Selective and Non-Selective Control of Invasive Plants: The Short-Term Effects of Growing-Season Prescribed Fire, Herbicide, and Mowing in Two Texas Prairies

摘要

Conservation of North American grasslands is hampered by the impact of invasive herbaceous species. Selective control of these plants, although desirable, is complicated by the shared physiology and phenology of the invader and the native components of the invaded plant community. Fortunately, there is evidence that some management practices, such as prescribed fire, herbicide, and mowing, can cause differential responses in native and invasive grassland species. However, timing of treatment is critical, and fire has been shown to increase rates of invasion when implemented during the dormant season. Bothriochloa ischaemum, an introduced C4 Eurasian grass is an increasing problem in grasslands, particularly in southern and central regions of North America. To date, there has been little success in effective selective control. Two invaded grassland sites representative of Blackland Prairie and Edwards Plateau ecoregions were subjected to two growing-season prescribed fire treatments, single and double herbicide applications, and single and double mowing treatments. Mowing had no effect on either B. ischaemum or other dominant species at either site one-year posttreatment. However, growing-season fire and herbicide were both effective at reducing the abundance of B. ischaemum, with other codominant species responding either negatively to herbicide or neutrally or positively to fire. The vulnerability of B. ischaemum to growing-season fire may be associated with the ecology of its native range. The negative growth response to growing-season fire, combined with its lower implementation costs, indicates that this method warrants further investigation as a selective management tool for other problematic species in invaded grasslands.