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| Axelsen, Jørgen Aagaard; Toft, Søren; Lôvei, Gabor. |
| The abundance and species composition of natural enemies (spiders and carabid beetles) and some of their important arthropod food sources (microarthropods, dipterans and hymenopterans) were sampled by soil extraction, pitfall traps and sticky traps in winter wheat placed in an organic crop with undersown catch crops and animal manure (slurry). The working hypothesis was that the undersown crops and animal manure would stimulate the microarthropods and other food sources, thereby enhancing the abundance of natural enemies. The ANOVA analyses revealed no impact of manuring and undersown catch crops on the microarthropods, but there was a larger abundance of most predator groups in the manured plots. There was not found any impact of undersown crops on the... |
| Tipo: Journal paper |
Palavras-chave: Cereals; Pulses and oilseeds Biodiversity and ecosystem services. |
| Ano: 2007 |
URL: http://orgprints.org/12309/1/12309.pdf |
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| Bruus, Marianne; Axelsen, Jørgen Aagaard; Tybirk, Knud. |
| Generally, it is expected to find food webs and food chains in all ecosystems, also highly disturbed ones such as agricultural fields. However, in a preliminary study in Danish conventionally managed fields it was not possible to identify food web nodes between weeds and herbivores, and it was hypothesized that the weed density in conventionally managed Danish agricultural fields were too low to support a more or less specialised herbivorous arthropod fauna. This hypothesis was investigated through an analysis of data on weeds and arthropods from conventionally and organically managed fields in Denmark. Sampling of arthropods was done by aid of D-vac and the sampling of weeds and crop was done at exactly the same site within two days. Most weeds and some... |
| Tipo: Journal paper |
Palavras-chave: Biodiversity and ecosystem services. |
| Ano: 2013 |
URL: http://orgprints.org/23252/2/23252.pdf |
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| Axelsen, Jørgen Aagaard; Holmstrup, Martin. |
| Earthworms are known to play a role in the nitrogen mineralisation in agricultural soils. Here we present simulations of the population dynamics of two earthworm species that are dominating in danish arable land, and compare the simualtions with observed densities (number and biomass) of the two species from three fields in Denmark. The simulations show an acceptable fit to the observations. The simulation model is used to quantify the impact of the observed earthworm populations on the minearalisation of nitrogen and in turn the crop production. The simulations show an increase in yield due to the earthworm contribution to mineralisation, and that the earthworms can be responsible for about 1/3 of the biologically mineralised nitrogen. |
| Tipo: Journal paper |
Palavras-chave: Cereals; Pulses and oilseeds Production systems Soil biology Biodiversity and ecosystem services. |
| Ano: 2005 |
URL: http://orgprints.org/4661/2/4661.pdf |
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| Bruus, Marianne; Axelsen, Jørgen Aagaard; Tybirk, Knud. |
| Weeds are important as food for both herbivorous insects and farmland birds. Especially monophagous, herbivorous insects depend on the presence of one or a few weed species, and consequently a shortage of such weed species may hamper parts of the food web of the agricultural ecosystem. In any ecosystem on the earth food webs and food chains are expected, i.e. that there are species from one trophic level feeding on the lower trophic levels. These levels may be organised as organic matter – degrader, plant – herbivore and predator – prey, where preys may be degraders, herbivores and other predators. In describing ecosystems the trophic connections are often described as nodes linking species from one trophic level to another, and in most ecosystems it is... |
| Tipo: Journal paper |
Palavras-chave: Biodiversity and ecosystem services. |
| Ano: 2013 |
URL: http://orgprints.org/23251/3/23251.pdf |
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| Bruus Pedersen, M.; Axelsen, Jørgen Aagaard; Tybirk, Knud. |
| Correlations between the weed flora and the arthropod fauna of conventionally and organically managed fields were analysed. The results indicate that the abundance of weeds in Danish conventionally grown cereal fields is too low to sustain a population of more or less species specific herbivores, i.e. too low to maintain functioning food chain links between weeds and herbivores. Organically grown fields with a higher abundance of weeds may be capable of sustaining a fauna of arthropods relying on the weeds. The data from extra- weedy areas support this hypothesis, indicating that particularly weed-rich fields can better support herbivorous insects. |
| Tipo: Journal paper |
Palavras-chave: Biodiversity and ecosystem services. |
| Ano: 2011 |
URL: http://orgprints.org/19041/6/19041.pdf |
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