Adjacent Semi-natural Habitats Research Articles

Effect of land-use intensity and adjacent semi-natural habitats on wild and honey bees of meadows

Most terrestrial ecosystems are shaped by the pollination service provided by insects, foremost bees. As bees are also important pollinators of crop plants, they are key for both the pollination of wild plants and for agricultural production. Meadows and semi-natural habitats (SNHs) are important habitats for bees. However, there is limited knowledge on how land-use intensity of meadows affects wild bees and managed Western honey bees. Further, it is unknown whether SNHs adjacent to meadows affect bees in meadows. Here, we examined in a landscape dominated by grasslands, the effects of land-use intensity (nitrogen input, grazing intensity, mowing frequency), flower availability and adjacent SNHs on bee communities in meadows. We recorded more than 5000 individuals of 87 species of bees and found no effect of land-use intensity on wild and honey bees. Flowering plant species richness had a positive effect on bee species richness in one study year. Though we recorded more bee species in SNHs than meadows, overall and specifically in ecologically specialized bee species (e.g. parasitic bees, oligoleges), the availability of adjacent SNHs did not affect bee abundance and richness in meadows. We discuss why land-use intensity and SNHs adjacent to meadows did not affect bees in meadows and conclude that SNHs are important in sustaining functionally diverse bee communities in landscapes dominated by grasslands.

Spiders (Araneae) of olive groves and adjacent semi-natural habitats from central Italy

In the Monte Pisano area (Tuscany, central Italy), spiders were collected within two research projects during three years (2010, 2013, 2014). Olive groves and adjacent semi-natural habitats (wood and Mediterranean garrigue) were investigated with three sampling methods (pitfall trapping, beating at branches and hand collection in the canopy). A total of 148 species was identified. The ground spider (Gnaphosidae) Zelotes fulvaster (Simon, 1878) was recorded for the first time in Italy.

Mixed effects of ecological intensification on natural pest control providers: a short-term study for biotic homogenization in winter wheat fields.

Agricultural intensification is one of the major drivers of biotic homogenization and has multiple levels ranging from within-field management intensity to landscape-scale simplification. The enhancement of invertebrate assemblages by establishing new, semi-natural habitats, such as set-aside fields can improve biological pest control in adjacent crops, and mitigate the adverse effect of biotic homogenization. In this study we aimed to examine the effects of ecological intensification in winter wheat fields in Hungary. We tested how pests and their natural enemies were affected at different spatial scales by landscape composition (proportion of semi-natural habitats in the surrounding matrix), configuration (presence of adjacent set-aside fields), and local field management practices, such as fertilizer (NPK) applications without applying insecticides. We demonstrated that at the local scale, decreased fertilizer usage had no direct effect either on pests or their natural enemies. Higher landscape complexity and adjacent semi-natural habitats seem to be the major drivers of decreasing aphid abundance, suggesting that these enhanced the predatory insect assemblages. Additionally, the high yield in plots with no adjacent set-aside fields suggests that intensive management can compensate for the lower yields on the extensive plots. Our results demonstrated that although complexity at the landscape scale was crucial for maintaining invertebrate assemblages, divergence in their response to pests and pathogens could also be explained by different dispersal abilities. Although the landscape attributes acted as dispersal filters in the organization of pest and pathogen assemblages in croplands, the presence of set-aside fields negatively influenced aphid abundance due to their between-field isolation effect.

Distribution of ground beetles of the genus Amara Bonelli, 1810 (Coleoptera, Carabidae) in the agrolandscape in Northwestern Russia

The article investigates the abundance of beetles of the genus Amara in the agrolandscape of the Leningrad Region. In the period from 2004 to 2010, 14 Amara species were collected by pitfall trapping. Amara fulva (O.F. Müll.) is the most common species in the potato and clean fallow fields, Amara similata (Gyll.) – in the grain and grasses fields, and A. communis (Pz.) ˗ in adjacent semi-natural habitats respectively. The cluster analysis shows that assemblages of ground beetles of the genus Amara in fields of different crops, field boundaries, and adjacent habitats are separated from each other. In the agrolandscape, the population of beetles of the genus Amara reaches its greatest species richness and abundance in perennial grassfields. In addition, to our best knowledge, this research was a first time when Amara ingenua (Duft.) was observed feeding on the flowering spikelets of timothy grass (Phleum pratense L.).

Spillage of Viable Seeds of Oilseed Rape along Transportation Routes: Ecological Risk Assessment and Perspectives on Management Efforts

Seed spillage during handling and transportation promotes establishment and invasion of feral crops into adjacent semi-natural habitats. This is also the case for oilseed rape (OSR, Brassica napus), where seed spillage may lead to establishment of herbicide resistant OSR populations in countries without cultivation of genetically modified OSR. Using data from Austria – where cultivation and import of genetically modified OSR are banned – as a prime example, we demonstrate that ports, oil mills, switchyards, and border railway stations to countries with different electric current systems – where trains have to stop – are the sites of primary concern with respect to seed spillage. Based on the results of the Austrian case study we discuss common measures to limit crop seed spillage which include intensified controls at border railway stations and the mode of seed packing during transportation. We further recommend sufficient cleaning both of goods wagons and of loading areas of trucks and ships as well as an appropriate weed management.

Mass-flowering crops dilute pollinator abundance in agricultural landscapes across Europe.

Mass‐flowering crops (MFCs) are increasingly cultivated and might influence pollinator communities in MFC fields and nearby semi‐natural habitats (SNHs). Across six European regions and 2 years, we assessed how landscape‐scale cover of MFCs affected pollinator densities in 408 MFC fields and adjacent SNHs. In MFC fields, densities of bumblebees, solitary bees, managed honeybees and hoverflies were negatively related to the cover of MFCs in the landscape. In SNHs, densities of bumblebees declined with increasing cover of MFCs but densities of honeybees increased. The densities of all pollinators were generally unrelated to the cover of SNHs in the landscape. Although MFC fields apparently attracted pollinators from SNHs, in landscapes with large areas of MFCs they became diluted. The resulting lower densities might negatively affect yields of pollinator‐dependent crops and the reproductive success of wild plants. An expansion of MFCs needs to be accompanied by pollinator‐supporting practices in agricultural landscapes.

Temporal variability of aphid biological control in contrasting landscape contexts

Landscape complexity may provide ecosystem services to agriculture through the provision of natural enemies of agricultural pests. Strong positive effect of adjacent semi-natural habitats on natural enemies in croplands has been evidenced, but the resulting impact on biological control remains unclear. Taking into account the temporal dynamics of pest and natural enemies in agricultural landscapes provides better resolution to the studies and better understanding of the biological control service.In this study, the population dynamics of aphids and two groups of predators (coccinellid and carabid beetles) were examined. Insects were sampled in 20 wheat fields, surrounded by structurally simple and complex landscapes in Chilean central valley. Considering the whole sampling period, the diversity of aphids and natural enemies were similar in wheat crops surrounded by both types of landscapes, and the abundance of ladybirds was higher in crops in the complex landscapes. The dynamics of predators was more advanced in complex landscapes than in the simple ones, whereas the dynamics of aphids were similar in both types of landscape. Negative correlation between abundance of predators and aphid population growth rate in both landscape contexts were observed suggesting a control of the pest population by the predators. Different temporal patterns were observed in these correlations in the two landscape contexts, which suggests differences in the biological control related to the landscape composition.The present study shows that colonization of crops by natural enemies occurs sooner in structurally complex landscapes and suggests that this early colonization may facilitate an early and efficient control of aphid populations, nevertheless the biological control efficiency seems to be higher in structurally simple landscapes later in the season.

Herbicide and fertilizers promote analogous phylogenetic responses but opposite functional responses in plant communities

Throughout the world, herbicides and fertilizers change species composition in agricultural communities, but how do the cumulative effects of these chemicals impact the functional and phylogenetic structure of non-targeted communities when they drift into adjacent semi-natural habitats? Based on long-term experiment we show that fertilizer and herbicides (glyphosate) have contrasting effects on functional structure, but can increase phylogenetic diversity in semi-natural plant communities. We found that an increase in nitrogen promoted an increase in the average specific leaf area and canopy height at the community level, but an increase in glyphosate promoted a decrease in those traits. Phylogenetic diversity of plant communities increased when herbicide and fertilizer were applied together, likely because functional traits facilitating plant success in those conditions were not phylogenetically conserved. Species richness also decreased with increasing levels of nitrogen and glyphosate. Our results suggest that predicting the cumulative effects of agrochemicals is more complex than anticipated due to their distinct selection of traits that may or may not be conserved phylogenetically. Precautionary efforts to mitigate drift of agricultural chemicals into semi-natural habitats are warranted to prevent unforeseeable biodiversity shifts.

Diversity of Pollinator Insects in Relation to Seed Set of Mustard (Brassica rapa L.: Cruciferae)

Pollinators provide key services to both natural and agricultural ecosystems. Agricultural productivity depends, in part, on pollinator populations from adjacent seminatural habitats. Here we analysed the diversity of pollinator insects and its effect to seed set of mustard (Brassica rapa) planted in agricultural ecosystem near the Gunung Halimun-Salak National Park, West Java. At least 19 species of insects pollinated the mustard, and three species, i.e. Apis cerana, Ceratina sp., and Apis dorsata showed a high abundance. The higher abundance and species richness of pollinators occurred at 08.30-10.30 am and the diversity was related to the number of flowering plants. Insect pollinations increased the number of pods, seeds per pod, seed weights per plant, and seed germination. Key words: diversity, pollinator insects, social bees, solitary bees, seed set, Brassica rapa

Overwintering of arthropods in soils of arable fields and adjacent semi-natural habitats

In order to determine the significance of field margins for the overwintering of arthropods in agricultural landscapes, different sites of an integrated and of an organically managed farm were investigated in the northwest of Switzerland. During December 1995 and January 1996, soil samples were taken with an electronic-hydraulic soil borer (depth: 25 cm, diameter: 8 cm). After hand sorting the larger arthropods, the small ones were extracted with a modified MacFadyen apparatus. The abundance of arthropods in the arable fields was significantly lower than in the adjacent semi-natural habitats. Highest abundances and species diversities were found in a sown wildflower strip, a hedge, a permanent meadow and a meadow under the cherry trees of the organic farm. With a total of 90 arthropod species in the semi-natural habitats, five times more species were found than in the arable fields. Staphylinids, carabids, spiders and chilopods were the most abundant arthropod groups. The data showed that undisturbed semi-natural habitats and extensively managed field margins play a key role as overwintering sites for many predatory arthropods.