Impacts of urbanization and agricultural legacy on taxonomic and functional diversity in isolated wetlands

Native plant turnover and limited exotic spread explain swamp biotic differentiation with urbanization

“…An increase in exotic richness can initially promote differentiation, but be followed by a homogenization phase as exotics spread and eventually dominate less competitive species (Sax and Gaines, 2003). As previously shown, important time lags can occur in swamp ecosystems with delayed vegetation response to land use legacies such as former agricultural uses (Loiselle et al, 2020). Besides time lags in vegetation response to land use changes, exotic introduction history can also influence vegetation shifts.…”

“…Urbanization, on the other hand, has been mostly associated with high species turnover among plant communities, and notably with a replacement of local plant specialists by generalists or exotics, leading to biotic homogenization (McKinney and Lockwood, 1999; Olden and Poff, 2003; McKinney, 2006; Olden and Rooney, 2006; La Sorte et al, 2014). Discrepancies in the relative contribution of exotics vs native generalists to this homogenization process have nevertheless been reported, as previous studies have alternatively attributed declines in beta diversity to an increase of exotic species (Cadotte et al, 2017; Loiselle et al, 2020; Price et al, 2020) or to the spread of native species (Tabarelli et al, 2012; McCune and Vellend, 2013; Trentovani et al, 2013; Beauvais et al, 2016; Brice et al, 2017; Blouin et al, 2019). Furthermore, in some cases, urbanization has been shown to promote biotic differentiation (i.e., increased beta diversity; McKinney, 2008), depending on factors such as the size and composition of the initial species pool (Olden and Poff, 2003), the balance between native vs non‐native species and their residence time (Kühn and Klotz, 2006; Lososová et al, 2012, 2016) or the intensity and type of urbanization (Flynn et al, 2009; Allan et al, 2015; Newbold et al, 2015).…”

“…Empirical evidence shows that wetland ecosystem services related to water quality are generally improved by higher plant diversity, including increased nitrogen removal as well as reduced phosphorus loss and methane efflux (Engelhardt and Ritchie, 2001; Bouchard et al, 2007; Brisson et al, 2020). Yet, wetlands are generally highly vulnerable to invasion by exotics (Zedler and Kercher, 2004; Loiselle et al, 2020; Price et al, 2020) and wetland plants are more widely distributed than upland ones (Santamaría, 2002; Ricklefs et al, 2008), which suggests that these ecosystems are prone to biotic homogenization. Changes in ecological conditions due to urbanization indeed generally promote the dispersal of exogenous species, either native generalists or exotics, from surrounding heterogeneous urban lands to open wetlands (Ehrenfeld and Schneider, 1991; Findlay and Bourdages, 2000; Ehrenfeld, 2008; Cutway and Ehrenfeld, 2009).…”

“…Such a pattern was previously evidenced in riparian forests, where urbanization has been associated with a decrease of flooding period and duration, a stress release process that led to a greater variation in species composition across sites (Brice et al, 2017). Despite recent investigations (Loiselle et al, 2020), the response of swamp vegetation to urbanization still remains to be explored to generalize the impact of urbanization on forested wetland flora.…”

Effect of Anthropogenic Disturbance on Floristic Homogenization in the Floodplain Landscape: Insights from the Taxonomic and Functional Perspectives

“…Each of these changes could potentially act as an environmental stressor that differentially shapes plant species distribution depending on their environmental niches and traits [11]. Thus the distinction of species composition might be explained by the regeneration time, or lifespan, of the dominant species in floodplains at different degradation levels [34]. On the other hand, Ise City represented small cities in Central Japan.…”