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Using intensive indicators of wetland condition to evaluate a rapid assessment methodology in Oregon tidal wetlands
Citation:
WEILHOEFER, C. L. AND W. G. NELSON. Using intensive indicators of wetland condition to evaluate a rapid assessment methodology in Oregon tidal wetlands. Presented at Society of Wetland Scientists Annual Meeting, Washington, DC, May 26 - 30, 2008.
Impact/Purpose:
In 2011, the US EPA and its partners will conduct the first-ever national survey on the condition of the Nation’s wetlands.
Description:
In 2011, the US EPA and its partners will conduct the first-ever national survey on the condition of the Nation’s wetlands. This survey will utilize a three-tiered assessment approach that includes landscape level indicators (Level 1), rapid indicators (Level 2), and intensive, quantitative biological and physicochemical indicators (Level 3) of wetland condition. Prior to the onset of this survey, the scientific soundness of Level 1 and Level 2 indicators must be evaluated using intensive measures of wetland condition. We used intensive measurements of plant community characteristics, water quality, sediment composition, and plant tissue composition to evaluate a Level 2 assessment methodology, the California Rapid Assessment Method for Wetlands (CRAM), in 40 Oregon tidal wetlands. Since the 2011 survey proposes to use a fixed wetland area, we modified the CRAM methodology to assess a 1963-m2 area of each wetland (circle with radius = 25 m). Preliminary analysis shows that overall CRAM scores were significantly correlated with several intensive indicators, particularly plant indicators (e.g., invasive species richness, r = -0.4; Salicornia depressa %N, r = 0.5). In addition, individual CRAM attributes were significantly correlated to appropriate intensive indicators (e.g., CRAM buffer and landscape context attribute with invasive species richness, r = -0.5; hydrology attribute with salinity, r = 0.5). Our findings suggest that CRAM may be a useful tool in assessing the condition of Oregon tidal wetlands.