Floristic Quality Assessment: a critique, a defense, and a primer

Floristic Quality Assessment (FQA) measures have become extraordinarily influential ecological metrics in North America over the past 20 yr. Government agencies, conservation organizations, land managers, and researchers alike utilize this plant-based measure to evaluate habitat conservation value, ecological integrity, and naturalness. Its relative uniqueness, utility, and ease of use, among vegetation measures, portend the continued popularity of FQA going forward. FQA's use and influence far exceeds its study—where the literature addressing questions and criticisms regarding its methodology and ecological meaning has not kept pace with reliance upon it. Furthermore, the lack of literature review has led to disorder and confusion among its users. This review addresses these issues in three parts. First, it concisely explains the metrics and their methods, and most importantly, it synthesizes the often-misinterpreted conceptual basis behind FQA. The bulk of the review then tackles common questions from researchers and non-technical users alike regarding the measures. It does this with two lists. The first list reviews FQA's most common criticisms and summarizes evidence for and against them. The second list confronts the most common mistakes surrounding FQA, regarding both its application and misunderstanding in the literature. In each instance, straightforward guidelines and answers to uncertainties are emphasized.