Complex Undisturbed Riparian Zones Are Resistant to Colonisation by Invasive Alien Plant Species

Abstract

We investigated the presence and abundance of invasive alien plant species (IAS) in the riparian zones of rivers in relation to different environmental parameters. We surveyed the spatial and human-influenced characteristics of the riparian zones, river channels, and land use along seven Slovenian rivers. We further monitored the presence and abundance of IAS with different natural properties and different human impacts to define the characteristics of non-infected and heavily infected reaches. Special attention was given to different life forms of IAS. The presence and abundance of IAS positively correlated with distance from river source, current velocity, and water depth, and negatively correlated with altitude, naturalness of the land use, width and completeness of the riparian zone, height and structure of its vegetation, and condition of the riverbed and banks. Annuals prevailed among IAS at 48%, with 37% herbaceous perennials and 15% woody species. The vine Echinocystis lobata was the most abundant IAS, which was found in 179 out of the 414 river reaches analysed, followed by the annual Impatiens glandulifera and the herbaceous perennial Solidago gigantea. E. lobata was spread over the native riparian vegetation and was affected by the natural gradients of the rivers in terms of altitude and distance from the river’s source. Reaches without IAS significantly differed from reaches colonised with IAS in the width of riparian zone, vegetation height and structure, land-use next to the river, and distance from the source. As IAS in riparian zones affect riparian and aquatic communities, there is the need for management practices to maintain and establish complex riparian zones that are resistant to IAS colonisation.

Macrophyte communities as indicators of the ecological status of drainage canals and regulated rivers (Eastern Poland)

“…1). These variables define the physical niches in rivers and may exert a negative impact on macrophyte community structure (Baattrup-Pedersen et al, 2006 ; O`Hare et al, 2010 ; Zelnik et al, 2020 , 2021 ). In our study, the lowest abundance and species richness of macrophytes were observed in canal.…”

“…The plant forms a canopy to exploit light near the water surface, but does not produce high biomass (Søndergaard et al, 2017 ). Elodea canadensis is typical of back-flowing and meso-eutrophic streams with medium-to-high nutrient load and higher water transparency and oxygen content (Schneider & Melzer, 2003 ; Šraj-Kržič et al, 2007 ; Zelnik et al, 2020 ), but the species also belongs to the group of macrophytes tolerant of habitat degradation. Elodea canadensis is also tolerant of other types of human impact, such as organic pollution and weed cutting (O’Hare et al, 2010 ).…”

The Relationships of Habitat Conditions, Height Level, and Geographical Position with Fruit and Seed Traits in Populations of Invasive Vine Echinocystis lobata (Cucurbitaceae) in Central and Eastern Europe

“…Echinocystis lobata grows fast and is adapted to moist and nutrient-rich habitats [35]. It is considered one of the most abundant invasive alien plants spreading in natural riparian habitats [56], whereas it is a rare species in urban woodlands [57]. In riparian habitats, where the soils are wet and fertile, E. lobata can achieve high seed viability and germinability and its rate of seedling recruitment is higher than in dry and nutrientpoor soils [34,58,59].…”

Guiding restoration of riparian ecosystems degraded by plant invasions: Insights from a complex social-ecological system in the Global South

“…Rivers and riparian zones are often associated with human activity due to their water provisioning services (Richardson et al 2007 ). As a result, these systems are degraded by human-mediated disturbances such as water abstraction, damming, land use changes, and recreational activities (Zelnik et al 2020 ). Direct impacts of such disturbances facilitate invasion of alien plants, some of which out-compete and replace native species due to their ability to rapidly colonize disturbed areas and alter microclimates (Stella et al 2012 ).…”