Institute of Ecology and Evolution, University of Bern, CH-3012, Bern, Switzerland
Journal of Landscape Ecology 01/2010; 3. DOI: 10.2478/v10285-012-0023-2


Habitat connectivity plays a paramount role in the biodiversity of fragmented landscapes. Commonly, connectivity is measured using simple structural metrics, e.g. Euclidean distances between habitat patches. Recently, functional measures such as cost-distance metrics have been proposed. Cost-distance metrics account for behavioural aspects of investigated organisms. They weight the habitats of the investigated landscape according to specific cost values, and model the optimal dispersal corridor according to these values. This study investigated i) if structural or functional connectivity measures explain biodiversity in a focal habitat better and ii) if the appropriateness of the measure differs between patch and landscape scale. We mapped the landscapes within a 500 m radius around 30 fragmented traditional orchards (focal patch). Connectivity measures were based on either Euclidean distances (structural) or cost-distances (functional) to other suitable habitat patches. Birds were used as biodiversity indicators. For analysis, we calculated species richness and total abundance of all species with a preference for woody habitats. In addition, abundances of four wood-preferring bird species were also examined individually. Linear models were created using stepwise forward selection. The relative performance of structural and functional connectivity measures was scale dependent. Structural metrics explained more variance at the patch scale whereas functional metrics explained more variance at the landscape scale. We conclude that simple structural metrics can be used to investigate local or small-scale effects on bird diversity but that investigations of landscape scale connectivity should consider behavioural aspects by using more complex functional metrics. The comparison between group and single species showed that not all individual species behave similarly to group results. Whilst the use of organism groups must be treated with caution, it is certainly worthy of future study.

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    • "In addition to the initially purely descriptive purpose of quantifying landscape structures (O'Neill et al., 1988; Turner, 1990; Riitters et al., 1995; McGarigal, 2002; Herzog and Lausch, 2001; Lausch and Herzog, 2002; Lang and Blaschke, 2007) attempts were made to identify potential relationships between landscape structures and spatiotemporal biotic and abiotic processes within the landscape (Turner, 1989), such as the spread of species or populations and biodiversity (Mühlner et al., 2010; Walz and Syrbe, 2013) or effect of soil characteristics on vegetation patterns distributions (Schmidtlein et al., 2012; Lausch et al., 2013a). As a result, the quantification of landscape structures based on PMM was increasingly used for assessing and planning landscapes (Syrbe et al., 2007), quantification of landscape functions (Bolliger et al., 2007; Bolliger and Kienast, 2010) or quantification of ecosystem services (Syrbe and Walz, 2012). "
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