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See detailThe Paleoproterozoic fossil record: Implications for the evolution of the biosphere during Earth's middle-age
Javaux, Emmanuelle ULiege; lepot, kevin

in Earth-Science Reviews (2017)

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See detailUnderstanding the causes and consequences of past marine carbon cycling variability through models
Hülse, Dominik; Arndt, Sandra; Wilson, Jamie D. et al

in Earth-Science Reviews (2017), 171

On geological time-scales, the production and degree of recycling of biogenic carbon in the marine realm and ultimately its removal to sediments, exerts a dominant control on atmospheric CO2 and hence ... [more ▼]

On geological time-scales, the production and degree of recycling of biogenic carbon in the marine realm and ultimately its removal to sediments, exerts a dominant control on atmospheric CO2 and hence variability in climate. This is a highly complex system involving a myriad of inter-connected biological, chemical, and physical processes. For this reason alone, linking observations, often highly abstracted in the form of proxies, to the primary processes involved and ultimately to explanatory hypotheses for specific geological events and transitions, is challenging. The past few decades have seen a progressive improvement in theoretical and process-based understanding of the various components that make up the marine carbon cycle and, hand-in-hand with this, the development of numerical model representations of the complete system. Models have also been designed and/or adapted with paleoclimate questions in mind and applied to quantitatively explore the role of the marine carbon cycle in both perturbations and long-term geologic evolutionary trends in global climate, and possible feedbacks between them. However, we must ask whether paleoclimate models incorporate sufficiently appropriate representations of the dynamics and sensitivities of the marine carbon cycle, and indeed, whether in the geological context, we really know what these dynamics are. Here we provide a comprehensive overview of how marine carbon cycling and the biological carbon pump is treated in available paleoclimate models, with the aim of critically evaluating their ability to help interpret past marine carbon cycle and climate dynamics. To this end, we first provide an overview of commonly used paleoclimate models and some of their associated paleo-applications, drawing from a wide range of global carbon cycle box models and Earth system Models of Intermediate Complexity (EMICs). Secondly, we review and evaluate the three dominant processes involved in the cycling of organic and inorganic carbon in the marine system and how they are represented in models, namely: biological productivity at the ocean surface, remineralisation/dissolution of particulate carbon within the water column, and the benthic-pelagic coupling at the seafloor. We generate and employ illustrative examples using the model GENIE to show how different parameterisations of water-column and sediment processes can lead to significantly different model projections. Our compilation reveals the prevalence of static parametrisations of marine carbon cycling among existing paleoclimate models, which are commonly empirically derived from present-day observations. Although such approaches tend to represent carbon transfer in the modern ocean well, they are potentially compromised in their ability to reflect the true degree of freedom and strength of feedbacks with respect to past climate events, particularly those characterised by environmental boundary conditions that differ fundamentally from today. Finally, we discuss the importance of using models of different complexities and how questions of model uncertainty may start to be addressed. [less ▲]

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See detailHow fast do gully headcuts retreat?
Vanmaercke, Matthias ULiege; Poesen, J.; Van Mele, B. et al

in Earth-Science Reviews (2016), 154

Gully erosion has important on and off site effects. Therefore, several studies have been conducted over the past decades to quantify gully headcut retreat (GHR) in different environments. Although these ... [more ▼]

Gully erosion has important on and off site effects. Therefore, several studies have been conducted over the past decades to quantify gully headcut retreat (GHR) in different environments. Although these led to important site-specific and regional insights, the overall importance of this erosion process or the factors that control it at a global scale remain poorly understood. This study aims to bridge this gap by reviewing research on GHR and conducting a meta-analysis of measured GHR rates worldwide. Through an extensive literature review, GHR rates for 933 individual and actively retreating gullies have been compiled from more than 70 study areas worldwide (comprising a total measuring period of >19 600 years). Each GHR rate was measured through repeated field surveys and/or analyses of aerial photographs over a period of at least one year (maximum: 97 years, median: 17 years). The data show a very large variability, both in terms of gully dimensions (cross-sectional areas ranging between 0.11 and 816 m2 with a median of 4 m2) and volumetric GHR rates (ranging between 0.002 and 47 430 m3 year- 1 with a median of 2.2 m3 year- 1). Linear GHR rates vary between 0.01 and 135 m year- 1 (median: 0.89 m year- 1), while areal GHR rates vary between 0.01 and 3628 m2 year- 1 (median: 3.12 m2 year- 1). An empirical relationship allows estimating volumetric retreat rates from areal retreat rates with acceptable uncertainties. By means of statistical analyses for a subset of 724 gullies with a known contributing area, we explored the factors most relevant in explaining the observed 7 orders of magnitudes of variation in volumetric GHR rates. Results show that measured GHR rates are significantly correlated to the runoff contributing area of the gully (r2 = 0.15) and the rainy day normal (RDN; i.e. the long-term average annual rainfall depth divided by the average number of rainy days; r2 = 0.47). Other factors (e.g. land use or soil type) showed no significant correlation with the observed GHR rates. This may be attributed to the uncertainties associated with accurately quantifying these factors. In addition, available time series data demonstrate that GHR rates are subject to very large year-to-year variations. As a result, average GHR rates measured over short (<5 year) measuring periods may be subject to very large (>100%) uncertainties. We integrated our findings into a weighted regression model that simulates the volumetric retreat rate of a gully headcut as a function of upstream drainage area and RDN. When weighing each GHR observation proportional to its measuring period, this model explains 68% of the observed variance in GHR rates at a global scale. For 76% of the monitored gullies, the simulated GHR values deviate less than one order of magnitude from their corresponding observed value. Our model clearly indicates that GHR rates are very sensitive to rainfall intensity. Since these intensities are expected to increase in most areas as a result of climate change, our results suggest that gully erosion worldwide will become more intense and widespread in the following decades. Finally, we discuss research topics that will help to address these challenges. © 2016 Elsevier B.V. [less ▲]

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See detailA systematic review of geological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan
Garrett, Ed; Fujiwara, Osamu; Garrett, Philip et al

in Earth-Science Reviews (2016)

The Nankai-Suruga Trough, the subduction zone that lies immediately south of Japan’s densely populated southern coastline, generates devastating great earthquakes (magnitude > 8) characterised by intense ... [more ▼]

The Nankai-Suruga Trough, the subduction zone that lies immediately south of Japan’s densely populated southern coastline, generates devastating great earthquakes (magnitude > 8) characterised by intense shaking, crustal deformation and tsunami generation. Forecasting the hazards associated with future earthquakes along this >700 km long fault requires a comprehensive understanding of past fault behaviour. While the region benefits from a long and detailed historical record, palaeoseismology has the potential to provide a longer-term perspective and additional crucial insights. In this paper, we summarise the current state of knowledge regarding geological evidence for past earthquakes and tsunamis along the Nankai-Suruga Trough. Incorporating literature originally published in both Japanese and English and enhancing available results with new age modelling approaches, we summarise and critically evaluate evidence from a wide variety of sources. Palaeoseismic evidence includes uplifted marine terraces and biota, marine and lacustrine turbidites, liquefaction features, subsided marshes and tsunami deposits in coastal lakes and lowlands. While 75 publications describe proposed evidence from more than 70 sites, only a limited number provide compelling, well-dated evidence. The best available records enable us to map the most likely rupture zones of twelve earthquakes occurring during the historical period. This spatiotemporal compilation suggests the AD 1707 earthquake ruptured almost the full length of the subduction zone and that earthquakes in AD 1361 and 684 may have been predecessors of similar magnitude. Intervening earthquakes were of lesser magnitude, highlighting the variability in rupture mode that characterises the Nankai-Suruga Trough. Recurrence intervals for ruptures of the same seismic segment range from less than 100 to more than 450 years during the historical period. Over longer timescales, palaeoseismic evidence suggests intervals between earthquakes ranging from 100 to 700 years, however these figures reflect a range of thresholds controlling the of creation and preservation of evidence at any given site as well as genuine earthquake recurrence intervals. At present, there is no geological data that suggest the occurrence of a larger magnitude earthquake than that experienced in AD 1707, however few studies have sought to establish the relative magnitudes of different earthquake and tsunami events along the Nankai-Suruga Trough. Alongside the lack of research designed to quantify the maximum magnitude of past earthquakes, we emphasise issues over alternative hypotheses for proposed palaeoseismic evidence, the paucity of robust chronological frameworks and insufficient appreciation of changing thresholds of evidence creation and preservation over time as key issues that must be addressed by future research. [less ▲]

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See detailA review of the mechanical effects of plant roots on concentrated flow erosion rates
Vannoppen, W.; Vanmaercke, Matthias ULiege; De Baets, S. et al

in Earth-Science Reviews (2015), 150

Living plant roots modify both mechanical and hydrological characteristics of the soil matrix (e.g. soil aggregate stability by root exudates, soil cohesion, infiltration rate, soil moisture content, soil ... [more ▼]

Living plant roots modify both mechanical and hydrological characteristics of the soil matrix (e.g. soil aggregate stability by root exudates, soil cohesion, infiltration rate, soil moisture content, soil organic matter) and negatively influence the soil erodibility. During the last two decades several studies reported on the effects of plant roots in controlling concentrated flow erosion rates. However a global analysis of the now available data on root effects is still lacking. Yet, a meta-data analysis will contribute to a better understanding of the soil-root interactions as our capability to assess the effectiveness of roots in reducing soil erosion rates due to concentrated flow in different environments remains difficult. The objectives of this study are therefore: i) to provide a state of the art on studies quantifying the effectiveness of roots in reducing soil erosion rates due to concentrated flow; and ii) to explore the overall trends in erosion reduction as a function of the root (length) density, root architecture and soil texture, based on an integrated analysis of published data. We therefore compiled a dataset of measured soil detachment ratios (SDR) for the root density (RD; 822 observations) as well as for the root length density (RLD; 274 observations). A Hill curve model best describes the decrease in SDR as a function of R(L)D. An important finding of our meta-analysis is that RLD is a much more suitable variable to estimate SDR compared to RD as it is linked to root architecture. However, a large proportion of the variability in SDR could not be attributed to RD or RLD, resulting in a low predictive accuracy of these Hill curve models with a model efficiency of 0.11 and 0.17 for RD and RLD respectively. Considering root architecture and soil texture did yield a better predictive model for RLD with a model efficiency of 0.37 for fibrous roots in non-sandy soils while no improvement was found for RD. The unexplained variance is attributed to differences in experimental set-ups and measuring errors which could not be explicitly accounted for due to a lack of additional data. Based on those results, it remains difficult to predict the effects of roots on soil erosion rates. However, by using a Monte Carlo simulation approach, we were able to establish relationships that allow assessing the likely erosion-reducing effects of plant roots, while taking these uncertainties into account. Overall, this study demonstrates that plant roots can be very effective in reducing soil erosion rates due to concentrated flow. © 2015 Elsevier B.V. [less ▲]

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See detailStepwise evolution of Paleozoic tracheophytes from South China: Contrasting leaf disparity and taxic diversity
Xue, Jinzhuang; Huang, Pu; Ruta, Marcello et al

in Earth-Science Reviews (2015), 148

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See detailFe–Ti–V–P ore deposits associated with Proterozoic massif-type anorthosites and related rocks
Charlier, Bernard ULiege; Namur, Olivier; Bolle, Olivier ULiege et al

in Earth-Science Reviews (2015), 141(0), 56-81

Magmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the ... [more ▼]

Magmatic rocks containing economic concentrations of iron, titanium, vanadium and phosphorous are commonly associated with massif-type anorthosites and related rocks. This rock association is part of the anorthosite–mangerite–charnockite–(rapakivi-)granite suites that are restricted to the Proterozoic. Understanding the geochemistry and emplacement mechanisms of ilmenite, magnetite and apatite ore deposits is crucial for exploration, efficient mining operations and ore processing. This review discusses the controlling factors on the grade of an ore, its mineralogy, and its major and trace element distribution. We present petrogenetic models of currently mined deposits (Lac Tio, Tellnes, Damiao) and discuss the characteristics of minor ore bodies from anorthosite provinces worldwide (Grenville, North China Craton, East European Craton, Rogaland, Laramie). Models of formation of anorthosite and related rocks are presented, as well as the nature of the possible parental magmas of the suite. A mineralogical classification of Fe–Ti ores is proposed: (1) Gabbro-noritic ilmenite ore ± apatite ± magnetite; (2) Ti-magnetite-dominated ore; (3) Nelsonite (Fe–Ti oxides + apatite); and (4) Rutile-ilmenite ore. The stability of ilmenite and magnetite is then critically reviewed and the influence of various factors, particularly oxygen fugacity and crystallization pressure, is examined. We discuss liquidus compositions of Fe–Ti oxides and the behavior of important trace elements such as Cr and V, both of which are sensitive to fO2 variations. Post-cumulus evolution of both oxides can occur due to re-equilibration with trapped liquid, re-equilibration with ferromagnesian silicates, exsolution, oxidation, reaction between ilmenite and magnetite, and metamorphic overprinting. These various processes are described and their effects on the oxide geochemistry are emphasized. Several potential ore-forming processes have been invoked and can explain the formation of huge concentration of ilmenite, ± magnetite, ± apatite. Fractional crystallization can be combined with crystal sorting and plagioclase buoyancy to produce relative enrichment of dense ore minerals. Silicate liquid immiscibility can segregate conjugate Si-rich and Fe-rich melts, the latter being enriched in Fe–Ti–P. Magma mixing can produce hybrid magmas located in a single-phase field of the phase diagram and precipitate a pure ilmenite cumulate. Alternative processes are also described, such as ejection of Fe–Ti-enriched residual melts by filter-pressing and compaction, solid-state remobilization of ilmenite in veins, and hydrothermal transport of Fe and Ti from the host anorthosite followed by concentration in veins and lenticular ore bodies. The magnetic properties of Fe–Ti ore deposits present contrasting signatures, depending on whether the natural remanent magnetization is dominated by hemo-ilmenite or multi-domain magnetite. Micro- and macro-scale deformation features of ore rocks are intimately correlated with magma emplacement, and with ballooning of the anorthosite diapir associated with gravitational sagging of dense ore bodies. Exploration perspectives show that oxide-apatite gabbronorites are interesting targets because ilmenite in these rocks is poorer in Cr and Mg, and because the Ti-resource may be combined with apatite and vanadiferous magnetite. [less ▲]

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See detailCorrigendum to "Predicting soil erosion and sediment yield at regional scales: Where do we stand?" [Earth-Sci. Rev. 127 (2013) 16-29]
De Vente, J.; Poesen, J.; Verstraeten, G. et al

in Earth-Science Reviews (2014), 133

[No abstract available]

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See detailSediment yield in Africa
Vanmaercke, Matthias ULiege; Poesen, J.; Broeckx, J. et al

in Earth-Science Reviews (2014), 136

Several studies have compiled and analysed measured contemporary catchment sediment yield (SY, [tkm-2 y-1]) values for various regions of the world. Although this has significantly contributed to our ... [more ▼]

Several studies have compiled and analysed measured contemporary catchment sediment yield (SY, [tkm-2 y-1]) values for various regions of the world. Although this has significantly contributed to our understanding of SY, Africa remains severely underrepresented in these studies. The objective of this article is therefore: (1) to review and compile available SY data for Africa; (2) to explore the spatial variability of these SY data; and (3) to examine which environmental factors explain this spatial variability. A literature review resulted in a dataset of SY measurements for 682 African catchments from 84 publications and reports, representing more than 8340 catchment-years of observations. These catchments span eight orders of magnitude in size and are relatively well spread across the continent. A description of this dataset and comparison with other SY datasets in terms of spatial and temporal distribution and measurement quality is provided. SY values vary between 0.2 and 15,699tkm-2y-1 (median: 160tkm-2y-1, average: 634tkm-2y-1). The highest SY values occur in the Atlas region with SY values frequently exceeding 1000tkm-2y-1. Also the Rift region is generally characterised by relatively high SY values, while rivers in Western and Central Africa have generally low SY values. Spatial variation in SY at the continental scale is mainly explained by differences in seismic activity, topography, vegetation cover and annual runoff depth. Other factors such as lithology, catchment area or reservoir impacts showed less clear correlations. The results of these analyses are discussed and compared with findings from other studies. Based on our results, we propose a simple regression model to simulate SY in Africa. Although this model has a relatively low predictive accuracy (40%), it simulates the overall patterns of the observed SY values well. Potential explanations for the unexplained variance are discussed and suggestions for further research that may contribute to a better understanding of SY in Africa are made. © 2013 Elsevier B.V. [less ▲]

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See detailPredicting soil erosion and sediment yield at regional scales: Where do we stand?
De Vente, J.; Poesen, J.; Verstraeten, G. et al

in Earth-Science Reviews (2013), 127

Assessments of the implications of soil erosion require quantification of soil erosion rates (SE) and sediment yield (SSY) at regional scales under present and future climate and land use scenarios. A ... [more ▼]

Assessments of the implications of soil erosion require quantification of soil erosion rates (SE) and sediment yield (SSY) at regional scales under present and future climate and land use scenarios. A range of models is available to predict SE and SSY, but a critical evaluation of these models is lacking. Here, we evaluate 14 models based on 32 published studies and over 700 selected catchments. Evaluation criteria include: (1) prediction accuracy, (2) knowledge gain on dominant soil erosion processes, (3) data and calibration requirements, and (4) applicability in global change scenario studies. Results indicate that modelling of SE and SSY strongly depends on the spatial and temporal scales considered. In large catchments (>10,000km2), most accurate predictions of suspended sediment yield are obtained by nonlinear regression models like BQART, WBMsed, or Pelletier's model. For medium-sized catchments, best results are obtained by factorial scoring models like PSIAC, FSM and SSY Index, which also support identification of dominant erosion processes. Most other models (e.g., WATEM-SEDEM, AGNPS, LISEM, PESERA, and SWAT) represent only a selection of erosion and sediment transport processes. Consequently, these models only provide reliable results where the considered processes are indeed dominant. Identification of sediment sources and sinks requires spatially distributed models, which, on average, have lower model accuracy and require more input data and calibration efforts than spatially lumped models. Of these models, most accurate predictions with least data requirements were provided by SPADS and WATEM-SEDEM. Priorities for model development include: (1) simulation of point sources of sediment, (2) balancing model complexity and the quality of input data, (3) simulation of the impact of soil and water conservation measures, and (4) incorporation of dynamic land use and climate scenarios. Prediction of the impact of global change on SE and SSY in medium sized catchments is one of the main challenges in future model development. No single model fulfils all modelling objectives; a further integration of field observations and different model concepts is needed to obtain better contemporary and future predictions of SE and SSY. © 2013 Elsevier B.V. [less ▲]

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See detailWhat is the best way to measure extinction? A reflection from the palaeobotanical record
Cascales - Miñana, Borja ULiege; Cleal, Christopher J.; Diez, José B.

in Earth-Science Reviews (2013), 124

Documenting extinction phenomena remains a vital topic in palaeontology, especially in the context of the marine fossil record. It has been widely assumed that the methods that have been developed in ... [more ▼]

Documenting extinction phenomena remains a vital topic in palaeontology, especially in the context of the marine fossil record. It has been widely assumed that the methods that have been developed in these studies are of universal application throughout palaeontology, but there have been few attempts to test them with plant fossils. We explored the adequacy of the most common methods for documenting extinction events and the associated loss of diversity through time by exploring the monographic knowledge of tracheophytes, especially the record of non-flowering seed-plants. The measure of extinctions was addressed by evaluating diversity fluctuations and the corresponding sampling biases, by measuring levels of taxonomic extinctions, and by exploring disruptions to similarity patterns between time units. Results revealed a strong relationship between diversity and sampling effort based on various different sampling proxies. This suggests that it is vital to take into account the effect of sampling bias when trying to use palaeobotanical diversity dynamics to quantify the real scale of extinction. After testing 16 metrics in two different temporal frameworks, by using criteria like the adjustment between the descriptive extinction metric and the derived probabilistic profile, the interpretation of extinction intensity was overall improved by using normalized metrics that discounted short-lived taxa. Results also revealed that sample size has a significant effect on such analyses and must be evaluated independently for each study before data interpretation. Complementarily, the results showed how the main disturbances of diversity curves generally attributed to extinction events are reflected as abrupt reductions of similarity coefficients between successive time units, which are clearly revealed using clustering methods. © 2013. [less ▲]

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See detailHow effective are soil conservation techniques in reducing plot runoff and soil loss in Europe and the Mediterranean?
Maetens, W.; Poesen, J.; Vanmaercke, Matthias ULiege

in Earth-Science Reviews (2012), 115(1-2), 21-36

The effects of soil and water conservation techniques (SWCTs) on annual runoff (R a), runoff coefficients (RC a) and annual soil loss (SL a) at the plot scale have been extensively tested on field runoff ... [more ▼]

The effects of soil and water conservation techniques (SWCTs) on annual runoff (R a), runoff coefficients (RC a) and annual soil loss (SL a) at the plot scale have been extensively tested on field runoff plots in Europe and the Mediterranean. Nevertheless, a comprehensive overview of these effects and the factors controlling the effectiveness of SWCTs is lacking. Especially the effectiveness of SWCT in reducing R a is poorly understood. Therefore, an extensive literature review is presented that compiles the results of 101 earlier studies. In each of these studies, R a and SL a was measured on field runoff plots where various SWCTs were tested. In total, 353 runoff plots (corresponding to 2093 plot-years of data) for 103 plot-measuring stations throughout Europe and the Mediterranean were considered. SWCTs include (1) crop and vegetation management (i.e. cover crops, mulching, grass buffer strips, strip cropping and exclosure), (2) soil management (i.e. no-tillage, reduced tillage, contour tillage, deep tillage, drainage and soil amendment) and (3) mechanical methods (i.e. terraces, contour bunds and geotextiles). Comparison of the frequency distributions of SL a rates on cropland without and with the application of SWCTs shows that the exceedance probability of tolerable SL a rates is ca. 20% lower when SWCT are applied. However, no notable effect of SWCTs on the frequency distribution of RC a is observed. For 224 runoff plots (corresponding to 1567 plot-year data), SWCT effectiveness in reducing R a and/or SL a could be directly calculated by comparing measured R a and/or SL a with values measured on a reference plot with conventional management. Crop and vegetation management techniques (i.e. buffer strips, mulching and cover crops) and mechanical techniques (i.e. geotextiles, contour bunds and terraces) are generally more effective than soil management techniques (i.e. no-tillage, reduced tillage and contour tillage). Despite being generally less effective, no-tillage, reduced tillage and contour tillage have received substantially more attention in the literature than the other SWCTs. Soil and water conservation techniques are generally less effective in reducing R a than in reducing SL a, which is an important consideration in areas where water is a key resource and in regions susceptible to flooding. Furthermore, all SWCTs show a more consistent and effective reduction of both R a and SL a with increasing R a and SL a magnitude, which is attributed to the reduced influence of measurement uncertainties. Although some significantly negative correlations between SWCT effectiveness and plot slope length, slope gradient or annual precipitation were found, the importance of these factors in explaining the observed variability in effectiveness seems limited. Time-series analyses of R a during multiple years of SWCT application strongly indicate that no-tillage and conservation tillage become less effective in reducing R a over time. Such an effect is not observed for SL a. © 2012 Elsevier B.V. [less ▲]

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See detailPlant biodiversity changes in Carboniferous tropical wetlands
Cleal, Christopher J.; Uhl, Dieter; Cascales - Miñana, Borja ULiege et al

in Earth-Science Reviews (2012), 114(1-2), 124-155

Using a combination of species richness, polycohort and constrained cluster analyses, the plant biodiversity of Pennsylvanian (late Carboniferous) tropical wetlands ("coal swamps") has been investigated ... [more ▼]

Using a combination of species richness, polycohort and constrained cluster analyses, the plant biodiversity of Pennsylvanian (late Carboniferous) tropical wetlands ("coal swamps") has been investigated in five areas in Western Europe and eastern North America: South Wales, Pennines, Ruhr, Saarland and Sydney coal basins. In all cases, species richness expansion followed an essentially logistic curve typical of that associated with ecologically closed habitats, with niche saturation being achieved in about three million years. The resulting steady-state ("climax") coal swamp vegetation had a local-scale (within an area of c. 0.1ha) species diversity in South Wales of 16±7 and Simpson Diversity Indices of 4.53±2.55, which are very similar to values obtained from studies on North American coal swamp vegetation. Landscape diversity (within an area 105km2) varied between 50 and 100 species in the lower to middle Westphalian Stage, falling to about 40-50 species in the upper Westphalian Stage. Regional-scale diversity (within an area>105km2) is difficult to estimate but was at least 120 species. Species turn-over was typically very low, at about 4 species per million years, but there were a number of intervals of more rapid species turn-over in the early Langsettian, late Duckmantian, early Bolsovian and middle Asturian times, which are recognised today as biozonal boundaries. The swamps were mostly subject to ecological stasis during early and middle Westphalian times, although they contracted locally in response to drying of substrates. Later in Westphalian times, however, the swamps were subject to regional-scale changes in composition and aerial extent, probably in response to climate change. The coal swamps had a much lower species diversity compared to modern-day tropical rain forests. © 2012 Elsevier B.V.. [less ▲]

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See detailLate Frasnian - Famennian climates based on palynomorph analyses and the question of the late Devonian glaciations.
Streel, Maurice ULiege; Caputo, MV; Loboziak, S et al

in Earth-Science Reviews (2000), 52(1-3), 121-173

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See detailReconnaissance of the general circulation of the North-Western European Continental Shelf by means of a three-dimensional turbulent closure model
Delhez, Eric ULiege

in Earth-Science Reviews (1996), 41(1-2), 3-29

The general circulation of the North-Western European Continental Shelf is investigated by means of a three-dimensional macroscale mathematical model. Results corresponding to typical winter and summer ... [more ▼]

The general circulation of the North-Western European Continental Shelf is investigated by means of a three-dimensional macroscale mathematical model. Results corresponding to typical winter and summer conditions are described in detail. Prominent features are explained from a dynamic point of view by referring to the main forcing factors of the macroscale circulation on the North-Western European Continental Shelf: seasonal mean wind stress and atmospheric pressure, large a scale sea surface slope, non-linear interactions of the higher frequency processes and density differences. The role of the bottom topography is also highlighted. The largest seasonal variations are mainly due to the occurrence of a thermal stratification in summer over large parts of the shelf. In such conditions, there is only a weak interaction between the surface and bottom layers that have therefore significantly different dynamics. [less ▲]

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See detailHierarchy and scales in marine ecohydrodynamics
Nihoul, Jacques ULiege; Djenidi, Salim ULiege

in Earth-Science Reviews (1991), 31(3-4), 255-277

Recent investigations reveal, in marine ecosystems, an ecohydrodynamic hierarchical organization resulting from the different rates of ecological processes confronted to a multi-scale physical environment ... [more ▼]

Recent investigations reveal, in marine ecosystems, an ecohydrodynamic hierarchical organization resulting from the different rates of ecological processes confronted to a multi-scale physical environment. Major marine hydrodynamic processes are briefly analyzed here in an ecohydrodynamic perspective, emphasizing the effects they have on ecosystems at different levels of hierarchy and identifying appropriate “spectral windows” for modelling. A case study application to the Northern Bering Sea's Summer Ecohydrodynamics is given in illustration. [less ▲]

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See detailModelling the general circulation of shelf seas by 3Dk-ε models
Nihoul, Jacques ULiege; Deleersnijder, Eric; Djenidi, Salim ULiege

in Earth-Science Reviews (1989), 26(1-3), 163-189

One examines the modifications which must be made-and the limitations which must be set-to classicalk-ε models to extend their application to the simulation of marine mesoscale, synopticscale and ... [more ▼]

One examines the modifications which must be made-and the limitations which must be set-to classicalk-ε models to extend their application to the simulation of marine mesoscale, synopticscale and macroscale processes which compose the weather-like and general circulations of the sea. The case of the general circulation—for which sub-grid scale fluctuations include such semi-organized motions as tides and storm surges-is discussed in more detail. A 3Dk-ε model appropriate to the study of the general circulation in a shallow stratified sea is presented and illustrated with the results of a simulation of the general summer circulation in the Northern Bering Sea, made in the scope of the NSF ISHTAR (“Inner Shelf Transfer and Recycling”) Program. [less ▲]

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