Non-saturated porous flow with discontinuous hydraulic conductivity 11 numerical solution of the self-problem problem

En el problema planteado por Barenblatt y expuesto en la primera parte de este trabajo, seestudia la propagación de una masa de fluido a partir de una inyección. Se muestra la diferenciaque existe en la solución al problema cuando se ignora la retención residual del fluido en elsuelo, en cuyo caso corresponde a la tradicional solución de la ecuación de difusión. Sin embargo,el problema debe plantearse considerando retención residual, lo cual da lugar a un problema deconductividad hidráulica discontinua y debe plantearse una nueva una ley de similaridad queincluye en su forma funcional un exponente anómalo. A partir de las ecuaciones de flujo ycondiciones de frontera se genera un problema de autovalor que en este trabajo es resuelto enforma numérica utilizando un algoritmo combinado de Runge-Kutta y Euler modificado, el cualpermite hallar el exponente en función de los valores de conductividad hidráulica y obtener lasolución completa del problema. Se puede observar la evolución del volumen de fluido, el tiempoy la distancia de propagación de algunos fluidos, considerando o no retención residual en elsuelo.  In the problem posed by Barenblatt and exposed in the first part of this work, the propagation of a mass of fluid from an injection is studied. The difference that exists in the solution to the problem is shown when the residual fluid retention in the soil is ignored, in which case it corresponds to the traditional solution of the diffusion equation. However, the problem must be considered considering residual retention, which gives rise to a problem of discontinuous hydraulic conductivity and a new law of similarity that includes in its functional form an anomalous exponent. From the flow equations and boundary conditions a self-value problem is generated which in this work is solved in numerical form using a combined algorithm of Runge-Kutta and modified Euler, which allows finding the exponent as a function of the values Of hydraulic conductivity and obtain the complete solution of the problem. It is possible to observe the evolution of the volume of fluid, the time and the propagation distance of some fluids, considering or not residual retention in the soil

Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

This is the final version of the article. Available from Wiley via the DOI in this record.Understanding the processes that determine above-ground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody productivity [woody net primary productivity (NPP)] and the rate at which carbon is lost through tree mortality. Here, we test whether two direct metrics of tree mortality (the absolute rate of woody biomass loss and the rate of stem mortality) and/or woody NPP, control variation in AGB among 167 plots in intact forest across Amazonia. We then compare these relationships and the observed variation in AGB and woody NPP with the predictions of four DGVMs. The observations show that stem mortality rates, rather than absolute rates of woody biomass loss, are the most important predictor of AGB, which is consistent with the importance of stand size structure for determining spatial variation in AGB. The relationship between stem mortality rates and AGB varies among different regions of Amazonia, indicating that variation in wood density and height/diameter relationships also influences AGB. In contrast to previous findings, we find that woody NPP is not correlated with stem mortality rates and is weakly positively correlated with AGB. Across the four models, basin-wide average AGB is similar to the mean of the observations. However, the models consistently overestimate woody NPP and poorly represent the spatial patterns of both AGB and woody NPP estimated using plot data. In marked contrast to the observations, DGVMs typically show strong positive relationships between woody NPP and AGB. Resolving these differences will require incorporating forest size structure, mechanistic models of stem mortality and variation in functional composition in DGVMs.This paper is a product of the European Union's Seventh Framework Programme AMAZALERT project (282664). The field data used in this study have been generated by the RAINFOR network, which has been supported by a Gordon and Betty Moore Foundation grant, the European Union's Seventh Framework Programme projects 283080, ‘GEOCARBON’; and 282664, ‘AMAZALERT’; ERC grant ‘Tropical Forests in the Changing Earth System’), and Natural Environment Research Council (NERC) Urgency, Consortium and Standard Grants ‘AMAZONICA’ (NE/F005806/1), ‘TROBIT’ (NE/D005590/1) and ‘Niche Evolution of South American Trees’ (NE/I028122/1). Additional data were included from the Tropical Ecology Assessment and Monitoring (TEAM) Network – a collaboration between Conservation International, the Missouri Botanical Garden, the Smithsonian Institution and the Wildlife Conservation Society, and partly funded by these institutions, the Gordon and Betty Moore Foundation, and other donors. Fieldwork was also partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico of Brazil (CNPq), project Programa de Pesquisas Ecológicas de Longa Duração (PELD-403725/2012-7). A.R. acknowledges funding from the Helmholtz Alliance ‘Remote Sensing and Earth System Dynamics’; L.P., M.P.C. E.A. and M.T. are partially funded by the EU FP7 project ‘ROBIN’ (283093), with co-funding for E.A. from the Dutch Ministry of Economic Affairs (KB-14-003-030); B.C. [was supported in part by the US DOE (BER) NGEE-Tropics project (subcontract to LANL). O.L.P. is supported by an ERC Advanced Grant and is a Royal Society-Wolfson Research Merit Award holder. P.M. acknowledges support from ARC grant FT110100457 and NERC grants NE/J011002/1, and T.R.B. acknowledges support from a Leverhulme Trust Research Fellowship

Right-handed Sneutrino Dark Matter in Supersymmetric B-L Model

We show that the lightest right-handed sneutrino in TeV scale supersymmetric B-L model with inverse seesaw mechanism is a viable candidate for cold dark matter. We find that it accounts for the observed dark matter relic abundance in a wide range of parameter space. The spin-independent cross section of B-L right-handed sneutrino is consistent with the recent results CDMS II and XENON experiments and it is detectable in future direct detection experiments. Although the B-L right-handed sneutrinos annihilate into leptons, the PAMELA results can not be explained in this model unless a huge boost factor is considered. Also the muon flux generated by B-L right-handed sneutrino in the galactic center is smaller than Super-Kamiokande's upper bound.Comment: 16 pages, 7 figures; version accepted for publication in Journal of High Energy Physic

Plant diversity patterns in neotropical dry forests and their conservation implications

This is the author accepted manuscript. The final version is available from American Association for the Advancement of Science via the DOI in this record.Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale.This paper is the result of the Latin American and Caribbean Seasonally Dry Tropical Forest Floristic Network (DRYFLOR), which has been supported at the Royal Botanic Garden Edinburgh by a Leverhulme Trust International Network Grant (IN-074). This work was also supported by the U.K. Natural Environment Research Council grant NE/I028122/1; Colciencias Ph.D. scholarship 529; Synthesys Programme GBTAF-2824; the NSF (NSF 1118340 and 1118369); the Instituto Humboldt (IAvH)–Red colombiana de investigación y monitoreo en bosque seco; the Inter-American Institute for Global Change Research (IAI; Tropi-Dry, CRN2-021, funded by NSF GEO 0452325); Universidad Nacional de Rosario (UNR); and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The data reported in this paper are available at www.dryflor.info. R.T.P. conceived the study. M.P., A.O.-F., K.B.-R., R.T.P., and J.W. designed the DRYFLOR database system. K.B.-R. and K.G.D. carried out most analyses. K.B.-R. R.T.P., and K.G.D. wrote the manuscript with substantial input from A.D.-S., R.L.-P., A.O.-F., D.P., C.Q., and R.R. All the authors contributed data, discussed further analyses, and commented on various versions of the manuscript. K.B.-R. thanks G. Galeano who introduced her to dry forest research. We thank J. L. Marcelo, I. Huamantupa, C. Reynel, S. Palacios, and A. Daza for help with fieldwork and data entry in Peru

Non-saturated porous flow with discontinuous hydraulic conductivity 11 numerical solution of the self-problem problem

En el problema planteado por Barenblatt y expuesto en la primera parte de este trabajo, seestudia la propagación de una masa de fluido a partir de una inyección. Se muestra la diferenciaque existe en la solución al problema cuando se ignora la retención residual del fluido en elsuelo, en cuyo caso corresponde a la tradicional solución de la ecuación de difusión. Sin embargo,el problema debe plantearse considerando retención residual, lo cual da lugar a un problema deconductividad hidráulica discontinua y debe plantearse una nueva una ley de similaridad queincluye en su forma funcional un exponente anómalo. A partir de las ecuaciones de flujo ycondiciones de frontera se genera un problema de autovalor que en este trabajo es resuelto enforma numérica utilizando un algoritmo combinado de Runge-Kutta y Euler modificado, el cualpermite hallar el exponente en función de los valores de conductividad hidráulica y obtener lasolución completa del problema. Se puede observar la evolución del volumen de fluido, el tiempoy la distancia de propagación de algunos fluidos, considerando o no retención residual en elsuelo.  In the problem posed by Barenblatt and exposed in the first part of this work, the propagation of a mass of fluid from an injection is studied. The difference that exists in the solution to the problem is shown when the residual fluid retention in the soil is ignored, in which case it corresponds to the traditional solution of the diffusion equation. However, the problem must be considered considering residual retention, which gives rise to a problem of discontinuous hydraulic conductivity and a new law of similarity that includes in its functional form an anomalous exponent. From the flow equations and boundary conditions a self-value problem is generated which in this work is solved in numerical form using a combined algorithm of Runge-Kutta and modified Euler, which allows finding the exponent as a function of the values Of hydraulic conductivity and obtain the complete solution of the problem. It is possible to observe the evolution of the volume of fluid, the time and the propagation distance of some fluids, considering or not residual retention in the soil

Plant diversity patterns in neotropical dry forests and their conservation implications

Seasonally dry tropical forests are distributed across Latin America and the Caribbean and are highly threatened, with less than 10% of their original extent remaining in many countries. Using 835 inventories covering 4660 species of woody plants, we show marked floristic turnover among inventories and regions, which may be higher than in other neotropical biomes, such as savanna. Such high floristic turnover indicates that numerous conservation areas across many countries will be needed to protect the full diversity of tropical dry forests. Our results provide a scientific framework within which national decision-makers can contextualize the floristic significance of their dry forest at a regional and continental scale

Plot Data from "Diversity and carbon storage across the tropical forest biome."

Tropical forests are global centres of both biodiversity and carbon storage. Many tropical countries aspire to protect forest to fulfil biodiversity and climate mitigation policy targets, but the conservation strategies needed to achieve these two functions depend critically on the tropical forest diversity-carbon relationship and this remains largely unexplored. Attempts to assess and understand this relationship in tropical forest ecosystems have been hindered by the scarcity of inventories where carbon storage in aboveground biomass and species identifications have been simultaneously and robustly quantified. Here, we compile a unique pan-tropical dataset of 360 plots located in old-growth closed-canopy forest, surveyed using standardised methods, allowing a multi-scale evaluation of the relationship between carbon storage and tree diversity. We find strongly contrasting variation in diversity and carbon among continents. Thus, on average, African forests have high carbon storage but relatively low diversity, Amazonian forests have high diversity but less carbon, and Southeast Asian forests have both high diversity and high carbon storage. Carbon-diversity relationships among all plots across the tropics are absent, and within continents are either weak (Asia) or absent (Amazonia, Africa). Within 1 ha plots a weak positive relationship is detectable, indicating that diversity effects in tropical forests may be scale dependent. The absence of clear diversity-carbon relationships at scales relevant to most conservation planning means that carbon-centred conservation strategies alone would miss many high diversity ecosystems. As tropical forests can have any combination of tree diversity and carbon stocks both will require explicit consideration when optimising policies to manage tropical carbon and biodiversity