Floristic Inventory of Woollen’s Gardens Nature Preserve, Indianapolis, Marion County, Indiana, USA, with Quantitative Vegetation Sampling of Permanent Plots in 2003 and 2016

Abstract

Urban forest fragments face challenges to habitat quality due to small size, isolation from larger natural areas, and close association with anthropogenic disturbance. Monitoring changes in vegetation can inform management practices targeted at preserving biodiversity in the face of these threats. Woollen’s Gardens is a high-quality mesic upland forest preserve in the city of Indianapolis, Indiana, USA, with a beechmaple older-growth forest and a significant display of showy spring wildflowers. The entire preserve was inventoried and quantitative vegetation analysis along seven 100 m transects was conducted in 2003 and again in 2016 to track changes. Data from both years document a high-quality flora with few non-native plants. Floristic Quality Index values for native species, derived from Floristic Quality Assessment, were 50.2 in 2003
and 47.3 in 2016. Native mean C-values of 4.5 and 4.3 for each year support that the site is comparable to the highest quality natural areas in central Indiana. Values declined little when non-natives were included, indicating non-natives are having little negative impact on the flora. Although non-natives comprised less than 10% of the flora, 11 of the 16 species are considered invasive in Indiana. In 2003, invasive Amur honeysuckle (Lonicera maackii) was among species in plots with the highest relative importance value. In 2016, invasive wintercreeper (Euonymus fortunei) was among these species. Limited public access to Woollen’s Gardens minimizes human disturbance, but invasive species are a threat to vegetation quality. Continuation of eradication efforts is strongly recommended before populations of these non-natives become more difficult to control.