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This paper provides an overview of the last 40 years of use, and in many cases abuse, of the natural resources in Catalonia, a country that is representative of European countries in general, and especially those in the Mediterranean region. It analyses the use of natural resources made by mining, agriculture, livestock, logging, fishing, nature tourism, and energy production and consumption. This use results in an ecological footprint, i.e., the productive land and sea surface required to generate the consumed resources and absorb the resulting waste, which is about seven times the amount available, a very high number but very similar to other European countries. This overexploitation of natural resources has a huge impact on land and its different forms of cover, air, and water. For the last 25 years, forests and urban areas have each gained almost 3% more of the territory at the expense of agricultural land; those municipalities bordering the sea have increased their number of inhabitants and activity, and although they only occupy 6.7% of the total surface area, they account for 43.3% of the population; air quality has stabilized since the turn of the century, and there has been some improvement in the state of aquatic ecosystems, but still only 36% are in good condition, while the remainder have suffered morphological changes and different forms of nonpoint source pollution; meanwhile the biodiversity of flora and fauna remains still under threat. Environmental policies do not go far enough so there is a need for revision of the legislation related to environmental impact and the protection of natural areas, flora, and fauna. The promotion of environmental research must be accompanied by environmental education to foster a society which is more knowledgeable, has more control and influence over the decisions that deeply affect it. Indeed, nature conservation goes hand in hand with other social and economic challenges that require a more sustainable vision. Toda

This paper provides an overview of the last 40 years of use, and in many cases abuse, of the natural resources in Catalonia, a country that is representative of European countries in general, and especially those in the Mediterranean region. It analyses the use of natural resources made by mining, agriculture, livestock, logging, fishing, nature tourism, and energy production and consumption. This use results in an ecological footprint, i.e., the productive land and sea surface required to generate the consumed resources and absorb the resulting waste, which is about seven times the amount available, a very high number but very similar to other European countries. This overexploitation of natural resources has a huge impact on land and its different forms of cover, air, and water. For the last 25 years, forests and urban areas have each gained almost 3% more of the territory at the expense of agricultural land; those municipalities bordering the sea have increased their number of inhabitants and activity, and although they only occupy 6.7% of the total surface area, they account for 43.3% of the population; air quality has stabilized since the turn of the century, and there has been some improvement in the state of aquatic ecosystems, but still only 36% are in good condition, while the remainder have suffered morphological changes and different forms of nonpoint source pollution; meanwhile the biodiversity of flora and fauna remains still under threat. Environmental policies do not go far enough so there is a need for revision of the legislation related to environmental impact and the protection of natural areas, flora, and fauna. The promotion of environmental research must be accompanied by environmental education to foster a society which is more knowledgeable, has more control and influence over the decisions that deeply affect it. Indeed, nature conservation goes hand in hand with other social and economic challenges that require a more sustainable vision. Toda

The objective of this work is to compare the emissivity estimates corresponding to the thermal band of the Landsat-5 TM sensor obtained following the algorithms of Valor and Caselles (1996), Sobrino and Raissouni (2000) and Wittich (1997). Their evaluation through soil field measurements shows that they produce values within the ranges. Furthermore, the capability of TM to detect a significant increase of soils emissivity (up to 0.018) according to their water content is demonstrated. The study shows a discrepancy between the methods in emissivity estimates lower than 0.014, depending on the land cover type. An spatio-temporal analysis by thematic classes allows observing the seasonal changes of crops, reproduced in a similar way by the three methods. To conclude, the presented comparison highlights the importance of choosing both the algorithm to be applied and the correct definition of the input constants taking into account the spectral characteristics of the study area., El objetivo de este trabajo es comparar las estimaciones de emisividad de la banda térmica del sensor TM de Landsat-5 obtenidas según los algoritmos Valor y Caselles (1996), Sobrino y Raissouni (2000) y Wittich (1997). La evaluación de dichos algoritmos a través de medidas terreno sobre suelos demuestra que proporcionan estimaciones enmarcadas dentro de los valores esperados. Además, se demuestra la capacidad de TM para detectar un aumento significativo (hasta 0.018) de la emisividad de los suelos en función de su contenido de humedad. Asimismo, el estudio pone de manifiesto una discrepancia entre métodos en las estimaciones de emisividad menores a 0.014, variable según el tipo de cubierta. Un análisis espacio-temporal por clases temáticas permite, de manera similar en los tres métodos, observar los cambios estacionales de los cultivos. En conclusión, la comparación aquí realizada destaca la importancia de la elección del algoritmo a aplicar y de la correcta definición de las constantes de entrada teniendo en cuenta las características espectrales de la zona de estudio.

Changes in the spatio-temporal distribution of arboreal ecosystems are a reflection of anthropogenic disturbances as well as the changes caused by climate dynamics. In this regard, it is of special interest to study the movements in the tree line, defined as a geographical area where environmental conditions no longer allow trees to develop in community. In this context, this study focuses on three pilot areas of the central Pyrenees (1800-2600 m a.s.l.), and it has been performed by photo interpretation of aerial images taken in 1948, 1972, 1995 and 2003. The work shows, using GIS techniques, that in these areas, close to the tree line, an increase in the area covered by forest (ranging between 0.46 and 0.95 ha per year) and a densification of pre-existing arboreal ecosystems occurs. It also shows the positional variations of the tree line as well as linear displacements (between 26 and 94 m) in the altitudinal position of the pioneer’s trees along the 55 years of study, Los cambios en la distribución espacio-temporal de los ecosistemas arbóreos son un reflejo de las perturbaciones de origen antrópico así como de los cambios provocados por la dinámica del clima. En este sentido, resulta de especial interés el estudio de los movimientos en la tree line, definida como área geográfica donde las condiciones ambientales ya no permiten que los árboles se desarrollen en colectividad. En este contexto, el presente estudio se centra en tres zonas piloto de los Pirineos centrales (1.800-2.600 m s.n.m.), y se ha realizado mediante fotointerpretación de imágenes aéreas tomadas en 1948, 1972, 1995 y 2003. El trabajo constata, mediante técnicas SIG, que en estas zonas, cercanas a la tree line, se produce un aumento de la superficie ocupada por bosque (que oscila entre 0,46 y 0,95 ha por año) así como una densificación de los ecosistemas arbóreos pre-existentes. Además muestra las variaciones posicionales de la tree line así como los desplazamientos lineales (entre 26 y 94 m) en la posición altitudinal de los árboles pioneros a lo largo de los 55 años de estudio.

The use of Pseudoinvariant Areas (PIA) makes it possible to carry out a reasonably robust and automatic radiometric correction for long time series of remote sensing imagery, as shown in previous studies for large data sets of Landsat MSS, TM, and ETM+ imagery. In addition, they can be employed to obtain more coherence among remote sensing data from different sensors. The present work validates the use of PIA for the radiometric correction of pairs of images acquired almost simultaneously (Landsat-7 (ETM+) or Landsat-8 (OLI) and Sentinel-2A (MSI)). Four pairs of images from a region in SW Spain, corresponding to four different dates, together with field spectroradiometry measurements collected at the time of satellite overpass were used to evaluate a PIA-based radiometric correction. The results show a high coherence between sensors (r2 = 0.964) and excellent correlations to in-situ data for the MiraMon implementation (r2 > 0.9). Other methodological alternatives, ATCOR3 (ETM+, OLI, MSI), SAC-QGIS (ETM+, OLI, MSI), 6S-LEDAPS (ETM+), 6S-LaSRC (OLI), and Sen2Cor-SNAP (MSI), were also evaluated. Almost all of them, except for SAC-QGIS, provided similar results to the proposed PIA-based approach. Moreover, as the PIA-based approach can be applied to almost any image (even to images lacking of extra atmospheric information), it can also be used to solve the robust integration of data from new platforms, such as Landsat-8 or Sentinel-2, to enrich global data acquired since 1972 in the Landsat program. It thus contributes to the program’s continuity, a goal of great interest for the environmental, scientific, and technical community