Lespedeza cuneata: How an Invasive Legume is Altering Fire Ecology in Tallgrass Prairie

Abstract

Biodiversity within the tallgrass prairies of Flint Hills in Kansas is being threatened by an invasive legume, sericea lespedeza (Lespedeza cuneata). Management techniques, like herbicide applications and grazing, can be expensive and ineffective if not correctly targeted. The primary treatment for sericea lespedeza is annual spring prescribed burns. Fire can be an effective tool to manage invasives in vulnerable periods during their life-cycle (e.g. during seed set), especially in fire-adapted ecosystems such as tallgrass prairie. However, annual spring burns increase rates of germination and productivity for sericea lespedeza. I investigated how sericea lespedeza affects fire and how fire affects sericea lespedeza productivity. My main objectives were to determine 1) flammability characteristics of sericea lespedeza and the affect sericea lespedeza has on fire, 2) spring fires in conjunction with secondary treatments impact on sericea lespedeza, and 3) fall fires in conjunction with secondary treatments impact on sericea lespedeza. Flammability characteristics were conducted at Humboldt State University, and seasonal prescribed burns, in conjunction with secondary treatments, were conducted at Marais des Cygnes National Wildlife Refuge. Sericea lespedeza drastically decreases flammability characteristics as a result of decreased oxygen availability and increased moisture retention. Reduction in flammability characteristics can reduce fire intensity that result in adverse effects for tallgrass prairie ecosystems that lead to increased germination rates of sericea lespedeza seeds. Prescribed burns in the fall, in conjunction with secondary management techniques target sericea lespedeza, and increases seed mortality, compared to spring burns. The true test for land owners treating for sericea lespedeza results in two questions: How much time do they have, and how much money are they willing to invest in the treatment for sericea lespedeza?