Diversity of Macrophytes and Environmental Assessment of the Ljubljanica River (Slovenia)

Vanja Janež,Alenka Gaberščik,Mateja Germ,Igor Zelnik

doi:10.3390/d13060278

Abstract

The present research aimed to determine the diversity of macrophyte taxa in the Ljubljanica River and its relationship with environmental parameters. In each of the 19 river sections, the presence and abundance of plant taxa were recorded, and basic physical and chemical parameters were measured. Additionally, selected environmental parameters were assessed using a modified version of the Riparian, Channel and Environmental (RCE) method. We compared the obtained data set with survey data from the year 2004. In 2019, a total of 34 macrophyte taxa were recorded. The dominant taxa with the highest abundance were Sparganium emersum, Callitriche sp., and the invasive alien species Elodea canadensis. The species richness and diversity of macrophytes decreased with distance from the source, an increase in pH, and alterations of the riverbed structure due to interference in the riverine ecosystem in the lower part of the Ljubljanica River and its catchment. The comparison of 2004 and 2019 surveys revealed a decrease in the overall presence and abundance of P. natans and in the frequency of occurrence of the species Myriophyllum spicatum and an increase in the presence and abundance of the invasive alien species Elodea canadensis.

Highlights

The comparison of 2004 and 2019 surveys revealed a decrease in the overall presence and abundance of P. natans and in the frequency of occurrence of the species Myriophyllum spicatum and an increase in the presence and abundance of the invasive alien species Elodea canadensis
The Ljubljanica River sensu stricto, which is the subject of our research, is a 41-kmlong surface flow belonging to the Ljubljanica River sensu lato, which is known as the river of seven names [30]
Their diversity varied within individual river sections

Summary

Introduction

The dominant taxa with the highest abundance were Sparganium emersum, Callitriche sp., and the invasive alien species Elodea canadensis. The species richness and diversity of macrophytes decreased with distance from the source, an increase in pH, and alterations of the riverbed structure due to interference in the riverine ecosystem in the lower part of the Ljubljanica River and its catchment. Alteration of riparian vegetation, riverbed regulation, and alteration of the hydrological regime of the river, strongly influence the structure and function of ecosystems. Such changes significantly impact all processes within the ecosystem [2,3,4] as they disrupt its natural balance and ecosystem function [5,6]

Objectives

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Conclusion