The purpose of this investigation was to determine the effect of fertilizer on the growth of the invasive purple loosestrife (Lythrum salicaria L.) compared to that of eastern North American native wetland plants, common cattails (Typha latifolia), winged loosestrife (Lythrum alatum), and Joe Pye weed (Eupatorium maculutum). Wetlands provide essential ecosystem services such as water purification and flood control. Purple loosestrife, an herbaceous perennial, has spread in wetlands throughout the eastern United States and Canada, becoming a serious threat to the biodiversity of wetlands. Purple loosestrife forms dense stands, crowding out native plants, resulting in loss of habitat for native plant and animal species and changes in nutrient flows within the wetland ecosystem. Purple Loosestrife can be observed growing in wet areas that receive runoff containing high levels of nutrients due to inorganic or organic fertilizer.
Results/Conclusions
Seeds for purple loosestrife from Sussex County NJ and the United Kingdom, winged loosestrife, Joe Pye weed, and common cattails from Sussex County and Kentucky were grown under greenhouse conditions and four fertilization levels. Purple loosestrife plants that received fertilizer were taller and had greater mass than those did not, while the other species showed less of a response or no response. The greater response to fertilizer by purple loosestrife allows the purple loosestrife to outcompete native plants and spread through wetlands. These results show that the ability to respond more efficiently to fertilizer may contribute to the invasiveness of purple loosestrife.