Javier Velázquez
Technical University of Madrid
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Featured researches published by Javier Velázquez.
Biodiversity and Conservation | 2010
Ana Hernando; Rosario Tejera; Javier Velázquez; María Victoria Núñez
The main goal of Natura 2000 network is to guarantee the favourable conservation status of habitats and species ensuring European biodiversity. As a result, certain forest areas have been included in this network listed as 9230-Quercus pyrenaica habitat and 9340-Quercus ilex subsp. rotundifolia forest habitat. These areas were previously used for firewood extraction or livestock grazing and browsing. Nowadays these habitats are coppice forests with asexual regeneration, which is far from the desired conservation status. Traditional timber harvesting plans do not take account of the new objectives required for these Natura sites, which attempt to ensure biodiversity and recreational uses instead of simply focusing on timber production. This paper proposes a flexible methodology (applied to the study area “Dehesa Boyal” in Ávila, Spain) for managing Natura 2000 forest sites by stands for sustainable forest management and the new requirements. The methodology has two phases. The first, “Division of the forest area into stands”, defines homogeneous patches of vegetation distinct in species composition, physiognomic structure and future management. The second, “Conservation status assessment of stands”, quantifies the conservation status of each previously classified stand considering a series of factors such as: functional health, restoration, floral richness and structure. A total value integrating the conservation status of stands is then calculated for the habitat. Both phases use Geographic Information System tools for managing information and visualizing results. The proposed methodology provides forest managers with a good knowledge of the territory and subsequently enables them to take appropriate conservation measures to maintain biodiversity.
Photogrammetric Engineering and Remote Sensing | 2012
Ana Hernando; Lara A. Arroyo; Javier Velázquez; Rosario Tejera
Natura 2000 is a European network of protected areas established under the Habitats Directive (92/43/EEC). According to the Habitats Directive, habitat maps must be periodically updated, which requires the development of cost- and time-efficient mapping practices. In this study, we propose a methodology for habitat mapping using very high spatial resolution (QuickBird) images with Object-Based Image Analysis (OBIA). We classified five segmentation levels: level 5 incorporated the prior knowledge of the study area into the analysis; level 4 and 1 were used to identify arable areas and land covers, respectively. The information contained in levels 1, 4, and 5 was then combined to classify plant species in level 2. Finally, habitats were classified in level 3 using level 2 class-related features. The habitat map obtained had an overall accuracy of 86.3 percent. Classification accuracies were higher for tree-and pasture-dominated habitats than for shrub-dominated habitats.
Mycorrhiza | 2009
Inmaculada Valverde-Asenjo; Luis G. García-Montero; Asunción Quintana; Javier Velázquez
Calcareous amendments are being used in Tuber melanosporum truffle plantations in attempts to eradicate Tuber brumale. However, there are no studies available which provide soil analysis and statistical data on this topic. We studied 77 soil samples to compare the values for carbonates, pH and total organic carbon in T. brumale truffières with the values for T. melanosporum truffières on contaminated farms and in natural areas. Statistical analyses indicate that the concentrations of active carbonate and total carbonate in the soil are significantly higher in T. brumale truffières than in T. melanosporum truffières, but that there are no significant differences in pH and total organic carbon. We conclude that liming would not suppress T. brumale ectomycorrhizas in contaminated T. melanosporum farms, and calcareous amendments do not therefore seem be a means of eradicating T. brumale in these farms.
Archive | 2012
Rosario Tejera; María Victoria Núñez; Ana Hernando; Javier Velázquez; Ana Pérez-Palomino
© 2012 Tejera et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biodiversity and Conservation Status of a Beech (Fagus sylvatica) Habitat at the Southern Edge of Species ́Distribution
Forest Ecology and Management | 2011
Santiago Saura; Peter Vogt; Javier Velázquez; Ana Hernando; Rosario Tejera
Journal for Nature Conservation | 2010
Javier Velázquez; Rosario Tejera; Ana Hernando; María Victoria Núñez
Journal for Nature Conservation | 2012
Victoria Núñez; Ana Hernando; Javier Velázquez; Rosario Tejera
Land Use Policy | 2018
Javier Velázquez; Javier Gutiérrez; Ana Hernando; Antonio García-Abril; M.A. Martín; P. Irastorza
Pesquisa Florestal Brasileira | 2017
Javier Velázquez; Víctor Rincón; Javier Gutiérrez; Eva Mayenco; Ana Hernando; Ángela Bedoya
International Conference on Education and New Learning Technologies | 2016
Ana Hernando; Mathieu Legrand; Javier Velázquez; Moisés Silva; Antonio García-Abril