Mapping soil texture classes using field textuing, particle size distribution and local knowledge by both conventional and geostatisical methods

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90525/1/j.1365-2389.1999.00255.x.pd

Developing an index for forest productivity mapping - A case study for maritime pine production regulation in Portugal

Productivity is very dependent on the environmental and biotic factors present at the site where the forest species of interest is present. Forest site productivity is usually assessed using empirical models applied to inventory data providing discrete predictions. While the use of GIS-based models enables building a site productivity distribution map. Therefore, the aim of this study was to derive a productivity index using multivariate statistics and coupled GIS-geostatistics to obtain a forest productivity map. To that end, a study area vastly covered by naturally regenerated forests of maritime pine in central Portugal was used. First, a productivity index (PI) was built based on Factorial Correspondence Analysis (FCA) by incorporating a classical site index for the species and region (Sh25 - height index model) and GIS-derived environmental variables (slope and aspect). After, the PI map was obtained by multi-Gaussian kriging and used as a GIS layer to evaluate maritime pine areas by productivity class (e.g., low, intermediate and high). In the end, the area control method was applied to assess the size and the number of compartments to establish by productivity class. The management compartments of equal productivity were digitized as GIS layer and organized in a temporal progression of stands’ age regularly available for cutting each year during a 50-year schedule. The methodological approach developed in this study proved that can be used to build forest productivity maps which are crucial tools to support forest production regulation.A produtividade florestal depende dos fatores ambientais e bióticos da estação onde a espécie florestal se encontra. A produtividade da estação florestal é geralmente avaliada com modelos empíricos aplicados a dados de inventário fornecendo previsões discretas. Enquanto o uso de modelos num SIG permite a construção de mapas de distribuição de produtividade da estação. Assim, o objetivo deste estudo foi desenvolver um índice de produtividade utilizando estatística multivariada e geoestatística acopladas ao SIG para obter um mapa de produtividade florestal. Para o efeito, selecionou-se uma área de estudo com floresta de regeneração natural de pinheiro bravo no centro de Portugal. Primeiramente, o índice de produtividade (PI) foi construído usando a Análise Fatorial das Correspondências (FCA) com um índice de qualidade de estação para a espécie e região (Sh25- modelo de índice de altura) e variáveis ambientais (declive e exposição). Depois, o mapa PI foi obtido por Krigagem multi-Gaussiana e usado como camada SIG para avaliar as áreas da espécie por classe de produtividade (p.e., baixa, intermedia e alta). No final, o método de controle da área foi aplicado para determinar o tamanho e o número de parcelas a serem estabelecidas por classe de produtividade. As parcelas de igual produtividade foram digitalizadas em SIG e organizadas segundo uma progressão de idades disponíveis regularmente para abate anual ao longo de 50 anos. A abordagem metodológica desenvolvida neste estudo provou ser útil na construção de mapas de produtividade florestal que são instrumentos fundamentais para apoiar a regulação da produção florestal.info:eu-repo/semantics/publishedVersio

Highly efficient room temperature spin injection in a metal-insulator-semiconductor light emitting diode

We demonstrate highly efficient spin injection at low and room temperature in an AlGaAs/GaAs semiconductor heterostructure from a CoFe/AlOx tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOx tunnel barrier. The measurements of the circular polarization of the electroluminescence in the Oblique Hanle Effect geometry reveal injected spin polarizations of at least 24% at 80K and 12% at room temperature

Discriminative training for Convolved Multiple-Output Gaussian processes

Multi-output Gaussian processes (MOGP) are probability distributions over vector-valued functions, and have been previously used for multi-output regression and for multi-class classification. A less explored facet of the multi-output Gaussian process is that it can be used as a generative model for vector-valued random fields in the context of pattern recognition. As a generative model, the multi-output GP is able to handle vector-valued functions with continuous inputs, as opposed, for example, to hidden Markov models. It also offers the ability to model multivariate random functions with high dimensional inputs. In this report, we use a discriminative training criteria known as Minimum Classification Error to fit the parameters of a multi-output Gaussian process. We compare the performance of generative training and discriminative training of MOGP in emotion recognition, activity recognition, and face recognition. We also compare the proposed methodology against hidden Markov models trained in a generative and in a discriminative way

Multiscale entropy-based analyses of soil transect data

A deeper understanding of the spatial variability of soil properties and the relationships between them is needed to scale up measured soil properties and to model soil processes. The object of this study was to describe the spatial scaling properties of a set of soil physical properties measured on a common 1024-m transect across arable fields at Silsoe in Bedfordshire, east-central England. Properties studied were volumetric water content ({theta}), total porosity ({pi}), pH, and N2O flux. We applied entropy as a means of quantifying the scaling behavior of each transect. Finally, we examined the spatial intrascaling behavior of the correlations between {theta} and the other soil variables. Relative entropies and increments in relative entropy calculated for {theta}, {pi}, and pH showed maximum structure at the 128-m scale, while N2O flux presented a more complex scale dependency at large and small scales. The intrascale-dependent correlation between {theta} and {pi} was negative at small scales up to 8 m. The rest of the intrascale-dependent correlation functions between {theta} with N2O fluxes and pH were in agreement with previous studies. These techniques allow research on scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scale

Ecological strategies in stable and disturbed environments depend on species specialisation

Ecological strategies are integral to understanding species survival in different environments. However, how habitat specialisation is involved in such strategies is not fully understood, particularly in heterogeneous and disturbed environments. Here, we studied the trait associations between specialisation, dispersal ability, competitiveness, reproductive investment and survival rate in a spatially explicit metacommunity model under various disturbance rates. Though no unique trait values were associated with specialisation, relationships were uncovered depending on environmental factors. We found strong trait associations mainly for generalist species, while specialist species exhibited a larger range of trait combinations. Trait associations were driven first by the disturbance rate and second by species’ dispersal ability and generation overlap. With disturbance, low dispersal ability was strongly selected against, for specialists as well as for generalists. Our results demonstrate that habitat specialisation is critical for the emergence of trait strategies in metacommunities and that disturbance in interaction with dispersal ability limits not only the range of trait values but also the type of possible trait associations

In vitro production of bovine embryos derived from individual donors in the Corral® dish

Background: Since the identity of the embryo is of outmost importance during commercial in vitro embryo production, bovine oocytes and embryos have to be cultured strictly per donor. Due to the rather low yield of oocytes collected after ovum pick-up (OPU) per individual cow, oocyte maturation and embryo culture take place in small groups, which is often associated with inferior embryo development. The objective of this study was to improve embryonic development in small donor groups by using the Corral (R) dish. This commercial dish is designed for human embryo production. It contains two central wells that are divided into quadrants by a semi-permeable wall. In human embryo culture, one embryo is placed per quadrant, allowing individual follow-up while embryos are exposed to a common medium. In our study, small groups of oocytes and subsequently embryos of different bovine donors were placed in the Corral (R) dish, each donor group in a separate quadrant. Results: In two experiments, the Corral (R) dish was evaluated during in vitro maturation (IVM) and/or in vitro culture (IVC) by grouping oocytes and embryos of individual bovine donors per quadrant. At day 7, a significantly higher blastocyst rate was noted in the Corral (R) dish used during IVM and IVC than when only used during IVM (12.9% +/- 2.10 versus 22.8% +/- 2.67) (P < 0.05). However, no significant differences in blastocyst yield were observed anymore between treatment groups at day 8 post insemination. Conclusions: In the present study, the Corral (R) dish was used for in vitro embryo production (IVP) in cattle; allowing to allocate oocytes and/or embryos per donor. As fresh embryo transfers on day 7 have higher pregnancy outcomes, the Corral (R) dish offers an added value for commercial OPU/IVP, since a higher blastocyst development at day 7 is obtained when the Corral (R) dish is used during IVM and IVC