The effects of shifting vegetation mosaics on habitat suitability for coastal dune fauna—a case study on sand lizards (Lacerta agilis)

Encroachment of tall grasses and shrubs in coastal dunes has resulted in loss of vegetation heterogeneity. This is expected to have negative effects on animal diversity. To counteract encroachment and develop structural heterogeneity grazing is a widely used management practice. Here, we aim to functionally interpret changes in vegetation composition and configuration following grazing management on habitat suitability for sand lizards. Aerial photographs taken over a period of 16 years were used to quantify changes in vegetation composition. A GISbased method was developed to calculate habitat suitability for sand lizards in a spatially explicit manner, encompassing differences in vegetation structure and patch size. From 1987 to 2003 dune vegetation shifted from small patches of moss and sand to larger patches covered by shrubs and grasses. Grazing management did not have any significant effect on the overall level of heterogeneity, measured as habitat suitability for sand lizards. However, on a more local scale highly suitable patches in 1987 were deteriorating whereas unsuitable patches became more suitable in 2003. This inversion results from a broad shift with shrubs being a limiting habitat element in 1987 to sandy patches being the limiting element in 2003. Future changes are believed to negatively impact sand lizards. The habitat suitability model has proven to be a useful tool to functionally interpret changes in coastal dune vegetation heterogeneity from an animal’s perspective. Further research should aim to include multiple species operating on B. Wouters (*) :M. Nijssen :H. Van Kleef : E. Remke : W. Verberk Bargerveen Foundation, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands e-mail: [email protected] M. Nijssen e-mail: [email protected] H. Van Kleef e-mail: [email protected] E. Remke e-mail: [email protected] W. Verberk e-mail: [email protected] G. Geerling Centre for Sustainable Management of Resources, ISIS, Radboud University Nijmegen, toernooiveld 1, 6525 ED Nijmegen, The Netherlands e-mail: [email protected] H. Van Kleef Department of Environmental Science, Institute for Wetland and Water Research, Radboud University Nijmegen, toernooiveld 1, 6525 ED Nijmegen, The Netherlands B. Wouters :M. Nijssen : E. Remke :W. Verberk Department of Animal Ecology and Ecophysiology, Institute for Wetland and Water Research, Radboud University Nijmegen, toernooiveld 1, 6525 ED Nijmegen, The Netherlands Present Address: W. Verberk Marine Biology and Ecology Research Centre, University of Plymouth, Davy Building, Drake Circus, PL4 8AA Plymouth, UK e-mail: [email protected] J Coast Conserv (2012) 16:89–99 DOI 10.1007/s11852-011-0177-9