Baltimore Ecosystem Study Institute of Ecosystem Studies

2014 BES Annual Meeting Presentation and Poster Abstracts

Riparian Links and Nitrogen Sinks; The effects of riparian connectivity and invasive species on N-cycling in urban riparian zones
Tomat-Kelly, Giovanna (re-submission of abstract!)
Co-Authors: Giovanna Tomat-Kelly and Dr. Peter Groffman

Abstract: Riparian ecosystems are important nutrient sinks that are useful in preventing excessive nitrogen loading into aquatic ecosystems. Nitrate, (NO3−), the most common and mobile form of reactive N, is a prominent water pollutant that is poisonous to humans in high concentrations Excessive N loading into coastal waters also results in eutrophication- increased algae growth which results in anoxic zones and the death of aquatic organisms. The primary mechanism of N removal in riparian ecosystems is denitrification, an anaerobic microbial process that converts inorganic nitrate into N gas. The process is carried out primarily by heterotrophic bacteria, and is optimized in the oxygen poor and carbon rich environments that are characteristic of wetland and riparian ecosystems. Unfortunately, increasing urbanization has lead to a suite of degrading effects in riparian ecosystems including hydraulic disconnection, erosion, drier soils and increased vulnerability to exotic plant invasions. Two prominent invasive plants found in urban riparian zones are Aliliaria petiolata and Microstigium vimineum, herbaceous C3 and C4 plants, respectively, that are known to alter soil chemistry and composition through various secondary effects. The objective of this study was to determine how hydrologic disconnection and the presence of A. petiolata and M. vimineum affect the ability of urban riparian ecosystems to function as N sinks.