Predictors of Rare and Specialist Plant Occurrence in Midwestern Calcareous Fens

• DOI: 10.1007/s13157-021-01475-w
• Publication Date: 2021-07-01T18:04:43Z
• Authors: David Bart; Austin Yantes
• Keywords: 0106 biological sciences; 15. Life on land; 01 natural sciences

Calcareous fens provide habitat for a disproportionate number of rare and specialist plant species, yet little is known about the conditions that allow fens to support these species. We compared the importance of geography, land-use legacies, current hydrologic disturbance, and stressors in predicting rare and specialist species occurrence and richness in calcareous fens throughout their Wisconsin range. On each fen, we measured the occurrence and richness rare and specialist species, as well as potential predictors including stress variables (root-zone saturation and nutrient availability), land-use-legacies (history of plowing or abandoned drainage projects), current groundwater extraction (high-capacity-well pumping), and geographic variables (UTM coordinates). We used Partial Least Squares Regression models to assess the predictive power of each of these factors. We found that stressor models best predicted occurrence and richness of most species. Groundwater saturation was the best single predictor of high species occurrence and richness, while historic plowing and drainage, high-capacity-wells, and high nitrogen availability were the best predictors of species absence and low richness. Our results suggest that high saturation and low nutrient availability are likely drivers of rare and specialist species occurrence and richness in calcareous fens, while anthropogenic activities that alter stressors contribute to the continued imperilment of these species.