AN ANALYSIS OF RESTORATION PRACTICES: A SOIL SURVEY OF THE UNIONVILLE SERPENTINE BARRENS, CHESTER CO., PA

The Unionville Serpentine Barrens 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 endemic, rare and endangered plant species tolerant of harsh soil conditions. Ecological succession phases out serpentine barrens as added organic material dilutes serpentine soils’ effects, allowing grasslands to become forests. Historical activities, like the impacts of megafauna movement in the Pleistocene and more recent burnings by Native Americans reset ecological succession processes by maintaining the chemically and physically inhospitable soil characteristic. Despite these landscape alterations, Unionville Serpentine Barrens, similar to other regional trends, have shrunk to 8 of its earliest recorded 63 acres. Mining and quarrying, development, and communities’ fear of prescribed burning mark key reasons for the disappearance of important ecological site.

To maintain the unusual and ecologically complex serpentine barren habitat, this study, through an extensive soil survey, evaluates evaluate various restoration practices used at the National Lands Trust owned and preserved Unionville Serpentine Barrens. As a shallow depth to bedrock, narrow organic layer, low Ca:Mg ratio, and abundant heavy metal concentrations are characteristic of serpentine soils, these studies consisted of the majority of the project. One hundred and twenty samples sites were located along a 600-meter transect that dissects a selective tree removal in 2012 and 2015 prescribed burn area. 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 exchangeable cations (exch. Ca, Mg, K, Fe, Cr and Ni) were detected using an ICP-OES to analyze bio-available nutrients. C and N data was obtained via Elemental Analysis. Analyzing the effectiveness of selective tree removal and prescribed burnings informs future restoration practices used in maintaining rare and shrinking serpentine ecosystems.