Klumpp A., Ansel W., Klumpp G., Calatayud V., Pierre Garrec J., He S., Peñuelas J., Ribas A., Ro-Poulsen H., Rasmussen S., Sanz M.J., Vergne P. (2006) Ozone pollution and ozone biomonitoring in European cities. Part I: Ozone concentrations and cumulative exposure indices at urban and suburban sites. Atmospheric Environment. 40: 7963-7974.EnllaçDoi: 10.1016/j.atmosenv.2006.07.017
In the frame of a European research project on air quality in urban agglomerations, data on ozone concentrations from 23 automated urban and suburban monitoring stations in 11 cities from seven countries were analysed and evaluated. Daily and summer mean and maximum concentrations were computed based on hourly mean values, and cumulative ozone exposure indices (Accumulated exposure Over a Threshold of 40 ppb (AOT40), AOT20) were calculated. The diurnal profiles showed a characteristic pattern in most city centres, with minimum values in the early morning hours, a strong rise during the morning, peak concentrations in the afternoon, and a decline during the night. The widest amplitudes between minimum and maximum values were found in central and southern European cities such as Düsseldorf, Verona, Klagenfurt, Lyon or Barcelona. In the northern European cities of Edinburgh and Copenhagen, by contrast, maximum values were lower and diurnal variation was much smaller. Based on ozone concentrations as well as on cumulative exposure indices, a clear north-south gradient in ozone pollution, with increasing levels from northern and northwestern sites to central and southern European sites, was observed. Only the Spanish cities did not fit this pattern; there, ozone levels were again lower than in central European cities, probably due to the direct influence of strong car traffic emissions. In general, ozone concentrations and cumulative exposure were significantly higher at suburban sites than at urban and traffic-exposed sites. When applying the newly established European Union (EU) Directive on ozone pollution in ambient air, it was demonstrated that the target value for the protection of human health was regularly surpassed at urban as well as suburban sites, particularly in cities in Austria, France, northern Italy and southern Germany. European target values and long-term objectives for the protection of vegetation expressed as AOT40 were also exceeded at many monitoring sites. © 2006 Elsevier Ltd. All rights reserved.
Klumpp A., Ansel W., Klumpp G., Vergne P., Sifakis N., Sanz M.J., Rasmussen S., Ro-Poulsen H., Ribas A., Peñuelas J., Kambezidis H., He S., Garrec J.P., Calatayud V. (2006) Ozone pollution and ozone biomonitoring in European cities Part II. Ozone-induced plant injury and its relationship with descriptors of ozone pollution. Atmospheric Environment. 40: 7437-7448.EnllaçDoi: 10.1016/j.atmosenv.2006.07.001
Within the scope of a biomonitoring study conducted in twelve urban agglomerations in eight European countries, the ozone-sensitive bioindicator plant Nicotiana tabacum cv. Bel-W3 was employed in order to assess the occurrence of phytotoxic ozone effects at urban, suburban, rural and traffic-exposed sites. The tobacco plants were exposed to ambient air for biweekly periods at up to 100 biomonitoring sites from 2000 to 2002. Special emphasis was placed upon methodological standardisation of plant cultivation, field exposure and injury assessment. Ozone-induced leaf injury showed a clearly increasing gradient from northern and northwestern Europe to central and southern European locations. The strongest ozone impact occurred at the exposure sites in Lyon and Barcelona, while in Edinburgh, Sheffield, Copenhagen and Düsseldorf only weak to moderate ozone effects were registered. Between-site differences within local networks were relatively small, but seasonal and inter-annual differences were strong due to the variability of meteorological conditions and related ozone concentrations. The 2001 data revealed a significant relationship between foliar injury degree and various descriptors of ozone pollution such as mean value, AOT20 and AOT40. Examining individual sites of the local monitoring networks separately, however, yielded noticeable differences. Some sites showed no association between ozone pollution and ozone-induced effects, whereas others featured almost linear relationships. This is because the actual ozone flux into the leaf, which is modified by various environmental factors, rather than ambient ozone concentration determines the effects on plants. The advantage of sensitive bioindicators like tobacco Bel-W3 is that the impact of the effectively absorbed ozone dose can directly be measured. © 2006 Elsevier Ltd. All rights reserved.
Llusià J., Peñuelas J., Alessio G.A., Estiarte M. (2006) Seasonal contrasting changes of foliar concentrations of terpenes and other volatile organic compound in four dominant species of a Mediterranean shrubland submitted to a field experimental drought and warming. Physiologia Plantarum. 127: 632-649.EnllaçDoi: 10.1111/j.1399-3054.2006.00693.x
To test the effect of forecasted drought and warming conditions for the next decades by GCM and ecophysiological models on foliar concentrations of volatile organic compounds (VOCs) and especially of volatile terpenes, we studied four typical Mediterranean woody plants (Pinus halepensis L., Pistacia lentiscus L., Rosmarinus officinalis L. and Globularia alypum L.) under a field experimental drought and warming generated using automatically sliding curtains. Terpenes were detected in the four studied species (R. officinalis L., P halepensis L., Pistacia lentiscus L. and G. alypum L.). In general, maximum concentrations of terpenes were found in the coldest periods and minimum concentrations in the summer. Their concentrations ranged between 0.003 mg g-1 DM (eugenol) in G. alypum under drought conditions and 37 mg g-1 DM in R. officinalis under control conditions. Main volatile terpenes found in all studied species except in G. alypum were α-pinene, camphene, β-pinene, β-phellandrene and caryophyllene. In general, VOC leaf concentrations increased when soil moisture increased and decreased when air temperature increased. However, contrasting not consistent responses to the drought and warming treatments were found among species, seasons and years. For example, in P. halepensis, the concentrations decreased in response to drought in winter and instead increased in summer. Contrarily, drought decreased concentrations in summer and increased them in winter in Pistacia lentiscus. In any case, the data on seasonal VOC concentration in Mediterranean woody species provided here will add new knowledge of seasonal variation in essential oil contents of these species. These data might help in the study of flammability of Mediterranean ecosystems and in improving prediction algorithms, inventories and modelling of monoterpene emissions in response to climate change, which mostly do not consider the changes in concentration under drought stress. However, the lack of general and consistent response patterns to increasing drought and warming among species, seasons and years found here makes this task difficult. Copyright © Physiologia Plantarum 2006.
Ogaya R., Peñuelas J. (2006) Contrasting foliar responses to drought in Quercus ilex and Phillyrea latifolia. Biologia Plantarum. 50: 373-382.EnllaçDoi: 10.1007/s10535-006-0052-y
Leaf morphology, longevity, and demography were examined in Quercus ilex and Phillyrea latifolia growing in a holm oak forest in Prades mountains (northeast Spain). Four plots (10 × 15 m) of this forest were submitted to an experimental drought during three years (soil moisture was reduced about 15 %). Leaf area, thickness and leaf mass per area ratio (LMA) were measured in sun and shade leaves of both species. Leaf longevity, the mean number of current-year shoots produced per previous-year shoot (Sn/Sn-1), the mean number of current-year leaves per previous-year shoot (Ln/Sn-1), and the percentage of previous-year shoots that developed new ones were measured once a year, just after leaf flushing. LMA and leaf thickness increased since leaf unfolding except in summer periods, when stomatal closure imposed low photosynthetic rates and leaves consumed their reserves. LMA, leaf area, and leaf thickness were higher in Q. ilex than in P. latifolia, but leaf density was higher in the latter species. Drought reduced the leaf thickness and the LMA of both species ca. 2.5 %. Drought also increased leaf shedding up to ca. 20 % in Phillyrea latifolia and decreased it up to ca. 20 % in Q. ilex. In the later species, Sn/Sn-1 decreased by 32 %, Ln/Sn-1 by 41 %, percentage of shoots developed new ones by 26 %, and leaf area by 17 %. Thus the decrease of leaf number and area was stronger in the less drought-resistant Q. ilex, which, under increasingly drier conditions, might lose its current competitive advantage in these Mediterranean holm oak forests. © 2006 Institute of Experimental Botany, Academy of Sciences of the Czech Republic.
Owen S.M., Peñuelas J. (2006) Response to Firn and Jones: Volatile isoprenoids, a special case of secondary metabolism . Trends in Plant Science. 11: 113-114.EnllaçDoi: 10.1016/j.tplants.2006.01.002
[No abstract available]
Owen S.M., Peñuelas J. (2006) Response to Pichersky et al.: Plant volatile isoprenoids and their opportunistic functions. Trends in Plant Science. 11: 423-0.EnllaçDoi: 10.1016/j.tplants.2006.07.009
Peñuelas J., Sardans J., Stefanescu C., Parella T., Filella I. (2006) Lonicera implexa leaves bearing naturally laid eggs of the specialist herbivore Euphydryas aurinia have dramatically greater concentrations of iridoid glycosides than other leaves. Journal of Chemical Ecology. 32: 1925-1933.EnllaçDoi: 10.1007/s10886-006-9118-8
We tested in the field the hypothesis that the specialist butterfly Euphydryas aurinia (Lepidoptera: Nymphalidae, Melitaeinae) lays eggs on leaves of Lonicera implexa (Caprifoliaceae) plants with greater iridoid concentrations. We conducted our investigations in a Mediterranean site by analyzing leaves with and without naturally laid egg clusters. There were no significant differences in iridoid glycoside concentrations between leaves from plants that did not receive eggs and the unused leaves from plants receiving eggs, a fact that would seem to indicate that E. aurinia butterflies do not choose plants for oviposition by their iridoid content. However, the leaves of L. implexa that bore egg clusters had dramatically greater (over 15-fold) concentrations of iridoid glycosides than the directly opposite leaves on the same plant. These huge foliar concentrations of iridoids (15% leaf dry weight) may provide specialist herbivores with compounds that they either sequester for their own defense or use as a means of avoiding competition for food from generalist herbivores. Nevertheless, it may still be possible that these high concentrations are detrimental to the herbivore, even if the herbivore is a specialist feeder on the plant. © Springer Science + Business Media, Inc. 2006.
Ribas A., Peñuelas J. (2006) Surface ozone mixing ratio increase with altitude in a transect in the Catalan Pyrenees. Atmospheric Environment. 40: 7308-7315.EnllaçDoi: 10.1016/j.atmosenv.2006.06.039
Tropospheric ozone mixing ratios and their phytotoxicity and NO2 mixing ratios were measured along an altitudinal gradient at the Meranges valley in the Catalan Pyrenees. Biweekly measurements using Radiello passive samplers were taken along a transect of seven stations ranging from 1040 to 2400 m ASL from May to December 2004. As well, at each station biweekly evaluations were made of the visual symptoms of ozone damage in Bel-W3 and Bel-B tobacco cultivars. Whereas ozone mixing ratios increased with altitude, NO2 mixing ratios decreased from the valley floor upwards. Ozone damage rates were found to vary with time and space depending on local environmental and meteorological conditions, although the highest ozone damage to foliage was found in the stations at greatest altitude, especially wherever altitudinal micrometeorological conditions enhanced plant sensitivity. © 2006 Elsevier Ltd. All rights reserved.
Ogaya R, Peñuelas J (2006) Set anys de sequera experimental a l'alzinar de Prades. Efectes en al fenologia reproductiva de les principals espècies dominants. Els límits de la pressió humana en el medi natural. Paratge Natural d'Interès Nacional de Poblet (ed). Actes de les Segones Jornades sobre el Bosc de Poblet.. L'Espluga de Francolí. pp. 259-267
Sardans J., Peñuelas J. (2006) Introduction of the factor of partitioning in the lithogenic enrichment factors of trace element bioaccumulation in plant tissues. Environmental Monitoring and Assessment. 115: 473-498.EnllaçDoi: 10.1007/s10661-006-7241-1
Bioindicators are widely used in the study of trace elements inputs into the environment and great efforts have been conducted to separate atmospheric from soil borne inputs on biomass accumulation. Many monitoring studies of trace element pollution take into account the dust particles located in the plant surface plus the contents of the plant tissues. However, it is usually only the trace element content in the plant tissues that is relevant on plant health. Enrichment factor equations take into account the trace element enrichment of biomasses with respect soil or bedrocks by comparing the ratios of the trace element in question to a lithogenic element, usually Al. However, the enrichment equations currently in use are inadequate because they do not take into account the fact that Al (or whichever reference element) and the element in question may have different solubility-absorption-retention levels depending on the rock and soil types involved. This constrain will become critical when results from different sites are compared and so in this article we propose that the solubility factors of each element are taken into account in order to overcome this constrain. We analysed Sb, Co, Ni, Cr, Pb, Cd, Mn, V, Zn, Cu, As, Hg, and Al concentration in different zones of Catalonia (NE Spain) using the evergreen oak Quercus ilex and the moss Hypnum cupressiforme as target species. We compared the results obtained in rural and non industrial areas with those from the Barcelona Metropolitan Area. We observed differences in Al concentrations of soils and bedrocks at each different site, together with the differences in solubility between Al and the element in question, and a weak correlation between total soil content and water extract content through different sites for most trace elements. All these findings show the unsuitability of the current enrichment factors for calculating lithospheric and atmospheric contributions to trace element concentrations in biomass tissues. The trace element enrichment factors were calculated by subtracting the part predicted by substrate composition (deduced from water extracts from soils and bedrock) from total concentrations. Results showed that for most of the trace elements analysed, trace elements enrichment factors were higher inside the Barcelona Metropolitan Area than outside, a finding that indicates that greater atmospheric inputs occur in urban areas. The results show that the most useful and correct way of establishing a reference for lithospheric and atmospheric inputs into the plant tissues is, first, to analyse samples of the same plant species collected from a number of sites possessing similar environmental conditions (climate, vegetation type, soil type) and, second, to use this new enrichment factor obtained by subtracting from the total concentration in plant tissue the predicted contribution of soil or bedrock extracts instead of that of total soil or bedrock concentrations. © Springer Science+Business Media, Inc. 2006.
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