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

Abstract

Riparian 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.

Occurrence of invasive alien plant species in the floodplain forests along the Mura River in Slovenia

“…It was recorded in only 4 relevés out of 130 (Table 1). Our results are in accordance with the results of Tiébré et al (33) and Zelnik et al (31), as they claim that habitat destruction, fragmentation and short-term disturbance play very important roles in the distribution of F. japonica and they found it in abundance in the places where anthropogenic disturbances are frequent. We detected this species in some cases to be abundant, but mainly outside forest.…”

“…Water and occasional floods are a very important factor and vector for dispersing IAS (17). Zelnik et al (31) found out that the number and abundance of IAS in a riparian zone were strongly positively correlated with the distance from a river source, while they were negatively correlated with altitude, vegetation structure complexity, completeness of riparian zone and current velocity.…”

Distribution patterns of plant communities and their associations with environmental soil factors on the eastern shore of Lake Taihu, China

“…So, understanding the current vegetation and the distribution patterns of plant communities can promote the succession of vegetation restoration. Vegetation acted as one of the most important factors in wetland ecosystems, and distribution patterns of plant communities strongly affected wetland ecosystem properties (Zelnik, Haler, and Gaberščik 2015;Hwang et al 2016;Zuo et al 2016). According to Zuo et al (2016), the recovery of vegetation succession can provide theoretical support for wetland restoration and health evaluation.…”

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

“…The modified Riparian, Channel and Environmental (RCE) method for ecomorphological evaluation of rivers [46] was used with a four-level scale to assess the various parameters. The four-level scale reflected the naturalness of the assessed parameters to reflect the gradients of these parameters due to human impact and the longitudinal character of the rivers [10]. The highest score (4) represents the most natural conditions/undisturbed by humans, and the lowest score (1) was given to the most altered or disturbed conditions (e.g., [9,47]).…”

“…The input of organic matter into a river that derives from riparian vegetation can account for 80% to 95% of the total input mass [6]. The function of riparian vegetation depends on the properties of the riparian zones in terms of their width, complexity, and vegetation type, which are closely related to the ecological status of a river [9,10].…”