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Statistical analysis - PowerPoint PPT Presentation

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Statistical analysis

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  1. Bryony Tolhurst¹,Iain Allan¹, Deborah Glass², Paul Atkins², Becky Taylor², Claudine Morvan3, Béatrice Potez4, and Sergey Mikhalovsky¹ The effect of widespread flax (Linumusitatissimum) cultivation in Normandy, France, on farmland wildlife Introduction European wildlife is inextricably linked with agriculture, with 75% of animal and plant species associated with farmland. Conservation of this biodiversity is essential for maintaining ecosystem services e.g. pollination of food crops, soil integrity. Land use in the UK and France is legislated by the Habitats Directive (1992) hence recent proposals to increase UK cultivation of flax to levels similar to those in Normandy, NW France, must be accompanied by an Environmental Impact Assessment (EIA). Our study represents a preliminary EIA of vertebrate bio-indicators. We tested the hypothesis that flax should be a crop favoured by nesting songbirds because it is spring-sown and less dense than conventional crops. We investigated bird and mammal occupancy of flax and other crops in Normandy, species, to inform UK best practice for flax cultivation. Results so far... UK Flax and Hemp production: The impact of changes in support measures on the competitiveness and future potential of UK fibre production and industrial use. DEFRA, 2005; Brown and Shepherd, 1993.A method for censusing upland breeding waders. Bird Study (1993) 40, 189-195 Methods We used the Brown and Shepherd (1993) grid transect survey method. 12 grid squares, each containing large flax fields, were surveyed on foot 1 hour after sunrise, twice yearly. Individuals/breeding territories of brown hare and skylark. No. of over-wintering skylarks in different crops No. of hares recorded in different crops * includes stubble Statistical analysis We used Generalised Linear Modelling (GLM) and Mixed Modelling (GLMM) to determine the impact of crop type (‘Crop’) on skylark and hare occupancy, controlling for differences between seasons, years and survey squares. Crop significantly predicted skylark numbers (GLM, df=11, % deviance explained = 66.821, p<0.001), but flax was significantly less likely to be occupied than other crops. Crop significantly predicted brown hare numbers (GLM, df=11, % deviance explained = 54.360, p<0.001), but significant variation in square, season and year was also detected (% deviance values 27.34, 15.52, and 2.78 respectively). The Flax project has been selected as part of the INTERREG IV A France (Channel) – England cross-border European cooperation programme, part-financed by the ERDF) Agricultural landscape, Normandy, June. Inset = flax plants in the fields These species were chosen because they are declining rapidly across Europe. No. of summer skylark territories in different crops Conclusions Our data show the opposite effect of that predicted; i.e. there appears to be selection against flax by both species. Although crop type predicts occupancy , skylarks and hares are more likely to be recorded in other crops, e.g. sugar beet ,than in flax. This may be related to the short growing season of flax (100 days), with at least one pesticide/ herbicide application, potentially affecting insect and arable weed food abundance. The study is ongoing, hence further data may elucidate the findings. Exterior PlumptonCollege ¹School of Pharmacy and Biomolecular Sciences; ²Plumpton College, ³CNRS, Rouen, 4 Linière de BoscNouvel Example of 1km² survey square. Squares were spaced > 4km apart to ensure spatial independence of the data