Floristic Composition and Soils of Three Grassy Forest Openings on the Unglaciated Allegheny Plateau, Strouds Run State Park, Ohio, U.S.A.

Abstract

Grassy openings are relatively uncommon on the unglaciated Allegheny Plateau, and the limited sites that do exist contribute disproportionately to the diversity and biological heritage of the region by providing habitat for locally uncommon plant species. Three grassy openings with areas of 0.1-0.2 ha are present on limestone-capped ridgetops at Strouds Run State Park in Athens County, Ohio. Although previous inventories of the park have documented the presence and character of these openings, the sites had not been thoroughly surveyed. Here we describe the vascular flora and soils of the openings and recommend management activities to conserve grassy openings within the park. The openings were surveyed monthly during the 2013 growing season, with frequent additional visits during the growing seasons in 2014-2019. Soils were collected from the openings and adjacent forest for analysis of pH, texture, and bulk density. We documented 135 species of vascular plants across the three sites; 27 were nonnative. The openings were dominated by forbs and grasses intermixed with woody species characteristic of limestone glades (e.g., Celtis pumila and Juniperus virginiana) and other open habitats. Andropogon gerardi was the dominant grass and openland forbs such as Asclepias tuberosa, Lithospermum canescens, and Ratibida pinnata also occurred in the three openings. Soil pH was significantly higher in openings and edge zones than in the forest matrix, suggesting that soils are a contributing factor shaping the grassy communities. However, woody plant encroachment was progressing inward from the edges of the openings, suggesting that a lack of disturbance is threatening the persistence of these unique communities. We suggest selective thinning of woody species to maintain the character and diversity of these sites; the practicality of controlled burns in small sites at close proximity to residential structures is limited.