The goal of my research will be to define better success criteria for wetlands mitigation projects in North Carolina. I aim to describe clear, quantitative and pragmatic goals that lead to more successful wetland restorations.
Ecological restoration has become a topic of increased concern over
the last decade or two. As more value has been placed on healthy ecosystem functions such
as wildlife habitat and water quality, the desire for reparation of damaged and
replacement of disappearing ecosystems has increased. However, “(r)estoration is one
of those terms loosely defined and often loosely applied”(Schweitzer 1998). What exactly constitutes restoration is still
to a degree an open question (Stanturf 1998). Perhaps the most central aspect regarding
this question is the criteria used to judge successful restoration. There has been a
recognized lack of good criteria for a long time (Westman 1991 and Kentula 2000).
Gradually a consensus about some components of such criteria has emerged. The role of
reference wetlands in judging successful mitigation is one example (Brinson 1996). For
wetlands, the acknowledged factors involved in restoration are hydrology, soil and
vegetation (Schweitzer 1998). Fauna is sometimes
considered.
A reference wetland type should define the target species composition. Much study has been given to describing community composition for a huge variety of plant communities (Schafale 1990 and Grossman 1998). Success should be measured by growth toward that goal or put another way movement along a trajectory toward mean (reference sites) population composition. I plan to measure community health by traditional forestry methods of gathering height and coverage for the individual species.
Even with such general agreement of the components of a successful wetlands creation/restoration, no successful criteria have emerged. NCDENR, for example, still uses criteria based on wetlands delineation guidelines from the U.S. Army Corps of Engineers. These criteria are widely viewed as lacking (Schweitzer 1999 and Stanturf 2000). Other criteria have been proposed but considerations including some combination of ambiguity, implementation cost, complexity and lack of scientific basis have hampered their acceptance. The hydrogeomorphic approach (Brinson 1995), for example, could be used to define targets for mitigation projects. However, these targets only roughly correspond to immature created wetlands. No clear path from “infancy” to maturity is described. How confident would a regulator or owner be that a wetland with a hydrogeomorphic rating of 112 in the fifth and final year of monitoring would result in a functioning wetland to replace the wetland it’s compensating for?
I will define a group of factors strongly correlated to successfully functioning wetlands which when taken together will describe populations for several types of wetlands. Correlation will be determined using an analysis of covariance among the criteria in data from existing natural wetlands and created wetlands of a given type. Bioequivalence tests will be used to measure the practical equivalence of both past and current mitigation projects to their wetland type population.
Select proposed criteria: January 2001 – May 2002
a. Literature review.
b. Course work.
SSC570
BO405
FOR750
Data collection: January 2002 – August 2002
a. Published
a. Existing
wetlands – e.g., Beissel
b. Successful
mitigations – e.g., Clewell
c.
Growth information – e.g., Weyerhauser
b. Field
collection
a. Reference
wetlands
b. Previous
mitigations
c. Mitigations
in progress
Data analysis: August 2002 – January 2003
a. Conceptual model development
b. Statistical analysis
Through analysis of existing data on natural wetlands, current and past mitigation projects as well as the development of a conceptual model of wetland creation to explain the interaction of the major processes involved, I plan to advance a set of success criteria for wetlands mitigation projects. I will demonstrate, by application of statistical tests, a course to be followed for wetlands of several representative types. That course will lead to the creation of a functioning wetland. The representative wetland populations will be described by characteristics that define the parameters of a statistical model. The statistical tests applied intend to show movement over time toward membership in the reference population.
Bedford, B. L.. 1996. The need to define hydrologic equivalence at the landscape scale for freshwater wetland mitigation. Ecol. Appl. 6: 57-68.
Brinson, M.M., F. R. Hauer, L. C. Lee, W. L. Nutter, R. D. Smith and D. Whigham. 1995. Guidebook for Application of Hydrogeomorphic Assessments to Riverine Wetlands (Operational Draft). Wetland Research Program Technical Report WRP-DE-11. U.S. Army Engineer Waterways Experiment Station, Vicksburg, MS.
Brinson, M. M. and R. Rheinhardt. 1996. The role of reference wetlands in functional assessment and mitigation. Ecol. Appl. 6: 69-77.
Curry, J. P. and J. A. Good. 1992. Creation and restoration of wetlands: some design consideration for ecological engineering. Advances in Soil Science 17:171-215.
Grossman, D. H., D. Faber-Langendoen, A. S. Weakley, M.
Anderson, P. Bourgeron, R. Crawford, K. Goodin, S. Landaal, K. Metzler, K. D. Patterson,
M. Pyne, M. Reid and L. Sneddon. 1998. International classification of ecological
communities: terrestrial vegetation of the United States. Volume I. The National
Vegetation Classification System: development, status, and applications. The Nature
Conservancy, Arlington, Virginia, USA.
Kentula, M. E.. 2000. Perspectives on setting success criteria for wetland restoration. Ecological Engineering 15:199-209.
Mitsch, W. J. and J. K. Cronk. 1992. Creation and restoration of wetlands: some design consideration for ecological engineering. Advances in Soil Science 17:217-259.
Richter, B. D., J.V. Baumgartner, J. Powell and D.P. Braun. 1996. A Method for Assessing Hydrologic Alteration within Ecosystems. Conservation Biology. 10: 1163-1171.
Schweitzer, C.J.. 1998. What
is restoring bottomland hardwood forests? A study from the Lower Mississippi Alluvial
Valley. in Wadsworth, Kelly G., ed., Transactions of the 63rd North American Wildlife and
Natural Resources Conference; 20-25 March 1998;Orlando, FL. Wildlife Management Institute,
Washington, DC. 147-155.
Schweitzer, C. J. and J.A.
Stanturf. 1999. A comparison of large-scale reforestation techniques commonly used on
abandoned fields in the Lower Mississippi Alluvial Valley. Tenth Biennial Southern
Silvicultural Research Conference. 136-141.
Schafale, M. P. and A. S. Weakley. 1990. Classification of the Natural Communities of North Carolina, Third Approximation. North Carolina Natural Heritage Program, Division of Parks and Recreation, North Carolina Department of Environment, Health and Natural Resources. Raleigh, North Carolina.
Stanturf, J.A., C. J.
Schweitzer, S. H. Schoenholtz, J. P. Barnett, C. K. McMahon and D. Tomczak. 1998. Ecosystem restoration: fact or fancy. in
Wadsworth, Kelly G., ed., Transactions of the 63rd North American Wildlife and Natural
Resources Conference; 20-25 March 1998; Orlando, FL. Wildlife Management Institute,
Washington, DC. 376-383.
Stanturf, J. A., E.S. Gardiner, M. S. Hamel, T. D. Leininger, and M. E. Warren. 2000. Restoring Bottomland Hardwood Ecosystems in the
Lower Mississippi Alluvial Valley. Journal of Forestry, 98: 10–16.
Westman, W. E.. 1991. Ecological Restoration Projects: Measuring Their Performance. Environmental Professional 13: 207-215.