Effects of management intensity, function and vegetation on the biodiversity in urban ponds

Malgorzata Blicharska,Johan Andersson,Johannes Bergsten,Ulf Bjelke,Tuija Hilding-Rydevik,Frank Johansson

doi:10.1016/j.ufug.2016.08.012

Abstract

Ponds are important elements of green areas in cities that help counteract the negative consequences of urbanization, by providing important habitats for biodiversity in cities and being essential nodes in the overall landscape-scale habitat network. However, there is relatively little knowledge about the impacts of pond management intensity, function and environmental variables on urban pond biodiversity. In this study we addressed this gap by investigating which factors were correlated with the level of biodiversity in urban ponds, indicated by species richness of aquatic insects, in Stockholm, Sweden. Our study did not confirm any direct link between the perceived intensity of management or function of ponds and overall biodiversity. However, it seems that management can influence particular groups of species indirectly, since we found that Trichoptera richness (Caddisflies) was highest at intermediate management intensity. We suggest that this is caused by management of vegetation, as the amount of floating and emergent vegetation was significantly correlated with both the overall species richness and the richness of Trichoptera (Caddisflies). This relationship was non-linear, since ponds with an intermediate coverage of vegetation had the highest richness. Interestingly, the amount of vegetation in the pond was significantly affected by pond function and pond management. The overall species richness and richness of Trichoptera were also positively correlated with pond size. Since we found that the pattern of relations between species richness and environmental variables differed between the insect groups we suggest that it will be difficult to provide overall design and management recommendations for ponds in urban green areas. Therefore, it is recommended that to provide high aquatic diversity of species in urban areas one should aim at promoting high diversity of different types of ponds with differing management and environmental factors that shape them.

Highlights

The on-going global trend of urbanisation has important consequences for biodiversity, leading to the increasing fragmentation of natural environments and habitat loss (McDonald et al, 2008; Miller and Hobbs 2002)
We excluded ponds located in golf courses, most often situated outside the populated areas, even if they have shown a great potential for fostering biodiversity in urban areas (Colding et al, 2009)
Former studies have shown that other taxonomic groups significantly contribute to the biodiversity of urban ponds (Hassall and Anderson, 2015; Hill et al, 2015), the taxa selected for the purpose of this study provide an accurate proxy of general biodiversity, because these invertebrates represent different functional groups and their biodiversity is correlated with biodiversity of plants, vertebrates and other invertebrate groups (Hassall et al, 2011; Oertli et al, 2010)

Summary

Introduction

The on-going global trend of urbanisation has important consequences for biodiversity, leading to the increasing fragmentation of natural environments and habitat loss (McDonald et al, 2008; Miller and Hobbs 2002). Detrimental influences of urban environments can be alleviated by the presence of green areas that may offer important habitats for biodiversity in cities and provide essential nodes in the overall landscape-scale habitat network (Angold et al, 2006; McKinney 2006). In some cases, these areas provide habitats for species that are decreasing elsewhere Growing recognition of the importance of ponds and other small water bodies for maintaining biodiversity in cities (Colding et al, 2009; Fuyuki et al, 2014; Hassall and Anderson 2015) extends to conservation programmes for endangered species (Vermonden et al, 2009). Growing recognition of the importance of ponds and other small water bodies for maintaining biodiversity in cities (Colding et al, 2009; Fuyuki et al, 2014; Hassall and Anderson 2015) extends to conservation programmes for endangered species (Vermonden et al, 2009). Hassall and Anderson (2015) revealed that urban storm water management ponds can provide a similar level of biodiversity as urban wetlands in Ottawa, Canada

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Conclusion