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