Presentation Abstract

Estuaries affected by physical barriers, such as culverts, experience reduced hydrological inputs and reduced connectivity resulting in the loss of ecological processes. To address reduction in ecological connectedness, culverts at three sites were removed and replaced with bridges. An observational field study was conducted in Kitsap County, Washington of three sites where culverts were replaced with bridges three, eight, and 13 years ago. Data was collected at a reference site where the estuary contains a culvert. It is hypothesized that estuary restoration will recover plant species, carbon sequestration, and nutrient cycling homogeneity above and below the restoration site. However, the length of time for recovery is not well understood. Soil and plant height was collected from random quadrats. Soil carbon and nitrogen were analyzed using an elemental analyzer and soil macro and micro-nutrients were analyzed using the Mehlich 3 Extraction method. Plant species richness was significantly higher (P<0.01) at the intermediate and oldest post-restoration sites. Species diversity was significantly higher (P<0.01) at the oldest post-restoration site, which was comprised of a mix of native, naturalized, and invasive species. Hierarchical clustering produced two distinct clusters of plant communities associated by within site location and one cluster from the site aged eight years (χ2=40.82, df=6, P<0.001). Percent soil carbon below the site of impact was significantly lower at the youngest post-restoration site (P=0.02). Steady increases in carbon sequestration was noted through time with carbon levels recovering at year 12. Calcium, magnesium, sulfur, copper, boron, zinc, and phosphorus (all P<0.05) were negatively correlated with plant height. The results of this study will aid resource managers by providing a timeline for the return of native plant communities and biogeochemical dynamics within a recovering estuary system.

Session Title

Habitat Restoration

Keywords

Estuary, Restoration, Plants, Community

Conference Track

SSE1: Habitat Restoration and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE1-141

Start Date

5-4-2018 11:00 AM

End Date

5-4-2018 11:15 AM

Type of Presentation

Oral

Contributing Repository

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

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 11:00 AM Apr 5th, 11:15 AM

Plant community and nutrient development within four estuary restoration sites in Kitsap County, Washington

Estuaries affected by physical barriers, such as culverts, experience reduced hydrological inputs and reduced connectivity resulting in the loss of ecological processes. To address reduction in ecological connectedness, culverts at three sites were removed and replaced with bridges. An observational field study was conducted in Kitsap County, Washington of three sites where culverts were replaced with bridges three, eight, and 13 years ago. Data was collected at a reference site where the estuary contains a culvert. It is hypothesized that estuary restoration will recover plant species, carbon sequestration, and nutrient cycling homogeneity above and below the restoration site. However, the length of time for recovery is not well understood. Soil and plant height was collected from random quadrats. Soil carbon and nitrogen were analyzed using an elemental analyzer and soil macro and micro-nutrients were analyzed using the Mehlich 3 Extraction method. Plant species richness was significantly higher (P<0.01) at the intermediate and oldest post-restoration sites. Species diversity was significantly higher (P<0.01) at the oldest post-restoration site, which was comprised of a mix of native, naturalized, and invasive species. Hierarchical clustering produced two distinct clusters of plant communities associated by within site location and one cluster from the site aged eight years (χ2=40.82, df=6, P<0.001). Percent soil carbon below the site of impact was significantly lower at the youngest post-restoration site (P=0.02). Steady increases in carbon sequestration was noted through time with carbon levels recovering at year 12. Calcium, magnesium, sulfur, copper, boron, zinc, and phosphorus (all P<0.05) were negatively correlated with plant height. The results of this study will aid resource managers by providing a timeline for the return of native plant communities and biogeochemical dynamics within a recovering estuary system.