Baltimore Ecosystem Study Cary Institute of Ecosystem Studies

2012 BES Annual Meeting Presentation and Poster Abstracts

Organic Matter in Streams and the Urban Watershed Continuum
Belt, Ken
Co-Authors: Belt, K. T., Kaushal, S., Swan, C., and R. Pouyat

Abstract: We developed an urban watershed continuum framework (1) that considers both engineered and natural hydrologic flow paths to help researchers and managers to think about the flows of urban water and its constituents in new ways. Given current interest in greening (e.g., urban tree canopy goals, green infrastructure) this framework is also useful in studying organic matter movement and fate in the urban landscape. Leaf litter is an integral part of the trophic structure of stream ecosystems in forest streams and is often the source of an organic matter flow continuum, with breakdown of leaves providing food for a diversity of downstream biota. This is different for urban streams, where leaves (CPOM) and dissolved and particulate breakdown products (DOC/FPOM) arrive at the stream via storm drainage infrastructure rather than from riparian or in-stream sources (Figure 1). These inputs can be large, constituting a important “gutter subsidy” to urban streams. Sampling and experiments revealed that urbanization affected leaf breakdown and its products in BES streams. American Sycamore and London Planetree leaf breakdown rates were greater in the suburban stream, but only after ca. 70 days, when stormwater runoff events coincided with large leaf litter mass losses (Figure 2). DOC and FPOM concentrations and fluxes in five streams were greatly influenced by hydrology and impervious cover (Figure 3). We discuss these concepts and data, and emphasize the need to incorporate the study and management of organic matter into an integrated engineered-ecological system. 1 Kaushal, S. and K. Belt. 2012 The Urban Watershed Continuum: evolving spatial and temporal dimensions. Urban Ecosystems 15:409-435.