Presentation Title

Soil Organic Carbon Content of Compensatory Wetland Mitigation Projects in Auburn, Washington

Session Title

General protection, remediation and restoration topics

Conference Track

Protection, Remediation, & Restoration

Conference Name

Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type of Presentation

Poster

Abstract

Wetlands provide many essential ecosystem services, such as water quality improvement, flood prevention, and critical species habitat. 5.5% of land cover in the U.S. is categorized as wetland, yet wetlands are estimated to account for 20-71% of earth’s terrestrial carbon storage (Dahl, 2011, Reddy & DeLaune, 2008). Natural wetlands are often permitted to be developed, and replacement wetlands are subsequently either constructed or restored in their place to fulfill federal regulation. Laws dictate that no net loss of ecosystem function may result due to permitting activity, therefore it is obligatory to engineer wetlands functionally equivalent to those lost. However, despite this requirement there is still a significant loss to wetland ecosystems in both function and areal extent (Turner, Redmond, & Zedler, 2001). This study compares 2 ecosystem functions of constructed and restored wetland mitigation sites in Auburn, Washington: (1) soil organic carbon storage and (2) species richness, and investigates if physical parameters such as size, age, or adjacent land use affect these functions. There was no correlation between size, age, and adjacent land use and these functions. No significant difference was found between the mean species richness of constructed and restored wetlands. It was observed that constructed wetlands store half the % soil organic matter (SOM) (7.8 ±4.0) as restored wetlands (15.312.1) (χ2(1)=9.4, p=0.002) These values are drastically lower than % SOM in similar natural wetlands in the area (45.5 ±34.2) (Horner, Cooke, Reinelt, Ludwa, & Chin, 2001). Soil bulk density was a much better predictor (R2=0.584) of % SOM than soil texture (R2=0.020). The wetlands that were excavated using heavy equipment and layered with top soil had the lowest % SOM values, indicating that this activity is compacting soil and limiting the soil development of these mitigation sites and capacity to store soil organic carbon.

Rights

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Language

English

Format

application/pdf

Type

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Soil Organic Carbon Content of Compensatory Wetland Mitigation Projects in Auburn, Washington

2016SSEC

Wetlands provide many essential ecosystem services, such as water quality improvement, flood prevention, and critical species habitat. 5.5% of land cover in the U.S. is categorized as wetland, yet wetlands are estimated to account for 20-71% of earth’s terrestrial carbon storage (Dahl, 2011, Reddy & DeLaune, 2008). Natural wetlands are often permitted to be developed, and replacement wetlands are subsequently either constructed or restored in their place to fulfill federal regulation. Laws dictate that no net loss of ecosystem function may result due to permitting activity, therefore it is obligatory to engineer wetlands functionally equivalent to those lost. However, despite this requirement there is still a significant loss to wetland ecosystems in both function and areal extent (Turner, Redmond, & Zedler, 2001). This study compares 2 ecosystem functions of constructed and restored wetland mitigation sites in Auburn, Washington: (1) soil organic carbon storage and (2) species richness, and investigates if physical parameters such as size, age, or adjacent land use affect these functions. There was no correlation between size, age, and adjacent land use and these functions. No significant difference was found between the mean species richness of constructed and restored wetlands. It was observed that constructed wetlands store half the % soil organic matter (SOM) (7.8 ±4.0) as restored wetlands (15.312.1) (χ2(1)=9.4, p=0.002) These values are drastically lower than % SOM in similar natural wetlands in the area (45.5 ±34.2) (Horner, Cooke, Reinelt, Ludwa, & Chin, 2001). Soil bulk density was a much better predictor (R2=0.584) of % SOM than soil texture (R2=0.020). The wetlands that were excavated using heavy equipment and layered with top soil had the lowest % SOM values, indicating that this activity is compacting soil and limiting the soil development of these mitigation sites and capacity to store soil organic carbon.