Floristic quality assessment scores and vegetation patterns across regions, habitat types, and plant communities of Illinois

Background/Question/Methods Floristic Quality Assessment (FQA) scores are intended to rank and score ecological degradation of plant communities across large areas (e.g., North Dakota) of diverse habitats (e.g., Florida). Within political boundaries, size and diversity represent potential obstacles if FQA scores are intended to be comparable across regions and plant community types— especially as scores are used to make jurisdictional decisions (wetlands mitigation), to direct land acquisition, or to foster conservation/ecological inquiry. For example, in order to be useful across large landscapes one would need to be confident that a particular plant community type in the north of a state typically scores the same as one in the south. Or, that a high-quality, remnant prairie, scores the same as a high-quality marsh, or a high-quality, old growth forest. With these questions in mind, we used a 10-year, 500 site dataset, to compare FQA scores from vegetation surveys of randomly selected forests, wetlands, and grasslands habitats across Illinois. Results/Conclusions We found subtle differences in mean community scores across regions, primarily associated with latitude. We also found differences in frequency distributions of scores, which were perhaps more informative than means. We discuss observed differences and suggest explanations for their meaning. We explore four (non-exclusive) explanations for patterns in scores:  1) Scoring biases of Coefficient’s of Conservatism; 2) Inherent biological properties of regions and communities reflected by their plants (e.g., latitudinal gradient in diversity and productivity, variable resilience of communities to disturbance); 3) Inherent patterns and legacies of human disturbance histories in regions or habitat types (e.g., highly agricultural or urbanized regions). We discuss implications of these results for FQA usage, as well as describing future paths of inquiry.