Effects of fertilization and elevated CO<Subscript>2</Subscript> on larval food and butterfly nectar amino acid preference in<Emphasis Type="Italic"> Coenonympha pamphilus</Emphasis> L.

The effects of larval diet on the nutritional preferences of butterflies has rarely been examined. This study investigates whether alterations in the larval diet result in changes in adult preferences for nectar amino acids. Larvae of Coenonympha pamphilus were raised on fertilized or unfertilized Festuca rubra, grown under ambient (350 ppm) or elevated (750 ppm) atmospheric CO ₂environments. Fertilization led to marked increases in leaf nitrogen concentration. In plants grown under elevated CO ₂conditions, leaf water and nitrogen concentrations were significantly lower, and the C/N-ratio increased significantly. Fertilization of the host plant shortened the development time of C. pamphilus larvae, and pupal weight increased. In contrast, larvae of C. pamphilus developed significantly slower on F. rubra grown under elevated CO ₂, but adult emergence weight was not affected by CO ₂treatment of the plant. C. pamphilus females showed a clear preference for nectar mimics containing amino acids, whereas males, regardless of treatment, either preferred the nectar mimic void of amino acids or showed no preference for the different solutions. Female butterflies raised on fertilized plants showed a significant decline in their preference for nectar mimics containing amino acids. A slight, but not significant, trend towards increased nectar amino acid preference was found in females raised on plants grown under elevated CO ₂. We clearly demonstrate that alterations in larval host quality led to changes in butterfly nectar preferences. The ability of the butterfly to either rely less on nectar uptake or compensate for poor larval conditions represents a trade-off between larval and adult butterfly feeding.     

Ozon in Waldökosystemen aus atmosphärenchemischer und pflanzenphysiologischer Sicht

The trend of rising ozone concentrations in forest ecosystems and the phytotoxicity of ozone demand a realistic risk assessment according to an internationally accepted and flux-based quality standard. Ozone fluxes within the canopy are influenced by chemical gas-phase reactions with nitrogen oxide and biogenic hydrocarbons and by surface deposition processes. Therefore, a differentiation of the ozone flux within the canopy is needed between stomatal uptake and other transport pathways. The Eddy Covariance technique is the method of choice for the determination of trace gas fluxes relevant for ozone chemistry. This method is also used for stomatal conductance measurements based on evapotranspiration fluxes and for emission measurements of biogenic hydrocarbons by PTR-MS. Although considerably research efforts were directed to canopy measurements in recent years, the underlying processes are not fully understood yet. Thus, major differences occur in the ratios of stomatal ozone uptake, non-stomatal deposition and gas-phase chemistry between different studies. Furthermore, the vertical concentration gradients within the canopy measured at several forest sites are rather inconsistent and the existing deposition models do rarely account for chemical transformation and detoxification processes. Only a simultaneous measurement of all photochemically relevant trace gases, plant physiological parameters at different sites and forest species over entire vegetation periods, and model parameterization according to the measurement results from the experimental sites will contribute to the clarification of the canopy processes and will ensure realistic risk assessments.     

Ökologische Situation der Region Leipzig-Halle

The deposition of heavy metals bound to air dust and their ecological effects depend, to a large degree, on particle size, which influences the transport processes in the environment. To estimate the size range of the particles mainly taken up by the pine needles, concentration gradients along a sector leeward of Leipzig were modelled according toGauss plume calculations. The results show that the aerodynamic size is between 1 and 10 μm. Particles of this size range can be taken up by lungs and, thus, have a particular toxicological relevance.