Controlling the invader Urochloa decumbens: Subsidies for ecological restoration in subtropical Campos grassland

Questions Restoration of grassy biomes is currently of large importance, and controlling invasive grasses is often key to restoring these ecosystems in the tropics and subtropics. We combined different ecological restoration techniques to evaluate potential to control the invasive grass Urochloa decumbens and restore plant species composition. Specific questions were: (a) are herbicide application and topsoil removal efficient to control U. decumbens cover and allow native species establishment; and (b) are hay transfer and sowing native grass species efficient to reintroduce native species and increase their cover? Location Campos grasslands, southern Brazil. Methods We combined the follow restoration techniques: (a) herbicide application or topsoil removal to control the invasive species, and (b) hay transfer or sowing of native grasses to reintroduce native species. We assessed and compared native plant species richness, vegetation cover, native species cover, U. decumbens cover and other exotic species cover in 2016 and 2017. Results Herbicide application reduced invasive species cover more than topsoil removal, even though both were effective. The decrease of U. decumbens cover led to an increase in native species cover and native species richness. Hay transfer and sowing native grasses did not produce satisfactory results for native species reintroduction. Native species richness and U. decumbens cover increased from 2016 to 2017. Conclusion Herbicide application was a better option to control U. decumbens and to allow recovery of native species. However, use of herbicides in restoration is controversial, and more detailed studies on impacts are necessary. Environmental filters appear to be a major cause for failure of hay transfer and seeding species. Recovery of the native plant community is a great challenge in invaded subtropical grasslands, and additional management actions and time are necessary to increase the establishment of native species.