Carabids (Coleoptera: Carabidae) in a forest patchwork: a connectivity analysis of the Bereg Plain landscape graph
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For many species, one important key to persistence is maintaining connectivity among local populations that allow for dispersal and gene flow. This is probably true for carabid species (Coleoptera:Carabidae) living in the fragmented forests of the Bereg Plain (NE Hungary and W Ukraine). Based on field data, we have drafted a landscape graph of the area representing the habitat network of these species. Graph nodes and links represented two kinds of landscape elements: habitat (forest) patches and corridors, respectively. The quality of habitat patches and corridors were ranked (from low (1) to high (4)), reflecting local population sizes in the case of patches and estimated permeability in the case of corridors. We analysed (1) the positional importance of landscape elements in maintaining the connectivity of the intact network, (2) the effect of inserting hypothetical corridors into the network, (3) the effects of improving the quality of the existing corridors, and (4) how to connect every patch in a cost-effective way. Our results set quantitative priorities for conservation practice by identifying important corridors: what to protect, what to build and what to improve. Several network analytical techniques were used to account for the directed (source-sink) and highly fragmented nature of the landscape graph. We provide conservation priority ranks for the landscape elements and discuss the conditions for the use of particular network indices. Our study could be of extreme relevance, since a new highway is being planned through the area.
KeywordsLandscape graph Reachability Isolation Connectivity Carabidae Hungary Directed graph
We are grateful for Zoltán Peresztegi-Nagy for developing a computer programme for one part of the analysis, András Báldi and Gábor Lövei for useful discussions and three anonymous reviewers for their comments on the manuscript. We thank K. Csepi and G. Lövei for linguistic revision. FJ and TM were supported by grants from the Hungarian Scientific Research Fund (OTKA T 37726 and F 61651, respectively). FJ was also supported by Society in Science: the Branco Weiss Fellowship from ETH Zürich, Switzerland.
- Baudry J, Burel F (2004) Trophic flows and spatial heterogeneity in agricultural landscapes. In: Polis GA, Power ME, Huxel GR (eds) Food webs at the landscape level. University of Chicago Press, Chicago, pp 317–332Google Scholar
- Borgatti SP (2003) The key player problem. In: Breiger R, Carley K, Pattison P (eds) Dynamic Social Network Modeling and Analysis: Workshop Summary and Papers, Committee on Human Factors, National Research Council, pp 241–252Google Scholar
- Collinge SK (2000) Effects of grassland fragmentation on insect species loss, colonization, and movement patterns. Ecology 81:2211–2226Google Scholar
- Davies KF, Margules CR, Lawrence JF (2000) Which traits of species predict population declines in experimental forest fragments? Ecology 81:1450–1461Google Scholar
- Keitt TH, Urban DL, Milne BT (1997) Detecting critical scales in fragmented landscapes. Conserv Ecol 1(1):4Google Scholar
- Lövei GL, Magura T, Tóthmérész B, Ködöböcz V (2006) The influence of matrix and edges on species richness patterns of ground beetles (Coleoptera, Carabidae) in habitat islands. Glob Ecol Biogeogr 15: 283–289Google Scholar
- Magura T, Tóthmérész B, Molnár T (2000) Spatial distribution of carabid species along a grass-forest transects. Acta Zoologica Academiae Scientiarium Hungariae 46:1–17Google Scholar
- Thiele HU (1977) Carabid beetles in their environments. Springer Verlag, New YorkGoogle Scholar
- Turner MG, Gardner RH, O’Neill RV (2001) Landscape ecology. Springer Verlag, BerlinGoogle Scholar
- Urban D, Keitt T (2001) Landscape connectivity: a graph-theoretic perspective. Ecology 82:1205–1218Google Scholar
- Wassermann S, Faust K (1994) Social network analysis. Cambridge University Press, CambridgeGoogle Scholar