Linear and non-linear effects of goldenrod invasions on native pollinator and plant populations

Abstract

The increased introduction of non-native species to habitats is a characteristic of globalisation. The impact of invading species on communities may be either linearly or non-linearly related to the invaders' abundance in a habitat. However, non-linear relationships with a threshold point at which the community can no longer tolerate the invasive species without loss of ecosystem functions remains poorly studied. We selected 31 wet meadow sites that encompassed the entire coverage spectrum of invasive goldenrods, and surveyed the abundance and diversity of pollinating insects (bees, butterflies and hover flies) and native plants. The species richness of native plants decreased linearly with goldenrod cover, whereas the abundance and species richness of bees and butterflies decreased non-linearly with increasing goldenrod cover. However, no statistically significant changes across goldenrod cover were noted for the abundance and species richness of hover flies. Because of the nonlinear response, goldenrod had no visible impact on bees and butterflies until it reached cover in a habitat of about 50% and 30-40%, respectively. Moreover, changes driven by goldenrod in the plant and

Restoration of ecologically valuable grassland on sites degraded by invasive Solidago: lessons from a 6‐year experiment

“…Therefore, the experimental outcomes regarding the species number can be considered to be satisfactory. Other studies have suggested that the species richness of semi-natural grasslands invaded by Solidago decreases linearly with the Solidago cover (Moro n et al, 2019), indicating that further reduction in the invader cover would be beneficial to the plant species richness in our study.…”

“…Moreover, they may spread rapidly if mowing is ceased. Therefore, any reduction of the invaders would be beneficial for ensuring plant diversity (Moro n et al, 2019) and high hay quality and quantity (per the results of this study). The trajectory of cover reduction observed as a function of time suggests that further mowing would reduce the Solidago cover even more.…”

“…Moroń et al (2019) observed that invasive Solidago had no visible impact on either the individual numbers of bees and butterflies or their species richness until the plants reached a cover of approximately 50% for bees and 30%–40% for butterflies in a habitat. Therefore, the grassland created in this study could be assumed to serve as a good habitat for bees and butterflies; thus, the restoration was also successful in terms of the preservation of these two important insect groups.…”

“…Another threat to grassland maintenance is biological invasions that alter a wide range of ecosystem services, including biodiversity conservation (Vila & Ibáñez, 2011). Considerable areas of abandoned agricultural land continue to be overgrown by invasive species (Bartha et al, 2014; Fenesi et al, 2015), which also eventually encroach on semi‐natural grasslands (Czarniecka‐Wiera et al, 2020; Helm, 2015; Török et al, 2021), altering their functioning (Bartha et al, 2014; Fenesi et al, 2015; Moroń et al, 2019). Two of the most successful perennial plant invaders in Europe are giant goldenrod ( Solidago gigantea Aiton) and Canadian goldenrod ( Solidago canadensis L.), both of which are native to North America and have spread almost globally (Weber, 2003).…”

Modelling the damage costs of invasive alien species

“…The relationships between ecological impacts and the population density of an IAS have often been examined (also known as density-impact curves), with both linear and non-linear relationships proposed (Nava-Camberos et al 2001;Finnoff et al 2005;Laverty et al 2017;Bradley et al 2019;Moroń et al 2019); however, only a few studies have attempted to link this to the damage costs incurred. For a more thorough investigation of the variety of forms of the cost-density function (i.e., the accumulated cost C as a function of density u), we chose to rely on the functional types proposed by Yokomizo (2009), written as:…”