Hydrophytes in the Mid-Atlantic Region: Ecology, Communities, Assessment, and Diversity

Abstract

Hydrophytes, or wetland plants, are the most conspicuous and perhaps most colorful element of wetland systems. In the mid-Atlantic region, hydrophytes have been the focus of many studies, resulting in a wealth of information on wetland classifi cation, vegetation stressors, and plant-based assessment tools. For example, exploration of the relationship between hydrophytes and the physical aspects of wetlands has led to a new hydrogeomorphic classifi cation of headwater systems that combines three previously distinct classes. Studies of stressors have shown that plants respond differentially to human-mediated disturbances in the surrounding landscape. Reed canary grass ( Phalaris arundinacea ), a native but highly invasive wetland grass in regional wetlands, exhibits increased establishment, growth, and biomass in response to nutrient additions, and surprisingly, in some instances, to increased sedimentation, while blue vervain ( Verbena hastata ), a denizen of freshwater wetland habitats, is intolerant of increased sediment loading. Hydrophtyes have also served as the foundation for some of the most powerful wetland assessment tools in the region. Floristic Quality Assessment (FQA) and biotic indices have been developed by a number of states within the region and in the case of FQA, for the region as a whole. This chapter examines the role of hydrophytes in these studies, as well as spotlights invasive and special status wetland species found in wetland habitats in the region.

Native biodiversity increases with rising plant invasions in temperate, freshwater wetlands

“…All non-native and invasive species are assigned a score of 0 in this study. The establishment of CC values and the use of the adjusted FQAI provides a standardized way to evaluate the floristic condition of each wetland site and compare spatio-temporal variations between sites (Miller and Wardrop 2006;Chamberlain and Ingram 2012;Chamberlain et al 2013;Chamberlain and Brooks 2016). Higher species diversity is generally thought to indicate a more complex and healthier community as a greater variety of species allows for more species interactions, and therefore, greater system stability.…”

STATE-OF-THE-SCIENCE REPORT Trends in Floristic Quality Assessment for Wetland Evaluation

“…Across the geographic domain of FQA application, the approach is being used in a variety of ways to evaluate wetland condition. Examples include ambient monitoring and assessment, targeting and prioritizing sites for conservation, assessment for impact analysis in wetland regulatory programs, performance evaluation for wetland mitigation sites, identification of reference sites for functional assessment, and incorporation into larger assessment models such as IBIs (Cronk and Fennessy 2001;Medley and Scozzafava 2009;Chamberlain et al 2013). Further, FQA methods have been developed for a broad and growing geographic range engaging a diversity of wetland habitats types within which the method has been tested for research purposes.…”

“…in the mode that FQA should take for this type of analysis (i.e., FQI, C̅ , or modified index versions; see Box 1 and index discussion below). Irrespective of the specific index chosen, the general trends suggest that it is the conservatism concept itself that provides the basis for consistency in condition evaluation, the foundation of which is vetted through expert opinion in the C-value listing process (see Box 2) (Swink and Wilhelm 1994;Chamberlain and Ingram 2012;Chamberlain et al 2013). Studies showing significant negative correlations between FQA metrics and a gradient of anthropogenic disturbance abound (e.g., Fennessy et al 1998a;Cohen et al 2004;Bried et al 2013), indicating that higher FQA index values routinely correspond to a lower incidence of disturbance in wetlands, and vice versa.…”