Escudero M., Querol X., Ávila A., Cuevas E. (2007) Origin of the exceedances of the European daily PM limit value in regional background areas of Spain. Atmospheric Environment. 41: 730-744.LinkDoi: 10.1016/j.atmosenv.2006.09.014
The origin of the daily exceedances of 50 μg PM10 m-3 (daily limit value or DLV of the EU air quality directive) and of an arbitrary daily value (DV) 35 μg PM2.5 m-3 recorded in 2001-2003 in 13 regional background stations of the Iberian Peninsula were interpreted. This was carried out by means of back-trajectory analysis, available PM model outputs, satellite data and meteorological maps. This allows the detection of high PM episodes on a regional scale and the study of their seasonal and geographical variability. The number of exceedances of the PM10 DLV ranged in 2001-2003 from 6 to 41 depending on the monitoring site. For the selected PM2.5 DV, the range of daily exceedances was 0-10 in the study period. The majority of the PM10 (>70% in most stations) and PM2.5 (17-55% in most stations) exceedances in regional background monitoring stations are caused by African dust outbreaks. These exceedances were less frequent in winter than in summer due to: (a) the frequent long range transport of dust in the warm seasons over Iberia, (b) the re-suspension associated with convective atmospheric dynamics, and (c) the relative low rainfall favouring re-suspension and high residence time of PM. Moreover, a regional contribution of secondary aerosols derived from the efficient photochemical transformation of gaseous precursors may coincide with African transport in summer. Episodes with lack of advective conditions caused 2-29% and 20-50% of the PM10 and PM2.5 exceedances. These occurred mainly in summer due to poor renovation of air masses, increased convective re-suspension, dispersion of pollutants towards rural areas and regional re-circulation and aging of air masses which result in the proliferation of secondary inorganic species. Long-range transport of PM from continental Europe caused exceedances (9-40% and 18-38% of the PM10 and PM2.5 exceedances, respectively), only in northern Iberia because, as the European air masses evolve towards the south, the pollutants suffer dispersion/dilution. Local exceedances are associated with the advection of the clean Atlantic air masses, which cannot increase PM levels to a great extent without the influence of a local source of PM. The proportion of local exceedances of PM10 and PM2.5 ranged 6-33% and 17-40%, respectively. © 2006 Elsevier Ltd. All rights reserved.
Espadaler X., Tartally A., Schultz R., Seifert B., Nagy Cs. (2007) Regional trends and preliminary results on the local expansion rate in the invasive garden ant, Lasius neglectus (Hymenoptera, Formicidae). Insectes Sociaux. 54: 293-301.LinkDoi: 10.1007/s00040-007-0944-7
The expansion process of the invasive garden ant, Lasius neglectus in Europe and Asia is described in terms of: a) local expansion through colony growing measured on four supercolonies (Seva, Debrecen, Buda Castle and Budatétény) from two distant and climatically different countries (Spain, Hungary), and b) regional expansion, using data from all published and several new non-native localities. Short, local distance processes (few meters to 89 m year-1), as colony budding, are two to five orders of magnitude smaller than long regional distances (ten km to >1000 km). This suggests direct human intervention in the invasive spread. The regional trend also shows that the invasive garden ant has been quickly and steadily increasing the number of non native localities (77) and countries (14) it has reached during the last 30 years. © 2007 Birkhäuser Verlag.
Prat E, Serral I, Aloy J, Olivet M, Fusté J, Pons X (2007) Implementacion de un Sistema de Información Geográfica para la gestión de los recursos sanitarios de Catalunya. Actas de la 7ª Setmana Geomàtica. Sensores de alta resolución y sus aplicaciones [CD_ROM]. 2007. Fitxer: pap091.pdf. D.L. B-9432-2007.
Estevan H., Lloret F., Vayreda J., Terradas J. (2007) Determinants of woody species richness in Scot pine and beech forests: climate, forest patch size and forest structure. Acta Oecologica. 31: 325-331.LinkDoi: 10.1016/j.actao.2007.01.003
We analysed patterns of woody species richness in Pinus sylvestris and Fagus sylvatica forests in Catalonia (NE Spain) from forestry inventory databank in relation to climate and landscape structure. Both types of forests are found within the same climatic range, although they have been managed following somewhat different goals. Overall, woody species richness significantly increased when conditions get closer to the Mediterranean ones, with milder temperatures. Differences between the two types of forests arose when comparing the relationship between richness and forest patch size. Woody species richness increased in pine forests with patch size, while the opposite trend was observed in beech forests. This pattern is explained by the different behaviour of structural canopy properties, since leaf area index and canopy cover showed a steeper increase with increasing forest patch size in Fagus forests than in Pinus ones. Accordingly, richness decreased with canopy cover in Fagus plots, but not in Pinus ones. We suggest that these differences would be related to management history, which may have enhanced the preservation of beech stands in larger forest landscape units. © 2007 Elsevier Masson SAS. All rights reserved.
Estiarte M., De Castro M., Espelta J.M. (2007) Effects of resource availability on condensed tannins and nitrogen in two Quercus species differing in leaf life span. Annals of Forest Science. 64: 439-445.LinkDoi: 10.1051/forest:2007021
Seedlings of Quercus ilex and Q. cerrioides, an evergreen and a winter-deciduous oak co-occurring in western-Mediterranean forests, were grown at two light regimes (8 and 36% of photosynthetically active radiation), at two water regimes (500 and 800 mm) and with two nutrient availabilities (standard substrate and 7% increase in soil N). The concentrations of soluble condensed tannins (CT) and nitrogen in the leaves were analyzed to test the phenotypic plasticity of these commonly related parameters in two congeneric species with contrasting leaf habit. Q. ilex contains seven times more CT and a few less N than Q. cerrioides. Light increased CT, whereas neither fertilization nor water had an effect on CT. N concentration was decreased by light, increased by fertilization and not affected by water treatment. Plant growth was increased by light but not affected by fertilization or water treatment. CT were negatively correlated with N concentration. CT of the evergreen species exhibited greater plasticity than the deciduous one as reflected by a steeper negative correlation among nitrogen and CT concentrations in Q. ilex. Given the antiherbivory activity of CT, this implies that in less shaded environments, e.g. canopy aperture by disturbances, leaf tissue quality for herbivores will be much more reduced in Q. ilex than in Q. cerrioides. Higher leaf CT in Q. ilex and its higher plasticity to light availability may explain the higher browsing by sheep in Q. cerrioides than in Q. ilex resprouts, as well as the low recruitment rates of seedlings of the former species, reported in other studies. © INRA, EDP Sciences, 2007.
Filella I., Wilkinson M.J., Llusià J., Hewitt C.N., Peñuelas J. (2007) Volatile organic compounds emissions in Norway spruce (Picea abies) in response to temperature changes. Physiologia Plantarum. 130: 58-66.LinkDoi: 10.1111/j.1399-3054.2007.00881.x
Volatile organic compound (VOC) emissions from Norway spruce (Picea abies) saplings were monitored in response to a temperature ramp. Online measurements were made with a proton transfer reaction - mass spectrometer under controlled conditions, together with plant physiological variables. Masses corresponding to acetic acid and acetone were the most emitted VOCs. The emission rates of m137 (monoterpenes), m59 (acetone), m33 (methanol), m83 (hexanal, hexenals), m85 (hexanol) and m153 (methyl salicylate, MeSa) increased exponentially with temperature. The emission of m61 (acetic acid) and m45 (acetaldehyde), however, increased with temperature only until saturation around 30°C, closely following the pattern of transpiration rates. These results indicate that algorithms that use only incident irradiance and leaf temperature as drivers to predict VOC emission rates may be inadequate for VOCs with lower H, and consequently higher sensitivity to stomatal conductance. © Physiologia Plantarum 2007.
Garcia Pausas J, Lloret F (2007) Spatial and temporal patterns of plant functional types under simulated fire regimes. International Journal of Wildland Fire 16: 484–492
Serra P, Moré G, Pons X (2007) Monitoring Winter Flooding of Rice Fields on the Coastal Wetland of Ebre Delta with Multitemporal Remote Sensing Images. IEEE International Geoscience and Remote Sensing Symposium (IGARSS 2007). Barcelona. Dep. legal: B39244-2007 PID409039.pdf. DOI 10.1109/IGARSS.2007.4423984
Ojeda G (2007) La retenció d'aigua als sòls, explicada mitjançant models fractals. UAB Divulga 09/2007
Gracia M., Montané F., Piqué J., Retana J. (2007) Overstory structure and topographic gradients determining diversity and abundance of understory shrub species in temperate forests in central Pyrenees (NE Spain). Forest Ecology and Management. 242: 391-397.LinkDoi: 10.1016/j.foreco.2007.01.056
Understanding the factors that determine the distributions of understory plants is important because they represent the largest component of temperate forest diversity. In the present study, we investigate the influence of topographic gradients and overstory structure on composition and abundance of understory shrub species in Massís de l'Orri (central Pyrenees, Lleida, Spain). We established 329 plots in two opposing hills in the massif at elevations ranging from 1500 to 2200 m, where we measured understory composition, overstory structure and physiographic features. Overall richness and diversity did not vary with aspect and showed only a small decrease with elevation. However, understory composition showed drastic changes related to elevation and aspect. Most species had differences between slopes, some of them showing higher cover in south-facing plots and the others in north-facing plots. Elevation also influenced percent cover of many understory shrub species, which showed either a decrease (Arctostaphylos uva-ursi, Rosa sp.), a maximum at intermediate values (Cytisus purgans) or an increase (Rhododendron ferrugineum) with elevation. The effect of the two variables was not independent, and percent cover of the different species depended on the overall effect of aspect and elevation. The species with highest occurrence in plots, Vaccinium myrtillus, increased with elevation in south-facing slopes but showed similar values in north-facing slopes. Compared to topographic variables, the effect of overstory variables on understory was considerably smaller. Understory species richness and diversity were inversely but weakly correlated with overstory cover but not with basal area. These overstory variables only affected negatively the presence of C. purgans and Juniperus communis, two shade-intolerant species that decrease their abundance when light decreases. Overall, the results obtained suggest that topographic variables have a stronger influence on understory composition than overstory structure in the study area, which is located in the southern distribution limit of temperate forests in Europe. © 2007 Elsevier B.V. All rights reserved.
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