Classification > Plant Associations

Plant Associations

In 2003, CNHP produced the Field Guide to the Wetland and Riparian Plant Associations of Colorado. This 466-page publication is based on field data collected by numerous wetland scientists over more than 10 years and describes 184 plant associations found across the states.

Plant associations, or plant communities, are the finest scale of the U.S. National Vegetation Classification and are based on repeated patterns of species combinations (e.g., Narrowleaf Cottonwood / Thinleaf Alder Woodland).

In order to manage, restore and protect Colorado wetlands adequately, we must know which types exist, their functions and attributes, relative frequency or rarity, and distribution across the landscape. CNHP therefore created “The Field Guide to the Wetland and Riparian Plant Associations of Colorado” to assist land owners and managers in the protection of wetland habitat and wetland-dependent species, and to establish a basis for focusing wetland research, land management, and conservation efforts where they will be most effective and beneficial.

The unit of classification used in the guide is the plant association, the most basic level of the U.S. National Vegetation Classification (USNVC) standard. Each association is assigned a name based on the scientific names of the diagnostic species that have a high degree of constancy between wetland locations. In the association names, plant species used in the name occurring in the same stratum are separated by the "-" symbol, and those occurring in different strata of the vegetation are separated by the "/" symbol (e.g., Quercus macrocarpa/Corylus cornuta-Corylus americana Woodland).

As a rule, the diagnostic species for associations are consistently present (constant) in occurrences of the community. In situations where a diagnostic species is not consistently present in occurrences of a community, that species is placed in parentheses. For example Populus deltoides-(Salix amygdaloides)/Salix exigua Woodland means Populus deltoides and Salix exigua are present in most of the stands while Salix amygdaloides may not be.

Profiles of 184 associations are presented in the guide. These associations are based on floristic data from samples collected in thousands of vegetation stands throughout Colorado. In spite of the large sample size, sampling efforts were not necessarily uniform across all habitat types of the state, and data gaps remain. There are undoubtedly additional types which have yet to be identified and many of the associations described may be further subdivided in the future.

The guide covers wetland and riparian associations occurring within the boundaries of the state of Colorado, although many of the associations included are also found in neighboring states.

A dichotomous key to the wetland and riparian associations of Colorado begins on page 17. Because species identification is a critical requirement for the identification of most associations, drawings of dominant species are included where possible. However, for many species more detailed information will be required, and the reader is urged to consult the many keys and field guides available for this purpose.