The influence of urban land use on seed dispersal and wetland invasibility

Abstract

Urban habitats are generally considered highly invaded by exotic species due to the frequency and extent of disturbance caused by human activities and development. Our previous study had demonstrated that forested wetlands within residential areas are more extensively invaded than wetlands within industrial-commercial areas. In this study, we investigate whether the structure of the forest edge and seed dispersal can explain the differential in the invasion of wetlands surrounded by industrial and residential land use. Our results indicate that edges of industrially bordered wetlands are denser, with vegetation concentrated at the boundary of tree growth, whereas the edges of residentially bordered wetlands are more open and diffuse. This difference influences the number of seeds and species capable of dispersing into the wetland. Less dense edges resulted in a higher number of seeds entering residential wetlands; however, there were no differences in the numbers of exotic seeds or exotic species in the seed rain residential and industrial wetlands. Although seed dispersal could not directly explain differences in the current extent of invasion of these sites, seed dispersal did follow corridor pathways, including ditches and trails that breach the edges and extend through the wetlands. These disturbances act as corridors for seed dispersal into both types wetlands and may play a role in introducing new species to the interior of the wetland, an outcome supported by a higher number of exotic species in the seed banks of residential sites. Our results suggest that both the type of adjoining land use and the provision of access to people on trails in urban wetlands can affect the composition of these communities.

Spatio-temporal variation of seed rain between urban and rural fragments of humid tropical forests

“…Thus, the hypothesis of greater species richness in the rural fragment was not accepted. This behavior is opposite to that registered in the literature, where is a trend of greater species richness in rural fragments over time (Campos et al, 2009;Cutway & Ehrenfeld, 2010;Freitas et al, 2013;Knorr & Gottsberg, 2012;Overdyck & Clarkson, 2012).…”

“…that in rural fragment (Cole et al, 2010;Freitas et al, 2013;Knorr & Gottsberg, 2012;Overdyck & Clarkson, 2012) the seed density was higher than recorded for urban forests (Campos et al, 2009;Cutway & Ehrenfeld, 2010;Overdyck & Clarkson, 2012;Pivello et al, 2006). When the seed density of rural and urban fragments inserted in the same landscape is compared, as in the case of this study, it is verified that the seed number remains superior in the rural fragment.…”

“…Overdyck & Clarkson, 2012). For example, species richness and seed density from the seed rain are higher in rural fragments than in urban fragments (Campos et al, 2009;Cole et al, 2010;Cutway & Ehrenfeld, 2010;Freitas et al, 2013;Knorr & Gottsberg, 2012); species richness and seed density of the seed rain may be higher during the dry season or dry-rainy transition in urban and rural fragments (Gratzer et al, 2022;Jara-Guerrero et al, 2020); seed rain composition differs between urban and rural fragments (Overdyck & Clarkson, 2012).…”

Understanding urban wetland dynamics: cross-scale detection and analysis of remote sensing

“…Azous and Horner (2000) found high toxic metal accumulation in inlet zones of wetlands caused by urban runoff, which affected wetlands when their concentrations exceeded the absorbable limit of wetlands. Cutway and Ehrenfeld (2010) identified that wetlands within residential and industrial areas were suffering more extensive and severe biological invasions, which were threatening the ecological balance that was structured around the water environment as core. On the other hand, Ji and Murambadoro (2010) observed that new open waters such as reservoirs, ponds, and lakes were created as part of planned urban development.…”

Responses of Different Plant Taxonomic Groups to Complex Environmental Factors in Peri-Urban Wetlands

“…Urban wetlands are highly anthropogenically influenced ecosystems in urban landscapes [7][8][9][10], which can lead to an increase in water pollutants and exotic species [11]. Larson et al [12] sampled vegetation and soils from eight urban wetlands and compared them to six forested wetlands, five shrubby wetlands, and seven newly constructed wetlands.…”