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Landscape and Urban Planning

Review

Carabid beetle assemblages forth urban to rural gradients: A review

Abstract

Urbanisation causes similar landscape patterns across the world; cities are characterised past a densely populated and highly disturbed urban core, a less disturbed suburban zone and a least disturbed rural surroundings. In 1998, we set upwards a projection to investigate the effects of this urbanisation gradient on the responses of carabid beetles (Carabidae, Coleoptera) in different cities across the earth. To date, eight cities have participated in this project and the findings tin be summarised equally follows. In general, carabid abundance and species richness increased from the metropolis centres to the rural environs. Forest specialist species tended to be more mutual in suburban and rural zones, while open-habitat species predominate in the urban core. The highly disturbed urban environments were as well generally characterised past a few dominant species and species capable of flight, while suburban and rural areas were characterised by larger-sized species and species incapable of flight. Deviations from these general patters do occur, notably the occurrence and loftier affluence of introduced carabid species in urban Edmonton, Canada. The challenge now is to infer procedure from these patterns. In item, community and species specific responses demand to be related to characteristics of the urbanised landscape, i.e. the urban–rural slope needs to exist operationalised in terms of specific disturbance features. Furthermore, the results should now exist communicated to decision-makers so that they can be considered in planning.

Introduction

In a rapidly urbanising world, knowledge of ecosystem responses to urbanisation is needed to ensure that cities are planned for the well-being of residents and nature (McDonnell and Pickett, 1990, Niemelä, 1999). The effects of urbanisation on biotic communities can be illuminated through studies across urban–rural gradients (Blair, 1996, McDonnell et al., 1997, Niemelä, 1999, Niemelä, 2000, Niemelä et al., 2000, Niemelä et al., 2002). Such gradients, from densely congenital city cores to increasingly rural environment occur all over the world, and they provide a useful framework for comparative work on a global scale, every bit they reflect, in general, similar anthropogenic patterns and processes (Niemelä, 2000).

To assess the responses of species and communities to a change in urban landscapes we developed the GLOBENET programme that uses a common field methodology (pitfall trapping) to sample the same taxonomic group (carabid beetles) in visually like land-mosaics (urban–suburban–rural), in different parts of the globe (Niemelä et al., 2000). The goal is to provide a framework for ecologists to identify general patterns in the responses of communities to urbanisation across the earth, and to distinguish these from more locally occurring phenomena. Furthermore, the compiled noesis could foster collaboration among researchers and managers in finding means to mitigate the adverse ecological effects of urbanisation. It is important to notation that in the GLOBENET programme we practise not compare cities per se, but patterns along urbanisation gradients betwixt cities. Thus far, GLOBENET studies take only been conducted in forested habitats, primarily in the boreal and temperate zones.

Specific hypotheses can be derived from the gradient arroyo and can subsequently be tested in different cities. Here we examine whether predictions on how the community responds to stressors (Grayness, 1989) concord for carabid beetles in urban environments, i.e. (a) diverseness should increase from a depression in urban areas to a loftier in rural areas, (b) opportunistic species (i.due east. habitat generalists) should gain authorization in urban areas, and (c) mean body size of the dominating species should increase from more disturbed to less disturbed habitat (Blake et al., 1994, Blake et al., 1996), here from urban to rural areas.

GLOBENET studies take been performed in forested habitats, which are commonly small and fragmented in urban areas. Therefore, – and based on earlier studies – nosotros presume that forest-associated species will be less common in urban areas than in suburban or rural areas where there are more forested habitats. Open-habitat species are expected to be more mutual even in urban forests, which are characteristically smaller with more edge habitat, and more open than are rural forests. Furthermore, information technology is expected that species with good dispersal abilities are better in colonising patchy and modest habitat fragments in urban areas, while species with poorer dispersal abilities would mainly be able to persist in suburban and especially in rural areas where green areas are more continuous and larger in size.

Ground beetles (Coleoptera, Carabidae) were selected for these studies every bit they are sufficiently varied taxonomically and ecologically, arable, and are sensitive to man-caused disturbances to be a reliable monitoring group (Lövei and Sunderland, 1996), and have been widely studied in relation to land utilize throughout the globe (e.g. Rainio and Niemelä, 2003).

In this paper we summarise the results of studies in different parts of the world (spanning eight cities in the boreal and temperate zones) that have used the GLOBENET protocol since its launch in 1998. We are particularly interested in identifying general, recurring patterns and distinguishing them from local, unique ones. About of the papers examined or tested patterns in relation to the hypotheses presented above, and we summarise the results in the context of these hypotheses. We besides discuss improvements to the protocol, in particular on how to quantify the urban-to-rural disturbance gradient, and provide time to come research directions.

Section snippets

The GLOBENET protocol

The standard GLOBENET protocol is as follows (Niemelä et al., 2000): (1) select 3 urban disturbance regimes; highly disturbed urban, less disturbed suburban, and to the lowest degree disturbed rural, (2) inside each disturbance regime select iv replicate sites (a total of 12 sites), (3) within each site identify ten pitfall traps in a random arrangement, at to the lowest degree ten   m apart, to ensure independent sampling (a total of 120 traps installed across the urban–rural gradient), (4) traps are plastic collecting cups,

Geographical extent of GLOBENET studies

To date the GLOBENET approach has been employed in at least 8 cities in the boreal and temporal zones in Europe, North America and Asia; Brussels (Kingdom of belgium), Sofia (Republic of bulgaria), Edmonton (Canada), Sorø (Denmark), Birmingham (England), Helsinki (Finland), Debrecen (Hungary) and Hiroshima (Nippon) (Alaruikka et al., 2002, Niemelä et al., 2002, Ishitani et al., 2003, Venn et al., 2003, Magura et al., 2004, Magura et al., 2008, Gaublomme et al., 2005, Gaublomme et al., 2008, Sadler et al., 2006,

Discussion and future prospects

Results from the eight cities indicate that, more often than not, activity density and species richness of carabid beetles increased from city centres to the rural environment (come across Table 1). Furthermore, the highly disturbed urban environments were by and large characterised past a few dominant species, more so than the suburban and rural sites. In terms of trunk size, the proportion of large-sized carabid beetles commonly decreased towards the urban center centres. Woods specialists tended to be more than common in the

Acknowledgements

We thank all scientists who accept contributed to the GLOBENET project, and who are still involved in expanding and refining the goals of the project. The preparation of this paper has been supported by the Academy of Finland (projects 110388 and 126915). Nosotros thank Tibor Magura, Ivailo Stoyanov and Eva Gaublomme for providing datasets for our analyses. Rarefied species richness values were calculated using the R statistical parcel (R Evolution Cadre Team (2008)), and we thank Bob O'Hara for help

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