Factors influencing butterfly diversity in a long-term experiment differing in grazing intensity Sabrina Jerrentrup 1 Nicole Wrage 2 Johannes Isselstein 1 1 2

Butterflies (Lepidoptera) Semi-natural grasslands: important habitat group ( Balmer & Erhardt 2000 ) Butterfly populations are declining across grasslands in Europe (Van Swaay et al. 2006) Ecosystem services:  Pollination Many crops are dependent on pollination (Klein et al. 2007)  Food source Key food group for many farmland birds (Wilson et al. 1999) Indicator function 2 Introduction Material & Methods Results Discussion Sabrina Jerrentrup

Impact of grazing Spatial heterogeneity  low grazing intensity: positive feedback of grazing on forage quality (WallisDeVries 1996)  Patchy pattern of heavily and lightly (/un-) grazed areas Butterflies & grazing intensity Structural diversity hypothesis  Structural diversity of tall vegetation is higher (Morris 1971)  More niches and nectar resources (Morris 2000) at lower grazing intensities Intermediate disturbance hypothesis  unimodal diversity-disturbance relationship (Dynamic Equilibrium Model: Huston 1979, Pöyry et al ) Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Research questions  Is the lowest grazing intensity needed for the protection of butterflies?  Are there other factors determining the response of butterflies? Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Experimental site  Germany, Lower Saxony  Relliehausen  Solling Upland  Altitude: ~250m  Pelosol brown earth  Lolio-Cynosuretum  moderately species rich  Mean temperature: 8.2 °C  Mean precipitation: 750 mm / year Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Experimental Design  Since 2002: long-term experiment (FORBIOBEN)  No fertilizer used  Factor grazing intensity (target sward height) moderate grazing (6 cm) lenient grazing (12 cm) very lenient grazing (since 2005) (18 cm)  Grazing intensity adjusted by stocking rate  Breed: German Simmental  Continuous grazing system  3 replications, randomized block system  9 paddocks (1 ha each) 6 Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Sabrina Jerrentrup Experimental Design A, B, C = Block Treatments moderate grazing: 1 lenient grazing: 2 very lenient grazing: 3 7 Introduction Material & Methods Results Discussion

Butterfly recordings  Adult butterflies  Pollard walk: 50m - transects  Identifying to species level  5 min per transect  Suitable weather conditions  3 summer walks June/July, July, August/September and revisited  Sum (of transects and dates per year) Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Additional measurements (2011) Middle transects Sward surface height (Sward Stick), 100 points  Sward surface height  Sward heterogeneity Cover of flower heads in 30 cm-circles, same points  Flower abundance Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Effect of Grazing intensity Sabrina Jerrentrup Grazing intensity: p < 0.05 Year: p < 0.001, Interaction: n.s. Grazing intensity: n.s., Year: p < 0.05, Interaction: n.s. Mixed models accounting for repeated measures over years Introduction Material & Methods Results Discussion

Effect of Grazing intensity Sabrina Jerrentrup Grazing intensity: p < 0.01Grazing intensity: p < 0.05, Year: p < 0.05, Interaction: n.s. Mixed models accounting for repeated measures over years Model simplification by using the AIC Introduction Material & Methods Results Discussion

Influencing factors in 2011 Multiple regression models Model simplification by using the AIC Sabrina Jerrentrup Introduction Material & Methods Results Discussion Species richnessAbundance F-value R P-value F-valueP-valueF-valueP-value Grazing intensity Flower abundance Sward surface height---- Sward heterogeneity

Discussion Lower intensities with higher species richness and abundance fits to results of some other studies (Dumont et al and Franzén & Ranius 2004) Own results of grasshoppers on the same site comparable (Jerrentrup et al. 2011) Effect of flower abundance Sward surface height didn‘t improve the models of 2011 Spatial heterogeneity: even though not significant, it was not eliminated in the model Sabrina Jerrentrup Introduction Material & Methods Results Discussion

Conclusions  Grazing intensity is important to manage biodiversity → Lenient grazing enhances diversity → But very lenient grazing-treatment does not provide better opportunities → Unimodal relationship? (intermediate disturbance hypothesis: Pöyry et al ) → Extensive grazing offers good opportunities to combine conservation issues and farmers‘ interests Sabrina Jerrentrup

15 Thank you! The research leading to these results has received funding from the European Community‘s Seventh Framework Programme (FP7/ ) under the grant agreement n°FP Corresponding author:

Literature Balmer, O. & Erhardt, A. (2000) Consequences of Succession on Extensively Grazed Grasslands for Central European Butterfly Communities: Rethinking Conservation Practices. Conservation Biology 14: Dumont, B.; Farruggia, A.; Garel, J.-P.; Bachelard, P.; Boitier, E. & Frain, M. (2009) How does grazing intensity influence the diversity of plants and insects in a species-rich upland grassland on basalt soils? Grass and Forage Science 64: Franzén, M. & Ranius, T. (2004) Occurrence patterns of butterflies (Rhopalocera) in semi-natural pastures in southeastern Sweden. Jounal for nature conservation 12: Huston, M. (1979) A general hypothesis of species diversity. The American Naturalist 113: Jerrentrup, J.S.; Wrage, N. & Isselstein, J. (2011) Effects of grazing intensity and sward structure on grasshopper (Orthoptera) diversity and abundance. Grassland Science in Europe 16, Klein, A.-M.; Vaissière, B.E.; Cane, J.H.; Steffan-Dewenter,I.; Cunningham, S.A.; Kremen, C. & Tscharntke, T. (2007) Importance of pollinators in changing landscapes for world crops. Proceedings of the Royal Society, Series B 274: Morris, M.G. (1971) The management of grassland for the conservation of invertebrate animals. In: Duffey, E.; Watt, A.S. (Eds.) The Scientific Management of Animal and Plant Communities for Conservation. Blackwell, Oxford : 527–552 Morris, M.G. (2000) The effects of structure and its dynamics on the ecology and conservation of arthropods in British grasslands. Biological Conservation 95: Sabrina Jerrentrup

Literature Pöyry, J.; Luoto, M.; Paukkunen, J.; Pykälä, J.; Raatikainen, K. & Kuussaari, M. (2006) Different responses of plants and herbivore insects to a gradient of vegetation height: an indicator of the vertebrate grazing intensity and successional age. Oikos 215: Van Swaay C., Warren N. & Loïs G. (2006) Biotope use and trends of European butterflies. Journal of insect conservation 10: WallisDeVries, M.F. (1996) Effects of resource distribution patterns on ungulate foraging behaviour: a modelling approach. Forest Ecology and Management 88: Wilson, J.D.; Morris, A.J.; Arroyo, B.E.; Clark, S.C. & Bradbury, R.B. (1999) A review of the abundance and diversity of invertebrate and plant foods of granivorous birds in northern Europe in relation to agricultural change. Agriculture, Ecosystems & Environment 75: Sabrina Jerrentrup

Butterfly species Sabrina Jerrentrup Aglais urticae Aphantopus hyperantus Argynnis paphia Coenonympha pamphilus Colias hyale Gonepteryx rhamni Inachis io Maniola jurtina Melanargia galathea Papilio machaon Pieris sp. Polyommatus icarus Polyommatus thersites Thymelicus sylvestris Vanessa atalanta Vanessa cardui

Butterfly species Sabrina Jerrentrup Lycaenidae (Blues & Coppers) Polyommatus icarus (the Common Blue) Polyommatus thersites (the Chapman‘s Blue) Hesperiidae (Skippers) Thymelicus sylvestris (the Small Skipper) Papilionidae (Swallowtails & Birdwings) Papilio machaon (the Old World Swallowtail) Nymphalidae (Brush-footed butterflies) Aglais urticae (the Small Tortoiseshell) Aphantopus hyperantus (the Ringlet) Argynnis paphia (the Silver-washed Fritillary) Coenonympha pamphilus (the Small Heath) Inachis io (the Peacock) Maniola jurtina (the Meadow Brown) Melanargia galathea (the Marbled White) Vanessa atalanta (the Red Admiral) Vanessa cardui (the Painted Lady) Pieridae (Whites & Yellow-Whites) Colias hyale (the Pale Clowded Yellow) Pieris sp. (garden whites) Gonepteryx rhamni (the Brimstome) Rhopalocera