Ecological networks reveal resilience of agro-ecosystems to changes in farming management

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Agricultural intensification and biodiversity partitioning in European landscapes comparing plants, carabids, and birds

Effects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (n = 1350), farm (n = 270), and European-region (n = 9) scale. We partitioned diversity into its additive components a, ß, and ¿, and assessed the relative contribution of ß diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to ß diversity on larger scales up to the farm and region level, and thereby was an indicator of farm- and region-wide biodiversity losses. At the scale of farms (12.83–20.52%) and regions (68.34–80.18%), ß diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of a diversity decreased with AI, while relative importance of ß diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agri-environmental schemes in agroecosystem

Mixed effects of organic farming and landscape compexity on farmland biodiversity and biological control potential across Europe

1. Organic farming in Europe has been shown to enhance biodiversity locally, but potential interactions with the surrounding landscape and the potential effects on ecosystem services are less well known. 2. In cereal fields on 153 farms in five European regions, we examined how the species richness and abundance of wild plants, ground beetles and breeding birds, and the biological control potential of the area, were affected by organic and conventional farming, and how these effects were modified by landscape complexity (percentage of arable crops within 1000 m of the study plots). Information on biodiversity was gathered from vegetation plots, pitfall traps and by bird territory mapping. The biological control potential was measured as the percentage of glued, live aphids removed from plastic labels exposed in cereal fields for 24 h. 3. Predation on aphids was highest in organic fields in complex landscapes, and declined with increasing landscape homogeneity. The biological control potential in conventional fields was not affected by landscape complexity, and in homogenous landscapes it was higher in conventional fields than in organic fields, as indicated by an interaction between farming practice and landscape complexity. 4. A simplification of the landscape, from 20% to 100% arable land, reduced plant species richness by about 16% and cover by 14% in organic fields, and 33% and 5·5% in conventional fields. For birds, landscape simplification reduced species richness and abundance by 34% and 32% in organic fields and by 45·5% and 39% in conventional fields. Ground beetles were more abundant in simple landscapes, but were unaffected by farming practice. 5. Synthesis and applications. This Europe-wide study shows that organic farming enhanced the biodiversity of plants and birds in all landscapes, but only improved the potential for biological control in heterogeneous landscapes. These mixed results stress the importance of taking both local management and regional landscape complexity into consideration when developing future agri-environment schemes, and suggest that local-regional interactions may affect other ecosystem services and functions. This study also shows that it is not enough to design and monitor agri-environment schemes on the basis of biodiversity, but that ecosystem services should be considered too

Agricultural intensification and biodiversity partitioning in European landscapes comparing plants, carabids, and birds

Ecological Applications 21. 5 (2011): 1772-1781 copyright by the Ecological Society of AmericaEffects of agricultural intensification (AI) on biodiversity are often assessed on the plot scale, although processes determining diversity also operate on larger spatial scales. Here, we analyzed the diversity of vascular plants, carabid beetles, and birds in agricultural landscapes in cereal crop fields at the field (n=1350), farm (n=270), and European-region (n= 9) scale. We partitioned diversity into its additive components α, β, and γ, and assessed the relative contribution of β diversity to total species richness at each spatial scale. AI was determined using pesticide and fertilizer inputs, as well as tillage operations and categorized into low, medium, and high levels. As AI was not significantly related to landscape complexity, we could disentangle potential AI effects on local vs. landscape community homogenization. AI negatively affected the species richness of plants and birds, but not carabid beetles, at all spatial scales. Hence, local AI was closely correlated to β diversity on larger scales up to the farm and region level, and thereby was an indicator of farm-and region-wide biodiversity losses. At the scale of farms (12.83-20.52%) and regions (68.34-80.18%), β diversity accounted for the major part of the total species richness for all three taxa, indicating great dissimilarity in environmental conditions on larger spatial scales. For plants, relative importance of a diversity decreased with AI, while relative importance of β diversity on the farm scale increased with AI for carabids and birds. Hence, and in contrast to our expectations, AI does not necessarily homogenize local communities, presumably due to the heterogeneity of farming practices. In conclusion, a more detailed understanding of AI effects on diversity patterns of various taxa and at multiple spatial scales would contribute to more efficient agrienvironmental schemes in agroecosystemsWe also thank the European Science Foundation and the connected eight national science foundations for funding the presented study through the Eurodiversity AGRIPOPES (agricultural policy-induced landscape changes: effects on biodiversity and ecosystem services) program and the biology program BIOPLEX of the German Federal Ministry of Education and Science (BMBF

The Green Revolution in Zimbabwe

This paper presents a historical overview of plant breeding research, variety release and seed supply of staple food grains in Zimbabwe, and assesses the impacts of the new varieties on yields using national aggregate yield data. The paper also analyses farm-level factors determining farmers’ adoption decisions in the semi-arid areas, where the mini-green revolution lagged behind more favorable areas. The results indicate that the adoption of improved crop varieties will not lead to substantial yield gains unless improved soil management methods, such as application of manure and fertilizer, are also adopted..Green Revolution, maize, semi-arid areas, soil fertility management, drought, Zimbabwe