Controlling invasive plant species in ecological restoration: A global review

Abstract

Invasive plant species can hinder the establishment and growth of native plants and impact several ecosystem properties, such as soil cover, nutrient cycling, fire regimes and hydrology. Controlling invasive plants is then a necessary, yet usually expensive, step towards the restoration of an ecosystem. A synthesis of literature is needed to understand variation in invasive plants' impacts and their practical control in restoration contexts, and to identify associated knowledge gaps. We reviewed 372 articles published from 2000 to 2019 covering the control of undesirable plants (both exotic invasive and overabundant native plant species) in ecological restoration to gather information on the main plants being controlled and methods used, and considering the distribution of studies among biomes and countries grouped according to the Human Development Index (HDI). Grasses and forbs were the most‐studied invasive plant species in restoration sites, but invasive trees were well studied in the tropics. Poaceae and Asteraceae were the most studied families of invasive plants. Non‐chemical interventions (mostly mowing and prescribed fire) were used in more than half of the reviewed studies globally, but chemical methods (mainly glyphosate spraying, used in 40% of projects using herbicides) are also common. The reviewed studies were mostly performed in countries with very high HDI. Countries with low and medium HDI used only non‐chemical methods. Synthesis and applications. Decisions about which control method to use depend heavily on the invasive plant species' growth forms, the local economic situation where the restoration sites are located and resources available for control. More developed countries tend to use more chemical control, whereas less developed ones use mainly non‐chemical methods. Since most of the reviewed studies were performed in countries with very high HDI, we lack information from developing countries, which concentrates global hotspots for biodiversity conservation and global commitments of forest and landscape restoration.

Priority effects and ecological restoration

“…In North America, South America, and Australasia, invasive exotic species strongly limited restoration success. Recent reviews have shown that there are more studies of controlling invasive species in restoration in North America compared to other countries (Kettenring & Adams 2011; Weidlich et al 2020). Thus, the main goal of using priority effects derived from native species was to make communities more resistant to invasion (Funk et al 2008).…”

“…Restoration often involves manipulating which plant species are introduced, sown, planted, or transferred to a disturbed or degraded site at a given time (Weidlich et al 2020). If the order of arrival of these species can affect ecosystem functioning or community composition over time, then priority effects can determine successful or unsuccessful restoration.…”

Exploring the potential of using priority effects during ecological restoration to resist biological invasions in the neotropics

“…In contrast, there is no specific knowledge on the role of priority effects in neotropical ecosystems, which have been increasingly invaded by non‐native plants (Fine 2002; Foxcroft et al 2010; Essl et al 2020). Considering that the control of invasive non‐native plants is often part of restoration projects/programs (Machado et al 2020; Weidlich et al 2020b), manipulating plant order of arrival can be an alternative strategy to thwart the establishment of invasive non‐native plants by steering the community along a desired trajectory (Young et al 2017).…”

Forest restoration by different nucleation techniques in Urochloa grassland

“…Many pastures are formed by grasses of the genus Urochloa, which inhibits natural regeneration (Fragoso et al, 2017;Weidlich et al, 2020). In grasslands, seedling recruitment is reduced due to factors such as: competition for water, light, and nutrients; allelopathy; absence of dispersing fauna; predation; inadequate microclimate conditions; and physical and chemical soil degradation (Maza-Villalobos et al, 2011;Sobanski & Marques, 2014).…”