Sensitivity analysis of a parameterization of the stomatal component of the DO3SE model for Quercus ilex to estimate ozone fluxes

A sensitivity analysis of a proposed parameterization of the stomatal conductance (g(s)) module of the European ozone deposition model (DO(3)SE) for Quercus ilex was performed. The performance of the model was tested against measured g(s) in the field at three sites in Spain. The best fit of the model was found for those sites, or during those periods, facing no or mild stress conditions, but a worse performance was found under severe drought or temperature stress, mostly occurring at continental sites. The best performance was obtained when both f(phen) and f(SWP) were included. A local parameterization accounting for the lower temperatures recorded in winter and the higher water shortage at the continental sites resulted in a better performance of the model. The overall results indicate that two different parameterizations of the model are needed, one for marine-influenced sites and another one for continental sites.     

Trophic segregation between sexes in the Black Skimmer revealed through the analysis of stable isotopes

The degree of individual or gender variation when exploiting food resources is an important aspect in the study of foraging ecology within a population. Previous information on non-breeding skimmers obtained through conventional methodologies suggested sex-related differences in prey species. In this study, stable isotope techniques were used to investigate the intraspecific segregation in diet and foraging habits of the Black Skimmer (Rynchops niger intercedens) at Mar Chiquita Coastal Lagoon (37°40′S, 57°22′W), Argentina. These results were compared with contemporary data on the trophic composition obtained by conventional methodologies. Blood samples were taken from birds captured with mist-nets during their non-breeding season. The isotopic signatures of skimmers showed a diet mainly composed of marine prey with some degree of estuarine fish intake. When comparing diet between sexes, males showed enrichment in ¹⁵N compared to females, while no differences were observed in ¹³C. The use of mixing models revealed differences in the relative composition of prey in the diet of male and female skimmers. This study highlights stable isotope analysis as a valuable tool to test inter-individual differences and sexual segregation in trophic ecology of Black Skimmers as compared to conventional methodologies. The results show a trophic segregation in the Black Skimmer during the non-breeding season that can be explained by differences in prey species and larger prey sizes of male skimmers. Our findings have significant implications for conservation since any environmental change occurring at wintering areas might have profound effects on several avian life-history traits, and could be different for males and females due to trophic segregation.     

Exploring Chemical Variables in Ligustrum lucidum Ait. F. Tricolor (Rehd.) Rehd. in Relation to Air Pollutants and Environmental Conditions

Ligustrum lucidum Ait. f. tricolor (Rehd.) Rehd. in relation to atmospheric pollutants in Córdoba city, Argentina. The study area receives regional pollutants and was categorized taking into account traffic level, industrial density, type of industry, location of the sample point in relation to the street corner, treeless condition, and topographic level. Dried weight/fresh weight ratio (DW/FW) and specific leaf area (SLA) were calculated, and concentrations of chlorophylls, carotenoids, total sulfur, soluble proteins, malondialdehyde (MDA), and hydroperoxy conjugated dienes (HPCD) were determined in leaf samples. Sulfur content correlates positively with traffic density and SLA correlates negatively with some combinations of the categorical variables; MDA correlates positively with topographic level and total protein concentration correlates negatively with treeless condition. On the basis of our results, traffic, location of trees, type of industry, situation of a tree with respect to others, and topographic level are the environmental variables to bear in mind when selecting analogous sampling points in a passive monitoring program. An approximation to predict tree injury may be obtained by measuring DW/FW ratio, proteins, pigments, HPCD, and MDA as they are responsible for the major variability of data.     

Assessment of environmental changes in the Orinoco River delta

Major anthropogenic driven changes in the hydrologic and sedimentation patterns of the Orinoco River have had an impact on environmental conditions in the delta. The abrupt water flow reduction from 3,600 to 200 m³ s^–1 in one of its major distributaries resulting from dam construction forced its transformation from a fresh-water body into a tidal channel with an increase in salinity level (as far as 100 km upstream) and with well-mixed water at the mouth and estuarine connection to the Paria Gulf. Three different sectors along this distributary can be identified (indicated by the Na/Cl ratio in the water). As a result, noticeable changes have occurred in the mangrove community which moved about 60 km further upstream. The changes have also promoted the formation of new islands of sediment progradation at the mouth of this distributary, where successional colonization and species replacement by different species of grasses and mangroves take place. Electronic Publication     

The Influence of Linear Elements on Plant Species Diversity of Mediterranean Rural Landscapes: Assessment of Different Indices and Statistical Approaches

This paper mainly aims to study the linear element influence on the estimation of vascular plant species diversity in five Mediterranean landscapes modeled as land cover patch mosaics. These landscapes have several core habitats and a different set of linear elements -habitat edges or ecotones, roads or railways, rivers, streams and hedgerows on farm land- whose plant composition were examined. Secondly, it aims to check plant diversity estimation in Mediterranean landscapes using parametric and non-parametric procedures, with two indices: Species richness and Shannon index.Land cover types and landscape linear elements were identified from aerial photographs. Their spatial information was processed using GIS techniques. Field plots were selected using a stratified sampling design according to relieve and tree density of each habitat type. A 50×20 m² multi-scale sampling plot was designed for the core habitats and across the main landscape linear elements. Richness and diversity of plant species were estimated by comparing the observed field data to ICE (Incidence-based Coverage Estimator) and ACE (Abundance-based Coverage Estimator) non-parametric estimators.The species density, percentage of unique species, and alpha diversity per plot were significantly higher (p < 0.05) in linear elements than in core habitats. ICE estimate of number of species was 32% higher than of ACE estimate, which did not differ significantly from the observed values. Accumulated species richness in core habitats together with linear elements, were significantly higher than those recorded only in the core habitats in all the landscapes. Conversely, Shannon diversity index did not show significant differences.     

Finding threatened forest areas in the central volcanic mountain range conservation area in Costa Rica

The degree at which tropical forests are exposed to human pressure is spatially dependent. Population density, proximity to roads, terrain slope, logging activities and land distribution projects are well known factors inducing deforestation and forest degradation in Latin America. Using expert knowledge to weight these threat factors and a Geographical Information System for spatial modeling, a multi-criteria analysis procedure is presented, that allows stratifying a study region in categories of deforestation threat. The procedure was implemented in the Central Volcanic Mountain Range Conservation Area (CVMRCA) in Costa Rica with the purpose of finding areas with a combination of physical and socioeconomic characteristics that is particularly predisposing to a high probability of deforestation. To validate the map, the CVMRCA was stratified in categories of deforestation risk, and the result was superposed to historical deforestation data of the period 1986–1996. The good correlation between risk category and historical deforestation (r = 0.91, p < 0.001) indicates that the map can be used as a decision support tool for defining priority areas for conservation action.     

Determination of selected quaternary ammonium compounds by liquid chromatography with mass spectrometry. Part I. Application to surface, waste and indirect discharge water samples in Austria

A method for simultaneous quantitative determination of alkyl benzyl, dialkyl and trialkyl quaternary ammonium compounds (QACs) has been developed, validated and subsequently applied to real water samples in Austria. The method employs liquid-liquid extraction (LLE) followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS), using electrospray ionization (ESI) in positive mode. The overall method quantification limits range from 4 to 19ng/L for the enrichment of 500mL water samples and analyte recoveries are between 80 and 99%. The method was applied to 62 of the respective water samples without filtration to avoid the loss of the analytes due to the high adsorption capacity of these compounds. Maxima in the mg/L range, especially in the wastewater of hospitals and laundries, could be detected for the selected target compounds.