Native species richness of commercial plant vendors in the Midwestern United States

Abstract

Native plants have substantial horticultural and ecological value, which has created a market for plant vendors to sell native plant materials. Availability of native plant species within the commercial plant trade, however, and the plant diversity available at different vendor types, are not well understood. In this study, we characterized the commercial species pool, which is the set of species available through commercial vendors, in the Midwestern USA. We recorded native, non-cultivar species presence and materials available for sale from 557 plant vendors across 7 states in the Midwest. Vendors included native plant nurseries as well as conventional vendors, such as general nurseries/garden centers and tree farms that sell to the public. We compared species richness among types of plant vendors, determined the number and frequency of commercially available species, and characterized the type of materials that vendors sold (for example, potted plants or seed). We found that 44% of the possible regional native species pool was available for purchase from vendors, which is a greater representation of the species pool than has been found in other regions. Significant differences in species diversity occur among vendor types; compared to conventional vendors, native plant nurseries sold more species and a larger variety of materials for each species. Most commercially available species were rarely offered for sale in native nurseries, and commonly offered species were few in number and were often charismatic wildflower or shade tree species. Specialized native nurseries are important reservoirs of native plant diversity, particularly because they hold a majority of the rare species in the commercial pool. Nonetheless, a majority of species in the commercial pool were offered for sale by the set of conventional vendors. This study is a detailed characterization of a commercial species pool, and it highlights the biodiversity value and complementarity of types of commercial vendors.