Intensivierung der Landwirtschaft und biologische Vielfalt

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1 Intensivierung der Landwirtschaft und biologische Vielfalt Teja Tscharntke Agrarökologie, Georg-August-Universität Göttingen, Dialogforum (UBA, BMU-BfN) Nachhaltige landwirtschaftliche Landnutzung, Stoffflüsse und Biodiversität, Juni 2010, Dessau

2 Agriculturally driven Global Change Tscharntke et al. 2007, in: Stewart et al., CABI Publ (Sala et al. 2000, Science)

3 Biodiversity of European wild birds PECBM 2005

4 Hoenybees: Colony Collapse Disorder Multiple stress including parasites (Varroa) and viruses (IAPV) Pesticide toxicity: Letal dose (LD50) vs. subletal effects 2008: Bienensterben im Rheintal: Neonicotinoide (Saatgut-Beizmittel Mais, Sonnenblumen) Albert Einstein zugeschriebenes Zitat: Wenn die Bienen verschwinden, hat der Mensch nur noch vier Jahre zu leben; keine Pflanzen, keine Tiere, keine Menschen mehr

5 Honeybees: Colony Collapse Disorder Californian almond industry 80% of world s almonds $ 2 billion 1.4 million bee hives 35 billion bees

6 Global crops and animal pollination Required for 60-90% of angiosperms Limiting factor for reproduction in most natural plant populations Improve production for 70% of globally important crops, influence 35% of global human food supply Alexandra Klein et al. (2007) Proc Roy Soc London B

7 Cherry yield in relation to flower visitation of wild bees Holzschuh, Dudenhöffer et al., in prep. initial fruit set final fruit set

8 Flower Power for biodiversity and biological control Habitat manipulation adjacent to crop fields spillover into crop fields (Felix Bianchi et al. 2006, Proc Roy Soc London B)) impact on biological control? partridge conservation project Barbara Scheid et al. 2010

9 Cereal aphids & natural enemies in cereals Parasitoids Aphids Predators in the vegetation Predators on the ground

10 Flower Power for biodiversity and biological control sown flower field sown flower strip grassy field margin wheat-wheat boundary -G: ground-dwelling -F: flying predators -G-F: total natural C: control predators & parasitoids enemy exclusion (no exclusion)

11 Flower Power for biodiversity and biological control C = control (no-exclusion) -G = ground-dwelling predator exclusion -F = flying predator & parasitoid exclusion -G-F = total natural enemy exclusion WWB = wheat-wheat boundaries GFM = grassy field margins SFS = sown flower strips SFF = sown flower fields

12 Flower Power for biodiversity and biological control Flower strips contribute to higher natural enemy density and diversity biological control of cereal aphids multi-purpose flower power for biodiversity conservation & associated ecosystem functions

13 Ecological-economic trade-offs: concept figure

14 Trade-offs between yield and biodiversity? 8 EU countries (9 regions) 1350 wheat fields Species richness: wild plants, carabid beetles, ground-nesting farmland birds biological aphid control experiment Components of agricultural intensification yield 13 management intensification variables (e.g. pesticides, fertilizer, ploughing, crop types/farm, % agri-environment scheme) 9 landscape structure variables (mean field size, % arable crops) Flavia Geiger et al. 2010, Basic Appl Ecol

15 Trade-offs between yield and biodiversity? 8 EU countries (9 regions) 1350 wheat fields Geiger et al. 2010, Basic Appl Ecol

16 Trade-offs between yield and biodiversity? Carabids Plants Birds Aphid survival (-) insecticides a.i. (-) mean field size (-) fungicides (+) AES (+) AES (-) herbicides (-) insecticides (-) fungicides a.i. (+) insecticides a.i. (-) AES Geiger et al. 2010, Basic Appl Ecol

17 Trade-offs between yield and biodiversity? Yield negatively related to species diversity at different trophic levels (plants, beetles, birds) and biological control potential Pesticides negatively related to species diversity and biological control potential Organic farming positively related to plant and carabid diversity Geiger et al. 2010, Basic Appl Ecol

18 Biodiversität, Produktivität & landwirtschaftliche Intensivierung Thies et al. 2010

19 Spatial scale matters Landscape Field Plant

20 20 landscape sectors around the city of Göttingen were digitally mapped (GIS)

21 Plots in the centre of a circle 20 landscape sectors around the city of Göttingen were digitally mapped (GIS)

22 Simple landscapes (>90% annual crops) Complex landscapes (>50% noncrop area)

23 Local vs. landscape management on plant and bee diversity Number of plant species Organic Conventional Plants: Indra Roschewitz et al. 2005, J Appl Ecol Doreen Gabriel et al. 2006, Ecol Appl Organic vs. conventional winter wheat, paired farms per landscape (Ø 2km) Bees: Andrea Holzschuh et al. 2007, J Appl Ecol

24 Landscape-moderated importance of hedges in conserving farmland bird diversity A: 0-1.5% D: >17% B : % C: % Organic: open bars Conventional: filled bars Peter Batary et al Biol Conserv Semi-natural habitat (500m radius) a: 0-1.5%; b: %; c: %; d: >17%

25 The intermediate landscape complexity hypothesis Biodiversity & Ecosystem Services Cleared Simple Complex In simple landscapes, effectiveness of agri-environment practices is highest (diversity of plants and bees, pest control) Tscharntke et al. 2005, Ecol Letters

26 Kompromisse zwischen Ertrag & Biodiversität? (1) Landwirtschaftliche Intensivierung und Ertrag = negative Effekte auf Biodiversität und assoziierte Funktionen (2) Pestizide spielen dabei eine prominente Rolle (3) Hohe Variabilität = viel Raum für ökologisch-ökonomische Kompromisse (4) Komplexität der Landschaft und Biodiversität sind eng korreliert (5) In einfach strukturierten Landschaften hat das lokale Management die größte Effizienz (Hypothese der mittleren Landschaftskomplexität)

27 Ecosystem functioning Insurance species Redundancy Number of species per functional group High diversity of insurance species increases - functioning under increased resource heterogeneity (at larger scales) - response diversity to disturbances under Global Change Bengtsson et al. 2003, Ambio; Elmqvist et al. 2003, Front Ecol Environm; Loreau et al. 2003, PNAS; Tscharntke et al. 2005, Ecol Letters

28 Landscape-wide effects of organic farming: spillover effects 42 fallow strips along organic (triangles) and conventional (circles) wheat fields Holzschuh et al Oikos

29 Complex landscapes: reduced rape damage & increased parasitism Edge effects only in simple landscapes! Carsten Thies & Tscharntke 1999, Science Tscharntke et al. 2002, Ecol Appl

30 Kompromisse zwischen Ertrag & Biodiversität? Geiger et al. 2010, BAAE