Vulnerability of a riparian zone towards invasion by alien plants depends on its structure

Abstract

AbstractRiparian zones support high biodiversity and are among the most vulnerable parts of the landscape. Their degradation facilitates the spread of invasive alien plant species. Our aim was to investigate the relationship between environmental characteristics of riparian zones and distribution and abundance of invasive alien plant taxa (IAT) along three rivers in Slovenia. In 100-m reaches of riparian zone we determined environmental characteristics and the presence and abundance of IAT. Canonical correspondence analysis was used to assess the relationship between IAT and environmental factors. The numbers and abundances of IAT in specific reaches were correlated with environmental factors using Spearman coefficient. These results revealed that the number and abundance of IAT in riparian zone were strongly positively correlated to the distance from river source, while they were negatively correlated with altitude, vegetation structure complexity, completeness of riparian zone and current velocity. Environmental factors that explained the distribution and abundance of IAT significantly were: the altitude, flow dynamics, distance from source, width of riparian zone, land-use, bank and channel structure, water depth and velocity. The research has pointed out the need for proper management of riparian zones to prevent invasion by IAT and also to strengthen other services provided by riparian zone as buffering anthropogenic impacts to water body, stabilising bank structure and increasing biodiversity.