Shocks and spatial regime fades in Spain's international migration distribution.

Using an exploratory space-time analysis called spMorph, this article explores how the spatial distribution of international migration across the Spanish provinces has evolved over the period 1998-2010. The chief advantage of this approach is that it permits the unambiguous identification of two key components in a spatial redistribution process, namely the shocks to the spatial distribution and the duration of regime fades. The results of the analysis show that administrative regions do not provide a reliable picture of the real dynamics in Spain’s international migration distribution. In addition, the identification of two spatial shocks reveals the existence of three spatial regimes that consistently characterize the various phases that international migration has been through since the late 1990s

Burrowing herbivores alter soil carbon and nitrogen dynamics in a semi-arid ecosystem, Argentina

Activities of burrowing herbivores, including movement of soil and litter and deposition of waste material, can alter the distribution of labile carbon (C) and nitrogen (N) in soil, affecting spatial patterning of nutrient dynamics in ecosystems where they are abundant. Their role in ecosystem processes in surface soil has been studied extensively, but effects of burrowing species on processes in subsurface soil remain poorly known. We investigated the effects of burrowing and grazing by plains vizcachas (Lagostomus maximus, Chinchilidae), a large colonial burrowing rodent native to South America, on the distribution and dynamics of C and N in soil of a semi-arid scrub ecosystem in central Argentina. In situ N mineralization (Nmin), potential Nmin and CO2 emissions were measured in surface soil (0-10 cm) and soil at the mean depth of burrows (65 ± 10 cm; mean ± 1 SD) in five colonial burrow systems and adjacent grazed and ungrazed zones. Decomposition and N dynamics of vizcacha feces on the soil surface and in burrow soil was assessed using litterbags. Total C and N in soil in burrows were 1.6 and 5.5 times greater than in undisturbed soil at similar depths, and similar to amounts in surface soil. Inorganic N, particularly NO3-, was consistently highest in burrows, intermediate in surface soil on burrow systems, and relatively low in all other zones. Despite high C and N content in all burrows, in situ net Nmin was highly variable in burrow soil. Feces decomposed and released N more rapidly in burrow soil. Laboratory incubations indicated that soil moisture limited Nmin under conditions that typically characterize burrow microclimate, and that rates increased dramatically at soil moisture contents \u3e25% field capacity, which likely occurs during pulsed rainfall events. Thus, the high and seasonally stable NO3- content in burrow soil likely originated from the accumulation of pulsed mineralization events over time. Burrowing and waste deposition by vizcachas produced “resource islands” at the landscape scale. At a measured density of 0.3 burrow systems per hectare, colonial burrow soil contained an amount of inorganic N equal to 21% and 30% of plant-available N in surface soil and subsurface soil, respectively, in an area that represented only 0.35% of the landscape. Our study indicates that burrowing and deposition of waste results in a highly active subsurface layer in which C and N dynamics function much like surface soil when soil moisture is not limiting

Invasive and non-invasive congeneric Centaurea (Asteraceae) show contrasting patterns of herbivory by snails

Background and aims – Once introduced into new regions, exotic species often experience shifts in resource allocation in response to the different environmental conditions found in the introduction range. Plants naturally respond to specialist herbivores with quantitative defences, by producing large amounts of toxic and non-toxic compounds that typically difficult digestion (e.g. tannins, cellulose), and to generalist herbivores with qualitative defences, like specialized noxious chemicals (e.g. alkaloids). The Shifting Defence Hypothesis (SDH) poses that invasive plants decrease the production of defences against specialist herbivores in their introduction range, where specialist herbivores are usually absent, while boosting the production of defences against generalist herbivores. Methods – We empirically assessed the response of a generalist herbivore, the common garden snail (Helix aspersa), to feeding with leaves of the annual herb Centaurea sulphurea, native to Europe and naturalized in North America; and the congeneric species C. solstitialis, which is also native to Europe and invasive in the Americas. Key results – Snails fed with leaves from Spanish native populations the non-invasive C. sulphurea grew significantly less compared to snails fed with leaves from non-native California. For snails fed with the invasive C. solstitialis significant differences were also found among regions, but the response was more complex, depending on population, with snails fed with Turkish and Australian plants presenting higher growth rates than the rest of the regions. Conclusions – Overall, our results stressed the importance of colonization history in shaping adaptive responses, and the stochasticity associated with colonization events of two closely related species, with contrasting invasive success and responses to herbivory.Fil: Filipe, João C.. Universidad de Coimbra; PortugalFil: Jorge, Andreia. Universidad de Coimbra; PortugalFil: Eren, Ozkan. Adnan Menderes Universitesi; TurquíaFil: Sotes, Gastón. Universidad de Concepción. Facultad de Ciencias Naturales y Oceanográficas. Departamento de Botánica; Chile. Universidad de Chile; ChileFil: Hierro, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Montesinos, Daniel. Universidad de Coimbra; Portuga

Sensory evaluation of bitterness and astringency sub-qualities of wine phenolic compounds: synergistic effect and modulation by aromas

[EN] Mouthfeel characteristics of wine phenolic compounds (catechin, epicatechin, coumaric acid, caffeic acid, protocatechuic acid and gallic acid) were evaluated by sensory analysis using a Labeled Magnitude Scale for rating the intensity of the perceived sensations. Synergisms on bitterness and on astringent sub-qualities were detected when the phenolic compounds were tested as mixtures in comparison to individual compounds, maintaining the total amount of stimulus constant in all tasted samples. Principal component analysis was applied to observe trends in the data and to indicate relationships between phenolic substances and sensory attributes. It allowed us to easily visualize the synergistic effect discussed above. To our knowledge, this is the first time that astringency synergism between phenolic compounds has been described. This research also shows that wine aromas may modulate the perception of the astringency. In this study, the addition of volatile compounds increased the intensity of the astringent perception of the flavanol solutions and also its persistence

Feasibility study on the use of near infrared spectroscopy to determine flavanols in grape seeds

[EN] The potential of near infrared spectroscopy to determine the content of flavanols directly recording the infrared spectra of grape seeds has been evaluated. Moreover, the study shows the potential of this technique to obtain qualitative information related to the samples. In this case, the feasibility to discriminate between possible vineyards of origin has also been evaluated. Modified Partial Least Squares (MPLS) regression was used to develop the quantitative models in order to predict the content of flavanols. These models have been validated showing differences between 3.5% and 14.3% in the external validation. Moreover, Discriminant Partial Least Squares algorithm was used in the qualitative analysis to distinguish between two possible vineyards of origin and showed a high degree of accuracy. Prediction rates of samples correctly classified with a mean of 95% in internal validation and 97% in external validation were obtained. The procedure reported here seems to have an excellent potential for a fast and reasonably inexpensive analysis of these flavanols in grape seeds and could also be a tool to distinguish between possible vineyards of origin

Influence of the physiological stage and the content of soluble solids on the anthocyanin extractability of Vitis vinifera L. cv. Tempranillo grapes

[EN] The influence and the extent of the anthocyanin extractability from grape skins at different physiological stages and different soluble solids contents within each stage were investigated. For this purpose three different physiological stages (pre-harvest, harvest and over-ripening) and three soluble solids contents (22, 24 and 26 °Brix) within each stage were taken into account using Vitis vinifera L. cv. Tempranillo. This study revealed the influence of physiological stages and soluble solids contents on the amounts of anthocyanins. The most important factor was the physiological stage although the soluble solid contents effect was also relevant, especially for anthocyanins monoglucosides. The highest contents in anthocyanins were found at pre-harvest, following by harvest and finally at over-ripening. Within each physiological stage, the relative abundance of acylated derivatives was influenced by the soluble solids contents. The percentages of acylated anthocyanins tend to decrease as the soluble solids contents. Differences in the anthocyanin extractabilities were highly influenced by the physiological stages and in a lesser extent by the soluble solids contents. The lowest extraction percentages were obtained in pre-harvest samples whatever soluble solids contents. Over-ripening samples present the lowest contents of anthocyanins but these compounds are easily released from tissues to the hydroalcoholic solution providing the highest extraction percentages. Generally, non-acylated anthocyanins were better extracted than the acylated anthocyanins

Evaluation of sensory parameters of grapes using near infrared spectroscopy

[EN] Grape seed and skin sensory parameters are important characteristics in making decisions concerning the optimal harvest time and producing high-quality red wines. The potential of near infrared spectroscopy to determine several sensory parameters of seeds and skins was evaluated. Taste (sourness), texture (astringency, tannic intensity, dryness and hardness), visual (colour) and olfactory (intensity and type of aroma) attributes were considered. Calibration models were performed by modified partial least squares regression. The differences between sensory analysis and NIRS analysis in external validation were lower in the case of seeds; they were between 4.5% for hardness and 8.7% for colour. For the skins, differences in external validation were between 9.8% for tannic intensity and 13.7% for astringency. The results obtained show that NIRS technology has considerable potential for predicting the above sensory attributes

Determination of phenolic compounds of grape skins during ripening by NIR spectroscopy

[EN] The potential of near infrared spectroscopy (NIRS) to determine the content of phenolic compounds in red grapes has been evaluated. The near infrared spectra of intact grapes and grape skins throughout maturity were recorded using a fibre-optic probe and a transport quartz cup, respectively. Reference values of phenolic compounds were obtained by HPLC-DAD-MS. Modified Partial Least Squares (MPLS) regression was used to develop the quantitative models for flavanols, flavonols, phenolic acids, anthocyanins and total phenolic compounds. The procedure reported here seems to have an excellent potential for fast and reasonable cost analysis. The results of this work show that the models developed using NIRS technology together with chemometric tools allow the quantification of total phenolic compounds and the families of main phenolic compounds in grape skins throughout maturation. The validation of these models showed the best results for the determination of flavonols (differences between HPLC and NIRS of 7.8% using grapes and 10.7% using grape skins) in the external validation procedure. Good results in the external validation were also obtained for the determination of total phenolic compounds (differences of 11.7% using grapes and 14.7% using grape skins). The best results were generally obtained recording the spectra directly in intact grapes

Colour and pigment composition of red wines obtained from co-maceration of Tempranillo and Graciano varieties

[EN] The Vitis vinifera L. cv Graciano is often used as an integral component of Rioja wines because it is considered to contribute significantly to the quality of Tempranillo based wines. The aim of this work was to determine the effect of the incorporation of the Graciano variety on the colour and pigment composition of Tempranillo based wine and to evaluate the possible differences between blending Tempranillo with Graciano varietal wine (W wine) in contrast to a wine obtained by mixing these two grape varieties in the prefermentative maceration step (M wine). Results indicated that pigment extraction and retention in M wine was higher than in Tempranillo (T) wine. Colour differences (DeltaE(ab)(*)) between wines at the end of the study (after 12 months in bottles) were detectable by the human eye (DeltaE(ab)(*) > or = 3) in all cases except for T and W. These wines have indistinguishable colours even when using analytical methods (DeltaE(ab)(*) < or = 1). Regarding hue h(ab), T and W presented higher values (more orange-red) than Graciano (G) and M (more blue-red). PCA allowed the colour and composition analytical data to be reduced to a small number of principal components that could separate successfully between T and G wines and between the different steps of the winemaking process