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UMBC. The Center for Urban Environmental Research and Education. CUERE. Altered Hydrology & Vegetation: Effects on the Transport and Breakdown of Organic Matter in Urban Streams Kenneth T. Belt 1 , Christopher Swan 2 , Richard Pouyat 1 , Sujay Kaushal 3 ,
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UMBC The Center for Urban Environmental Research and Education CUERE Altered Hydrology & Vegetation: Effects on the Transport and Breakdown of Organic Matter in Urban Streams Kenneth T. Belt1, Christopher Swan2, Richard Pouyat1, Sujay Kaushal3, Peter Groffman4, Istvan Turcsanyi5, William Stack6, and Gary Fisher7 1 USDA Forest Service, 2 UMBC Dept. of Geography and Environmental Systems 3 UMCES Appalachian Lab, 4 Institute of Ecosystem Studies, 5, UMBC Center for Urban Environmental Research & Education, 6 Baltimore City DPW, 7 USGS BES Annual Meeting, Baltimore, UMBC, October 19, 2006
Outline • Urban Drainage Networks • Leaf Breakdown • DOC Export (preliminary) • POM Export (preliminary) • Ongoing Work
Support… • Phyl (my wife)…arthritic bag making sessions, field work…putting up with me. • Rich Pouyat (USFS)…Guidance, encouragement, bag making…field work (the infamous blind rainstorm drive) • Chris Swan (UMBC GES)…guidance, encouragement, nutrient analysis, bug picking support • Sujay Kaushal (UMCES)…guidance, encouragement, DOC analyses • Peter Groffman/Dan Dillon, Gio et al. (IES)…sampling support, nutrient data; loan of an “ISCO” • Claire Welty (CUERE)…facilities, guidance; loan of 2 “ISCOs” • Istvan Turcsanyi (CUERE)…guidance and endless filtering and weighing • UMBC GES interns: Bill Greenwood, Yaakov Birnbaum, Heather Modic • All those technicians & colleagues…..
Motivation • Leaves (and breakdown products & leachate) in streams are an important energy (food) source • They also are habitat • They are important in a variety of BGC reactions and pathways • They also likely carry significant, not heretofore considered, elemental/pollutant loads
Urban Drainage • Networks
Increased Effective Drainage Density in Urban Streams Curb & Gutter Network
Civil Infrastructure and Organic Matter Forest Stand Urban Landscape Outputs To Stream Outputs To Stream POM Pollutants
How quickly do leaves breakdown in the stream benthic environment?
Breakdown Rates: Mass Loss Coefficients • Exponential decay model: • Wt W0-1 = e-kt • W0 = the initial leaf mass (g) • Wt is the mass (g) remaining on day t • k is the rate of breakdown (day-1)
Leaf Breakdown: Basic Questions…Streams, Sources & Landscape Position • Do leaves breakdown faster in suburban than in forested streams? • Do leaves from upland portions of the urban landscape breakdown faster than riparian leaves? • Do leaves from gutter sources break down faster than leaves from higher points in the landscape and riparian leaves? • Do riparian leaves from different locations along the urban-rural gradient differ in their breakdown rates?
Leaf Litter Breakdown Study Streams Stream Study Sites 10 kilometers Baismans Run (Forested) Gwynns Falls At Gwynnbrook (Suburban)
Study Stream Catchments Baismans Run (Forested) Gwynns Falls at Gwynnbrook (Suburban) Baltimore City Baismans Run Gwynns Falls at Gwynnbrook
Riparian Source Sites(Sycamore) Distal Riparian (rural) Suburban Riparian Proximal Riparian (rural) Urban, Riparian
Lawn (“Landscape”) & Gutter Source Sites(Planetree) Urban Landscape Suburban Landscape Suburban, Gutter Urban, Gutter
Study Streams: Light Green- Forested, Dark Green- Suburban Leaf Mass Loss Rates Forested Stream Suburban Stream Litter Sources (Planetree) (Sycamore)
Mass Loss: Urban vs. Suburban Streams Leaf Mass Loss Rates Urban Streams… Faster
Mass Loss Rates: Upland vs. Riparian Leaf Mass Loss Rates Riparian sources Slower
Litter Sources: Gutter vs. Landscape Leaf Mass Loss Rates “Gutter”… about the same as “Landscape” Urban… Much faster than Suburban
The Riparian Urban-Rural Gradient Leaf Mass Loss Rates No Effect for Riparian Leaves?
DOC Export in Urban Streams • How do urban DOC concentrations and export rates compare to “natural” systems ? • How much does DOC transport vary temporally (seasonal); how important is hydrology (storms)? • Is drainage density (and its attendant features) important?
Preliminary DOC & Flow Data • 8 of 13 sites • 15 to 20 samples at each site • July to November 2005 • Grab sampling…every few weeks • Mostly dry weather • Some with recent storm runoff activity (within days)
More ISC… More Runoff
More ISC… Higher DOC Conc
More ISC… Higher Catchment DOC Exports
Urban catchments… High DOC exports at higher flows
Urban catchments produce large DOC loads…including at elevated flows And these loads may be related to to impervious area cover & infrastructure…?
POM Export in Urban Streams • How do urban POM concentrations and export rates compare to “natural” systems ? • How much does POM transport vary temporally (seasonal); how important is hydrology (storms)? • Is drainage density (and its attendant features) important?
AFDM & TSS at 3 SitesBaismans R, GFalls at Gwynnbrook, Dead R; Apr to Sep 2006 Forested TSS AFDM % Organic Matter Forested: 31 % Suburban: 39 % Urban: 52% Suburban % Organic Matter Apr-MayJun-Sep Forested: 40 % 29 % Suburban: 50 % 37 % Urban: 42 % 54% Urban
Organic Matter…the Urban Dilemma • Urban streams: faster particle breakdown …greater export rates from the benthic ecosystem…carbon poor benthos • But…. • Higher urban imports (gutter subsidy)? • Smaller particles? • Leached loads (DOC)?
Organic Matter in Streams:Types of OM DOC- dissolved OM FPOM- fine particulate OM CPOM- coarse particulate OM
Organic Matter in Streams:Basic Transport Pathways Riparian & Upland Litterfall FPOM Surface Waters CPOM DOC Surface & Shallow Groundwater Leaching DOC Groundwater
Basic Approach • 13 gauged BES catchments…an urban-rural gradient • Storm and dry weather sampling • Intensive sampling with auto samplers at 3 catchments • Particulate and dissolved organic matter • Urban hydrology approach • Sediment exports (% organic matter)
Intensive Site Sampling Conceptual Scheme Discrete Storm CPOM Samples USGS Stage Recorder Discrete Storm FPOM Samples Bridge Automated Sampler Storm Flow Dry Weather Flow Peak Storm Flow CPOM Sampler (stationary) FPOM Grab (Dry Weather Flow) 24 hr CPOM Sampler (Dry Weather Flow) Whole Storm CPOM Sampler
BES Stream Sites: Routine & Intensive Small Headwater Stream Sites Subcatchment Stream Sites Gwynns Falls Main Channel Stream Sites POBR BARN Baismans Run GFGB 3 Intensive Monitoring Sites Gwynns Falls GFVN DRKR 13 Routine Sampling Sites: GFCP
BES Stream Sites: Auto Storm Composites Small Headwater Stream Sites Subcatchment Stream Sites Gwynns Falls Main Channel Stream Sites Baismans Run GFGB 7 Auto Sampler Storm Composite Samplers (including the 3 OM intensive Sites) Gwynns Falls GFVN BALT & LANV RGHT 13 Routine Sampling Sites:
A Multidisciplinary, Cooperative Effort… US Forest Service UMBC Geography & Environmental Systems UMCES Appalachian Lab Center for Urban Environmental Research and Education Baltimore Ecosystem Study/Institute of Ecosystem Studies City of Baltimore DPW US Geological Survey …and more partners to come