Monitoring rainfed alfalfa growth in semiarid agrosystems using Sentinel-2 imagery

The aim of this study was to assess the utility of Sentinel-2 images in the monitoring of the fractional vegetation cover (FVC) of rainfed alfalfa in semiarid areas such as that of Bardenas Reales in Spain. FVC was sampled in situ using 1 m2 surfaces at 172 points inside 18 alfalfa fields from late spring to early summer in 2017 and 2018. Different vegetation indices derived from a series of Sentinel-2 images were calculated and were then correlated with the FVC measurements at the pixel and parcel levels using different types of equations. The results indicate that the normalized difference vegetation index (NDVI) and FVC were highly correlated at the parcel level (R 2 = 0.712), where as the correlation at the pixel level remained moderate across each of the years studied. Based on the findings, another 29 alfalfa plots (28 rainfed; 1 irrigated) were remotely monitored operationally for 3 years (2017–2019), revealing that location and weather conditions were strong determinants of alfalfa growth in Bardenas Reales. The results of this study indicate that Sentinel-2 imagery is a suitable tool for monitoring rainfed alfalfa pastures in semiarid areas, thus increasing the potential success of pasture management.Andres Echeverria was supported by a predoctoral fellowship from the Government of Navarra. This work was supported by the knowledge transfer contract 2018020023 UPNA-Bardenas Reales Committee with partial collaboration of the project PID2019-107386RB-I00/AEI/10.13039/ 501100011033 (MINECO/FEDER-UE)

The added value of stratified topographic correction of multispectral images

Satellite images in mountainous areas are strongly affected by topography. Different studies demonstrated that the results of semi-empirical topographic correction algorithms improved when a stratification of land covers was carried out first. However, differences in the stratification strategies proposed and also in the evaluation of the results obtained make it unclear how to implement them. The objective of this study was to compare different stratification strategies with a non-stratified approach using several evaluation criteria. For that purpose, Statistic-Empirical and Sun-Canopy-Sensor + C algorithms were applied and six different stratification approaches, based on vegetation indices and land cover maps, were implemented and compared with the non-stratified traditional option. Overall, this study demonstrates that for this particular case study the six stratification approaches can give results similar to applying a traditional topographic correction with no previous stratification. Therefore, the non-stratified correction approach could potentially aid in removing the topographic effect, because it does not require any ancillary information and it is easier to implement in automatic image processing chains. The findings also suggest that the Statistic-Empirical method performs slightly better than the Sun-Canopy-Sensor + C correction, regardless of the stratification approach. In any case, further research is necessary to evaluate other stratification strategies and confirm these results.The authors gratefully acknowledge the financial support provided by the Public University of Navarre (UPNA). Part of the research presented in this paper is funded by the Spanish Ministry of Economy and Competitiveness in the frame of the ESP2013-48458-C4-2-P project

Validation of a simplified model to generate multispectral synthetic images

A new procedure to assess the quality of topographic correction (TOC) algorithms applied to remote sensing imagery was previously proposed by the authors. This procedure was based on a model that simulated synthetic scenes, representing the radiance an optical sensor would receive from an area under some specific conditions. TOC algorithms were then applied to synthetic scenes and the resulting corrected scenes were compared with a horizontal synthetic scene free of topographic effect. This comparison enabled an objective and quantitative evaluation of TOC algorithms. This approach showed promising results but had some shortcomings that are addressed herein. First, the model, originally built to simulate only broadband panchromatic scenes, is extended to multispectral scenes in the visible, near infrared (NIR), and short wave infrared (SWIR) bands. Next, the model is validated by comparing synthetic scenes with four Satellite pour l'Observation de la Terre 5 (SPOT5) real scenes acquired on different dates and different test areas along the Pyrenees mountain range (Spain). The results obtained show a successful simulation of all the spectral bands. Therefore, the model is deemed accurate enough for its purpose of evaluating TOC algorithms.The authors gratefully acknowledge the financial support provided by the Public University of Navarre (UPNA). Part of the research presented in this paper is funded by the Spanish Ministry of Economy and Competitiveness in the frame of the ESP2013-48458-C4-2-P project

Automatic detection of uprooted orchards based on orthophoto texture analysis

Permanent crops, such as olive groves, vineyards and fruit trees, are important in European agriculture because of their spatial and economic relevance. Agricultural geographical databases (AGDBs) are commonly used by public bodies to gain knowledge of the extension covered by these crops and to manage related agricultural subsidies and inspections. However, the updating of these databases is mostly based on photointerpretation, and thus keeping this information up-to-date is very costly in terms of time and money. This paper describes a methodology for automatic detection of uprooted orchards (parcels where fruit trees have been eliminated) based on the textural classification of orthophotos with a spatial resolution of 0.25 m. The textural features used for this classification were derived from the grey level co-occurrence matrix (GLCM) and wavelet transform, and were selected through principal components (PCA) and separability analyses. Next, a Discriminant Analysis classification algorithm was used to detect uprooted orchards. Entropy, contrast and correlation were found to be the most informative textural features obtained from the co-occurrence matrix. The minimum and standard deviation in plane 3 were the selected features based on wavelet transform. The classification based on these features achieved a true positive rate (TPR) of over 80% and an accuracy (A) of over 88%. As a result, this methodology enabled reducing the number of fields to photointerpret by 60–85%, depending on the membership threshold value selected. The proposed approach could be easily adopted by different stakeholders and could increase significantly the efficiency of agricultural database updating tasks.This study was funded by the Spanish National Institute for Agricultural and Food Research and Technology (INIA) through its training program for researchers

Teaching Development in Higher Education in Spain: the optimism of the will within a black box model.

[ES] La experiencia de formación en docencia en la universidad española es relativamente reciente, exceptuando el caso de algunas universidades. En la última década ha cobrado impulso debido al proceso de adaptación al Espacio Europeo de Educación Superior, el cual representa un cambio cultural profundo con respecto a los estudiantes y sus aprendizajes. Sin embargo, en España se ha querido impulsar desde referentes de naturaleza institucional y productiva, con orientaciones de orden técnico, en muy poco tiempo, y desde un modelo de ‘caja negra’ que pretende el logro de la calidad atendiendo a los resultados, ignorando los procesos y la necesaria formación para su mejor gestión. Desde los rectores hasta profesores se han visto constreñidos a cambiar elementos clave de la cultura precedente mediante referentes conceptuales y prácticos en los que no se reconocían. Sin embargo, los ejemplos de tres universidades muestran la importancia de considerar la formación de los profesores en el conocimiento de los procesos de enseñanza y aprendizaje para el logro una mejor calidad en la formación que se les propone a sus estudiantes.[EN] Training in teaching at the Spanish university is a relatively new experience, except for some universities. In the past decade it has attained a larger audience due to the process of adaptation to the Higher Education European Space, which represented a profound cultural change with respect to students and their learning. However, in Spain such change had been promoted according to an institutional frame, based on technical principles, within a model of black box. Such model wishes to improve quality attending its main outcomes and ignoring the processes and the necessary training for either those who develop or are involved in it. From Vice-Chancellors to the faculty staff, they had to deal with such change without the necessary understanding of its basic conceptions and its consequent related practices. Nevertheless, three cases of different universities depict how relevant such understanding can be. They emphasize the importance of teacher training when wishing at the improvement of the processes of teaching and learning, in order to attain a better quality in the proposed training to their students.Rué Domingo, J.; Arana Navarro, A.; González De Audícana Amenábar, M.; Abadía Valle, AR.; Blanco Lorente, F.; Bueno García, C.; Fernández March, A. (2013). El desarrollo docente en España en Educación Superior: el optimismo de la voluntad en un modelo de caja negra. REDU. Revista de Docencia Universitaria. 11(3):125-158. https://doi.org/10.4995/redu.2013.5523OJS125158113ANECA, DOCENTIA (2006). Programa de apoyo para la evaluación de la actividad docente del profesorado universitario. Modelo de evaluación, V. 1.0 - 14/11/2006.Bernal, J.L. (2006). Diseño curricular en la enseñanza universitaria desde la perspectiva de los ECTS. Colección Documentos. Zaragoza: Instituto de Ciencias de la Educación. Universidad de Zaragoza.Biggs, J. (2003). Teaching for quality learning at university, Buckinghamshire, Society for Research into Higher Education and Open University Press.Buela-Casal, G., Bermúdez, Mª P., Sierra, J. C., Quevedo-Blasco, R., Castro, A., GuillénRiquelme, A. (2012). Ranking de 2011 en producción y productividad en investigación de las universidades públicas españolas. Psicothema. Vol. 24 (4). pp. 505-515, www.psicothema.comConferencia de Rectores de las Universidades Españolas (2010). La Universidad Española en Cifras, Madrid: CRUE.Escudero, T. (2010). Sin tópicos ni malentendidos: fundamentos y pautas para una práctica evaluadora de calidad en la enseñanza universitaria. Colección Documentos. Zaragoza: Instituto de Ciencias de la Educación. Universidad de Zaragoza.European Association for Quality Assurance in Higher Education (ENQA). (2005). Documento Criterios y Directrices para la Garantía de Calidad en el Espacio Europeo de Educación Superior. http://docentia.uca.es/docs/normativa/ENQA%202005%20version%20ESP.pdfFernández, X., et al. (2011). Treball de recerca sobre l'abandonament dels estudis a la UPF, Informe Universitat Pompeu Fabra, abril de 2011. http://www.upf.edu/consellsocial/estudis_projectes/pdf/abandonament_estudi s.pdf [Consultado: 2 de noviembre 2012]Gibbs, G. (2010). Dimensions of Quality, The Higher Education Academy, Innovation Way, York Science Park, Heslington, York YO10 5BR, September, Report, 64 págs.Harvey, L. & Green, D. (1993). Defining quality. Assessment and Evaluation in Higher Education, 181, pp. 9-34.Harvey, L. & Williams, J. (2010). Fifteen years of quality in higher education. Quality in Higher Education, 16 (1), pp. 3-36.Ley de Reforma Universitaria, Ley Orgánica, 11/1983, de 25 de agosto.LEY ORGÁNICA de Universidades 6/2001, de 21 de diciembreMECD (2013). Propuestas para la reforma y la mejora de la calidad y eficiencia del Sistema Universitario Español, Informe entregado al Exmo. Sr Ministro de Educación, Cultura y Deporte, D. José Ignacio Wert Ortega, 12 de Febrero de 2013. http://portal.uned.es/pls/portal/docs/PAGE/UNED_MAIN/LAUNIVERSIDAD/UBIC ACIONES/05/PROCLAMAC.%20DEFINITIVA%20MIEMBROS%20JF%202012.PDF Visitado 22/02/2013Paricio, J. (2010). Un modelo de guía docente desde los resultados de aprendizaje y su evaluación. Colección Documentos de referencia para la calidad docente. Zaragoza: Instituto de Ciencias de la Educación. Universidad de Zaragoza.Rué, J. (2008). Formar en competencias en la universidad: entre la relevancia y la banalidad. Red U, Revista de Docencia universitaria, Año II. Número Monográfico 1, http://www.um.es/ead/Red_U/m1/dRué, J. (2012). La evaluación de la calidad de la docencia en las universidades españolas. Publicación RED-U. http://www.red-u.org 40p