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Measuring Response Variables


In addition to elevation measurements, a full range of processes that may contribute to or influence soil elevation change were also measured in this study. The full range of process measures were conducted seasonally over a three-year period from 2006-2009 in the vicinity of each SET-MH sampling station in the no burn, annual, 3-5 year, and 7-10 year treatments. Elevation change, vertical accretion, subsidence, plant biomass, litter accumulation, root production, soil organic matter and carbon, soil bulk density, and community structure will be used as response variables as they all contribute to soil elevation. Soil Eh, sulfide concentration, salinity, and elevation will be used as covariates.

Response Variable Method Citation
Elevation change,
vertical accretion, subsidence
Surface elevation table (SET),
artificial soil marker horizon
Cahoon et al. 2002a, b;
Cahoon & Turner 1989
Litter accumulation Litter collection in plots Robertson et al. 1999
Root production Implanted mass technique Gallagher et al. 1984
Soil organic matter / ash Loss on ignition ASTM (D2974) 1991
Soil carbon / nitrogen Standard Soil Methods for LTER Robertson et al. 1999
Soil Eh, sulfide, salinity Pt & Micro Ion Sulfide electrodes;
conductivity meter
McKee et al. 1988;
Patrick et al. 1996
Soil bulk density Piston corer; gravimetric Parent & Caron 1993
Biomass & community structure Stem density & height in plots  


Fig. 12. Measuring root production (left), biomass and community structure (middle), and soil redox (right) in experimental plots at BNWR.


Literature Cited

American Society for Testing and Materials. 1991. Annual book of ASTM standards. Philadelphia, Pa., USA.

Cahoon, D. R. and R. E. Turner. 1989. Accretion and canal impacts in a rapidly subsiding wetland II. Feldspar marker horizon technique. Estuaries 12 (4): 260-268.
Cahoon, D.R., et al.. 2002a. High precision measurement of wetland sediment elevation: I. recent improvements to the sedimentation-erosion table. J. Sed. Res., 72, 730-733.
Cahoon, D.R., J. C. Lynch, B. C. Perez, B. Segura, R. Holland, C. Stelly, G. Stephenson, and P. Hensel. 2002b. High precision measurement of wetland sediment elevation: II. the rod surface elevation table. J. Sed. Res., 72, 734-739.
Gallagher, J. L., P. L. Wolf, and W. J. Pfeiffer. 1984. Rhizome and root growth rates and cycles in protein and carbohydrate concentrations in Georgia Spartina alterniflora plants. Amer. J. Bot. 71 (2): 165-169.
McKee, K. L., I. A. Mendelssohn, and M. W. Hester. 1988. Reexamination of pore water sulfide concentrations and redox potentials near the aerial roots of Rhizophora mangle and Avicennia germanians. Am. J. Bot. 75:1352-1359.
Parent, L.E. and J. Caron.  1993.  Physical properties of organic soils. Pp. 441-458 in Soil Sampling and Methods of Analysis, M.R. Carter (ed.). Lewis Publishers, Boca Raton.
Patrick, W.H., Jr., R.P. Gambrell, and S.P. Faulkner. 1996. Redox measurements of soils. Pages 1255-1271 in Methods of Soil Analysis. Part 3. Chemical Methods. Soil Science Society of America, Madison, WI.
Robertson, G.P., D.C. Coleman, C.S. Bledsoe, and P. Sollins.  1999. Standard Soil Methods for Long-Term Ecological Research. Oxford University Press, New York.

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