Environmental Engineering Reference
In-Depth Information
wetland productivity or nutrient pollution (Little 2005 ). Analyzing the
environmental tolerances of dominant plant species can also be helpful in
modeling the dynamics of wetland plant communities (Squire and van der
Valk 1992 ). The concept of dominance is also important in wetland delineation
(Environmental Laboratory 1987 ). The wetland indicator status of dominant
species, as determined by the “50/20” rule, determines whether a plot area is
designated wetland.
￿ Plant Functional Groups: In order to effectively model plant communities, it is
helpful to reduce the hundreds of species present into a smaller more manage-
able set. Species are assigned to groups based upon traits that reflect similar
function in the ecosystem or community. Groups and traits are defined according
to the application at hand. For example, Raulings et al. ( 2010 ) used plant
response to flooding to create functional groups that they then modeled under
varying flooding regimes. Other types of functional groups are based upon
growth form (e.g., tussock, rhizomatous) or life history (e.g. annual, perennial)
or combinations of these (Bouchard et al. 2007 ). The wetland indicator status
used in wetland delineation (Lichvar and Kartesz 2011 ), is another example of a
plant functional group scheme. Exploring the relations between functional
groups and other organisms or environmental variables can yield interesting
patterns that help us better understand and make predictions about wetland
systems. Using established functional group definitions (such as the wetland
indicator status or status from the U.S.D.A. Plants database) makes it easier to
connect work to previously published studies, and is more acceptable to the
scientific community.
￿ Plant traits: Plant traits are genetically-determined characteristics, like leaf
shape, flowering time, seed number, or photosynthetic method that are inherent
to the taxa, irrespective of the environment (Violle et al. 2007 ). They may also
include genetically-determined responses to the environment, such as variation
in specific leaf area based upon light availability and nutrient status. Relations
can be drawn between plant traits and environmental attributes (e.g., carnivory
and nutrient-poor wetlands). Practitioners also use plant traits to predict the
behavior of individual species (e.g., invasiveness) or their response in wetland
restoration settings (e.g., assembly rules, (Matthews et al. 2009a )). Plant traits
can frequently be determined from the published literature after field work has
been completed. However, if researchers are working with a novel trait-species
combination, the trait parameters will need to be assessed in the field using
adequate and representative sampling from the population. Use a performance
curve to determine sampling adequacy.
5.3.8 Sampling Aquatic Vegetation
Many deep-water aquatic systems are not considered wetland, although they may
be surrounded by or grade into wetland systems and so are of interest here. Many of
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