Exploring BFAST to detect forest changes in Portugal

Costa, H., Giraldo, A., & Caetano, M. (2020). Exploring BFAST to detect forest changes in Portugal. In L. Bruzzone, F. Bovolo, & E. Santi (Eds.), Image and Signal Processing for Remote Sensing XXVI [1153308] (Proceedings of SPIE - The International Society for Optical Engineering; Vol. 11533). SPIE-International Society for Optical Engineering. https://doi.org/10.1117/12.2566669Landsat 8 data and Breaks For Additive Season and Trend (BFAST) were used in a region of central Portugal to detect forest clear-cuts and burnt areas. A total of 79 Landsat 8 images from 2013 to 2019 were downloaded for path/row 204/032, and the NDVI was calculated. The same data processing was done for path/row 203/032 to create a denser time series in the overlapping area, which increased to 124 images. The output of the analysis is a binary map of change (i.e., forest loss) and no-change. A probabilistic accuracy assessment based on random stratified sampling was implemented with 100 random points per stratum. Each point was interpreted as being either "no-change", "clear-cut"or "burnt area"based on reference data. Furthermore, the date of change (if any) was defined. Results show an overall accuracy of 0.85±0.02 for the binary classification with omission and commission errors of class "Change"of 0.30±0.02 and 0.19±0.02. Moreover, it is estimated that 32% of the forested area in path/row 204/032 went through at least one episode of clear-cut or fire in the period analyzed. The time lag between the date of change and detection was about 2.5 months on average, which decreased to 1.5 months in the regions of the denser time series. The results are promising but BFAST is somewhat slow and hence some concerns remain about its efficiency in operation use.authorsversionpublishe

Uncovering Vegetation Changes in the Urban–Rural Interface through Semi-Automatic Methods

Barbosa, B., Rocha, J., Costa, H., & Caetano, M. (2022). Uncovering Vegetation Changes in the Urban–Rural Interface through Semi-Automatic Methods. Applied Sciences, 12(5), 1-14. [2294]. https://doi.org/10.3390/app12052294 -------------- Funding: This research was funded by Portuguese Foundation for Science and Technology, I.P. (FCT), under the framework of the Project “FORESTER—Data fusion of sensor networks and fire spread modelling for decision support in forest fire suppression” [name of funder] grant number PCIF/SSI/0102/2017. The APC was funded by the Research Unit UIDB/00295/2020 and UIDP/00295/2020.Forest fires are considered by Portuguese civil protection as one of the most serious natural disasters due to their frequency and extent. To address the problem, the Fire Forest Defense System establishes the implementation of fuel management bands to aid firefighting. The aim of this study was to develop a model capable of identifying vegetation removal in the urban–rural interface defined by law for fuel management actions. The model uses normalised difference vegetation index (NDVI) of Sentinel-2 images time series and is based on the Welch t-test to find statistically significant differences between (i) the value of the NDVI in the pixel; (ii) the mean of the NDVI in the pixels of the same land cover type in a radius of 500 m; and (iii) their difference. The model identifies a change when the t-test points for a significant difference of the NDVI value in the ‘pixel’ as comparted to the ‘difference’ but not the ‘mean’. We use a moving window limited to 60 days before and after the analysed date to reduce the phenological variations of vegetation. The model was applied in five municipalities of Portugal and the results are promising to identify the places where the management of fuel bands was not carried out. This indicates which model could be used to assist in the verification of the annual management of the fuel bands defined in the law.publishersversionpublishe

Automatic detection of vegetation cover changes in urban-rural interface areas

Barbosa, B., Rocha, J., Costa, H., & Caetano, M. (2022). Automatic detection of vegetation cover changes in urban-rural interface areas. MethodsX, 9, 1-7. [101643]. https://doi.org/10.1016/j.mex.2022.101643 ---------- This work was financed by national funds through FCT—Portuguese Foundation for Science and Technology, I.P., under the framework of the Project “FORESTER - Data fusion of sensor networks and fire spread modelling for decision support in forest fire suppression” [PCIF / SSI / 0102 / 2017] and is relative to a scientific Research Fellowship BI_27_20.The present work started from the need to streamline the process of monitoring changes in vegetation in the in urban-rural interface fuel management bands, defined by Portuguese legislation as areas where the existing biomass must be totally or partially removed. The model developed uses a time series of Sentinel 2 satellite images to search for changes in the vegetation cover in a 100 meters buffer around built-up areas. The use of satellite data allows analysing large areas and speeds up the task of identifying the places where fuel management took place and the places where there is a need to carry out such management. The objective of the proposed method is to give a script in Python language that can verify the cleanliness of vegetation in the fuel management ranges through multi-temporal analysis of satellite images.publishersversionpublishe

Thematic Comparison between ESA WorldCover 2020 Land Cover Product and a National Land Use Land Cover Map

Duarte, D., Fonte, C., Costa, H., & Caetano, M. (2023). Thematic Comparison between ESA WorldCover 2020 Land Cover Product and a National Land Use Land Cover Map. Land, 12(2), 1-16. [490]. https://doi.org/10.3390/land12020490 --- Funding: This work has been supported by projects foRESTER (PCIF/SSI/0102/2017), SCAPEFIRE (PCIF/MOS/0046/2017) and FireLoc (PCIF/MPG/0128/2017), by Centro de Investigação em Gestão de Informação (MagIC) and grant UIDB/00308/2020, all funded by the Portuguese Foundation for Science and Technology (FCT). It was also supported by Compete2020 (POCI-05-5762-FSE-000368), funded by the European Social Fund.This work presents a comparison between a global and a national land cover map, namely the ESA WorldCover 2020 (WC20) and the Portuguese use/land cover map (Carta de Uso e Ocupação do Solo 2018) (COS18). Such a comparison is relevant given the current amount of publicly available LULC products (either national or global) where such comparative studies enable a better understanding regarding different sets of LULC information and their production, focus and characteristics, especially when comparing authoritative maps built by national mapping agencies and global land cover focused products. Moreover, this comparison is also aimed at complementing the global validation report released with the WC20 product, which focused on global and continental level accuracy assessments, with no additional information for specific countries. The maps were compared by following a framework composed by four steps: (1) class nomenclature harmonization, (2) computing cross-tabulation matrices between WC20 and the Portuguese map, (3) determining the area occupied by each harmonized class in each data source, and (4) visual comparison between the maps to illustrate their differences focusing on Portuguese landscape details. Some of the differences were due to the different minimum mapping unit ofCOS18 and WC20, different nomenclatures and focuses on either land use or land cover. Overall, the results show that while WC20 detail is able to distinguish small occurrences of artificial surfaces and grasslands within an urban environment, WC20 is often not able to distinguish sparse/individual trees from the neighboring cover, which is a common occurrence in the Portuguese landscape. While selecting a map, users should be aware that differences between maps can have a range of causes, such as scale, temporal reference, nomenclature and errors.publishersversionpublishe

Propriedades antibacterianas de compósitos de PU/npZnO

Mestrado em Materiais e Dispositivos BiomédicosO óxido de zinco, sob a forma de nanopartículas (npZnO), é um tema de elevado interesse na actualidade. É no entanto sabido que as suas propriedades e efeitos biológicos são muito dependentes do método de síntese. Nesse contexto, características como o comportamento antibacteriano e a citotoxicidade encontram-se ainda pouco estudadas. Tal como outros materiais nanoestruturados, o óxido de zinco, quando na forma de nanopartículas, pode ser potencialmente perigoso para o organismo humano caso as suas propriedades não sejam bem controladas. A fixação destas nanopartículas numa matriz de poliuretano, formando compósitos de PU/npZnO, é uma possível via de controlar essas propriedades. Trabalhos preliminares anteriormente realizados no Departamento de Engenharia de Materiais e Cerâmica da Universidade de Aveiro estabeleceram as condições necessárias para a síntese de npZnO, e para a preparação de compósitos de PU/npZnO, com características promissoras para utilização como agentes antibacterianos. O presente estudo teve como objectivo avaliar as propriedades antibacterianas de partículas de óxido de zinco nanoestruturadas, e de compósitos de PU/npZnO. Mais concretamente, pretende-se compreender qual o impacto das nanopartículas de óxido de zinco, sintetizadas com diferentes características físicas e químicas, bem como os compósitos, nos organismos vivos, designadamente bactérias. Foram sintetizadas nanopartículas de óxido de zinco, por precipitação química à temperatura ambiente, em condições de sobressaturação diferentes. Obtiveram-se nanoestruturas porosas e de elevada área superficial, mas com características fortemente condicionadas pelas condições de síntese. Além disso, as npZnO sintetizadas evidenciaram também características de superficie diferentes, refletidas pelas suas curvas de potencial zeta, que são distintas. Efectuaram-se estudos antibacterianos, com a estirpe de bactérias E.Coli ATCC 25922. Observou-se que, embora tendam a favorecer a proliferação bacteriana, se usadas em baixa concentração, as npZnO apresentam comportamento antibacteriano que se acentua quando se aumenta a concentração das npZnO. Deve referir-se que as npZnO, com menor valor de área superficial específica e potencial zeta mais acentuado foram as que apresentaram uma redução quase total da viabilidade bacteriana para a máxima concentração testada. Os compósitos PU/npZnO, preparados com as mesmas npZnO acima referidas, evidenciaram o mesmo comportamento. Estes resultados indiciam que o estado de superfície das npZnO tem um contributo efetivo para o comportamento antibacterianos das mesmas. Em conclusão, as npZnO sintetizadas no presente trabalho possuem propriedades antibacterianas, sendo possível a sua fixação numa matriz de poliuretano formando um compósito PU/npZnO, também ele com propriedades antibacterianas, com potencial interesse para tratamento localizado.Zinc oxide in the form of nanoparticles (npZnO) is currently a topic of high interest. However it is known that its properties and biological effects are highly dependent on the method of sunthesis. In that, context, characteristics such as the antibacterial performance and cytotoxicity are however still very little explored. Like other nanostructured materials, zinc oxide, when presented in the form of nanoparticles, can be potentially dangerous to the human body if their properties are not well controlled. Fixing these nanoparticles in a matrix of polyurethane (PU), forming a composite PU/npZnO is a possible way to control these properties. Preliminary work previously carried out in the Department of Materials Engineering and Ceramics of the University of Aveiro have established the necessary conditions for the synthesis of npZnO, and for the composite PU/npZnO, with promising characteristics for use as antibacterial agents. The present study aims to assess the antibacterial properties of nanostructured zinc oxide particles, and of the composite PU/npZnO. Specifically, the objective is to understand to what extent zinc oxide nanoparticles, synthetized with different physical and chemical characteristics, and their composites PU/npZnO, impact living organisms, paricularly bacteria. Zinc oxide nanoparticles were synthetized by a chemical precipitation method at room temperature, using diferent supersturation conditions. ZnO porous nanostructures with a high surface area were obtained, but mophological characteristics strongly influenced by the conditions of synthesis. In addition, the synthesized npZnO also showed different surface characteristics as reflected by their zeta potential curves which are different. Antibacterial studies were carried out with the bacterial strain E. Coli ATCC 25922. Although npZnO tendo to favor the bacterial growth when used in a low concentration, npZnO exhibit an antibacterial behavior that increases with the increasing concentration of npZnO. It should also be noted that npZnO with lower specific surface area and lower zeta potential showed the almost total reduction of bacterial viability for the highest concentration tested. The composites PU/npZnO prepared with the same npZnO mentioned above, also showed the same behavior. As conclusion, the npZnO synthesized in this work exhibit antibacterial properties. Furthermore it is possible to fix the npZnO in a polyurethane matrix, obtaining a composite with antibacterial properties which might offer a pontential interest for localized treatment

Mapping annual crops in Portugal with Sentinel-2 data

Benevides, P., Costa, H., Moreira, F. D., & Caetano, M. (2022). Mapping annual crops in Portugal with Sentinel-2 data. In C. M. U. Neale, & A. Maltese (Eds.), Proceedings of SPIE.Remote Sensing for Agriculture, Ecosystems, and Hydrology XXIV (Vol. 12262). SPIE. Society of Photo-Optical Instrumentation Engineers. https://doi.org/10.1117/12.2636125This paper presents an annual crop classification exercise considering the entire area of continental Portugal for the 2020 agricultural year. The territory was divided into landscape units, i.e. areas of similar landscape characteristics for independent training and classification. Data from the Portuguese Land Parcel Identification System (LPIS) was used for training. Thirty-one annual crops were identified for classification. Supervised classification was undertaken using Random Forest. A time-series of Sentinel-2 images was gathered and prepared. Automatic processes were applied to auxiliary datasets to improve the training data quality and lower class mislabeling. Automatic random extraction was employed to derive a large amount of sampling units for each annual crop class in each landscape unit. An LPIS dataset of controlled parcels was used for results validation. An overall accuracy of 85% is obtained for the map at national level indicating that the methodology is useful to identify and characterize most of annual crop types in Portugal. Class aggregation of the annual crop types by two types of growing season, autumn/winter and spring/summer, resulted in large improvements in the accuracy of almost all annual crops, and an overall accuracy improvement of 2%. This experiment shows that LPIS dataset can be used for training a supervised classifier based on machine learning with high-resolution remote sensing optical data, to produce a reliable crop map at national level.authorsversionpublishe

Detection and classification of changes in agriculture, forest, and shrublands for land cover map updating in Portugal

Costa, H., Benevides, P., Moreira, F. D., & Caetano, M. (2022). Detection and classification of changes in agriculture, forest, and shrublands for land cover map updating in Portugal. In C. M. U. Neale, & A. Maltese (Eds.), Proceedings of SPIE.Remote Sensing for Agriculture, Ecosystems, and Hydrology XXIV (Vol. 12262, pp. 19). SPIE. Society of Photo-Optical Instrumentation Engineers. https://doi.org/10.1117/12.2636127Portugal produced a land cover map for 2018 based on Sentinel-2 data and represents 13 classes, including agriculture, six tree forest species, and shrubland. The map was updated for 2020. The strategy focused on three strata where annual changes occur: S1 (agriculture) due to crop rotation, S2 (forest and shrubland) due to wildfires and clear-cuts, and S3 (fire scars and clear-cuts of previous years) where vegetation regeneration occurs. The methodology included i) change detection, ii) classification, and iii) knowledge-based rules. Stratum S1 was classified with images of the entire 2020 crop year and a training dataset extracted from the national Land Parcel Identification Systems (LPIS) of 2020. The land cover nomenclature was expanded and class agriculture was split in three distinct classes, hence resulting a map with 15 classes in total. Change detection, implemented in stratum S2, analyzed the profile of NDVI since 2018 to find potential loss of vegetation. S2 and S3 were classified through two stages. First, images of the entire 2020 crop year were used and then data of October 2020 (end of crop year) to capture late changes. The training points of the 2018 land cover map were used, but only if not associated with NDVI change. For all the three strata, knowledge-based rules corrected misclassifications and ensured consistency between the maps. A comparison between 2018 and 2020 reveal important land cover dynamics related to vegetation loss and regeneration on ~5% of the country.authorsversionpublishe

Assessment of the introduction of spatial stratification and manual training in automatic supervised image classification

Moraes, D., Benevides, P., Costa, H., Moreira, F., & Caetano, M. (2021). Assessment of the introduction of spatial stratification and manual training in automatic supervised image classification. In K. Schulz, U. Michel, & K. G. Nikolakopoulos (Eds.), Earth Resources and Environmental Remote Sensing/GIS Applications XII (Vol. 11863). [1186311] (PROCEEDINGS OF SPIE). SPIE-International Society for Optical Engineering. https://doi.org/10.1117/12.2599740 --------------------------------------------------- Funding Information: This work has been supported by project foRESTER (PCIF/SSI/0102/2017), SCAPEFIRE (PCIF/MOS/0046/2017), and by Centro de Investigação em Gestão de Informação (MagIC), all funded by the Portuguese Foundation for Science and Technology (FCT). Value-added data processed by CNES for the Theia data centre www.theia-land.fr using Copernicus products. The processing uses algorithms developed by Theia's Scientific Expertise Centres.The performance of supervised classification depends on the size and quality of the training data. Multiple studies have used reference datasets to extract training data automatically in an efficient way. However, automatic extraction might be inappropriate for some classes. Furthermore, classes can have distinct spectral characteristics across large areas. Thus, dividing the study area into subregions can be beneficial. This study proposes to assess the impact of the introduction of spatial stratification and manually collected training data on classification performance. Two classifications were conducted with the Random Forest classifier and multi-temporal Sentinel-2 data. The classifications’ performance was evaluated by accuracy metrics and visual inspection of the maps. The results indicate that introducing spatial stratification and manual training yielded a higher overall accuracy (66.7%) when compared to the accuracy of a benchmark classification (60.2%) conducted without stratification and with training data collected exclusively by automatic methods. Visual inspection of the maps also revealed some advantages of the novel approach, namely constraining some land cover classes to be present only within specific strata, which avoids commission errors of the class to spread freely across the map. Most of the classification improvements were observed in subregions with specific landscapes and spectral patterns, although these strata represent a small fraction of the study area, which might have contributed to the small increase in accuracy.publishersversionpublishe

DIE WECHSELWIRKUNGEN ZWISCHEN DEMOKRATISIERUNGSPROZESS UND KULTURELLEN VERÄNDERUNGEN DER LÄNDLICH-TRADITIONELLEN INSTITUTIONEN IN MOSAMBIK: Am Beispiel der ländlichen Regionen der Nampula-Provinz

Durch die Einführung der neuen mosambikanischen Verfassung 1990 und dem allgemeinen Friedensvertrag 1992 wurden die Bedingungen für die Demokratie in Mosambik geschaffen. Unterstützt werden die Demokratisierungsprozesse durch freie lokale Wahlen, Dezentralisie-rung und einem Wandel des öffentlichen und traditionellen Sektors. Parallel dazu entsteht eine Demokratieförderung durch den Staat und eine weitere Ausbildung bzw. Legalisierung der lokalen Gemeinschaftsautoritäten, die auch die ländliche Entwicklung beeinflussen. Die ständigen politischen Instabilitäten, die Marginalisierungen bzw. Ausnutzung der länd-lich-traditionellen Institutionen seit der Kolonialzeit und die schwache Legitimierung der so-zialistisch-marxistischen sowie westlich-demokratischen Institutionen führen in den Städten zu einer Wertekrise hinsichtlich der kulturellen Traditionen, der Geschichte, der öffentlichen Institutionen. Dies beeinflusst sowohl den allgemeinen Demokratisierungsprozess als auch die Entwicklung in den ländlichen Regionen. Jene Krisen-Phänomene um Identität und Legitimation sind nach Annahme zahlreicher For-schungsinstitutionen und Wissenschaftler eine unumgängliche Tatsache (u. a. Ética Moçam-bique, 2003), Ivala, 2003, Agenda 2025, 2004, Lalá & Ostheimer, 2004 und Magode, 2004). Die Ursachen dafür werden gesehen in den Folgen der 500jährigen Kolonialzeit, dem zehn Jahre dauernden Unabhängigkeitkampf, dem 16 Jahre währenden Burgerkrieg, in den politi-schen, Konflikt schürenden Wahlkämpfen, in der politischen Intoleranz gegenüber anderen Parteien oder ethnischen Gruppen, den ununterbrochen Gesetzesübertretungen, einem hohen Korruptionsniveau, in der Respektlosigkeit gegenüber lokalen und nationalen Symbolen, Werten, der Geschichte, Kultur, den Lokalinstitutionen und schließlich in moralische Fragili-täten. Mit der Reform des öffentlichen Sektors1 und der Anerkennung der etwa 5065 traditionellen und lokalen Gemeinschaftsautoritäten2 (autoridades tradicionais, sozialistisches System der Dynamisierungsgruppen) auf der ersten Stufe des Dekrets 15/2000 entsteht parallel zu den demokratischen Strukturen ein duales bzw. multiples System der Staatsverwaltung in den Dorfgemeinschaften und Distrikten. Genau in diesem Kontext entwickelt sich die Demokratisierung.In diesem Spannungsfeld steht auch der zentrale Untersuchungsgegenstand dieser Arbeit, der mit folgenden Fragen umrissen werden kann: In wieweit verzögern bzw. behindern die Spu-ren von Kolonialismus, Marxismus und kulturellen Traditionen die Demokratisierungsprozes-se in Mosambik? Gibt es auf der ländlichen Ebene Elemente, die mit dem entsprechenden Konzept von Demokratie korrespondieren? Und wenn ja, wie werden sie genutzt? Wie um-fangreich ist die politische Beteiligung der lokalen ländlichen Bevölkerung an den Demokra-tisierungsprozessen. Haben die Mosambikaner in den ländlichen Regionen eine alternative Perspektive bzw. Aussichten auf den Ausbau demokratischer Strukturen und die Entwicklung der ländlichen Institutionen? In einigen Ländern der SADC und des Commonwealth (z.B. Malawi, Uganda, Sambia, Na-mibia etc.) – auch Mosambik ist Mitglied – haben die ländlich-traditionellen Institutionen per Gesetz einen legalisierten Status. Aber trotz des mosambikanischen Dekrets 15/2000 sind die ländlich-traditionellen Institutionen immer noch ein problematisches Thema, das Politiker, Regierende, Wissenschaftler, Journalisten und die Bevölkerung beschäftigt. Dieses demokra-tische Problem spitzt sich regelmäßig zu während jeder exekutiven, legislativen und kommu-nalen Wahlkampagne. Schon ca. sechs Monate vor den ersten Provinzwahlen verschärft sich die Situation; für die ländlichen Regionen handelt es sich dabei um alltägliche Probleme. Die Verankerung der Demokratie auf der ländlichen Ebene wird zu einem Hauptfaktor der ländlichen Entwicklung. Ausgehend von dieser These beabsichtigt diese Forschungsarbeit, Erkenntnisse darüber zu gewinnen, wie die unterschiedlichen Akteure an den Demokratisie-rungsprozessen partizipieren, und welche Lokalinstitutionen, die mit der Reform des öffentli-chen Sektors in Verbindung stehen, dabei zum Tragen kommen

Ratio of land consumption rate to population growth rate - analysis of different formulations applied to mainland Portugal

ArticleThis paper presents a methodological approach for the assessment of the indicator 11.3.1: “Ratio of Land Consumption Rate to Population Growth Rate” proposed by the United Nations (UN), discussing the definitions and assumptions that support the indicator quantification, and analysing the results provided by different formulations applied to mainland Portugal, at the municipality level. Due to specific limitations related to the actual formula proposed by the UN (LCRPGR) for the computation of the indicator, an alternative formulation derived from Land Use Efficiency (LUE) was explored. Considering that the land to which the indicator refers may be described by specific classes represented in Land Cover Land Use (LCLU) maps, in the estimation of the land consumption rate we tested two LCLU datasets: Corine Land Cover and COS—the Portuguese LCLU reference map. For the estimation of the population growth rate, prior allocation of inhabitants to the areas where people are most likely to reside was deemed necessary, using a dasymetric mapping technique based on LCLU information. The results obtained for 2007–2011 and 2011–2015 showed, in most municipalities, an increase in the urban area and a decrease in urban population, leading to negative values both in LCRPGR and LUE in most of the territory. Clearly, LUE performed better than LCRPGR in what urban development monitoring and urban area dynamics trends are concerned. Furthermore, LUE was much easier to interpretinfo:eu-repo/semantics/publishedVersio