The unevenness of the north Iberian crustal root, a snapshot of an elusive stage in margin reactivation

Crustal roots are identified in collision chains worldwide. Frequently mirroring the summits of mountain systems, they elegantly encapsulate the concept of isostasy. The rugged topography of northern Iberia results from convergence with the European plate during the Alpine orogeny that formed the Pyrenean-Cantabrian mountain range. From east to west, the range comprises three distinct parts: the Pyrenees, the Basque Cantabrian region, and the Cantabrian Mountains. The identification of the Pyrenean root in the 1980s and the observation of a similar geometry beneath the Cantabrian range in the 1990s gave place to the current view of crustal thickening as a continuous feature, resulting from the northward subduction of Iberian crust. Recent developments in rift architecture have delivered a complex rifting template for the area prior to convergence, and contrasting views based on two-dimensional restorations have led to a debate over its evolution. A crucial geophysical constraint is Moho topography. Using two different data sets and techniques, we present the most accurate Moho surface to date, evidencing abrupt changes throughout the orogen. The complexity of hyperextended margins underlies the current Moho topography, and this is ultimately transferred to the nonuniform orogenic pattern found in northern Iberia.

Assessment of the continuity of the orogenic root beneath the Cantabrian-Pyrenean orogen

<p>Crustal roots are a consequence of the contraction of continental masses during orogenesis identified in collisional chains worldwide. Frequently mirroring the summits of mountain systems, they portray the fundamental topic of isostasy. The northern Iberian Peninsula presents a rugged topography resulting of the collision with the European plate and the partial closure of the Bay of Biscay during the Cenozoic. Three differentiated systems formed along, from east to west:  a continental collisional chain, the Pyrenees, occupying the isthmus between Iberia and Europe; facing the Bay of Biscay, a deep Mesozoic basin inverted during contraction, the Basque-Cantabrian region, and in the west a crustal pop-up of Palaeozoic basement, the Cantabrian Mountains. The last two extend underwater in the form of a shortened platform, and an accretionary wedge fossilized by post orogenic sediments. The identification of a crustal root beneath the Pyrenees in the 80´s and the observation of a similar morphology beneath the Cantabrian range in the 90´s gave place to the interpretation of the thickening as a continuous feature of the Iberian crust. <br>However, a reappraisal of vintage refraction profiles and new data from autocorrelations of ambient noise recordings, challenge the alleged continuity. The Pyrenean-Cantabrian orogeny is a three-plate interaction. Beyond the three types of convergent boundaries we may need to introduce the hyperextended-continent destructive boundary, where this is a well-studied example but not the only one. </p>

Evaluation of Sentinel-1 and 2 Time Series for Land Cover Classification of Forest–Agriculture Mosaics in Temperate and Tropical Landscapes

Monitoring forest–agriculture mosaics is crucial for understanding landscape heterogeneity and managing biodiversity. Mapping these mosaics from remotely sensed imagery remains challenging, since ecological gradients from forested to agricultural areas make characterizing vegetation more difficult. The recent synthetic aperture radar (SAR) Sentinel-1 (S-1) and optical Sentinel-2 (S-2) time series provide a great opportunity to monitor forest–agriculture mosaics due to their high spatial and temporal resolutions. However, while a few studies have used the temporal resolution of S-2 time series alone to map land cover and land use in cropland and/or forested areas, S-1 time series have not yet been investigated alone for this purpose. The combined use of S-1 & S-2 time series has been assessed for only one or a few land cover classes. In this study, we assessed the potential of S-1 data alone, S-2 data alone, and their combined use for mapping forest–agriculture mosaics over two study areas: a temperate mountainous landscape in the Cantabrian Range (Spain) and a tropical forested landscape in Paragominas (Brazil). Satellite images were classified using an incremental procedure based on an importance rank of the input features. The classifications obtained with S-2 data alone (mean kappa index = 0.59–0.83) were more accurate than those obtained with S-1 data alone (mean kappa index = 0.28–0.72). Accuracy increased when combining S-1 and 2 data (mean kappa index = 0.55–0.85). The method enables defining the number and type of features that discriminate land cover classes in an optimal manner according to the type of landscape considered. The best configuration for the Spanish and Brazilian study areas included 5 and 10 features, respectively, for S-2 data alone and 10 and 20 features, respectively, for S-1 data alone. Short-wave infrared and VV and VH polarizations were key features of S-2 and S-1 data, respectively. In addition, the method enables defining key periods that discriminate land cover classes according to the type of images used. For example, in the Cantabrian Range, winter and summer were key for S-2 time series, while spring and winter were key for S-1 time series.

Decline and recovery of a large carnivore: environmental change and long-term trends in an endangered brown bear population

Understanding what factors drive fluctuations in the abundance of endangered species is a difficult ecological problem but a major requirement to attain effective management and conservation success. The ecological traits of large mammals make this task even more complicated, calling for integrative approaches. We develop a framework combining individual-based modelling and statistical inference to assess alternative hypotheses on brown bear dynamics in the Cantabrian range (Iberian Peninsula). Models including the effect of environmental factors on mortality rates were able to reproduce three decades of variation in the number of females with cubs of the year ( Fcoy ), including the decline that put the population close to extinction in the mid-nineties, and the following increase in brown bear numbers. This external effect prevailed over density-dependent mechanisms (sexually selected infanticide and female reproductive suppression), with a major impact of climate driven changes in resource availability and a secondary role of changes in human pressure. Predicted changes in population structure revealed a nonlinear relationship between total abundance and the number of Fcoy , highlighting the risk of simple projections based on indirect abundance indices. This study demonstrates the advantages of integrative, mechanistic approaches and provides a widely applicable framework to improve our understanding of wildlife dynamics.