Developing coefficients of conservatism to advance floristic quality assessment in the Mid-Atlantic region1

Abstract Floristic Quality Assessment (FQA) is a recognized bioassessment technique for evaluating habitat nativity or resource condition (status) using conservatism of the plant community. The Mid-Atlantic Floristic Quality Assessment Project (MAR-FQA) was undertaken in 2009 to advance floristic quality assessment in the Mid-Atlantic region. The primary objectives of the project were to assign coefficients of conservatism to the regional flora; describe the Mid-Atlantic region in terms of its floristic composition, conservatism, and nativity; and examine the potential subjectivity of coefficient values. We identified 4208 unique plant species of which 2822 were ranked. The flora was dominated by perennial forbs and graminoids. Two-thirds was native to either all or part of the region, while one-third was considered non-native to the region or to North America. Most coefficient ranks fell within the mid to upper range of the scale with distribution noticeably skewed toward higher conservatism due to a greater number of taxa with coefficients of 8, 9, and 10. Our investigation of bias in the approach indicated that subjectively assigned conservatism values were remarkably accurate. Over 75% of highly conservative taxa were found exclusively at high-quality wetland sites while less than 5% of generalist taxa were restricted to a single condition category. While FQA has been successfully used to assess habitat on both the state and sub-regional scales, it is now possible to deploy it in the Mid-Atlantic region. As a bioassessment tool, it offers a relatively rapid, reliable, and repeatable approach to assessing the somewhat arbitrary concept of quality. As such, it is an important addition to any botanist's tool kit.Abstract Floristic Quality Assessment (FQA) is a recognized bioassessment technique for evaluating habitat nativity or resource condition (status) using conservatism of the plant community. The Mid-Atlantic Floristic Quality Assessment Project (MAR-FQA) was undertaken in 2009 to advance floristic quality assessment in the Mid-Atlantic region. The primary objectives of the project were to assign coefficients of conservatism to the regional flora; describe the Mid-Atlantic region in terms of its floristic composition, conservatism, and nativity; and examine the potential subjectivity of coefficient values. We identified 4208 unique plant species of which 2822 were ranked. The flora was dominated by perennial forbs and graminoids. Two-thirds was native to either all or part of the region, while one-third was considered non-native to the region or to North America. Most coefficient ranks fell within the mid to upper range of the scale with distribution noticeably skewed toward higher conservatism due to a greater number of taxa with coefficients of 8, 9, and 10. Our investigation of bias in the approach indicated that subjectively assigned conservatism values were remarkably accurate. Over 75% of highly conservative taxa were found exclusively at high-quality wetland sites while less than 5% of generalist taxa were restricted to a single condition category. While FQA has been successfully used to assess habitat on both the state and sub-regional scales, it is now possible to deploy it in the Mid-Atlantic region. As a bioassessment tool, it offers a relatively rapid, reliable, and repeatable approach to assessing the somewhat arbitrary concept of quality. As such, it is an important addition to any botanist's tool kit.