Abstract
An expanding network of roads and railways fragments natural habitat affecting the amount and quality of habitat and reducing connectivity between habitat patches with severe consequences for biodiversity and population persistence. To ensure an ecologically sustainable transportation system it is essential to find agreement between nature conservation and land use. However, sustainable road planning requires adequate tools for assessment, prevention and mitigation of the impacts of infrastructure. In this study, we present a spatially explicit model, SAIA (Spatial Amphibian Impact Assessment), to be used as a standardized and quantitative tool for assessing the impact of roads on pond-breeding amphibians. The model considers a landscape mosaic of breeding habitat, summer habitat and uninhabitable land. As input, we use a GIS-map of the landscape with information on land cover as well as data on observed frog populations in the survey area. The dispersal of juvenile frogs is simulated by means of individual-based modelling, while a population-based model is used for simulating population dynamics. In combination the two types of models generate output on landscape connectivity and population viability. Analyses of maps without the planned road constructions will constitute a “null-model” against which other scenarios can be compared, making it possible to assess the effect of road projects on landscape connectivity and population dynamics. Analyses and comparisons of several alternative road projects can identify the least harmful solution. The effect of mitigation measures, such as new breeding ponds and underpasses, can be evaluated by incorporating them in the maps, thereby enhancing the utility of the model as a management tool in Environmental Impact Assessments. We demonstrate how SAIA can be used to assess which management measures would be best to mitigate the effect of landscape fragmentation caused by road constructions by means of a case study dedicated to the Moor frog (Rana arvalis).
Highlights
Over the last decade a growing amount of literature has documented the severe impacts of transport infrastructure on biodiversity, population persistence and gene flow
We have developed a strategic management tool to be used in assessment and mitigation of road effects on a regional population of pond-breeding amphibians
The regional abundance of adult female frogs is estimated to be 157; the percentage of frogs surviving during dispersal is 57 %, and landscape connectivity is 55 (Figure 5)
Summary
Over the last decade a growing amount of literature has documented the severe impacts of transport infrastructure on biodiversity, population persistence and gene flow. Methods using least cost modelling (Adriaensen et al 2003; Epps et al 2007) or graph theoretical approaches (Bunn et al 2000; Minor and Urban 2008; Zetterberg et al 2010) usually combine GIS data with some species specific data such as dispersal distances or habitat suitability None of these methods considers the particular dispersal, survival and establishment of the animals, which depend on the quality of the habitat and on the behaviour of the animals, their responses to habitat conditions, landscape elements, interactions with other animals and many other factors. Individual based models (IBMs) have proved to be suitable for describing such processes (Grimm 1999; McLane et al 2011) and recently there has been an increase in IBM case studies demonstrating the potential for analysing population dynamics emerging from the interactions between landscape settings and animal behaviour (e.g. Graf et al 2007; Kramer-Schadt et al 2004; Pe’er et al 2011)
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