Search

A microwave‐based process to control invasive species (seeds and adult stages) in the field prior to plant community restoration is currently under development. We investigated the effect of four microwave treatment pairings of Power × Duration (2kW4min, 4kW2min, 2kW8min, and 4kW4min) on seedling emergence of (1) an abandoned field seed bank used as a model for various plant species and (2) seeds of three species invasive in Europe: Datura stramonium (Jimson weed), Reynoutria × bohemica (Bohemian knotweed), and Solidago gigantea (Giant goldenrod). In addition, we assessed whether nontreated seeds of these three invasive species could germinate on microwave‐treated soils. As microwave soil heating usually leads to nonhomogeneous temperatures within a sample, we also assessed whether the position of seeds in the soil during microwave treatment (center vs. edges) impacted seedling emergence. Results show that the most intensive microwave treatments (2kW8min and 4kW4min), enabling the soil to reach 85°C, are highly effective in inhibiting seedling emergence of invasive species and the seed bank. The 2kW8min treatment, combining lowest power and longest exposure, is the most effective, reducing seed bank seedling emergence by 98% compared to control. The results also reveal a species‐specific response to heat, and lower microwave effectiveness on seeds located at the soil surface, which may explain the incomplete effectiveness of intensive treatments. Our results also suggest that prior microwave soil treatment does not prevent a considerable proportion of newly arrived invasive species seeds from germinating, suggesting that this method should be followed by restoration of native plant cover. [ABSTRACT FROM AUTHOR]

As invasive plant species are a major driver of change on oceanic islands, their control is an important challenge for restoration ecology. The post-control recovery of native vegetation is crucial for the treatments to be considered successful, but few studies have evaluated the effects of control measures on both target and non-target species. To investigate the efficiency of manual control of Cinchona pubescens and its impacts on the sub-tropical highland vegetation of Santa Cruz Island, Galápagos, vegetation was sampled before and up to two years after control was carried out in permanent sampling plots. Manual control significantly reduced Cinchona density. Due to regeneration from the seed or bud bank, follow-up control is required, however, for long-term success. Despite heavy disturbance from tree uprooting, herbaceous angiosperms were little affected by the control actions, whereas dominant fern species declined in cover initially. Most native, endemic, and other introduced species regained their pre-control levels of cover 2 years after control; some species even exceeded them. The total number of species significantly increased over the study period, as did species diversity. The native highland vegetation appeared to be resilient, recovering to a level probably more characteristic of the pre-invasion state without human intervention after Cinchona control. However, some introduced species seemed to have been facilitated by the control actions, namely Stachys agraria and Rubus niveus. Further monitoring is needed to confirm the long-term nature of vegetation change in the area. [ABSTRACT FROM AUTHOR]

Restoration of communities invaded by exotic plants requires effective eradication of the invader and reestablishment of the resident plant community. Despite the commonly cited need for techniques to accomplish such goals, studies that test strategies for removing invasive plants, monitor effects on resident communities, and incorporate replicate sites are generally lacking. Microstegium vimineum is an exotic annual grass that is rapidly invading forests in the eastern United States and threatening to reduce biodiversity and inhibit forest regeneration. I conducted a field experiment at eight sites over two growing seasons in southern Indiana to evaluate hand-weeding (HW), a postemergent grass-specific herbicide (POST), and the postemergent herbicide plus a preemergent herbicide (POST + PRE) for removing Microstegium. Compared to reference plots (REF), the three treatments each reduced Microstegium biomass at the end of the growing seasons to relatively low levels. However, after the second year of the experiment, POST and POST + PRE resulted in very little spring cover of Microstegium, but HW plots were significantly reinvaded. HW and POST, but not POST + PRE, increased resident plant community productivity and spring resident community cover compared to reference plots. The amount of light at the research sites did not alter the effectiveness of treatments, but the recovery of resident communities was positively correlated with light availability under HW and POST + PRE. These results indicate that natural systems invaded by Microstegium can be restored using the POST or HW treatments, which will effectively remove the invasion and allow the resident plant community to recover when used over multiple growing seasons. [ABSTRACT FROM AUTHOR]