24.3.2014: Forschung international
Biolandbau fördert Biodiversität
L’agriculture biologique favorise la biodiversité
Sean L. Tuck et al.
Eine neue Meta-Analyse basierend auf 94 Studien liefert weitere Hinweise darauf, dass der biologische Landbau für die Biodiversität Vorteile bringt. Durchschnittlich erhöht die biologische Landwirtschaft im Vergleich zur konventionellen den Artenreichtum um ca. 30%. Dieser Effekt ist grösser in intensiven Landwirtschaftsregionen.
Une nouvelle méta-analyse basée sur 94 études apporte des indications supplémentaires montrant que l’agriculture biologique apporte des avantages pour la biodiversité. L’agriculture biologique augmente en moyenne la richesse en espèces de 30% comparé à l'agriculture conventionnelle. Cet effet est d’autant plus grand dans les régions avec une agriculture intensive.
The benefits of organic farming to biodiversity in agricultural landscapes continue to be hotly debated, emphasizing the importance of precisely quantifying the effect of organic vs. conventional farming. A research group conducted an updated hierarchical meta-analysis of studies that compared biodiversity under organic and conventional farming methods, measured as species richness. The effect size was calculated for 184 observations collected from 94 studies, and for each study, three standardized measures reflecting land-use intensity were obtained. We investigated the stability of effect sizes through time, publication bias due to the «file drawer» problem were investigated, and whether the current literature is representative of global organic farming patterns was considered.
On average, organic farming increased species richness by about 30%. This result has been robust over the last 30 years of published studies and shows no sign of diminishing. Organic farming had a greater effect on biodiversity as the percentage of the landscape consisting of arable fields increased, that is, it is higher in intensively farmed regions. The average effect size and the response to agricultural intensification depend on taxonomic group, functional group and crop type.
There is some evidence for publication bias in the literature; however, the results are robust to its impact. Current studies are heavily biased towards northern and western Europe and North America, while other regions with large areas of organic farming remain poorly investigated.
In conclusion, the analysis affirms that organic farming has large positive effects on biodiversity compared with conventional farming, but that the effect size varies with the organism group and crop studied, and is greater in landscapes with higher land-use intensity. Decisions about where to site organic farms to maximize biodiversity will, however, depend on the costs as well as the potential benefits. Current studies have been heavily biased towards agricultural systems in the developed world. The researchers recommend that future studies pay greater attention to other regions, in particular, areas with tropical, subtropical and Mediterranean climates, in which very few studies have been conducted.
Quelle: University of Oxford
Keywords:
Biologischer Landbau, Landwirtschaftssystem, Artenvielfalt
Art der Publikation:
Fachpublikation
Literatur:
Tuck S.L. et al. (2014): Land-use intensity and effects of organic farming on biodiversity: a hierarchical meta-analysis. Journal of Applied Ecology. Doi: 10.1111/1365-2664.12219.
http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12219/abstract
Kontaktadresse:
Sean L. Tuck
Departement of Plant Sciences
University of Oxford
OXI 3RB, UK
Sean.tuck@plant.ox.ac.uk
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