Global Change Abstracts The Swiss Contribution - SCNAT

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90 gus trees). Short discontinuations of CO 2 supply during morning hours had no measurable canopy temperature effects, most likely because the stomatal effects were small compared with the aerodynamic constraints in these dense, broad-leaved canopies. Hence, on a seasonal basis, these data suggest a < 10% reduction in water consumption in this type of forest when the atmosphere reaches 540% ppm CO 2. Global Change Biology, 2007, V13, N12, DEC, pp 2498-2508. 08.1-142 Anchorage of mature conifers: Resistive turning moment, root-soil plate geometry and root growth orientation Lundstroem T, Jonas T, Stöckli V, Ammann W Switzerland Forestry , Plant Sciences Eighty-four mature Norway spruce (Picea abies L. Karst), silver fir (Abies alba Mill) and Scots pine (Pinus sylvestris L.) trees were winched over to determine the maximum resistive turning moment (M-a) of the root-soil system, the root-soil plate geometry, the azimuthal orientation of root growth, and the occurrence of root rot. The calculation of M-a, based on digital image tracking of stem deflection, accounted not only for the force application and its changing geometry, but also for the weight of the overhanging tree, representing up to 42% of M-a. Root rot reduced M-a significantly and was detected in 25% of the Norway spruce and 5% of the silver fir trees. Excluding trees with root rot, differences in M. between species were small and insignificant. About 75% of the variance in M. could be explained by one of the four variablestree mass, stem mass, stem diameter at breast height squared times tree height, and stern diameter at breast height squared. Among the seven allometric variables assessed above ground, stem diameter at breast height best described the rootsoil plate dimensions, but the correlations were weak and the differences between species were insignificant. The shape of the root-soil plate was well described by a depth-dependent taper model with an elliptical cross section. Roots displayed a preferred azimuthal orientation of growth in the axis of prevailing, winds, and the direction of frequent weak winds matched the orientation of growth better than that of rare strong winds. The lack of difference in anchorage parameters among species probably reflects the similar belowground growth conditions of the mature trees. Tree Physiology, 2007, V27, N9, SEP, pp 1217-1227. Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 08.1-143 Wheat quality in organic and conventional farming: results of a 21 year field experiment Mäder P, Hahn D, Dubois D, Gunst L, Alföldi T, Bergmann H, Oehme M, Amado R, Schneider H, Graf U, Velimirov A, Fliebbach A, Niggli U Switzerland, Germany, Austria Agriculture, Soil Sciences , Plant Sciences Consumers have become more aware of healthy and safe food produced with low environmental impact. Organic agriculture is of particular interest in this respect, as manifested by 5.768 million hectares managed pursuant to Council Regulation (EEC) 2092/91 in Europe. However, there can be a considerable risk that the avoidance of chemical inputs in organic farming will result in poor food quality. Here the results of a study on the quality of wheat (Triticum aestivum L.) grown in a 21 year agrosystem comparison between organic and conventional farming in central Europe are reported. Wheat was grown in a ley (grass/clover) rotation. The 71% lower addition of plant-available nitrogen and the reduced input of other means of production to the organic field plots led to 14% lower wheat yields. However, nutritional value (protein content, amino acid composition and mineral and trace element contents) and baking quality were not affected by the farming systems. Despite exclusion of fungicides from the organic production systems, the quantities of mycotoxins detected in wheat grains were low in all systems and did not differ. In food preference tests, as an integrative method, rats significantly preferred organically over conventionally produced wheat. The findings indicate that high wheat quality in organic farming is achievable by lower inputs, thereby safeguarding natural resources. (c) 2007 Society of Chemical Industry. Journal of the Science of Food and Agriculture, 2007, V87, N10, AUG 15, pp 1826-1835. 08.1-144 No difference in competitive ability between invasive North American and native European Lepidium draba populations Mckenney J L, Cripps M G, Price W J, Hinz H L, Schwarzlaender M USA, Switzerland Ecology , Plant Sciences , Biodiversity The evolution of increased competitive ability (EICA) hypothesis states that plants introduced into a new range experience reduced herbivory, which in turn results in a shift in resource allocation from herbivore defense to growth. If genotypes of an invasive plant species from its native and introduced ranges are grown under common
Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 91 conditions, introduced genotypes are expected to grow more vigorously than conspecific native genotypes. We tested predictions of the EICA hypothesis with the invasive species Lepidium draba by comparing the growth of genotypes from its native European and introduced western US ranges under common conditions. To test potential differences in competitive ability, we grew L. draba from both continents with either Festuca idahoensis, a weak competitor native to North America, or Festuca ovina, a strong competitor native to Europe. Contrary to EICA predictions, there were no differences in the performance of native and introduced L. draba, independent of whether plants were grown with F. idahoensis, F. ovina, or alone. The strong competitor, F. ovina impaired the growth of L. draba more than the weak competitor F. idahoensis and conversely, F. idahoensis was generally more impaired by L. draba than was F. ovina. While the native F. idahoensis was equally affected by L. draba regardless of range, F. ovina was not: US L. draba had a stronger negative effect on F. ovina growth than European L. draba. Our data suggest that the EICA hypothesis is not suitable to explain the invasion success of L. draba in the US. Instead, the greater competitive effect of L. draba on the North American F. idahoensis and the asymmetric competitive effect of L draba from different origins on F. ovina may indicate superior competitive ability for resources, or the presence of allelopathic traits in L. draba, to which plant species in non-native ranges are maladapted. Plant Ecology, 2007, V193, N2, DEC, pp 293-303. 08.1-145 Effects of heavy metal soil pollution and acid rain on growth and water use efficiency of a young model forest ecosystem Menon M, Hermle S, Günthardt Goerg M S, Schulin R USA, Switzerland Agriculture, Soil Sciences , Modelling , Plant Sciences , Forestry , Ecology In a 4-year lysimeter experiment, we investigated the effects of topsoil heavy metal pollution (3,000 mg kg(-1) Zn, 640 mg kg(-1) Cu, 90 mg kg(-1) Pb and 10 mg kg(-1) Cd) and (synthetic) acid rain (pH 3.5) on tree growth and water use efficiency of young forest ecosystems consisting of Norway spruce (Picea abies), willow (Salix viminalis), poplar (Populus tremula) and birch (Betula pendula) trees and a variety of understorey plants. The treatments were applied in a Latin square factorial design (contaminated vs uncontaminated topsoil, acidified rain vs ambient rain) to 16 open-top chambers, with 4 replicates each. Each open-top chamber contained two lysimeters, one with a calcareous, and the other with acidic subsoil. The four tree species responded quite differently to heavy metal pollution and type of subsoil. The fine root mass, which was only sampled at the end of the experiment in 2003, was significantly reduced by heavy metal pollution in P. abies, P. tremula and B. pendula, but not in S. viminalis. The metal treatment responses of above-ground biomass and leaf area varied between years. In 2002, the heavy metal treatment reduced above-ground biomass and leaf area in P. tremula, but not in the other species. In 2003, metals did not reduce above-ground growth in P. tremula, but did so in the other species. It appears that the responses in aboveground biomass and leaf area, which paralleled each other, were related to changes in the relative competitive strength of the various species in the two experimental years. S. viminalis gained relative to P. tremula in absence of metal stress, in particular on calcareous subsoil, while P. abies showed the largest increases in growth rates in all treatments. Above- and below-ground growth was strongly inhibited by acidic subsoil in S. viminalis and to a lesser degree also in P. abies. In P. abies, this subsoil effect was enhanced by metal stress. Acid rain was not found to have any substantial effect. Whole-system water use efficiency was reduced by metal stress and higher on calcareous than on acidic subsoil. Plant and Soil, 2007, V297, N1-2, AUG, pp 171-183. 08.1-146 Distribution of polychlorinated biphenyls and polybrominated diphenyl ethers in birds of prey from Switzerland Naert C, van Peteghem C, Kupper J, Jenni L, Nägeli H Belgium, Switzerland Zoology , Toxicology Polychlorinated biphenyls (PCBs) and the structurally related polybrominated diphenyl ethers (PBDEs) have been associated with chronic neurotoxicity involving reduced motor activity and impaired attentiveness. Such fleurobehavioral effects indicate that the central nervous system may represent an important target organ for the action of these persistent contaminants in wildlife. As a consequence, the brain of different terrestrial and aquatic birds collected in Switzerland was analysed for PCBs and PBDEs. In parallel, the same contaminants were examined in the accompanying adipose tissue. After clean-up by means of glass columns containing acidified silica, deactivated alumina and anhydrous sodium sulphate,
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