DOI: 10.6073/pasta/d2d727c9638c0fc23bd5be55a767cfb5
title: Soil atmosphere fluxes of carbon dioxide, nitrous oxide and methane

description: Baltimore Ecosystem Study Long-Term Study Plot Soil Metadata
      
      
          Participants
      
          Peter Groffman, Cary Institute of Ecosystem Studies
      
      
          Richard V. Pouyat, U.S. Forest Service
      
      
      
      
          Introduction
      
      
      
          The Baltimore Ecosystem Study (BES) has established a network of long-term permanent biogeochemical study plots. These plots will provide long-term data on vegetation, soil and hydrologic processes in the key ecosystem types within the urban ecosystem. The current network of study plots includes eight forest plots, chosen to represent the range of forest conditions in the area, and four grass plots. These plots are complemented by a network of 200 less intensive study plots located across the Baltimore metropolitan area. See Baltimore's Vegetation Structure And Its Ability To Remove Air Pollutants And Sequester Carbon Dioxide, online: http://beslter.org/frame4-page_3b_02.html .
      
      
          Plots are currently instrumented with lysimeters (drainage and tension) to sample soil solution chemistry, time domain reflectometry probes to measure soil moisture, dataloggers to measure and record soil temperature and trace gas flux chambers to measure the flux of carbon dioxide, nitrous oxide and methane from soil to the atmosphere. Measurements of in situ nitrogen mineralization, nitrification and denitrification were made at approximately monthly intervals from Fall 1998 - Fall 2000. Detailed vegetation characterization (all layers) was done in summer 1998.
      
      
          Data from these plots has been published in Groffman et al. (2006, 2009), Groffman and Pouyat (2009) and Savva et al. (2010).  
      
      
      
      
          Plot Locations and Characterizations
      
      
          In November of 1998 four rural, forested plots were established at Oregon Ridge Park in Baltimore County northeast of the Gwynns Falls Watershed. Oregon Ridge Park contains Pond Branch, the forested reference watershed for BES. Two of these four plots are located on the top of a slope; the other two are located midway up the slope.
      
      
          In June of 2010 measurements at the mid-slope sites on Pond Branch were discontinued.  Monuments and equipment remain at the two plots.  These plots were replaced with two lowland riparian plots; Oregon upper riparian and Oregon lower riparian.  Each riparian sites has four 5 cm by 1-2.5 meter depth slotted wells laid perpendicular to the stream, four tension lysimeters at 10 cm depth, five time domain reflectometry probes, and four trace gas flux chambers in the two dominant microtopographic features of the riparian zones  -  high spots (hummocks) and low spots (hollows).  
      
      
          Four urban, forested plots were established in November 1998, two at Leakin Park and two adjacent to Hillsdale Park in west Baltimore City in the Gwynns Falls. One of the plots in Hillsdale Park was abandoned in 2004 due to continued vandalism.
      
      
          In May 1999 two grass, lawn plots were established at McDonogh School in Baltimore County west of the city in the Gwynns Falls. One of these plots is an extremely low intensity management area (mowed once or twice a year) and one is in a low intensity management area (frequent mowing, no fertilizer or herbicide use). In 2009, the McDonogh plots were abandoned due to management changes at the school.
      
      
          Two grass lawn plots were established on the campus of the University of Maryland, Baltimore County (UMBC) in fall 2000. One of these plots is in a medium intensity management area (frequent mowing, moderate applications of fertilizer and herbicides) and one is in a high intensity management area (frequent mowing, high applications of fertilizer and herbicides).
      
      
      
      
          Plot locations:
      
      
          Hillsdale 1: 39 deg 19 min 28.14"N, 76 deg 42 min 16.49 sec W
      
          Hillsdale 2: 39 deg 19 min 31.24"N, 76 deg 42 min 28.62 sec W
      
      
          Leakin 1: 39 deg 18 min 1.32"N, 76 deg 41 min 37.08 sec W
      
          Leakin 2: 39 deg 18 min 5.42"N, 76 deg 41 min 34.15 sec W
      
      
          McDonogh 1: 39 deg 23 min 44.31"N, 76 deg 46 min 19.26 sec W
      
          McDonogh 2: 39 deg 23 min 52.26"N, 76 deg 46 min 23.52 sec W
      
      
          Oregon top-slope - 1: 39 deg 28 min 51.11"N, 76 deg 41 min 22.50 sec W
      
          Oregon mid-slope - 1: 39 deg 28 min 51.32"N, 76 deg 41 min 18.24 sec W
      
          Oregon top-slope - 2: 39 deg 29 min 12.74"N, 76 deg 41 min 22.88 sec W
      
          Oregon mid-slope - 2: 39 deg 29 min 12.68"N, 76 deg 41 min 18.62 sec W
      
          Oregon upper riparian: 39 deg 29 min 9.03"N,  76 deg 41 min 15.86 sec W
      
          Oregon lower riparian: 39 deg 28 min 52.06"N,  76 deg 41 min 15.54 sec W
      
      
          McDonogh 1: 39 deg 23 min 44.31"N, 76 deg 46 min 19.26 sec W
      
          McDonogh 2: 39 deg 23 min 52.26"N, 76 deg 46 min 23.52 sec W
      
      
          UMBC 1: 39 deg 15 min 8.82"N, 76 deg 42 min 10.43 sec W
      
          UMBC 2: 39 deg 14 min 6.50"N, 76 deg 42 min 48.71 sec W
      
      
      
          Soil atmosphere fluxes of carbon dioxide, nitrous oxide and methane
      
      
          Trace gas (N2O, CO2, and CH4) fluxes from soil to the atmosphere were measured every four to six weeks at each plot using an in situ chamber design.  The lawn plots had chambers identical to those used by Bowden et al. (1990) installed flush with the soil surface to allow mowing.  These (three per plot, at least 5 m apart and at least 5 m from the plot boundary) consisted of 28.7-cm diameter (ID) by 4.0-cm high polyvinyl chloride (PVC) cylinders which were placed on permanently installed PVC base rings immediately prior to measurement. 
      
      
          From 1998 through September 2007, the forest plots had the chambers described by Goldman et al. (1995), constructed from 16.5 cm wide by 20 cm long pieces of PVC pipe fitted with a septum and an air-tight well cap. These chambers were placed 4 cm into the soil and had a total volume of 2 L.  Beginning in September 2007, the Bowden et al. (1990) chambers, which are used at many research sites across the world, were installed at the forest sites.  A brief period of side by side measurements suggested that the Bowden chambers produce lower gas fluxes than the Goldman chambers. The replacement dates for chambers at different sites are:
      
      
          -Leakin 1 September 2007
      
          -Leakin 2 Septemeber 2007
      
          -Hillsdale 1 Sept 2007
      
          -Oregon Ridge Upper 1 November 2007
      
          -Oregon Ridge Upper 2 November 2007
      
          -Oregon Ridge Middle 1 September 2007
      
          -Oregon Ridge Middle 2 September 2007
      
      
          At 0, 10, 20 and 30 min following placement of the chamber on the base or installation of the well cap, 9-mL gas samples were collected from gas sampling ports in the center of the chamber top by syringe. Samples were injected into 9 mL evacuated glass vials sealed with septa and aluminum rings. Samples were sent to the Cary Institute of Ecosystem Studies (CIES) for gas chromatography (GC) analysis. Concentrations of CO2 and N2O are measured on a GC equipped with thermal conductivity and electron capture detectors aligned in sequence. Concentrations of CH4 are measured on a GC equipped with a flame ionization detector. Samples and standards are introduced into this GC via syringe and sample loop. Fluxes were calculated from the linear rate of change in gas concentration, the chamber internal volume and soil surface area.
      
      
          Spike standards are processed along with each batch of flux samples.  These standards are generated by filling sample vials from a standard tank in the field laboratory in Baltimore and then processing these samples along with samples taken from flux chambers in the field.  Percent recoveries of the trip standards are used to correct flux values for leakage or gas absorption that may occur between sampling and analysis.  Exceptionally low recoveries for N2O (traced to a change in septa manufacture) led to loss of flux data for this gas for several dates from 2007 - 2009. 
      
      
      
          Literature Cited
      
      
          Bowden R, Steudler P, Melillo J and  Aber J. 1990. Annual nitrous oxide fluxes from temperate forest soils in the northeastern United States. J. Geophys. Res.Atmos. 95, 13997 14005.
      
      
          Driscoll CT, Fuller RD and Simone DM (1988) Longitudinal variations in trace metal concentrations in a northern forested ecosystem. J. Environ. Qual. 17: 101-107 
      
      
          Goldman, M. B., P. M. Groffman, R. V. Pouyat, M. J. McDonnell, and S. T. A. Pickett. 1995. CH4 uptake and N availability in forest soils along an urban to rural gradient. Soil Biology and Biochemistry 27:281-286.
      
      
          Groffman PM, Holland E, Myrold DD, Robertson GP and Zou X (1999) Denitrification. In: Robertson GP, Bledsoe CS, Coleman DC and Sollins P (Eds) Standard Soil Methods for Long Term Ecological Research. (pp 272-290). Oxford University Press, New York 
      
      
          Groffman PM, Pouyat RV, Cadenasso ML, Zipperer WC, Szlavecz K, Yesilonis IC,. Band LE and Brush GS. 2006. Land use context and natural soil controls on plant community composition and soil nitrogen and carbon dynamics in urban and rural forests. Forest Ecology and Management 236:177-192.
      
      
          Groffman, P.M., C.O. Williams, R.V. Pouyat, L.E. Band and I.C. Yesilonis. 2009. Nitrate leaching and nitrous oxide flux in urban forests and grasslands.  Journal of Environmental Quality 38:1848-1860.
      
      
          Groffman, P.M. and R.V. Pouyat.  2009. Methane uptake in urban forests and lawns.  Environmental Science and Technology 43:5229-5235. DOI:  10.1021/es803720h.
      
      
          Holland EA, Boone R, Greenberg J, Groffman PM and Robertson GP (1999) Measurement of Soil CO2, N2O and CH4 exchange. In: Robertson GP, Bledsoe CS, Coleman DC and Sollins P (Eds) Standard Soil Methods for Long Term Ecological Research. (pp 258-271). Oxford University Press, New York 
      
      
          Robertson GP, Wedin D, Groffman PM, Blair JM, Holland EA, Nadelhoffer KJ and. Harris D. 1999. Soil carbon and nitrogen availability: Nitrogen mineralization, nitrification and carbon turnover. In:  Standard Soil Methods for Long Term Ecological Research (Robertson GP, Bledsoe CS, Coleman DC and Sollins P (Eds) Standard Soil Methods for Long Term Ecological Research. (pp 258-271). Oxford University Press, New York 
      
      
          Savva, Y., K. Szlavecz, R. V. Pouyat, P. M. Groffman, and G. Heisler. 2010. Effects of land use and vegetation cover on soil temperature in an urban ecosystem. Soil Science Society of America Journal 74:469-480.