Trends in the Biodiversity and Invasive Species Dynamics: Local Implications on Forest, Grassland and Ruderal Vegetation in Bratislava City, Slovakia, Central Europe

Alena Rendekova,Zuzana Randakova,Jan Miskovic,Karol Micieta

doi:10.5539/enrr.v7n4p52

Abstract

Biological invasions represent one of the most serious global environmental threats. One of their negative aspects is a biodiversity loss in the natural ecosystems. Our study reports the results of the evaluation of changes in the proportion of invasive alien species and the results of the evaluation of the changes of the diversity in various types of forest, grassland and ruderal vegetation of Bratislava city over the time. In total, 26 invasive alien taxa were recorded in the vegetation of Bratislava. The majority of invasive taxa were recorded in both time periods. Five invasive species (Echinocystis lobata, Fallopia japonica, Helianthus tuberosus, Juncus tenuis, and Solidago canadensis) were recorded only in the more recent period. Most of the invasive species prefer ruderal habitats, and some of them also invade the forest vegetation (mainly the floodplain forests). In the dry grasslands of the class Festuco-Brometea, no invasive species were recorded in both periods. The statistical analysis revealed the increase of the average percentual number of invasive alien species in the majority of classes of the forest and ruderal vegetation of Bratislava over the time. In the majority of classes, where the proportion of invasive species increased, the Shannon–Wiener index of diversity of all species decreased significantly over the time. Our results contribute to the knowledge about biological invasions in cities.

Highlights

Biological invasions of alien species are acknowledged as one of the serious environmental dangers for the conservation of native species and habitats worldwide (Pimentel et al, 2001)
Among the classes of the ruderal vegetation, the highest average percentual number of invasive alien species was recorded in the classes Sisymbrietea and Epilobietea angustifolii (Figure 1)
The deciduous and mixed forests of the class Carpino-Fagetea sylvaticae were less affected by the presence of invasive species (Figure 2), the percentual number of invasive species in this class was only 3.5% in both periods (Figure 2)

Summary

Introduction

Biological invasions of alien species are acknowledged as one of the serious environmental dangers for the conservation of native species and habitats worldwide (Pimentel et al, 2001). Among the places where the alien species can be found, cities and urban areas are the most invaded ones (Lonsdale, 1999; Chytrý, Pyšek, Tichý, Knollová, & Danihelka, 2005; Walter, Ess, Englisch, & Kiehn, 2005; Vilá, Pino, & Font, 2007; Chytrý et al, 2008; Pyšek et al, 2010; Medvecká et al, 2014; Lososová, Chytrý, Danihelka, Tichý, & Ricotta 2016). Among the various types of the vegetation of cities, the ruderal vegetation is the most represented type, and it harbours the highest proportion of alien species (Chytrý et al, 2005; Walter et al, 2005; Vilá et al, 2007; Chytrý et al, 2008; Simonová & Lososová, 2008; Medvecká, Jarolímek, & Zaliberová, 2009; Pyšek et al, 2010; Medvecká et al, 2014)

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Discussion

Conclusion