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

Agriculturally driven Global Change

Tscharntke et al. 2007, in: Stewart et al., CABI Publ (Sala et al. 2000, Science)

Biodiversity of European wild birds PECBM 2005

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“

Honeybees: Colony Collapse Disorder

Californian almond industry

80% of world‘s almonds $ 2 billion 1.4 million bee hives 35 billion bees

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

Global crops and animal pollination

Alexandra Klein et al. (2007) Proc Roy Soc London B

● initial fruit set ○ final fruit set

Cherry yield in relation to flower visitation of wild bees

Holzschuh, Dudenhöffer et al., in prep.

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 www.rebhuhnschutzprojekt.de

Flower Power for biodiversity and biological control

Barbara Scheid et al. 2010

Cereal aphids & natural enemies in cereals

Parasitoids

Predators in the vegetation

Predators on the ground

Aphids

sown flower field sown flower strip grassy field margin wheat-wheat boundary

Flower Power for biodiversity and biological control

-G: ground-dwelling

predators

-F: flying predators

& parasitoids

-G-F: total natural

enemy exclusion

C: control

(no exclusion)

C = control (no-exclusion) -G = ground-dwelling predator exclusion -F = flying predator & parasitoid exclusion -G-F = total natural enemy exclusion

Flower Power for biodiversity and biological control

WWB = wheat-wheat boundaries GFM = grassy field margins SFS = sown flower strips SFF = sown flower fields

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

Flower Power for biodiversity and biological control

Ecological-economic trade-offs: concept figure

Flavia Geiger et al. 2010, Basic Appl Ecol

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)

Trade-offs between yield and biodiversity?

8 EU countries (9 regions) 1350 wheat fields

Geiger et al. 2010, Basic Appl Ecol

•  (-) mean field size •  (+) AES •  (-) herbicides •  (-) insecticides •  (-) fungicides a.i.

•  (-) fungicides •  (+) insecticides a.i. •  (-) AES

•  (-) insecticides a.i. •  (+) AES

Carabids Plants Birds Aphid survival

Trade-offs between yield and biodiversity?

Geiger et al. 2010, Basic Appl Ecol

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

Thies et al. 2010

Biodiversität, Produktivität & landwirtschaftliche Intensivierung

Spatial scale matters

Plant

Field

Landscape

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

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

Plots in the centre of a circle

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

Organic Conventional

Local vs. landscape management on plant and bee diversity

Num

ber o

f pla

nt s

peci

es

Bees: Andrea Holzschuh et al. 2007, J Appl Ecol

Organic vs. conventional winter wheat, paired farms per landscape (Ø 2km)

Plants: Indra Roschewitz et al. 2005, J Appl Ecol Doreen Gabriel et al. 2006, Ecol Appl

Semi-natural habitat (500m radius) a: 0-1.5%; b: 1.5-4.5%; c: 4.5-17%; d: >17%

Landscape-moderated importance of hedges in conserving farmland bird diversity

Organic: open bars Conventional: filled bars

Peter Batary et al. 2010 Biol Conserv

A: 0-1.5%

C: 4.5-17%

D: >17%

B :1.5-4.5%

The intermediate landscape complexity hypothesis

Tscharntke et al. 2005, Ecol Letters

Cleared Simple Complex

Bio

dive

rsity

&

Eco

syst

em S

ervi

ces

In simple landscapes, effectiveness of agri-environment practices is highest (diversity of plants and bees, pest control)

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)

Number of species per functional group

Ecos

yste

m fu

nctio

ning

Redundancy

Insurance species

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

Holzschuh et al. 2008 Oikos

Landscape-wide effects of organic farming: spillover effects

42 fallow strips along organic (triangles) and conventional (circles) wheat fields

Edge effects only in simple landscapes!

Carsten Thies & Tscharntke 1999, Science Tscharntke et al. 2002, Ecol Appl

Complex landscapes: reduced rape damage & increased parasitism

Geiger et al. 2010, BAAE

Kompromisse zwischen Ertrag & Biodiversität?