Bohemian knotweed forms in dense thickets that displace native plants and reduce biodiversity. They compete with native vegetation for space light, nutrients and water. Secondary losses of native species are often caused when they succumb to the herbicides that are sprayed on the knotweed for eradication purposes. Large colonies rabidly change structure and species composition of local ecosystems, in turn affecting many other plant and animal species. These plants also contain allelopathic compounds that are toxic to surrounding vegetation. This hybrid is considered to be more vigorous than either of it parents, as it spreads quicker and may be harder to eradicate. Bohemian knotweed may leave unkept growths of dead stems that trap debris andmay become litter dumps. They can also cause difficulties of access on river banks and floodplains. Once these plants die, in the winter, they leave the soil prone to flood erosion , which requires costly removal and bank reinforcement.