Influencias humanas en los bosques de pino y de laurel de las islas Canarias

Les fôrets endémiques de pins (Pinus Canariensis) et de lauriers (Laurus spp.) on été l'objet d'une exploitation intensive dès les débuts de l'établissement des espagnols dans les îles occidentales des Canaries, les plus humides de l'Archipel. Les excès des bûcherons, des récolteurs de poix (pez) et des charbonniers (tout d'abord pour la production de sucre), les incendies, les incursions des paysans et de leurs troupeaux et le manque perpétuel de gardiens, tout cela a contribué à ce qu'il fut très tôt considéré comme un désastre écologique. Les conseils municipaux insulaires et, plus tard, des sociétés civiques comme les Sociedades Económicas ont essayé en vain d'enrayer ces ravages. Après quatre siècles de surexploitation ininterrompue les pinèdes on été en grande partie restaurées (avec un succès particulier à Ténérife) au moyen d'un vigoureux programme gouvernemental de repeuplement forestier, aujourd'hui sous la responsabilité d'ICONA (l'0ffice National des Fôrets Espagnol), plus de 25.000 ha ayant été plantées dans les dernières années. Les buts principaux recherchés ont été l'obtention d'un maximum de précipitation horizontale (par dégouttement du brouillard) et la protection des lignes de partage des eaux, plutôt que la production de bois. Ces dernières années on a aussi accordé une importance croissante aux considérations d'ordre esthétique et a l'utilisation des fôrets pour les loisirs. Aujourd'hui les Canaries ont des pinèdes plus étendues et exubérantes que dans la période qui a suivi l'arrivée des Européens il y a cinq siècles, mais dans la plupart des contrées le "monte verde" n 'est guère plus qu'un souvenir et il est devenu depuis longtemps des terrains de culture ou une garrigue secondaire.From the early Spanish establishment on the better-watered western Canary Islands the endemic pine (Pinus canariensis) and laurel (Laurus spp.) forests were the object of intense exploitation. The excesses of the woodcutters, pitch (pez) collectors and charcoal makers (initially for sugar manufacturing), the destructive fires, the incursions of peasant cultivators and their livestock, and the perpetual shortage of reliable guards, all contributed to what was early seen as an ecological disaster in the making. Efforts to stem the devastation by the island councils and, later, by such civic groups as the Sociedades Económicas were to no avail. After four centuries of continued abuse the pinares have been largely reestablished, most successfully on Tenerife, through a vigorous government afforestation program, now under the charge of ICONA. More than 25.000 ha have been planted. The maximizing of horizontal precipitation ("fog drip") and watershed protection, not the production of lumber, has been the guiding rationale. Recently esthetic and recreational values have been given comparable emphasis. The Canaries today support stands of pines of greater luxuriance and extent than have been known at any time since the arrival of Europeans five centuries ago. But the "monte verde", in most areas is little more than a memory, long since converted to cropland or secondary scrub.Els boscos endèmics de pi (Pinus canariensis) i de llorer (Laurus spp.) foren l'objecte d'una intensa explotació des dels inicis de l'establiment d'espanyols a les més humides illes occidentals de les Canàries. Els excessos dels llenyataires, dels recol·lectors de pega (pez) i dels carboners (primer per a la producció de sucre), els incendis destructors, les incursions dels pagesos i de llur bestiar i la perpètua escassesa de guardians de confianca, tot plegat va contribuir a allò que aviat fou considerat un desastre ecològic en marxa. Endebades s'esforcaren a aturar la devastació els ajuntaments insulars i, més tard, els grups cívics com les Sociedades Económicas. Després de quatre segles de sobreexplotació ininterrompuda, els pinares han estat en gran mesura restaurats, de la manera més reexida a Tenerife, mitjancant un vigorós programa governamental de repoblació forestal actualment a càrrec d'ICONA. S'han plantat més de 25.000 ha. La directriu seguida ha estat la d'obtenir el màxim de precipitació horitzontal (degoteig de la boira) i la protecci6 de les divisòries d'aigües, més que no pas la producció de fusta. Darrerament hom ha donat una importància semblant a consideracions estètiques i recreatives. Avui les Canàries tenen pinedes més extenses i exuberants que les conegudes en cap altra època d'ençà de l'arribada dels europeus fa cinc segles. Però a la majoria d'àrees el "monte verde" no és gaire cosa més que un record, i ja fa molt temps que ha esdevingut terra de conreu o matoll secundari

Elevated pCO2 enhances bacterioplankton removal of organic carbon.

Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000-1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 -~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean

Modularity of the Oral Jaws Is Linked to Repeated Changes in the Craniofacial Shape of African Cichlids

The African cichlids of the East-African rift-lakes provide one of the most dramatic examples of adaptive radiation known. It has long been thought that functional decoupling of the oral and pharyngeal jaws in cichlids has facilitated their explosive evolution. Recent research has also shown that craniofacial evolution from radiations in lakes Victoria, Malawi, and Tanganyika has occurred along a shared primary axis of shape divergence, whereby the preorbital region of the skull changes in a manner that is, relatively independent from other head regions. We predicted that the preorbital region would comprise a variational module and used an extensive dataset from each lake that allowed us to test this prediction using a model selection approach. Our findings supported the presence of a preorbital module across all lakes, within each lake, and for Malawi, within sand and rock-dwelling clades. However, while a preorbital module was consistently present, notable differences were also observed among groups. Of particular interest, a negative association between patterns of variational modularity was observed between the sand and rock-dwelling clades, a patter consistent with character displacement. These findings provide the basis for further experimental research involving the determination of the developmental and genetic bases of these patterns of modularity

An adaptive two-arm clinical trial using early endpoints to inform decision making : design for a study of sub-acromial spacers for repair of rotator cuff tendon tears

Background There is widespread concern across the clinical and research communities that clinical trials, powered for patient-reported outcomes, testing new surgical procedures are often expensive and time-consuming, particularly when the new intervention is shown to be no better than the standard. Conventional (non-adaptive) randomised controlled trials (RCTs) are perceived as being particularly inefficient in this setting. Therefore, we have developed an adaptive group sequential design that allows early endpoints to inform decision making and show, through simulations and a worked example, that these designs are feasible and often preferable to conventional non-adaptive designs. The methodology is motivated by an ongoing clinical trial investigating a saline-filled balloon, inserted above the main joint of the shoulder at the end of arthroscopic debridement, for treatment of tears of rotor cuff tendons. This research question and setting is typical of many studies undertaken to assess new surgical procedures. Methods Test statistics are presented based on the setting of two early outcomes, and methods for estimation of sequential stopping boundaries are described. A framework for the implementation of simulations to evaluate design characteristics is also described. Results Simulations show that designs with one, two and three early looks are feasible and, with appropriately chosen futility stopping boundaries, have appealing design characteristics. A number of possible design options are described that have good power and a high probability of stopping for futility if there is no evidence of a treatment effect at early looks. A worked example, with code in R, provides a practical demonstration of how the design might work in a real study. Conclusions In summary, we show that adaptive designs are feasible and could work in practice. We describe the operating characteristics of the designs and provide guidelines for appropriate values for the stopping boundaries for the START:REACTS (Sub-acromial spacer for Tears Affecting Rotator cuff Tendons: a Randomised, Efficient, Adaptive Clinical Trial in Surgery) study

Extremes in dune preservation: controls on the completeness of fluvial deposits

Understanding sedimentary preservation underpins our ability to interpret the ancient sedimentary record and reconstruct palaeoenvironments and palaeoclimates. Dune sets are ubiquitous in preserved river deposits and are typically interpreted based on a model that that describes the recurrence of erosion in a vertical sequence, but without consideringspatial variability. However, spatial variability in flow and sediment transport will change the recurrence of erosion, and therefore dune preservation. In order to better understand the limits of these Interpretations and outline the causes of potential variability in preservation potential, this paper reviews existing work and presents new observations of an extreme end-member of dune preservation: ?form-sets?, formed by dunes in which both stoss- and lee- slopes are preserved Intact. These form-sets do not conform to models that are based on the recurrence of erosion, since erosion does not recur in their case, and can therefore be used to evaluate the assumptions that underpin sedimentary preservation. New Ground Penetrating Radar data from the Río Paraná, Argentina, show dune fields that are buried intact within larger scale barforms. These trains of form-sets are up to 300 m in length, are restricted to unit-bar troughs in the upper 5 m of the channel deposits, occur in >5% of the mid-channel bar deposits, show reactivation surfaces, occur in multiple levels, and match the size of average-flow dunes. A review of published accounts of form-sets highlights a diversity of processes that can be envisaged for their formation: i) abandonment after extreme floods, ii) slow burial of abandoned dune forms by cohesive clay in sheltered bar troughs and meander-neck cut-offs, iii) fast burial by mass-movement processes, and iv)climbing of dune sets due to local dominance of deposition over dune migration.Analysis of these new and published accounts of form-sets and their burial processes highlights that form-sets need not be indicative of extreme floods. Instead, form-sets are closely associated with surrounding geomorphology such as river banks, meander-neck cutoffs,and bars because this larger-scale context controls the local sediment budget and the nature of recurrence of erosion. Locally enhanced preservation by the ?extreme? dominance of deposition is further promoted by finer grain sizes and prolonged changes in flow stage. Such conditions are characteristic, although not exclusive, of large lowland rivers such as the Río Paraná. The spatial control on dune preservation is critical: although at-a-point models adequately describe near-horizontal sets of freely migrating dunes in uniform flows, they are unsuitable for inclined dune co-sets and other cases where multiple scales of bedforms interact. Spatial and temporal variations in flow and sediment transport betweenthe thalweg and different positions on larger bar-forms can change the preservation potential of dunes within river channels. Therefore, dune set thickness distributions are likely grouped in larger-scale units that reflect both formative dune geometries and bar-scale variations inpreservation potential. The multi-scale dynamics of preservation highlighted herein also provides a useful comparison for other sedimentary systemsFil: Reesink, Arnold J.. University Of Binghamton; Estados UnidosFil: Van den Berg, J. H.. University of Utrecht; Países BajosFil: Parsons, Daniel R.. University Of Hull; Reino UnidoFil: Amsler, Mario Luis. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Best, James L.. University of Illinois. Urbana - Champaign; Estados UnidosFil: Hardy, Richard J.. University Of Durham; Reino UnidoFil: Orfeo, Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Szupiany, Ricardo Nicolas. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas; Argentin

Limits of Principal Components Analysis for Producing a Common Trait Space: Implications for Inferring Selection, Contingency, and Chance in Evolution

<b>Background</b> Comparing patterns of divergence among separate lineages or groups has posed an especially difficult challenge for biologists. Recently a new, conceptually simple methodology called the “ordered-axis plot” approach was introduced for the purpose of comparing patterns of diversity in a common morphospace. This technique involves a combination of principal components analysis (PCA) and linear regression. Given the common use of these statistics the potential for the widespread use of the ordered axis approach is high. However, there are a number of drawbacks to this approach, most notably that lineages with the greatest amount of variance will largely bias interpretations from analyses involving a common morphospace. Therefore, without meeting a set of a priori requirements regarding data structure the ordered-axis plot approach will likely produce misleading results.<p></p> <b>Methodology/Principal Findings</b> Morphological data sets from cichlid fishes endemic to Lakes Tanganyika, Malawi, and Victoria were used to statistically demonstrate how separate groups can have differing contributions to a common morphospace produced by a PCA. Through a matrix superimposition of eigenvectors (scale-free trajectories of variation identified by PCA) we show that some groups contribute more to the trajectories of variation identified in a common morphospace. Furthermore, through a set of randomization tests we show that a common morphospace model partitions variation differently than group-specific models. Finally, we demonstrate how these limitations may influence an ordered-axis plot approach by performing a comparison on data sets with known alterations in covariance structure. Using these results we provide a set of criteria that must be met before a common morphospace can be reliably used.<p></p> <b>Conclusions/Significance</b> Our results suggest that a common morphospace produced by PCA would not be useful for producing biologically meaningful results unless a restrictive set of criteria are met. We therefore suggest biologists be aware of the limitations of the ordered-axis plot approach before employing it on their own data, and possibly consider other, less restrictive methods for addressing the same question

Children, family and the state : revisiting public and private realms

The state is often viewed as part of the impersonal public sphere in opposition to the private family as a locus of warmth and intimacy. In recent years this modernist dichotomy has been challenged by theoretical and institutional trends which have altered the relationship between state and family. This paper explores changes to both elements of the dichotomy that challenge this relationship: a more fragmented family structure and more individualised and networked support for children. It will also examine two new elements that further disrupt any clear mapping between state/family and public/private dichotomies: the third party role of the child in family/state affairs and children's application of virtual technology that locates the private within new cultural and social spaces. The paper concludes by examining the rise of the 'individual child' hitherto hidden within the family/state dichotomy and the implications this has for intergenerational relations at personal and institutional levels

Do charismatic species groups generate more cultural ecosystem service benefits?

The relationship between nature and cultural ecosystem service (CES) benefits is well accepted but poorly understood, as is the potential role of biodiversity in the relationship. By means of a public questionnaire survey in Wiltshire, UK, the relationship between the presence of a range of common species groups, species group ‘charisma’, group abundance in the landscape, and the benefit that people felt that they derived from the species groups was investigated for a lowland multifunctional landscape. Findings showed that species group charisma influenced the benefit reported by respondents for current abundance levels, and influenced their response to potential increases or decreases in abundance. Respondents reported high levels of benefit from species groups hypothesised to be charismatic (birds, flowering plants, butterflies) and there was high consistency in the pattern of response. Respondents reported less benefit from groups hypothesised to be less charismatic (beetles/bugs, brambles and nettles), the latter response patterns showing much greater variation. These results could be used to promote a more holistic understanding of the value of biodiversity by educating and informing the public so that they derive benefit not just from the charismatic, but also from the everyday, the commonplace and less obviously charismatic species

Leisure activities and social factors influence the generation of cultural ecosystem service benefits

The relationship between cultural ecosystem services (CES) and the many diverse aspects of biodiversity is complex and multi-faceted. A large public survey in Wiltshire, UK, was used to assess associations between public benefits from certain species groups in the local countryside, and (i) social antecedents, (ii) engagement in different outdoor leisure activities (iii) indirect nature experience via media-related activities and (iv) species group charisma and abundance. Practitioners of leisure activities with a nature-related theme, whether outdoor activities or indoor media-related activities, reported significantly higher levels of benefit from named species groups, as did respondents whose personal background demonstrated an elevated degree of nature-relatedness. Benefits were also related to the charisma of the species group: enhanced benefit through nature-related activities and social factors was significant for less charismatic species, but inconclusive for more charismatic species. Respondents who participated in outdoor leisure activities without a nature focus were unlikely to report enhanced benefits from species groups in the local landscape. To maximise people’s CES benefits from broader aspects of biodiversity it may be necessary to encourage an active interest in biodiversity, leading people to participate or seek knowledge and understanding, and in turn develop a stronger sense of connectedness to nature