretion of fine sediment and nutrient availability in bars of the gravel-bed Paloma river

摘要: Abstract Floodplain vegetation is fundamental in fluvial systems, controlling river corridor geomorphology and ecology through a series of hydraulic, sedimentological, biological processes. Changes caused by introduced plant species can thus result shifts regime, succession trajectories nutrient availability, affecting native biodiversity. The exotic bigleaf or marsh lupine Lupinus polyphyllus , Patagonia the last decades, aggressively invading corridors. It fills unoccupied ecological niches southern Chilean rivers, due to its capacity for nitrogen fixation, perennial habit, high shoot density leaf surface area. We investigated effects L. on vertical accretion fine sediment, soil carbon content, gravel bars Paloma river, Patagonia, where believed have been 1994. sampled plot pairs with without lupine, each pair located at same elevation above stage, plots distributed over reach scale. measured thickness horizon, grain size distribution, content. also compared aerial photographs evaluate changes spatial coverage along study reach. Presence was strongly correlated thicker layer finer turn characterized higher organic carbon, ratio, inorganic Contrary our expectations, we did not find any significant differences total nitrogen. Aerial reveal important between 2007 2010, but appears increased two dates, invaded appear be more stable. Lupine dominance otherwise sparsely vegetated Patagonian rivers greatest consequences bar physical structure (increased rates fines) secondary repercussions quality (increase recalcitrant matter), potential transient availability (possible metabolism, followed mineralization loss subsidy).