Biomass-modulated fire dynamics during the last glacial-interglacial transition at the central pyrenees (Spain)

Understanding long-term fire ecology is essential for current day interpretation of ecosystem fire responses. However palaeoecology of fire is still poorly understood, especially at high-altitude mountain environments, despite the fact that these are fire-sensitive ecosystems and their resilience might be affected by changing fire regimes. We reconstruct wildfire occurrence since the Lateglacial (14.7. cal. ka BP) to the Mid-Holocene (6. cal. ka BP) and investigate the climate-fuel-fire relationships in a sedimentary sequence located at the treeline in the Central Spanish Pyrenees. Pollen, macro- and micro-charcoal were analysed for the identification of fire events (FE) in order to detect vegetation post-fire response and to define biomass-fire interactions. mean fire intervals (mfi) reduced since the Lateglacial, peaking at 9-7.7. cal. ka BP while from 7.7 to 6. cal. ka BP no fire is recorded. We hypothesise that Early Holocene maximum summer insolation, as climate forcing, and mesophyte forest expansion, as a fuel-creating factor, were responsible for accelerating fire occurrence in the Central Pyrenees treeline. We also found that fire had long-lasting negative effects on most of the treeline plant communities and that forest contraction from 7.7. cal. ka BP is likely linked to the ecosystem's threshold response to high fire frequencies.This research has been funded by the projects DINAMO (CGL2009-07992) (funding EGPF — grant ref. BES-2010-038593 and MSC), DINAMO2 (CGL2012-33063), ARAFIRE (2012 GA LC 064), GRACCIE-CONSOLIDER (CSD2007-00067). GGR was funded by the Juan de la Cierva Program (grant ref. JCI2009-04345) and JAE-Doc CSIC Program, LLM was supported by a postdoctoral MINT fellowship funded by the Institute for the Environment (Brunel University), AMC is a Ramón y Cajal fellow (ref: RYC-2008-02431), APS holds a grant funded by the Aragon Government (ref. 17030G/5423/480072/14003) and JAE holds a grant funded by the Basque Country Government (BFI-2010-5)

Reconstrucción de la dinámica del fuego durante el Holoceno

4 páginas.- Presentación elaborada para las Jornadas IPErinas, celebradas el 13 de diciembre de 2012.Peer reviewe

Disentangling the probability of large fire occurrence in Mediterranean forests : management guidelides from a multiscale approach

Fire is one of the main disturbances in Mediterranenan ecosystems. In the recent decades, in Catalonia (NE Spain), the number of fires has decreased while burnt area has increased. This is related to changes in land use, climate and fire suppression policies which influenced horizontal and vertical fuel continuity. From all the factors influencing fire risk only fuel load is manageable by humans. For this reason it is important to understand the role of different land covers and forest structure in fire occurrence. This study aimed to understand the determinants of large fire occurrence at two different scales, 500m and 2000m around the ignition point (local and landscape scale, respectively). A binary logistic regression model was built using ignition points from the period 1989-2012 and considering 1000 control points. Forest structure variables obtained through interpolation techniques throughout Catalonia and land cover types were established as the independent variables at the two considered scales. A risk map for large fire occurrence in Catalonia was also built. Mediterranean pine forests and shrublands were the main variables influencing positively large fire occurrence. Specifically, Mediterranean pine forests with intermediate values of basal area and high understory increased the risk of large fires. Although large fires do not usually start in mixed forests, these forests were important at the scale at the landscape scale (2000m) probably because of their vertical continuity. Results showed that a multiscale management would be necessary which should focus on the landscape mosaic of different land cover types and less fire prone forest structures, particularly considering the uncertainty associated with global change and the large fires’ risk increase throughout Catalonia

Historia del fuego y la vegetación en una secuencia Holocena del Pirineo Central: La Basa de la Mora

[EN] The importance of studying past fire regimes is derived from the need to understand the effects of current Global Change on present and future fire activity. Studying the relationship between long-term fire ecology, ecosystems and climate allows us to understand how vegetation responds to this perturbation and to define the thresholds triggering irreversible changes in the vegetation. This work presents the last 10 000 years of vegetation change and fire activity on a high altitude ecosystem from the Pyrenees range: the mountain lake Basa de la Mora located in the central southern Pyrenees. Holocene fire activity has been inferred through fossil carbon particle identification in the sedimentary sequence obtained in this lake. We observe that the strongest Holocene fire activity in the area occurred between 8.1 and 4 cal Kyr BP. This period was followed by a phase, between 3.2 and 1.7 cal Kyr BP, where almost no fire activity was recorded. These changes seem to be due to biomass availability and fire-conductive climate conditions. Positive correlation has been found between fire activity and Betula, Corylus, as the key fueling taxa and groups of ariditytolerant taxa. Additionally, fire dynamics seems coupled to higher anthropogenic activities after 1.7 cal Kyr BP. © Universidad de La Rioja.[ES] La importancia del estudio de la actividad del fuego en el pasado está en la necesidad de comprender los efectos que el Cambio Global puede tener sobre la misma, tanto en la actualidad como en el futuro. Estudiar cómo se relaciona el fuego con los ecosistemas y el clima en escalas temporales lo suficientemente largas permite conocer la respuesta de la vegetación a esta perturbación y definir los umbrales que provocan cambios irreversibles en la composición vegetal. Este trabajo estudia la dinámica del fuego durante el Holoceno en el entorno de la Basa de la Mora, lago de origen glaciar situado en el Macizo de Cotiella, Pirineo Central. La historia del fuego se ha reconstruido a partir de la identificación de partículas de carbón fósil a lo largo de la secuencia sedimentaria extraída del lago, que cubre los últimos 10 000 años de historia. Se ha observado que la mayor actividad del fuego se produce entre 8.1 y 4 cal Ka BP, seguida de una fase de menor actividad entre 3.2 y 1.7 cal Ka BP. Estas fluctuaciones se deben principalmente a dos razones: la cantidad de biomasa disponible y susceptible de ser quemada, y la existencia de un clima favorable para la ocurrencia de incendios. En ese sentido, se han observado correlaciones positivas de la actividad del fuego, por un lado, con Betula y Corylus como taxones ligados a la mayor producción de biomasa, y por otro, con agrupaciones de taxones adaptados a la aridez como indicadores de climas favorables a la ocurrencia de incendios. Por último, a partir de 1.7 cal Ka BP se registra en la secuencia una mayor incidencia del fuego, probablemente vinculada a la intensificación de la acción antropogénica a nivel regional.Esta investigación ha sido financiada con los proyectos ARAFIRE Convenio DGAla Caixa ref. 2012 GA LC 064, DINAMO ref. CGL2009-07992, GRACCIE-CONSOLIDER ref. CSD2007-00067 y HORDA-OAPN ref: 83/2009.Peer Reviewe

Predicting Benzene Concentration Using Machine Learning and Time Series Algorithms

Benzene is a pollutant which is very harmful to our health, so models are necessary to predict its concentration and relationship with other air pollutants. The data collected by eight stations in Madrid (Spain) over nine years were analyzed using the following regression-based machine learning models: multivariate linear regression (MLR), multivariate adaptive regression splines (MARS), multilayer perceptron neural network (MLP), support vector machines (SVM), autoregressive integrated moving-average (ARIMA) and vector autoregressive moving-average (VARMA) models. Benzene concentration predictions were made from the concentration of four environmental pollutants: nitrogen dioxide (NO2), nitrogen oxides (NOx), particulate matter (PM10) and toluene (C7H8), and the performance measures of the model were studied from the proposed models. In general, regression-based machine learning models are more effective at predicting than time series models

Disentangling the probability of large fire occurrence in Mediterranean forests : management guidelides from a multiscale approach

Fire is one of the main disturbances in Mediterranenan ecosystems. In the recent decades, in Catalonia (NE Spain), the number of fires has decreased while burnt area has increased. This is related to changes in land use, climate and fire suppression policies which influenced horizontal and vertical fuel continuity. From all the factors influencing fire risk only fuel load is manageable by humans. For this reason it is important to understand the role of different land covers and forest structure in fire occurrence. This study aimed to understand the determinants of large fire occurrence at two different scales, 500m and 2000m around the ignition point (local and landscape scale, respectively). A binary logistic regression model was built using ignition points from the period 1989-2012 and considering 1000 control points. Forest structure variables obtained through interpolation techniques throughout Catalonia and land cover types were established as the independent variables at the two considered scales. A risk map for large fire occurrence in Catalonia was also built. Mediterranean pine forests and shrublands were the main variables influencing positively large fire occurrence. Specifically, Mediterranean pine forests with intermediate values of basal area and high understory increased the risk of large fires. Although large fires do not usually start in mixed forests, these forests were important at the scale at the landscape scale (2000m) probably because of their vertical continuity. Results showed that a multiscale management would be necessary which should focus on the landscape mosaic of different land cover types and less fire prone forest structures, particularly considering the uncertainty associated with global change and the large fires' risk increase throughout Catalonia

Disentangling the probability of large fire occurrence in Mediterranean forests : management guidelides from a multiscale approach

Fire is one of the main disturbances in Mediterranenan ecosystems. In the recent decades, in Catalonia (NE Spain), the number of fires has decreased while burnt area has increased. This is related to changes in land use, climate and fire suppression policies which influenced horizontal and vertical fuel continuity. From all the factors influencing fire risk only fuel load is manageable by humans. For this reason it is important to understand the role of different land covers and forest structure in fire occurrence. This study aimed to understand the determinants of large fire occurrence at two different scales, 500m and 2000m around the ignition point (local and landscape scale, respectively). A binary logistic regression model was built using ignition points from the period 1989-2012 and considering 1000 control points. Forest structure variables obtained through interpolation techniques throughout Catalonia and land cover types were established as the independent variables at the two considered scales. A risk map for large fire occurrence in Catalonia was also built. Mediterranean pine forests and shrublands were the main variables influencing positively large fire occurrence. Specifically, Mediterranean pine forests with intermediate values of basal area and high understory increased the risk of large fires. Although large fires do not usually start in mixed forests, these forests were important at the scale at the landscape scale (2000m) probably because of their vertical continuity. Results showed that a multiscale management would be necessary which should focus on the landscape mosaic of different land cover types and less fire prone forest structures, particularly considering the uncertainty associated with global change and the large fires' risk increase throughout Catalonia

Method for the Detection of Functional Outliers Applied to Quality Monitoring Samples in the Vicinity of El Musel Seaport in the Metropolitan Area of Gijón (Northern Spain)

Air pollution affects human health and is one of the main problems in the world, including in coastal cities with industrial seaports. In this sense, the city of Gijón (northern Spain) stands out as one of the 20 Spanish cities with the worst air quality. The study aims to identify outliers in air quality observations near the El Musel seaport, resulting from the emissions of six pollutants over an eight-year period (2014–2021). It compares methods based on the functional data analysis (FDA) approach and vector methods to determine the optimal approach for detecting outliers and supporting air quality control. Our approach involves analyzing air pollutant observations as a set of curves rather than vectors. Therefore, in the FDA approach, curves are constructed to provide the best fit to isolated data points, resulting in a collection of continuous functions. These functions capture the behavior of the data in a continuous domain. Two FDA approach methodologies were used here: the functional bagplot and the high-density region (HDR) boxplot. Finally, outlier detection using the FDA approach was found to be more powerful than the vector methods and the functional bagplot method detected more outliers than the HDR boxplot

Holocene climate variability, vegetation dynamics and fire regime in the central Pyrenees: The Basa de la Mora sequence (NE Spain)

[EN] High resolution multiproxy data (pollen, sedimentology, geochemistry, chironomids and charcoal) from the Basa de la Mora (BSM) lake sequence (42°32' N, 0°19' E, 1914m a.s.l.) show marked climate variability in the central southern Pyrenees throughout the Holocene. A robust age model based on 15 AMS radiocarbon dates underpins the first precise reconstruction of rapid climate changes during the Holocene from this area. During the Early Holocene, increased winter snowpack and high snowmelt during summer, as a consequence of high seasonality, led to higher lake levels, a chironomid community dominated by non-lacustrine taxa (Orthocladiinae) related to higher inlet streams, and a forested landscape with intense run-off processes in the watershed. From 9.8 to 8.1calkaBP, climate instability is inferred from rapid and intense forest shifts and high fluctuation in surface run-off. Shifts among conifers and mesophytes reveal at least four short-lived dry events at 9.7, 9.3, 8.8 and 8.3calkaBP. Between 8.1 and 5.7calkaBP a stable climate with higher precipitation favoured highest lake levels and forest expansion, with spread of mesophytes, withdrawal of conifers and intensification of fires, coinciding with the Holocene Climate Optimum. At 5.7calkaBP a major change leading to drier conditions contributed to a regional decline in mesophytes, expansion of pines and junipers, and a significant lake level drop. Despite drier conditions, fire activity dropped as consequence of biomass reduction. Two arid intervals occurred between 2.9 and 2.4calkaBP and at 1.2-0.7calkaBP (800-1300 AD). The latter coincides with the Medieval Climate Anomaly and is one of the most arid phases of the Holocene in BSM sequence. Anthropogenic disturbances were small until 700 AD, when human pressure over landscape intensified, with Olea cultivation in the lowlands and significant deforestation in highlands. Colder and unfavourable weather conditions during the second part of the Little Ice Age caused a temporary cease of high-land management. The most intense anthropogenic disturbances occurred during the second half of 19th century. Last decades are characterized by recovery of the vegetation cover as a result of land abandonment, and lowered lake levels, probably due to higher temperatures. © 2013 Elsevier Ltd.Financial support for research was provided by the former Spanish Inter-Ministry Commission of Science and Technology (CICIYT) through the projects DINAMO (CGL2009-07992), DINAMO2 (CGL2012-33063), GRACCIE-CONSOLIDER (CSD2007-00067) and HORDA (83/2008), from Parques Nacionales. Additional funding support has been provided by the Aragon Government through the project PM073/2007 and by Geoparque del Sobrarbe through the project “High resolution chronological control of Basa de la Mora”. Ana Pérez-Sanz has been supported by a PhD Fellowship provided by the Aragon Government. Ana Moreno, Graciela Gil-Romera and Mario Morellón hold post-doctoral contracts funded by the “Ramón y Cajal”, “Juan de la Cierva” and “JAE-DOC CSIC” programs, respectively. We thank to Santiago Giralt, Alberto Sáez, Armand Hernández, Carlos Martí, Mayte Rico, Juan Pablo Corella and Antonio Vallejo for coring assistance in 2008. We also thank Beatriz Bueno and Aída Adsuar for their help in lab procedures. We are indebted to Prof. Sandy Harrison for her assistance with the English review that has led to a noticeable improvement of the manuscript.Peer Reviewe

Primeras jornadas Iperinas: presentación de nuevas líneas de investigación del Instituto Pirenaico de Ecología (CSIC)

16 páginas, 2 figuras[ES] En diciembre de 2012, se celebraron las primeras Jornadas IPErinas, reunión que permitió compartir al personal del Instituto Pirenaico de Ecología (CSIC), muchos de los trabajos de investigación que actualmente se están llevando a cabo por los distintos grupos del centro. Estas Jornadas surgieron de la necesidad de compartir y difundir los principales objetivos y resultados más relevantes de nuevas líneas de investigación desarrolladas actualmente en el centro, como parte fundamental de la comunicación científica y transferencia de conocimiento a la sociedad. Bajo estas líneas, se presenta una reseña de la las primeras Jornadas IPErinas, a través de un breve resumen de las charlas presentadas.[EN] In December 2012, the first Jornadas IPErinas took place at the Pyrenean Institute of Ecology (CSIC). The aim of this meeting was to show many of the new research topics that nowadays are being developed in the Institute. This workshop grew out of the need to disseminate the main new research lines developed at the center, as a fundamental part of scientific communication and knowledge transfer to society. In this paper, we briefly review the topics presented in the first meeting Jornadas IPErinas, summarizing the oral contributions.Peer reviewe