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Pre-fire aboveground biomass, estimated from LiDAR, spectral and field inventory data, as a major driver of burn severity in maritime pine (Pinus pinaster) ecosystems

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Forest Ecosystems 2022年第2期9卷 234-246页

作者： Jose Manuel fernandez-Guisuraga Susana Suarez-Seoane Paulo MFernandes Victor fernandez-Garcia alfonso fernandez-manso Carmen Quintano Leonor Calvo Area of Ecology Department of Biodiversity and Environmental ManagementFaculty of Biological and Environmental SciencesUniversity of Leon24071LeonSpain Centro de Investigacao e de Tecnologias Agroambientais e Biologicas Universidade de Tras-os-Montes e Alto Douro5000-801Vila RealPortugal Department of Organisms and Systems Biology(Ecology Unit)and Research Unit of Biodiversity(IMIB UO-CSIC-PA)University of OviedoOviedoMieresSpain Agrarian Science and Engineering Department School of Agricultural and Forestry EngineeringUniversity of Leon24400PonferradaSpain Electronic Technology Department School of Industrial EngineeringUniversity of Valladolid47011ValladolidSpain Sustainable Forest Management Research Institute University of Valladolid-Spanish National Institute for Agriculture and Food Research and Technology(INIA)34004PalenciaSpain

Background:The characterization of surface and canopy fuel loadings in fire-prone pine ecosystems is critical for understanding fire behavior and anticipating the most harmful ecological effects of fire.Nevertheless,the joint consideration of both overstory and understory strata in burn severity assessments is often dismissed.The aim of this work was to assess the role of total,overstory and understory pre-fire aboveground biomass(AGB),estimated by means of airborne Light Detection and Ranging(LiDAR)and Landsat data,as drivers of burn severity in a megafire occurred in a pine ecosystem dominated by Pinus pinaster Ait.in the western Mediterranean Basin.Results:Total and overstory AGB were more accurately estimated(R^(2) equal to 0.72 and 0.68,respectively)from LiDAR and spectral data than understory AGB(R^(2)=0.26).Density and height percentile LiDAR metrics for several strata were found to be important predictors of AGB.Burn severity responded markedly and non-linearly to total(R^(2)=0.60)and overstory(R ^(2)=0.53)AGB,whereas the relationship with understory AGB was weaker(R ^(2)=0.21).Nevertheless,the overstory plus understory AGB contribution led to the highest ability to predict burn severity(RMSE=122.46 in dNBR scale),instead of the joint consideration as total AGB(RMSE=158.41).Conclusions:This study novelty evaluated the potential of pre-fire AGB,as a vegetation biophysical property derived from LiDAR,spectral and field plot inventory data,for predicting burn severity,separating the contri-bution of the fuel loads in the understory and overstory strata in Pinus pinaster stands.The evidenced relationships between burn severity and pre-fire AGB distribution in Pinus pinaster stands would allow the implementation of threshold criteria to support decision making in fuel treatments designed to minimize crown fire hazard.

关键词： Aboveground biomass Burn severity Landsat LiDAR Pinus pinaster

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Microstructural and photocatalytic characterization of cement-paste sol-gel synthesized titanium dioxide

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Frontiers of Structural and Civil Engineering 2016年第2期10卷 189-197页

作者： Elena CERRO-PRADA Miguel manso Vicente TORRES Jesfs SORIANO Civil Engineering Department Universidad Politecnica de Madrid Alfonso XII 3 Madrid 28014 Spain Applied Physics Department Universidad Aut6noma de Madrid Ciudad Universitaria de Cantoblanco Madrid 28049 Spain Laboratory of Materials CEDEX Ministerio de Fomento de Espana Alfonso XIL Madrid 28014 Spain

ABSTRACT A routte for the in paste synthesis of TiO2 loaded cement is described. TiO2 sols are blended with fresh cement paste as an alternative process to add photocatalytic functionality to cement. The modification of cement paste structure after the addition ofTiO2 sols is analyzed by XRD, SEM and TGA. As a particular microstructural feature, TiO2 containing calcium silicate hydrate （C-H-S） particles are identified as networking centers ofa C-S-H gel fiber matrix. The increase of the TiO2 sol concentration induces a decrease of pore size and an increase in the specific surface area in the cement composites. The photocatalytic activity of the TiO2/cement system is evaluated from the degradation of Methylene Blue （MB） under UV irradiation, monitored through the absorbance at 665 nm. The results show that, although TiO2 phases reveal no long range order structure, the cement paste exothermal treatment in presence of hydrate products and alkaline conditions leads to a photocatalytic composite. Such new cement matrix may be twofold advantageous since it additionally promotes the formation of C-S-H gel, main determinant of cement mechanical properties.

关键词： cement composites photocatalytic TiO2 sol-gel C-S-H gel microstructure

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