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- Author or Editor: J. A. García x
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Mediterranean forests are especially prone to fire, a periodic disturbance that affects all the ecosystem components in different ways. Gathering knowledge on the particular responses and rate of recovery of multiple ecosystem components following a wildfire is crucial to reliably evaluate its consequences on biodiversity. Using eight sampling transects, we studied the changes in four ecosystem components (topsoil, plants, carabids, and staphylinids) during three years after a spring wildfire in a Quercus pyrenaica forest; and compared them with the surrounding unburnt forest (hereafter control). We found great variety of responses to fire suggesting each component may deal with this recurring disturbance via different adaptations, and that the time spent to recover to pre-disturbance conditions depends on the group of focus. Topsoil characteristics were highly variable and minor differences were found between burnt and control transects. Plant community was considerably affected by fire but rapidly recovered exceeding the control forest in species richness and cover, partly due to proliferation of annual herbs. However, plant species composition differed between burnt and control forests during the whole study period. Carabid beetles were more abundant and richer in species in the burnt forest, thanks to the arrival of seed predators favoured by post-fire drier and warmer conditions. Staphylinid beetle composition differed between control and burnt transects during the whole period, although their abundance was strongly variable. Distinct post-fire plant, carabid and staphylinid species composition suggests scattered low-intensity wildfires in this region may help to maintain habitat heterogeneity benefiting biodiversity at the landscape scale.
Abstract
The effect of processing parameters on microencapsulation of oregano essential with maltodextrin:gum arabic using a disk atomiser spray-dryer was evaluated. By means of response surface methodology, the feed flow rate and inlet air temperature were optimised. Powder yield, moisture content, essential oil retention, and antioxidant activity of microparticles were evaluated. The best conditions to produce microencapsulated oregano essential oil were 0.6 L h−1 for feed flow rate and 200 °C for inlet air temperature. With this combination a microencapsulated powder with 89.8% powder yield, 2.1% moisture content, 92.1% essential oil retention, 76 s solubilisation time, 12.9 g of water/100 g of dry matter, 0.3371 g mL−1 bulk density, 0.5826 g mL−1 tapped density, and 8.2 μm of average particle size was produced. The microencapsulation of oregano essential oil preserves the antioxidant and antimicrobial activities of its bioactive compounds.
Abstract
Here we study the relationship between journal quartile rankings of ISI impact factor (at the 2010) and journal classification in four impact classes, i.e., highest impact, medium highest impact, medium lowest impact, and lowest impact journals in subject category computer science artificial intelligence. To this aim, we use fuzzy maximum likelihood estimation clustering in order to identify groups of journals sharing similar characteristics in a multivariate indicator space. The seven variables used in this analysis are: (1) Scimago Journal Ranking (SJR); (2) H-Index (H); (3) ISI impact factor (IF); (4) 5-Year Impact Factor (5IF); (5) Immediacy Index (II); (6) Eigenfactor Score (ES); and (7) Article Influence Score (AIS). The fuzzy clustering allows impact classes to overlap, thereby accommodating for uncertainty related to the confusion about the impact class attribution for a journal and vagueness in impact classes definition. This paper demonstrates the complex relationship between quartiles of ISI impact factor and journal impact classes in the multivariate indicator space. And that several indicators should be used for a distinct analysis of structural changes at the score distribution of journals in a subject category. Here we propose it can be performed in a multivariate indicator space using a fuzzy classifier.
Food partitioning among coexisting species in different habitats remains an important research topic in trophic ecology. In this work, we combined carbon and nitrogen stable isotope ratios and stomach content analyses to investigate differences in diet and niche overlap of two congeneric juvenile mullet species (Mugil curema and Mugil liza) coexisting in a marine surf-zone and an estuarine zone in southern Brazil (29oS). These habitats have contrasting levels of food availability, especially in terms of prey diversity, with higher microalgae diversity in the estuary than in the marine surf-zone. In these contrasting conditions, we predicted that both mullet species will have (a) higher niche overlap and smaller niche breadth at the marine surf-zone due to the common exploration of highly abundant surf-zone diatoms and (b) lower niche overlap and higher niche breadth inside the estuary due to selective feeding on more diverse food resources. Isotope niche areas (measured as standard ellipse areas) were higher in the estuary (6.10 and 6.18) than in the marine surf-zone (3.68 and 3.37) for both M. curema and M. liza, respectively. We observed an overlap of 52% in isotopic niches of both species in the marine surf-zone and none in the estuary. We also found contrasting patterns in the diet composition between species according to the habitat. At the marine surfzone, diatoms of the classes Bacillariophyceae and Coscinodiscophyceae dominated (> 99%) the food content of both mullet species. In contrast, green algae, cyanobacteria, dinoflagellates and flagellates comprised the diet of both species in the estuary. These results could be explained by spatial differences in food availability (especially regarding diversity of microalgae) between both habitats. At the marine site, both species explored the most abundant microalgae available (mostly the surf-zone diatom Asterionellopsis cf. guyunusae and fragments of Coscinodiscus), whereas in the estuary both species shifted their diets to explore the greater diversity of microalgae resources. Overall, our findings revealed that niche partitioning theory could not fully predict changes in breadth and overlap of food niches of estuarine dependent fish species with complex life cycles encompassing marine to estuarine systems with contrasting food availabilities.
Abstract
ZnxMg1-xFe2O4 mixed oxide spinels (x=0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) were prepared by conventional solid state reaction method. Bulk and surface characterization of these ferrites were carried out by different techniques. The ratios Zn/Fe and Mg/Fe determined by PIXE and AAS were nearly as expected from the synthesis mixture, i.e. following the substitution model. XRD shows only a spinel structure (fcc) with increasing lattice parameter as x increases from 0 to 1. The bulk ratios of tetrahedral to octahedral sites occupied by Fe cations measured by NGR are in good agreement with the theoretical bulk stoichiometry. LEIS results indicate a Mg substitution by Fe cations at the surface. Only octahedral sites are proposed at the surface. The transition from inverse to normal spinel was follow through NGR-spectra occurring at x=0.4.
Abstract
A university may be considered as having dimension-specific prestige in a scientific field (e.g., physics) when a particular bibliometric research performance indicator exceeds a threshold value. But a university has multidimensional prestige in a field of study only if it is influential with respect to a number of dimensions. The multidimensional prestige of influential fields at a given university takes into account that several prestige indicators should be used for a distinct analysis of the influence of a university in a particular field of study. After having identified the multidimensionally influential fields of study at a university their prestige scores can be aggregated to produce a summary measure of the multidimensional prestige of influential fields at this university, which satisfies numerous properties. Here we use this summary measure of multidimensional prestige to assess the comparative performance of Spanish Universities during the period 2006–2010.
In arid and semi-arid ecosystems, the presence of woody neighbours affects the existence of several herbaceous species by modifying critical aspects of the environment (e.g., soil humidity, nutrient content or light availability) beneath their canopies. Herbaceous species growing in the understory of Pinus pinaster may be distinct from those in open areas due to litter fall, light interception and changes in nutrient availability. We suggest that the overall effect of woody neighbours on herbaceous layer diversity may vary with the scale focus of analysis. To examine this hypothesis, we collected data on the abundance of herbaceous species in open pineland forests of the central Iberian Peninsula (Spain) using sample quadrats of 0.5 m × 0.5 m distributed beneath, at the edge, and outside the canopy of pines in a landscape composed of dunes and plains. The results of CCA ordination revealed significant spatial segregation of herbaceous species reflecting the occurrence of pines and dunes in the landscape. Nested ANOVA disclosed markedly lower species richness beneath the pines, particularly in the dune sites. Species richness partitioning showed higher pine-induced heterogeneity than expected from the sample-based randomized model, leading to significantly increased species richness at the patch level. Hence, the outcome of pine-induced effects on the herbaceous plant diversity is scale-dependent, negative if we focus on separate communities, but positive if the scale focus is extended to whole patches comprising the sum of communities beneath, at the edge, and outside pine tree canopies. These results emphasize the necessity of using various scale perspectives to clarify the different ways in which pines and other woody nurse species affect structure of herbaceous communities in semi-arid Mediterranean ecosystems.
A mass and energy balance to provide microbial growth yield efficiency in soil
Sensitivity to metal layering phosphates
Abstract
The control on the CO2 coming from soil handling, makes necessary the introduction of new methodologies that inform about the capacity of the soil as a carbon sink and about the carbon decay. It can be performed through the microbial growth yield efficiency concept by calorimetry and enthalpy balances. Here it is examined the sensitivity of these indicators to two metal layering phosphates, AZP [(NH)4Zn2(PO)4(HPO)4] and AIP [(NH)4Fe(PO)4H2O] to assess about their soil impact. Both compounds caused metabolic changes on soil microbial biomass when compared to appropriated references indicating that the proposed methodology is sensitive to different inorganic sources of microbial growth.
Abstract
The activity of 
-emitting radionuclides is usually measured by semiconductor detectors (surface barrier or ion implanted). Overlapping and composite bands are quite common problems depending on energy differences of the radionuclides and counting source preparation. The classical approach to activity quantification is based on peak integration and, when it is used, overlapping may be overcome by a detailed study of each case, whereas composite bands can not be completely resolved. Here, spectra of the -emitting plutonium isotopes, obtained by ion implanted semiconductor detectors, have been used to compare the classical approach with a multivariate calibration method (MVC-PLS). The study is performed at environmental activity levels (0–52 dpm). The relative errors obtained for239+240Pu activity determination, using either the classical or the MVC-PLS approach with replicates, are good enough to quantify isotopes at low level activities. The distribution of relative errors is asymmetric, with a positive component for 0–10.5 dpm subset, in the classical approach whereas it is more symmetric in the MVC-PLS method. The results show that the classical approach depends on peak overlap, whereas the MVC does not. As a whole, MVC is a more robust method than the classical approach. Composite bands were studied using the239Pu–240Pu mixture; the MVC approach did not allow individual quantification due to the lack of signal reproducibility. This instability does not affect the regular integration procedures but it is important in the deconvolution processes. The lack of reproducibility is related to the source preparation process.
