New version page

Development of Coefficients of Conservatism for Wetland

This preview shows page 1-2-3-4-5 out of 15 pages.

View Full Document
View Full Document

End of preview. Want to read all 15 pages?

Upload your study docs or become a GradeBuddy member to access this document.

View Full Document
Unformatted text preview:

Development of Coefficients of Conservatism for Wetland Vascular Flora of North and Central Mississippi Depressional wetland adjacent to auxiliary channel on Panther Swamp NWR, Yazoo County. Brook D. Herman1, John D. Madsen2, Gary N. Ervin1,3 1 Department of Biological Sciences, PO Box GY, Mississippi State, MS 39762 2 GeoResources Institute, Box 9652, Mississippi State, MS 39762-9652 3 corresponding author: Tel.: (662) 325-1203; e-mail: [email protected] GeoResources Institute Report 4001 (Water Resources) March 20, 2006Mississippi State University, GeoResources Institute Page 2 of 15 March 20, 2006 Development of Coefficients of Conservatism for Wetland Vascular Flora of North and Central Mississippi Brook D. Herman1, John D. Madsen2, Gary N. Ervin1 1 Department of Biological Sciences, PO Box GY, Mississippi State, MS 39762 2 GeoResources Institute, Box 9652, Mississippi State, MS 39762-9652 INTRODUCTION It has become vitally important to perform quick and effective assessments of the ecological quality of natural areas as these areas are modified by an ever-expanding human population. Examples of recent modifications to native vegetation include: removal of native communities for production of agricultural commodities, grazing by domestic livestock, timber harvesting, draining of wetlands, establishment and expansion of urban areas (consisting of large areas uninhabitable to or that impede the dispersal of species) and accidental and intentional introduction of non-native species. Correspondingly, native plant communities have changed in response to the different types of disturbances. In areas were there is little human activity, species with low levels of tolerance to disturbance will be in proportionally larger numbers. Conversely, areas with higher levels of human activity display a greater proportion of species adapted to frequent or more intense disturbance. The pressure on natural areas increases with time, so effective and efficient methods are needed to assess the quality of remaining natural areas, to aid in identification of high quality remnants and thereby facilitate the prioritization of conservation and preservation activities. Swink and Wilhem (1979, 1994) developed a floristic ranking system based on the fundamental principle that native plant taxa display a range of tolerances to disturbances and varying degrees of fidelity to a set of environmental parameters. This ranking system was based on what they called species conservatism. Each species was assigned a numerical score, called a coefficient of conservatism (CC), reflecting the species’ level of conservatism relative to other species present in the region (Table 1). Because species are assigned scores in relation to other elements in the local flora (Wilhelm Table 1. Descriptions of plant species characteristics used to assign Coefficients of Conservatism (modified from Lopez and Fennessy 2002). Description of habitat and Range of scores characteristics of species Non-native species 0 Native taxa that are found in disturbed sites 1−3 Native taxa that are typically associated with a 4−6 specific plant community, but tolerate moderate disturbance to that community Native taxa in plant communities in an advanced 7−8 successional stage that have undergone minor disturbance Native plants with high degrees of fidelity to a narrow 9−10 range of environmental characteristics (specialists, rare species)Mississippi State University, GeoResources Institute Page 3 of 15 March 20, 2006 and Ladd 1988), these scores become increasingly invalid as distance from the region of evaluation increases. Thus, CC scores must be developed regionally to ensure optimal information. Once CC scores are developed for a regional flora, they can be used in assessing the quality of vegetation in target ecosystems by calculating a mean CC for all species present (Swink and Wilhelm 1979), or by incorporation into one of the various floristic quality indices that have been developed for assessing terrestrial (Wilhelm and Ladd 1988, Ladd 1993, Taft et al. 1997) or wetland (Matthews 2003, Lopez and Fennessy 2002) ecosystems. Although this system of natural areas assessment has been used primarily in the Midwest, it presently is being developed and evaluated in other parts of North America (e.g., California, Connecticut, and Florida). Application of Coefficients of Conservatism: Average CC of an Area Wetland managers and assessment personnel need an efficient, economical, and accurate method of assessing the quality of wetland sites for potential impacts of development, gauging restoration efforts, and making other management decisions. The most accessible biotic component of wetlands is their vegetation. Vegetation composition reflects the degree of disturbances, human or natural. While native plant communities have evolved with natural disturbances relative to particular environments, a notable shift in the pattern of vegetation composition is usually associated with human influence (Magee et al. 1999). Following ecosystem disturbance, conservation-worthy species will be replaced gradually by more ruderal species. Assembling a list of species that occur in an area of interest and averaging their CC values generates a score that reflects the average conservatism (CC) of the plant community, which in turn reflects the quality of native species present. By using the CC, temporal changes in floristic quality can be measured. If there is an increase in more valuable species, the CC will increase to reflect the improved quality of the habitat. Application of Coefficients of Conservatism: Floristic Quality Assessment Index Wilhelm and Ladd (1988) further modified the use of the CCto account for the effect of area and therefore species richness. The average CC of the native species was multiplied by the square root of the number of native species; this score was then referred to as the Natural Area Index (NAI). Using the NAI and theCC, differences among areas could be measured and used to make decisions on possible development projects and to protect areas of high floristic quality. The NAI was later referred to as the Floristic Quality Assessment Index (FQAI) (Andreas and Lichvar 1995, Lopez and Fennessy 2002). NAI==CC N*CCNN∑=*CCN∑=FQAI The FQAI has been recommended in many facets: evaluating restoration and mitigation wetlands, measuring floristic quality differences


Loading Unlocking...
Login

Join to view Development of Coefficients of Conservatism for Wetland and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Development of Coefficients of Conservatism for Wetland and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?