The Experts below are selected from a list of 71112 Experts worldwide ranked by ideXlab platform

Rudi J Van Aarde - One of the best experts on this subject based on the ideXlab platform.

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Context Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs).

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs). To determine the influence of Matrix type on SARs. We surveyed birds within 59 coastal forest fragments in two Matrix types, anthropogenic (South Africa) and natural (Mozambique). We classified species as forest specialists or habitat generalists and fitted species-area models to compare how SAR slopes differed among Matrix types. We also calculated nestedness and evenness to determine if these varied among Matrix type and used logistic regressions to identify species-specific responses to Matrix type. For habitat generalists, SARs were weak within both matrices, while for forest specialists it was strong in the anthropogenic but weak in the natural Matrix. In the former, the SAR was similar to those recorded for real islands within archipelagos. Forest specialist assemblages were nested by area within anthropogenic, but not natural matrices. Matrix type did not influence evenness. Area only affected the occurrence of one species when the Matrix was natural, compared to 11 species when it was anthropogenic. Forest specialist bird species conformed to island biogeographic predictions of species loss in forest fragments embedded in anthropogenic, but not natural matrices. Extinctions from small forest fragments might be prevented by conserving natural- or restoring anthropogenic matrices, as well as by increasing forest area.

Marc T. Freeman - One of the best experts on this subject based on the ideXlab platform.

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Context Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs).

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs). To determine the influence of Matrix type on SARs. We surveyed birds within 59 coastal forest fragments in two Matrix types, anthropogenic (South Africa) and natural (Mozambique). We classified species as forest specialists or habitat generalists and fitted species-area models to compare how SAR slopes differed among Matrix types. We also calculated nestedness and evenness to determine if these varied among Matrix type and used logistic regressions to identify species-specific responses to Matrix type. For habitat generalists, SARs were weak within both matrices, while for forest specialists it was strong in the anthropogenic but weak in the natural Matrix. In the former, the SAR was similar to those recorded for real islands within archipelagos. Forest specialist assemblages were nested by area within anthropogenic, but not natural matrices. Matrix type did not influence evenness. Area only affected the occurrence of one species when the Matrix was natural, compared to 11 species when it was anthropogenic. Forest specialist bird species conformed to island biogeographic predictions of species loss in forest fragments embedded in anthropogenic, but not natural matrices. Extinctions from small forest fragments might be prevented by conserving natural- or restoring anthropogenic matrices, as well as by increasing forest area.

Pieter Ignatius Olivier - One of the best experts on this subject based on the ideXlab platform.

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Context Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs).

  • Matrix Transformation alters species-area relationships in fragmented coastal forests
    Landscape Ecology, 2018
    Co-Authors: Marc T. Freeman, Pieter Ignatius Olivier, Rudi J Van Aarde
    Abstract:

    Ecological theory suggests that large habitat fragments should harbour more species than small fragments. However, this may depend on the surrounding Matrix. Matrices in fragmented landscapes may either amplify or reduce area effects, which could influence predicted extinctions based on species-area relationships (SARs). To determine the influence of Matrix type on SARs. We surveyed birds within 59 coastal forest fragments in two Matrix types, anthropogenic (South Africa) and natural (Mozambique). We classified species as forest specialists or habitat generalists and fitted species-area models to compare how SAR slopes differed among Matrix types. We also calculated nestedness and evenness to determine if these varied among Matrix type and used logistic regressions to identify species-specific responses to Matrix type. For habitat generalists, SARs were weak within both matrices, while for forest specialists it was strong in the anthropogenic but weak in the natural Matrix. In the former, the SAR was similar to those recorded for real islands within archipelagos. Forest specialist assemblages were nested by area within anthropogenic, but not natural matrices. Matrix type did not influence evenness. Area only affected the occurrence of one species when the Matrix was natural, compared to 11 species when it was anthropogenic. Forest specialist bird species conformed to island biogeographic predictions of species loss in forest fragments embedded in anthropogenic, but not natural matrices. Extinctions from small forest fragments might be prevented by conserving natural- or restoring anthropogenic matrices, as well as by increasing forest area.

Béla J. Szekeres - One of the best experts on this subject based on the ideXlab platform.

  • Efficient Numerical Solution of Space-Fractional Diffusion Problems
    Progress in Industrial Mathematics at ECMI 2018, 2019
    Co-Authors: Ferenc Izsák, Béla J. Szekeres
    Abstract:

    An efficient numerical method is introduced for the solution of space-fractional diffusion problems. We use the spectral fractional Laplacian operator with homogeneous Neumann and Dirichlet boundary conditions. The spatial discretization is based on the Matrix Transformation method. Using a recent algorithm for the computation of fractional Matrix power-vector products and explicit time stepping, we develop a simple and efficient full discretization. The performance of our approach is demonstrated in some numerical experiments.

  • Efficient computation of Matrix power-vector products: Application for space-fractional diffusion problems
    Applied Mathematics Letters, 2018
    Co-Authors: Ferenc Izsák, Béla J. Szekeres
    Abstract:

    Abstract A novel algorithm is proposed for computing Matrix–vector products A α v , where A is a symmetric positive semidefinite sparse Matrix and α > 0 . The method can be applied for the efficient implementation of the Matrix Transformation method to solve space-fractional diffusion problems. The performance of the new algorithm is studied in a comparison with the conventional MATLAB subroutines to compute Matrix powers.

  • Convergence of the Matrix Transformation method for the finite difference approximation of fractional order diffusion problems
    Applications of Mathematics, 2017
    Co-Authors: Béla J. Szekeres, Ferenc Izsák
    Abstract:

    Numerical solution of fractional order diffusion problems with homogeneous Dirichlet boundary conditions is investigated on a square domain. An appropriate extension is applied to have a well-posed problem on R^2 and the solution on the square is regarded as a localization. For the numerical approximation a finite difference method is applied combined with the Matrix Transformation method. Here the discrete fractional Laplacian is approximated with a Matrix power instead of computing the complicated approximations of fractional order derivatives. The spatial convergence of this method is proved and demonstrated by some numerical experiments.

Fatemeh Nazemnejad - One of the best experts on this subject based on the ideXlab platform.

  • band ratios Matrix Transformation brmt a sedimentary lithology mapping approach using aster satellite sensor
    Sensors, 2018
    Co-Authors: Ghasem Askari, Amin Beiranvand Pour, Biswajeet Pradhan, Mehdi Sarfi, Fatemeh Nazemnejad
    Abstract:

    Remote sensing imagery has become an operative and applicable tool for the preparation of geological maps by reducing the costs and increasing the precision. In this study, ASTER satellite remote sensing data were used to extract lithological information of Deh-Molla sedimentary succession, which is located in the southwest of Shahrood city, Semnan Province, North Iran. A robust and effective approach named Band Ratio Matrix Transformation (BRMT) was developed to characterize and discriminate the boundary of sedimentary rock formations in Deh-Molla region. The analysis was based on the forward and continuous division of the visible-near infrared (VNIR) and the shortwave infrared (SWIR) spectral bands of ASTER with subsequent application of principal component analysis (PCA) for producing new transform datasets. The approach was implemented to ASTER spectral band ratios for mapping dominated mineral assemblages in the study area. Quartz, carbonate, and Al, Fe, Mg ⁻OH bearing-altered minerals such as kaolinite, alunite, chlorite and mica were appropriately mapped using the BRMT approach. The results match well with geology map of the study area, fieldwork data and laboratory analysis. Accuracy assessment of the mapping result represents a reasonable kappa coefficient (0.70%) and appropriate overall accuracy (74.64%), which verified the robustness of the BRMT approach. This approach has great potential and capability for mapping sedimentary succession with diverse local⁻geological⁻physical characteristics around the world.