Abstract:
The Unionville Serpentine Barrens (USB) of Chester County, Pennsylvania is one of few remaining barrens in the Northeast United States. Serpentine barrens, named for their grassland ecosystem in typically temperate forested areas, form above ophiolitic and ultramafic serpentinite bedrock. They host rare and endangered plant species tolerant of harsh soil conditions. The serpentinicity of a soil increases with shallow soil horizons, a Ca:Mg ratio <1, and abundant heavy metal concentrations. Serpentinicity decreases as organic material is added, diluting the effects of the harsh serpentine minerals. This study reports an extensive soil survey, and analyzes relationships between soil chemistry, topographic and location features and vegetation. through an extensive soil survey, analyzes soil chemistry, topographic features, location amidst serpentinite bedrock and Chrome soil series, and serpentine-characteristic vegetation. This study was conducted as part of an adaptive management plan underway at USB in order to restore the shrinking barrens. The soil and vegetation monitoring transect dissects two restoration tactics: a 2012 tree removal area and a 2015 prescribed burn. Depth to bedrock was measured and O, A, B and C horizon samples were collected at each site. Samples were air dried, ground and sieved to < 2mm grain particle size. Mineral samples were extracted via the Mehlich- 3 procedure and concentrations of plant exchangeable cations (exch. Ca, Mg, Fe, and Ni) were detected using an ICP-OES. Organic samples were extracted via EPA 3050b’s acid digest protocol. In addition to characterizing the soil, we found that serpentine-characteristic flora require time to respond to restoration tactics.
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