Biospec Publications

Three band indexes for nitrogen content estimation in Holm oak in a temporal scaleAmerican Geophysical Union (AGU) 2011 Fall Meeting. 5-9 December 2011 San Francisco (EE.UU)
A comparison of evapotranspiration and evaporative fraction estimates using the triangle method with MSG-SEVIRI, MODIS and LANDSAT 5 TM3rd iLEAPS Science Conference Garmisch-Partenkirchen (Alemania) 18-23 Septiembre 2011
Obtención de información espectral a diversas escalas para la estimación de parámetros biofísicos de la vegetación Mediterránea en el contexto del cambio global (BIOSPEC)XIV Congreso de la Asociación Española de Teledetección Mieres (Asturias) 21-23 Septiembre 2011.
Spectral measurements at flux tower sites: initial findings from the Eurospec project2011 RSPSoc Annual Conference. Bournemouth (UK) 13-15 Septiembre 2011
Linking spectral information at different spatial scales with biophysical parameters of Mediterranean vegetation in the context of global change (BIOSPEC)

Biospec propose a multi-source approach to combine remote sensing products of various spectral and spatial scales (field spectroscopy, airborne and satellite images) in order to analyze and quantify the potential uncertainties in the estimation of relevant vegetation parameters such as water and nitrogen content, LAI, etc in a complex Mediterranean ecosystem. The dataset underlying the study include various spaceborne
(Landsat and MODIS) as well as airborne (AHS and CASI) reflectance datasets with different spatial and spectral resolutions. Ground information have been obtained including spectral measurements using field spectroradiometers, measurements of biophysical vegetation parameters, meteorological variables and CO2, H2O and energy  fluxes from April 2009 to May 2011 in in a grazed pasture in northeastern province of
Cáceres (Spain) where an eddy-covariance flux tower (included in the Fluxnet network) has been operating since 2003 by Fundación Centro de Estudios Ambientales del Mediterráneo (CEAM).

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M. P. Martín, J. Pacheco-Labrador, A. Carrara, M. P. Echavarría, J. Gajardo, M. Gallardo, C. Gimeno, I. Gómez, R. González, F. J. Martínez, G. Mendiguren, H. Nieto, F. Pérez, D. Riaño and J. Salas
FLUXNET and SpecNet Open-Workshop: Towards Upscaling Flux Information from Towers to the Globe. Berkeley, CA June 2011
Leaf nitrogen estimation with hyperspectral Normalized Ratio Indexes in a Mediterranean wooded grassland ecosystem

OBJETIVE: Evaluate linear relationships between leaf optical response and nitrogen content (LNC) in Holm oak trees, and its coherence with nitrogen-compounds absorption features.

• Considering the variation of both LNC and Leaf Optical Response along phenological years achieves the independence of LNC and water content in young leaves, but not allows to relate LNC with N absorption bands.
• No good correlations related to N absorption features found .
• Red edge correlation may be due to leaf maturing. If increment of leathery is a cause, correlation may be applicable to another sclerophyll species.

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J. Pacheco-Labrador, M.R. González, M.P. Martín, D. Riaño
7th EARSeL SIG Imaging Spectroscopy workshop, Edimburgh, April 2011
Annual Variation of Foliar Nitrogen and Chlorophyll Contents in Mature Holm Oak Trees as a Basis for the Estimation of Canopy Nitrogen in a Mediterranean Wooded Grassland Ecosystem


- There have been found significant differences in the nitrogen concentrations between leaf age classes and also during the sampling dates. Three main periods were identified whose foliar N concentrations differed clearly: the time between sprouting and leaf elongation, the dry summer period and the wintertime. The first is characterized by a maximum of foliar N concentrations (in dry mass units, g/kg), not only related to the foliar chlorophyll contents. Water and thermal stress in summer produced a stabilization of N foliar concentrations over time and between age classes. During the fall-winter time the leaves accumulate increasingly N until the next new spring arrives.

 - The rate of leaf renovation in the crown is a usually unknown parameter. The time span of the year characterized by less variability over time and between leaf age classes was the dry summer period, in this study area between June and September. Therefore, average estimations of N at crown level will be less dependent of leaf renovation rate at this time of the year for evergreen species under Mediterranean climate conditions like the Quercus ilex of the study area.

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González Cascón, M.R., Pacheco Labrador, J., Martínez Vega F.J., Martín Isabel M.P.
Nitrogen & Global Change. Key findings-future chalenges. Edinburgh, April 2011.
Multi-scale estimation of vegetation and soil moisture in a Mediterranean wooded grassland (dehesa) using optical sensors

A multi-scale and multi-temporal approach was applied to estimate vegetation water content and soil moisture in a typical Mediterranean wooded grassland (Dehesa) using remote sensing data. A field campaign to sample vegetation water content was carried out in the test site located in NE Cáceres (Spain) from March to December 2009. Soil moisture was measured using Time Domain Reflectometry (TDR) at 4, 10 and 20 cm depths. Field spectra were acquired using ASD FieldSpec® 3 spectro-radiometer. Canopy Water Content (CWC) was estimated based on the inversion of a radiative transfer model (Trombetti et al. 2008) both for field spectra as well as from MODIS Terra satellite data. Simple regressions between vegetation, soil moisture and spectral indices were carried out. NDVI and NDW7 showed the best correlation with vegetation moisture (R2=0.91 and 0.90) both from field spectra and satellite data. Correlation with soil moisture was weak for spectral indices, except for CWC estimated from MODIS data (R2 = 0.56).


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Gorka Mendiguren, M. Pilar Martín, David Riaño, F. Javier Martínez, Javier Pacheco, Lara Vilar
Third Recent Advances in Quantitative Remote Sensing, September 2010, Valencia, Spain