Crustacean decapod assemblages associated with fragmented Posidonia oceanica meadows in the Alboran Sea (Western Mediterranean Sea): composition,temporal dynamics and influence of meadow structure          下载免费PDF全文

Ángel Mateo‐Ramírez  Javier Urra  Pablo Marina  José L. Rueda  José Enrique García Raso 《Marine Ecology》2016,37(2):344-358

The decapod assemblage associated with a Posidonia oceanica meadow located near its western limit of biogeographic distribution was studied over an annual cycle. Fauna samples were taken seasonally over a year (five replicates per season) in two sites located 7 km apart, using a non‐destructive sampling method (airlift sampler) for the seagrass. The dominant species of the assemblage, Pisidia longimana, Pilumnus hirtellus and Athanas nitescens, were associated with the protective rhizome stratum, which is mainly used as a nursery. The correlations between decapod assemblage structure and some phenological parameters of the seagrass shoots and wave height were negative or null, which reflects that species associated with the rhizome had a higher importance than those associated with the leaf stratum. The abundance and composition of the decapod assemblage as well as the ecological indexes displayed a seasonality trend with maximum values in summer‐autumn and minimum in winter‐spring, which were related to the seawater temperature and the recruitment periods of the dominant species. The spatial differences found in the structure and dynamics of the assemblages may be due to variations in the recruitment of the dominant species, probably as a result of the influence of local factors (e.g. temperature, currents) and the high dispersal ability of decapods, together with the patchy configuration and the surrounding habitats. The studied meadows are fragmented and are integrated within a mosaic of habitats (Cymodocea nodosa patches, algal meadows, rocky and sandy bottoms), which promotes the movement of individuals and species among them, maintaining a high species richness and evenness.  相似文献   

Population genetic diversity and structure of a dominant tropical seagrass,Cymodocea rotundata,in the Western Pacific region          下载免费PDF全文

Dan M. Arriesgado  Hiroyuki Kurokochi  Yuichi Nakajima  Yu Matsuki  Wilfredo H. Uy  Miguel D. Fortes  Wilfredo L. Campos  Kazuo Nadaoka  Chunlan Lian 《Marine Ecology》2016,37(4):786-800

Cymodocea rotundata is an ecologically important tropical pioneer seagrass species distributed in the Indo‐Pacific region. The population genetic diversity and structure of this species were analysed at 46 sites spanning the Philippines, Ryukyu Islands (northern limit) and Hainan Island, by using microsatellite simple sequence repeat (SSR) markers. Analyses revealed the persistence of C. rotundata likely relies on local population dynamics and fitness influenced by environmental gradients, with sexual reproduction prevalent in the Philippines while the Ryukyu and Hainan populations were predominantly established by clonal spread. Analysis of molecular variance showed significant genetic differentiation (P < 0.001) among three geographic regions: the Philippines, Ryukyu and Hainan. Furthermore, the mean fixation index value was very high (F_ST = 0.36), indicating poor dispersal potential or limited gene flow. Allelic richness and heterozygosity of C. rotundata was comparable in the Philippines and Ryukyu Islands populations. More private alleles were found in the Philippines and excess heterozygotes in the Ryukyu Islands. STRUCTURE analysis revealed that the Ryukyu and Hainan populations were mosaics of admixed alleles of individuals from the Philippines. An assignment test suggested that recruitment occurs from the Northeast Philippines to Ryukyu Islands. These results suggest that the Philippine populations are tropical seagrass hotspots and perhaps the origin of the populations in the Ryukyu and Hainan Islands. This scenario is most likely driven by the Kuroshio Current and island integration events during plate tectonic activities. The Philippine Archipelago is considered of high importance for conservation objectives and management plan of seagrasses. Likewise, the Ryukyu Islands are also important in terms of conserving regional diversity because locally adapted genotypes have important evolutionary potential in the face of environmental change.  相似文献   

Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas     

Maya P. Bhatt  Nozomu Takeuchi  Miguel F. Acevedo 《Aquatic Geochemistry》2016,22(1):35-64

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Miocene transgression in the central and eastern parts of the Sivas Basin (Central Anatolia,Turkey) and the Cenozoic palaeogeographical evolution     

André Poisson  Bruno Vrielynck  Roland Wernli  Alessandra Negri  Maria-Angela Bassetti  Yesim Büyükmeriç  Sacit Özer  Hervé Guillou  Kaan S. Kavak  Haluk Temiz  Fabienne Orszag-Sperber 《International Journal of Earth Sciences》2016,105(1):339-368

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The Cretaceous of the Swiss Jura Mountains: an improved lithostratigraphic scheme     

André Strasser  Jean Charollais  Marc André Conrad  Bernard Clavel  Antoine Pictet  Bruno Mastrangelo 《Swiss Journal of Geoscience》2016,109(2):201-220

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Mid and late Holocene forest fires and deforestation in the subalpine belt of the Iberian range,northern Spain     

José M. García-Ruiz  Yasmina Sanjuán  Graciela Gil-Romera  Penélope González-Sampériz  Santiago Beguería  José Arnáez  Paz Coba-Pérez  Amelia Gómez-Villar  Javier Álvarez-Martínez  Noemí Lana-Renault  Estela Pérez-Cardiel  Carlos López de Calle 《山地科学学报》2016,13(10):1760-1772

The conversion of subalpine forests into grasslands for pastoral use is a well-knownphenomenon, although for most mountain areas the timing of deforestation has not been determined. The presence of charcoal fragments in soil profiles affected by shallow landsliding enabled us to date the occurrence of fires and the periods of conversion ofsubalpine forest into grasslands in the Urbión Mountains, Iberian Range, Spain. We found that the treeline in the highest parts of the northwestern massifs of the Iberian Range(the Urbión, Demanda, Neila, and Cebollera massifs) is currently between 1500 and 1600 m a.s.l., probably because of pastoral use of the subalpine belt, whereas in the past it would have reached almost the highest divides(at approximately 2100–2200 m a.s.l.). The radiocarbon dates obtained indicate that the transformation of the subalpine belt occurred during the Late Neolithic, Chalcolithic, Bronze Age, Iron Age, and Middle Ages. Forest clearing was probably moderate during fires prior to the Middle Ages, as the small size of the sheep herds and the local character of the markets only required small clearings, and therefore more limited fires. Thus, it is likely that the forest recovered burnt areas in a few decades; this suggests the management of the forest and grasslands following a slash-andburn system. During the Middle and Modern Ages deforestation and grassland expansion affected most of the subalpine belt and coincided with the increasing prevalence of transhumance, as occurred in other mountains in the Iberian Peninsula(particularly the Pyrenees). Although the occurrence of shallow landslides following deforestation between the Neolithic and the Roman Period cannot be ruled out, the most extensive shallow landsliding processes would have occurred from the Middle Ages until recent times.  相似文献   

Exploring seven hundred years of transhumance,climate dynamic,fire and human activity through a historical mountain pass in central Spain     

José Antonio López-Sáez  Francisca Alba-Sánchez  Sandra Robles-López  Sebastián Pérez-Díaz  Daniel Abel-Schaad  Silvia Sabariego-Ruiz  Arthur Glais 《山地科学学报》2016,13(7):1139-1153

A high-altitude peat sequence from the heart of the Spanish Central System (Gredos range) was analysed through a multi-proxy approach to determine the sensitivity of high-mountain habitats to climate, fire and land use changes during the last seven hundred years, providing valuable insight into our understanding of the vegetation history and environmental changes in a mountain pass close to a traditional route of transhumance. The pollen data indicate that the vegetation was dominated by shrublands and grasslands with scattered pines in high-mountain areas, while in the valleys cereals, chestnut and olive trees were cultivated. Strong declines of high-mountain pines percentages are recorded at 1540, 1675, 1765, 1835 and 1925 cal AD, which may be related to increasing grazing activities and/or the occurrence of anthropogenic fires. The practice of mountain summer farming and transhumance deeply changed and redesigned the landscape of the high altitudes in central Spain (Gredos range) since the Middle Ages, although its dynamics was influenced in some way by climate variability of the past seven centuries.  相似文献   

Multi-temporal InSAR evidence of ground subsidence induced by groundwater withdrawal: the Montellano aquifer (SW Spain)     

Ana Ruiz-Constán  Antonio M. Ruiz-Armenteros  Francisco Lamas-Fernández  Sergio Martos-Rosillo  J. Manuel Delgado  David P. S. Bekaert  Joaquim João Sousa  Antonio J. Gil  Miguel Caro Cuenca  Ramon F. Hanssen  Jesús Galindo-Zaldívar  Carlos Sanz de Galdeano 《Environmental Earth Sciences》2016,75(3):242

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Effects of grain morphology on critical state: a computational analysis     

Alex X. Jerves  Reid Y. Kawamoto  José E. Andrade 《Acta Geotechnica》2016,11(3):493-503

We introduce a new DEM scheme (LS-DEM) that takes advantage of level sets to enable the inclusion of real grain shapes into a classical discrete element method. Then, LS-DEM is validated and calibrated with respect to real experimental results. Finally, we exploit part of LS-DEM potentiality by using it to study the dependency of critical state (CS) parameters such as critical state line (CSL) slope \(\lambda \), CSL intercept \(\varGamma \), and CS friction angle \(\varPhi _{\mathrm{CS}}\) on the grain’s morphology, i.e., sphericity, roundness, and regularity. This study is carried out in three steps. First, LS-DEM is used to capture and simulate the shape of five different two-dimensional cross sections of real grains, which have been previously classified according to the aforementioned morphological features. Second, the same LS-DEM simulations are carried out for idealized/simplified grains, which are morphologically equivalent to their real counterparts. Third, the results of real and idealized grains are compared, so the effect of “imperfections” on real particles is isolated. Finally, trends for the CS parameters (CSP) dependency on sphericity, roundness, and regularity are obtained as well as analyzed. The main observations and remarks connecting particle’s morphology, particle’s idealization, and CSP are summarized in a table that is attempted to help in keeping a general picture of the analysis, results, and corresponding implications.  相似文献   

Isotopic signatures for the assessment of snow water resources in the Moroccan high Atlas mountains: contribution to surface and groundwater recharge     

Angoran Baudelaire N’da  Lhoussaine Bouchaou  Barbara Reichert  Lahoucine Hanich  Yassine Ait Brahim  Abdelghani Chehbouni  El Hassane Beraaouz  Jean-Luc Michelot 《Environmental Earth Sciences》2016,75(9):755

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