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Understory and small trees contribute importantly to stemflow of a lower montane cloud forest 下载免费PDF全文
Teresa Margarita González‐Martínez Guadalupe Williams‐Linera Friso Holwerda 《水文研究》2017,31(5):1174-1183
Stemflow (Sf) measurements in tropical rain and montane forests dominated by large trees rarely include the understory and small trees. In this study, contributions of lower (1‐ to 2‐m height) and upper (>2‐m height and <5‐cm diameter at breast height [DBH]) woody understory, small trees (5 < DBH < 10 cm), and canopy trees (>10‐cm DBH) to Sf per unit ground area (Sfa) of a Mexican lower montane cloud forest were quantified for 32 days with rainfall (P) during the 2014 wet season. Rainfall, stemflow yield (Sfy), vegetation height, density, and basal area were measured. Subsequently, stemflow funneling ratios (SFRs) were calculated, and three common methods to scale up Sfy from individual trees to the stand level (tree‐Sfy correlation, P‐Sfy correlation, and mean‐Sfy extrapolation) were used to calculate Sfa. Understory woody plants, small trees, and upper canopy trees represented 96%, 2%, and 2%, respectively, of the total density. Upper canopy trees had the lowest SFRs (1.6 ± 0.5 Standard Error (SE) on average), although the lower understory had the highest (36.1 ± 6.4). Small trees and upper understory presented similar SFRs (22.9 ± 5.4 and 20.2 ± 3.9, respectively). Different Sf scaling methods generally yielded similar results. Overall Sfa during the study period was 22.7 mm (4.5% of rainfall), to which the understory contributed 70.1% (15.9 mm), small trees 10.6% (2.4 mm), and upper canopy trees 19.3% (4.4 mm). Our results strongly suggest that for humid tropical forests with dense understory of woody plants and small trees, Sf of these groups should be measured to avoid an underestimation of overall Sf at the stand level. 相似文献
114.
Thomas Aiglsperger Joaquín A. Proenza Salvador Galí Jordi Rius Francisco Longo Cristina Domènech 《地学学报》2017,29(2):106-116
For two decades, the nature of Fe‐rich, oxygen‐bearing, Ru–Os compounds found in the supergene environment has been debated. Ru–Os–Fe‐oxides and nano‐intergrowths of ruthenium with magnetite have been proposed. We applied FE‐SEM, EMPA, μ‐Raman spectroscopy and synchrotron tts‐μXRD to Ru–Os–Fe compounds recovered from Ni‐laterites from the Dominican Republic. The results demonstrate that a significant portion of Fe exists in a common structure with the Ru–Os alloy, that is, ruthenian hexaferrum. This mineral occurs both as nanoparticles and as micrometric patches within a matrix of Fe‐oxide(s). Our data suggest that supergene ruthenian hexaferrum with a (Ru0.4(Os,Ir)0.1Fe0.5)?1.0 stoichiometry represents the most advanced weathering product of primary laurite within Ni‐laterites from the Dominican Republic. 相似文献
115.
Dynamics of Saxothuringian subduction channel/wedge constrained by phase‐equilibria modelling and micro‐fabric analysis 下载免费PDF全文
S. Collett P. Štípská V. Kusbach K. Schulmann G. Marciniak 《Journal of Metamorphic Geology》2017,35(3):253-280
Subduction and exhumation dynamics can be investigated through analysis of metamorphic and deformational evolution of associated high‐grade rocks. The Erzgebirge anticline, which forms at the boundary between the Saxothuringian and Teplá‐Barrandian domains of the Bohemian Massif, provides a useful study area for these processes owing to the occurrence of numerous meta‐basites preserving eclogite facies assemblages, and coesite and diamond bearing quartzofeldspathic lithologies indicating subduction to deep mantle depths. The prograde and retrograde evolution of meta‐basite from the Czech portion of the Erzgebirge anticline has been constrained through a combination of thermodynamic modelling and conventional thermobarometry. Garnet growth zoning indicates that the rocks underwent burial and heating to peak conditions of 2.6 GPa and at least 615 °C. Initial exhumation occurred with concurrent cooling and decompression resulting in the growth of amphibole and zoisite poikiloblasts overgrowing and including the eclogite facies assemblage. The development of clinopyroxene–plagioclase–amphibole symplectites after omphacite and Al‐rich rims on matrix amphibole indicate later heating at the base of the lower crust. Omphacite microstructures, in particular grain size analysis and lattice‐preferred orientations, indicate that the prograde evolution was characterized by a constrictional strain geometry transitioning into plane strain and oblate fabrics during exhumation. The initial constrictional strain pattern is interpreted as being controlled by competing slab pull and crustal buoyancy forces leading to necking of the subducting slab. The transition to plane strain and flattening geometries represents transfer of material from the subducting lithosphere into a subduction channel, break‐off of the dense slab and rebound of the buoyant crustal material. 相似文献
116.
Segmentation and kinematics of the North America‐Caribbean plate boundary offshore Hispaniola 下载免费PDF全文
Sylvie Leroy Nadine Ellouz‐Zimmermann Jordane Corbeau Frédérique Rolandone Bernard Mercier de Lépinay Bertrand Meyer Roberte Momplaisir José‐Luis Granja Bruña Anne Battani Céline Baurion Evgueni Burov Valérie Clouard Rémy Deschamps Christian Gorini Youri Hamon Manfred Lafosse Jottin Leonel Laetitia Le Pourhiet Pilar Llanes Estrada Nicolas Loget Francis Lucazeau Daniel Pillot Jeffrey Poort Kevin R. Tankoo José‐Luis Cuevas José‐Fernando Alcaide Claude Jean Poix Alfonso Muñoz‐Martin Serge Mitton Yamil Rodriguez Julien Schmitz Leonardo Seeber Andres Carbo‐Gorosabel Santiago Muñoz 《地学学报》2015,27(6):467-478
We explored the submarine portions of the Enriquillo–Plantain Garden Fault zone (EPGFZ) and the Septentrional–Oriente Fault zone (SOFZ) along the Northern Caribbean plate boundary using high‐resolution multibeam echo‐sounding and shallow seismic reflection. The bathymetric data shed light on poorly documented or previously unknown submarine fault zones running over 200 km between Haiti and Jamaica (EPGFZ) and 300 km between the Dominican Republic and Cuba (SOFZ). The primary plate‐boundary structures are a series of strike‐slip fault segments associated with pressure ridges, restraining bends, step overs and dogleg offsets indicating very active tectonics. Several distinct segments 50–100 km long cut across pre‐existing structures inherited from former tectonic regimes or bypass recent morphologies formed under the current strike‐slip regime. Along the most recent trace of the SOFZ, we measured a strike‐slip offset of 16.5 km, which indicates steady activity for the past ~1.8 Ma if its current GPS‐derived motion of 9.8 ± 2 mm a?1 has remained stable during the entire Quaternary. 相似文献
117.
Throughfall patterns in sugarcane and riparian forest: understanding the effect of sugarcane age and land use conversion 下载免费PDF全文
Robson Willians da Costa Silva Luiz Felippe Salemi Rafael Pires Fernandes Tatiana Morgan Berteli de Andrade Jorge Marcos de Moraes Plínio Barbosa de Camargo Luiz Antonio Martinelli 《水文研究》2016,30(15):2579-2589
Sugarcane is an annual crop with a dynamic canopy that changes over time mainly because of genetic adaptation. There is uncertainty about the temporal trends of throughfall (TF) in this important commercial crop. In the present paper, we used troughs to measure TF in a third and fourth ratoon and subsequently in a fourth and fifth ratoon. Additional measurements were carried out in an adjacent riparian forest. There were no significant differences between cycles of sugarcane, growth phases and riparian forest. The TF results for ratoon crop and riparian forest in 2011/2012 were 76% and 79.5% of gross rainfall, respectively, while in 2012/2013, they were 79% and 78%, respectively. However, TF was remarkably lower in the riparian forest relative to ratoon from the second half of the culm formation and elongation phase (280 days after harvest) until harvest. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
118.
Towards more systematic perceptual model development: a case study using 3 Luxembourgish catchments 下载免费PDF全文
Sebastian Wrede Fabrizio Fenicia Núria Martínez‐Carreras Jérôme Juilleret Christophe Hissler Andreas Krein Hubert H. G. Savenije Stefan Uhlenbrook Dmitri Kavetski Laurent Pfister 《水文研究》2015,29(12):2731-2750
The synthesis of experimental understanding of catchment behaviour and its translation into qualitative perceptual models is an important objective of hydrological sciences. We explore this challenge by examining the cumulative understanding of the hydrology of three experimental catchments and how it evolves through the application of different investigation techniques. The case study considers the Huewelerbach, Weierbach and Wollefsbach headwater catchments of the Attert basin in Luxembourg. Subsurface investigations including bore holes and pits, analysis of soil samples and Electrical Resistivity Tomography measurements are presented and discussed. Streamflow and tracer data are used to gain further insights into the streamflow dynamics of the catchments, using end‐member mixing analysis and hydrograph separation based on dissolved silica and electrical conductivity. We show that the streamflow generating processes in all three catchments are controlled primarily by the subsolum and underlying bedrock. In the Huewelerbach, the permeable sandstone formation supports a stable groundwater component with little seasonality, which reaches the stream through a series of sources at the contact zone with the impermeable marls formation. In the Weierbach, the schist formation is relatively impermeable and supports a ‘fill and spill’‐type of flow mechanism; during wet conditions, it produces a delayed response dominated by pre‐event water. In the Wollefsbach, the impermeable marls formation is responsible for a saturation‐excess runoff generating process, producing a fast and highly seasonal response dominated by event water. The distinct streamflow generating processes of the three catchments are represented qualitatively using perceptual models. The perceptual models are in turn translated into quantitative conceptual models, which simulate the hydrological processes using networks of connected reservoirs and transfer functions. More generally, the paper illustrates the evolution of perceptual models based on experimental fieldwork data, the translation of perceptual models into conceptual models and the value of different types of data for processes understanding and model representation. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
119.
Unraveling complex hydrogeological processes in Andean basins in south‐central Chile: An integrated assessment to understand hydrological dissimilarity 下载免费PDF全文
Enrique Muñoz José Luis Arumí Thorsten Wagener Ricardo Oyarzún Victor Parra 《水文研究》2016,30(26):4934-4943
Groundwater storage, drainage, and interbasin water exchange are common hydrological processes but often difficult to quantify due to a lack of local observations. We present a study of three volcanic mountainous watersheds located in south‐central Chile (~36.9 ° S) in the Chillán volcanic complex (Chillán, Renegado, and Diguillín river basins). These are neighboring basins that are similar with respect to the metrics normally available for characterization everywhere (e.g., precipitation, temperature, and land cover). In a hydrological sense, similar (proportional) behavior would be expected if these catchments would be characterized with this general information. However, these watersheds show dissimilar behavior when analyzed in detail. The surface water balance does not fit for any of these watersheds individually; however, the water balance of the whole system can be explained by likely interbasin water exchanges. The Renegado river basin has an average annual runoff per unit of area on the order of 60–65% less than those of the Diguillín and Chillán rivers, which is contradictory to the hydrological similarity among the basins. To understand the main processes that control streamflow generation, two analyses were performed: (a) basin metrics (land cover, geologic, topographic, and climatological maps) and hydro‐meteorological data analyses and (b) a water balance model approach. The analyses contribute to a plausible explanation for the hydrogeological processes in the system. The soils, topography, and geology of the Chillán–Renegado–Diguillín system favor the infiltration and groundwater movements from the Renegado river basin, mainly to the neighboring Diguillín basin. The interbasin water exchanges affect hydrological similarity and explain the differences observed in the hydrological processes of these three apparently similar volcanic basins. The results highlight the complexity of hydrological processes in volcanic mountainous systems and suggest that a simple watershed classification approach based on widely available data is insufficient. Simple local analyses such as specific flow analysis with a review of the geology and morphology can contribute to a better understanding of the hydrology of volcanic mountainous areas. 相似文献