An exploration of the vascular flora of Pine City Natural Area, Monroe County, Arkansas, U.S.A., in comparison to the Mississippi Alluvial Plain in eastern Arkansas (U.S.A.)

Abstract

The Mississippi Alluvial Plain (MAP) ecoregion in eastern Arkansas has had >90% of its land area converted to agriculture and has historically been under-collected floristically, including the ecologically unique site, Pine City Natural Area (PCNA). Actively managed by the Arkansas Natural Heritage Commission, PCNA contains diverse loblolly pine-post oak flatwoods and some of the last known saline barrens in the MAP. Our inventory of the vascular flora in and around PCNA resulted in the documentation of 113 families, 308 genera, and 576 taxa (including infraspecific taxa); 482 (83.7%) are native, 9 (1.6%) are of state conservation concern, and 184 (31.9%) represent county records. The total taxa known for Monroe County, Arkansas, increased from 583 to 767. The most taxa-rich families included Poaceae (92 taxa), Asteraceae (65), Cyperaceae (48), and Fabaceae (42). In the surrounding ten-county region, 27 taxa (4.7%) documented at PCNA had not been vouchered, and 196 taxa (34.0%) are known from half or fewer surrounding MAP counties. We examined families in need of additional exploration in the MAP to better understand county-level floristic richness. The richest graminoid families, the Poaceae, Cyperaceae, and Juncaceae, are apparently the most understudied in the MAP, based on low relative numbers of herbarium specimens. The richness in the PCNA flora, in comparison to the broader MAP, demonstrates the need for continued floristic inventory in eastern Arkansas to locate areas of high conservation value in need of protection.