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

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.