Edaphic distinctiveness of Florida subtropical calcareous wet grasslands.

Subtropical calcareous wet grasslands (SCWG) are pyrogenic hyper-seasonal grasslands with exceptional vascular plant biodiversity and conservation value in south-central Florida with floristic affinities to southern Florida marl grasslands, and both are dominated by Muhlenbergia sericea. We sampled 62 sites (n = 124 samples), of which 62 were surface soil samples (upper 1–10 cm), and 62 were subsurface soils (above the spodic horizon) across the edaphic-hydrologic gradient of savanna-grassland landscape in south-central Florida. We sought to determine how soil chemistry (17 variables) and texture (7 categories) might correlate with floristic composition and distinguish SCWG from savanna-grassland community types in peninsular Florida. To test which soil PCA axes were associated with plant community types, we used correlations between NMDS plot scores and the scores of significant soil PCA axes. Surface and subsurface soil chemistry were significantly correlated with dimensions of variation in savanna-grassland plant community types. In SCWG, soil chemistry is segregated because of higher Ca, pH, and percentage base saturation in subsurface soils. Lower cation exchange capacity, surface and subsurface soil texture with greater fine sand particles, lower silt, and higher clay content differentiate SCWG. Our results highlight the edaphic-hydrologic distinctiveness of SCWG, which supports previous recognition based solely on floristic and species composition, where calciphilic habitat specialists coexist with plants otherwise characteristic of brackish marsh, acidic grassland, and xeric sands. [ABSTRACT FROM AUTHOR]