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Szabo K.,Corvinus University of Budapest | Boll S.,Bavarian State Institute for Viticulture and Horticulture | Eros-Honti Z.S.,Corvinus University of Budapest
Applied Ecology and Environmental Research | Year: 2014

Urban habitats are unique and harsh environments for established plant communities, basically due to the increased stress (disturbance, pollution, drought etc.). However, ever increasing is the need for extending the green areas of the cities. There are several possibilities for urban afforestation, yet most of them require the use of chemicals that burden the soil. A feasible solution is applying artificially modified microbiota to enhance the growth and stress tolerance of the ornamental species. Mycorrhiza is mutualistic interaction between plant roots and fungal hyphae that increases the ecological fitness of both partners, especially among harsh environmental conditions. As a consequence, exploiting the advantages of this symbiosis can be a proper and sustainable strategy for establishing artificial plant communities in urban areas. In the present article we review the most important questions of urban afforestation and describe the most important general features of mycorrhizae that are related to their extended use by the humankind. Afterwards, we sum up the actual knowledge on mycorrhizae of plants living in urban areas. Then we report about the Bavarian research project "Urban Green 2021". Finally, we introduce an extensive ongoing study aiming to gain new results on this topic among Hungarian conditions. © 2014, ALÖKI Kft., Budapest, Hungary. Source

Muller J.,Bavarian Forest National Park | Muller J.,Ludwig Maximilians University of Munich | Brustel H.,Purpan Engineering School | Brin A.,Purpan Engineering School | And 14 more authors.
Ecography | Year: 2015

Global warming and land-use change are expected to be additive threats to global diversity, to which insects contribute the highest proportion. Insects are strongly influenced by temperature but also require specific habitat resources, and thus interaction between the two factors is likely. We selected saproxylic beetles as a model group because their life cycle depends on dead wood, which is highly threatened by land use. We tested the extent to which higher temperatures compensate for the negative effects of low amounts of dead wood on saproxylic beetle species richness (Temperature-Dead wood compensation hypothesis) on both a macroclimate and a topoclimate scale (north- and south-facing slopes). We analyzed 1404 flight-interception trap catches across Europe to test for interaction effects of temperature and dead-wood amount on species richness. To experimentally test our findings from the activity trap data, we additionally reared beetles from 80 bundles of dead wood initially exposed at high and low elevations. At the topoclimate scale, we analyzed trap catches and reared beetles from dead wood exposed in 20 forest stands on south-facing and north-facing slopes in one region. On the macroscale, both temperature and dead-wood amount positively affected total and threatened species richness independently, but their interaction was significantly negative, indicating compensation. On both scales and irrespective of the method, species richness decreased with temperature decline. Our observation that increasing temperature compensates for lower amounts of dead wood has two important implications. First, managers of production forests should adapt their dead-wood enrichment strategy to site-specific temperature conditions. Second, an increase in temperature will compensate at least partially for poor habitat conditions in production forests. Such a perspective contrasts the general assumption of reinforcing impacts of global warming and habitat loss on biodiversity, but it is corroborated by recent range expansions of threatened beetle species. © 2014 The Authors. Source

Hessdorfer D.,Bavarian State Institute for Viticulture and Horticulture | Schwab A.,Bavarian State Institute for Viticulture and Horticulture | Gruber B.R.,Geisenheim Research Center
Acta Horticulturae | Year: 2014

The feasibility of continuous in-situ measurements of grapevine stem water potential by means of stem hygrometers was investigated. The comparison with pressure chamber measurements as reference method revealed close correlations at pre-dawn as well as during the day. It was possible to monitor the short term recoveries caused by drip irrigation. However, while absolute values of hygrometer and pressure chamber measurements at pre-dawn were on the same level, stem hygrometer values during the day tended to indicate more intense stress than pressure chamber measurements. Stem water potential continuously measured by stem hygrometers in field experiments showed a very close correlation to ambient VPD. In addition, sap flow rates of grapevine could be estimated by the daily courses of the water potential gradient between stem and pre-dawn water potential. Remounting of stem hygrometers due to exudates was necessary in intervals of several weeks. Source

Heidinger I.M.M.,Bee Institute | Heidinger I.M.M.,Bavarian State Institute for Viticulture and Horticulture | Meixner M.D.,Bee Institute | Berg S.,Bavarian State Institute for Viticulture and Horticulture | Buchler R.,Bee Institute
Insects | Year: 2014

We used radio-frequency identification (RFID) to record the duration and frequency of nuptial flights of honey bee queens (Apis mellifera carnica) at two mainland mating apiaries. We investigated the effect of a number of factors on flight duration and frequency: mating apiary, number of drone colonies, queen's age and temperature. We found significant differences between the two locations concerning the number of flights on the first three days. We also observed an effect of the ambient temperature, with queens flying less often but longer at high temperatures compared to lower temperatures. Increasing the number of drone colonies from 33 to 80 colonies had no effect on the duration or on the frequency of nuptial flights. Since our results agree well with the results of previous studies, we suggest RFID as an appropriate tool to investigate the mating behavior of honey bee queens. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

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