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A laboratory work has been carried out to determine the tolerance of soil bacterial communities to Ni and Zn and co-tolerance to tetracycline antibiotics (chlortetracycline (CTC), oxytetracycline (OTC) and tetracycline (TC)) in soils individually spiked with five different concentrations of Ni or Zn (1,000, 750, 500, 250, and 125 mg kg−1), and an uncontaminated (0 mg kg−1) control soil. The PICT parameter (pollution-induced community tolerance) was estimated for the bacterial community using the tritium (3H)-labeled leucine incorporation technique, and the values corresponding to log IC50 were used as toxicity index. The mean log IC50 values observed in the uncontaminated soil samples indicate that Zn (with log IC50 = −2.83) was more toxic than Ni (log IC50 = −2.73). In addition, for the soil with the lowest carbon content (C = 1.9%), Ni-contaminated samples showed increased tolerance when the Ni concentrations added were ≥500 mg kg−1, while for the soils with higher carbon content (between 5.3% and 10.9%) tolerance increased when Ni concentrations added were ≥1,000 mg kg−1. Regarding the soils contaminated with Zn, tolerance increased in all the soils studied when the Zn concentrations added were ≥125 mg kg−1, regardless of the soil carbon content. The co-tolerance increases obtained after exposure of the bacterial suspension to TC, OTC and CTC showed an identical behavior within these tetracycline antibiotics. However, it was dependent on the heavy metal tested (Ni or Zn). In the case of soils 1 (C = 1.1%) and 2 (C = 5.3%), the soil bacterial communities showed increases in co-tolerance to TC, OTC and CTC for Ni concentrations added of ≥125 mg kg−1, while for soil 3 (with C = 10.9%) co-tolerance took place when Ni was added at ≥1,000 mg kg−1. However, in soils contaminated with Zn, increases in co-tolerance to CTC, OTC and TC occurred at Zn concentrations added of ≥125 mg kg−1 for the 3 soils tested. These results can be considered relevant when anticipating possible environmental repercussions related to the simultaneous presence of various types of pollutants, specifically certain heavy metals and antibiotics., This study has been funded by the Spanish Ministry of Economy and Competitiveness through the projects CGL 2015-67333-C2-1-R and -2-R (FEDER Funds) and by Xunta de Galicia via BV1 research group (ED431C 2017/62-GRC). F-CD holds a Ramón y Cajal contract (RYC-2016-20411) financed by the Spanish Ministry of Economy, Industry and Competitiveness. S-MV Santás Miguel holds a posdoctoral fellowship (ED481B-2022-081) financed by Xunta de Galicia. A-RL hold a pre-doctoral fellowship (ED481A 2021/309) financed by Xunta de Galicia.

Trabajo presentado en el Lancare for the future, celebrado en Santiago de Compostela (España), del 16 al 18 de julio de 2018, In the last decade the aim of the research projects carried out by the Group of Forestry Protection (CIFL, Xunta de Galicia) and the Group of Biochemistry and Quality of Soils (IIAG-CSIC) were focused on the evaluation of the effects of wildfires of different severity on forest ecosystems (soil-plant systems) as well as to study the implementation of different emergence rehabilitation techniques (seeding and mulching): their efficacy to control post-fire erosion as well as their effects on soil quality. In order to do this, we performed numerous studies under field conditions in experimental areas affected by fires of different level of severity: wildfires and prescribed or experimental fires and the results of numerous soil burnt properties and vegetation cover as well as the erosion were measured and compared with the corresponding unburnt control soils. The results showed that wildfire effects and the recovery of soil-plant system are variable depending mainly on fire severity. With respect to post-fire stabilization treatments, data showed that the straw mulch was the most effective emergence treatment to control post-fire erosion since they reduce soil losses around 70-90% and have no effects on soil quality. The optimization of this technique was established controlling the way of straw application and different straw doses trying to find the minimum effective dose. In both Institutions different courses at different educational levels were organized, which include conferences and visits “in situ” to the experimental areas. These have focused on several aspects related to a fire (treatments for forest fire prevention, the use of fire retardants, effects of prescribed and wildfires on forest ecosystems, implementation of different soil rehabilitation techniques, recovery of forest ecosystems). Likewise an International Workshop was organized (http://www.iiag.csic.es/fuegored/libro.pdf) and different didactic resources such as videos (http://www.crtvg.es/informativos/no-ano-internacional-dossolos-o-csic-e-o-iiag-organizan-visitas-a-montes-queimados-1419235) and guides of actuations following the fire were elaborated and used in the educational program. http://fuegored.weebly.com/uploads/2/2/2/8/22283836/guia_planificacion_galicia.pdf http://sghn.org/Publicacions/Non_SGHN/Guia_de_actuaciones_en_una_zona_quemada_2018.pdf

Trabajo presentado en el VIII Congreso Ibérico de las Ciencias del Suelo (CICS 2018), celebrado en Donostia-San Sebastian, del 20 al 22 de junio de 2018, [ES] Las tetraciclinas, un grupo de antibióticos ampliamente usados para tratar enfermedades animales y como promotores de su crecimiento, representan en la unión Europea un 33.4% del total de antibióticos utilizados para este fin. Estos compuestos son poco absorbidos por el intestino animal, por lo que son excretados en notable proporción, llegando al suelo a través de la aplicación de esas excretas a los agro-sistemas. Estos antibióticos pueden tener un efecto importante sobre las comunidades bacterianas que participan en diferentes procesos en el suelo. Teniendo esto en cuenta, los objetivos del presente estudio son: a) evaluar el efecto de la adición de tetraciclina sobre las comunidades bacterianas del suelo a corto, medio y largo plazo, y b) observar el efecto de las propiedades de los suelos sobre la toxicidad de la tetraciclina. Los resultados obtenidos muestran que la toxicidad de la tetraciclina disminuye con el tiempo de incubación, ya que el rango de log IC50 (Logaritmo de la concentración que inhibe el 50% del crecimiento bacteriano) observado en el día 1 está comprendido entre 1.89 y 3.92, mientras que en el día 8 se encuentra entre 2.35 y 3.9 y en el día 42 los valores están entre 2.41 y 4.14, [EN] Tetracyclines are a group of antibiotics widely used in veterinary medicine, both to treat diseases and as growth promoters, representing 33.4% of the antibiotics used with these aims in the European Union. A considerable proportion of the doses of tetracyclines supplied to animals are not absorbed, and they are later excreted, reaching the soil through the spreading of manure and slurries to agro-systems. These antibiotics can have a relevant effect on bacterial communities that participate in different processes in the soil. In view of that, the objectives of the present study are: a) to assess the effect of tetracycline on soil bacterial communities in the short, medium and long term, and b) to determine the effect of soil properties on the toxicity of tetracycline. The results show that toxicity of tetracycline decreased with incubation time, since log IC50 (Logarithm of the concentration inhibiting 50% of bacterial growth) ranged between 1.89 and 3.92 on day 1, between 2.35 and 3.9 on day 8, and between 2.41 and 4.14 on day 42., Este estudio ha sido financiado por el Ministerio Español de Economía y Competitividad a través de los proyectos CGL2015-67333-C2-1-R y -2-R (Fondos FEDER). David Fernández Calviño posee un contrato Ramón y Cajal (RYC-2016- 20411) financiado por el Ministerio español de Economía, Industria y Competitividad.

Trabajo presentado en la IV Reunión de Internacional de FUEGORED (Red Temática efectos de los incendios forestales sobre los suelos), celebrada en Puerto de la Cruz, Tenerife (España), del 24 al 27 de octubre de 2012, The soil microbial community in a field experiment with different post-fire treatments (seeding, mulching) was characterized by means of phospholipids fatty acids analyses (PLFA). The soil was a Leptosol developed over granite with a slope of 38-54%, located in the N.W. (Spain), within the Atlantic humid temperate zone. The total biomass and the biomass of specific microbial groups (fungi, bacteria, actinomycetes, gram-positive bacteria, gram-negativebacteria) was assessed in soil samples taken from the A horizon (0-5 cm depth) at different sampling times over one year. The results showed that the total microbial biomass and the biomass of specific microbial groups in burnt soils were slightly lower than in the corresponding unburnt control. The fire decreased significantly the fungal:bacterial and gram-negative:gram-positive ratios. Differences in physiological state of the microbial communities were observed as consequence of the medium-term prescribed fire impact; the higher values in the ratios of saturated to unsaturated fatty acids and cyclopropyl fatty acids to monoicoc precursors exhibited by the burnt soils as compared with the unburnt soil suggested that the microbial communities were stressed by the experimental fire. The data also showed the absence of any medium-term response of microbial community to the seeding and mulching treatments., This study was supported by the Spanish Ministerio de Ciencia e Innovación (AGL2008-02823), and by the Consellería do Medio Rural da Xunta de Galicia (08MRU002400PR), Spain. A. Barreiro and A. Lombao are recipients of FPU grants from Spanish Ministry of Education.

Trabajo presentado en la IV Reunión de Internacional de FUEGORED (Red Temática efectos de los incendios forestales sobre los suelos), celebrada en Puerto de la Cruz, Tenerife (España), del 24 al 27 de octubre de 2012, The BIOLOG and PLFA techniques were used to evaluate the short- and medium- term effects produced by high and low severity fires on microbial diversity. Two scrublands ecosystems from Galicia (NW Spain) with different post-fire treatments (seeding and mulching) were used, one affected by an experimental fire of low-severity and the other affected by a high-severity wildfire and the diversity indices (R, microbial richness; H, Shannon-Weaver diversity index; E, Shannon’s eveness) were determined in soil samples collected from the top layer (0-2 cm) immediately and 90, 180 and 365 days after the fire. The H values calculated with the PLFA technique were strongly correlated with those obtained with the Biolog technique; thus, information concerning taxonomic diversity given by H-PLFA is consistent with that provided by H-Biolog, metabolic diversity. The values for the R, H and E indices tended to be higher in the burned soils than in the respective unburned control, indicating that the diversity was slightly higher and the microbial groups were distributed more equitably following the fire. These effects were more marked in high severity wildfire than in low severity fire and they persisted even one year after the fire. Independently of the method used (PLFA, BIOLOG) there was no evidence of any significant difference in the diversity indices among the two different post-fire treatments and the corresponding burned treatment on both sampling areas., This study was funded by the Spanish Ministerio de Ciencia e Innovación (AGL2008-02823), and by the Consellería do Medio Rural da Xunta de Galicia (08MRU002400PR), Spain. A. Barreiro and A. Lombao are recipients of FPU grants from the Spanish Ministry of Education.

Trabajo presentado en la Conferencia Internacional FUEGORED (Red Temática efectos de los incendios forestales sobre los suelos), celebrada en Aveiro (Portugal), del 24 al 26 de noviembre de 2016, Se evaluó la influencia del fuego y de la aplicación post-incendio de dos tratamientos de estabilización del suelo (mulching de paja y siembra de herbáceas) sobre la calidad de un suelo, 4 años después del incendio y de la aplicación de los tratamientos. La experiencia se realizó en parcelas de 5 m de ancho x 20 m de largo, por cuadruplicado, de un suelo desarrollado bajo matorral, localizado en Laza (Ourense, NO España), afectado por un incendio de alta severidad y susceptible de sufrir erosión post-incendio (pendiente 30 %). Se recogieron muestras de suelo a dos profundidades (0-2 cm y 2-5 cm) y se analizaron diversas propiedades físico-químicas, químicas, bioquímicas y biológicas del mismo (capacidad de retención de agua, pH, conductividad eléctrica, C y N totales, C extraíble y soluble, hidratos de C extraíbles y solubles, actividades enzimáticas (β-glucosidasa y ureasa), respiración, biomasa microbiana y fúngica, actividades bacteriana y fúngica, y el patrón de los ácidos grasos de los fosfolípidos (PLFA pattern). Los resultados demostraron, en primer lugar, que el efecto adverso del incendio sobre la mayoría de las propiedades del suelo analizadas persiste incluso 4 años después del mismo, siendo su influencia más acusada en la capa superficial del suelo (0-2 cm). Por lo que respecta a los tratamientos de estabilización no se observó ningún efecto sobre la mayoría de las propiedades analizadas y, por consiguiente, sobre la calidad del suelo, excepto sobre el patrón de los ácidos grasos de los fosfolípidos. Este análisis, combinado con el análisis de componentes principales, mostró que el principal factor que determina la estructura de la comunidad microbiana es el quemado del suelo, seguido, en orden de importancia, por la profundidad del suelo y por la aplicación de los tratamientos de estabilización del suelo. Las muestras de suelo tomadas a 0-2 cm de profundidad, tratadas con mulching de paja, se diferenciaron de las muestras restantes, lo que indica un ligero efecto de dicho tratamiento sobre la estructura o diversidad de la comunidad microbiana.

Trabajo presentado en la Conferencia Internacional FUEGORED (Red Temática efectos de los incendios forestales sobre los suelos), celebrada en Aveiro (Portugal), del 24 al 26 de noviembre de 2016, Estudios previos han demostrado que el mulching de paja es una de las técnicas más efectivas para controlar la erosión post-incendio en los suelos de la zona templado húmeda del NO de la Península Ibérica y que, además, no produce efectos a corto plazo sobre el sistema suelo-planta. Sin embargo, la información disponible acerca de los efectos a medio plazo de este tratamiento sobre la calidad del suelo es escasa. En esta investigación se evaluó la influencia de la aplicación de paja sobre la calidad de un suelo desarrollado sobre matorral, localizado en Saviñao (Lugo, NO España), que había sido afectado por un incendio no controlado de media-alta severidad en el año 2012, y susceptible de sufrir erosión post-incendio al estar situado en una ladera con una pendiente del 38%. En esta área quemada se instalaron parcelas de 10 m de ancho x 40 m de largo tratadas con paja de trigo, aplicado en franjas, a diferentes dosis (0, 0,8 y 1 Mg ha-1; 4 réplicas por tratamiento), suelo quemado sin ningún tratamiento (dosis global = 0 Mg ha-1), suelo quemado con 200 g m-2 paja en la mitad superior de la parcela en una franja de 20 m de longitud (dosis global = 1 Mg ha-1) y suelo quemado con 200 g m-2 de paja en dos franjas alternas intermedias de 8 m de longitud (dosis global = 0.8 Mg ha-1). Se recogieron muestras de suelo del horizonte superficial (0-2,5 cm) de los diferentes tratamientos 2 años después del incendio y de la aplicación de la paja de trigo y se analizaron diversas propiedades físico-químicas, químicas, bioquímicas y microbiológicas del suelo: capacidad de retención de agua, pH, conductividad eléctrica, C y N totales, C extraíble y soluble, hidratos de C extraíbles y solubles, actividades enzimáticas (β-glucosidasa, ureasa y fosfatasa), respiración, biomasa microbiana y fúngica, actividades bacteriana y fúngica, y biomasa microbiana total y específica de determinados grupos microbianos a partir del patrón de los ácidos grasos de los fosfolípidos (PLFA pattern). En las parcelas con tratamiento de paja se muestreó separadamente el suelo en las zonas cubiertas con paja y en las zonas sin paja. Los resultados demostraron que, independientemente de la forma de aplicación, la adición de paja no produjo ningún efecto a medio plazo sobre la calidad del suelo quemado en base a dichos parámetros. Sin embargo, el patrón de ácidos grasos de los fosfolípidos combinado con análisis de componentes principales nos permitió diferenciar ligeramente dentro de cada parcela la zona tratada con paja de la zona no tratada.

Trabajo presentado en el VII Simposio Nacional sobre el control de la Degradación y Restauración de Suelos, celebrado en Bilbao (España), del 23 al 26 de junio de 2015, Existen muy pocos estudios sobre el efecto a largo plazo de los agentes retardantes de llama sobre la microbiota edáfica. En el presente trabajo se analiza el impacto de una quema prescrita y de la posterior adición de tres de estos agentes (polifosfato, espumante y Firesorb) sobre diferentes propiedades relacionadas con la actividad y biomasa de los microorganismos del suelo, 10 años después de la citada experiencia. Los resultados mostraron, por una parte, un efecto de la quema sobre el pH y el C de la biomasa microbiana total, y, por otra, que el polifosfato ejerció una gran influencia sobre la actividad bacteriana y los microorganismos del ciclo del C (glucosidasa) mientras que el espumante y el Firesorb sólo modificaron la biomasa y la actividad fúngica, Trabajo financiado por el Ministerio Español de Economía y Competitividad (AGL2012-39686-C02-01). A. Barreiro y A. Lombao son beneficiarias de una beca FPU del Ministerio de Educación Cultura y Deporte.

Trabajo presentado en el VII Simposio Nacional sobre el control de la Degradación y Restauración de Suelos, celebrado en Bilbao (España), del 23 al 26 de junio de 2015, Se estudió, en condiciones de campo y en grandes parcelas, la eficacia de dos técnicas de protección del suelo (implantación de una cubierta vegetal y acolchado de paja) contra la erosión post-incendio; y su efecto sobre la calidad del suelo (propiedades físicas, químicas y biológicas) durante el primer año post-quema. Los resultados demostraron, por una parte, que la severidad del fuego condicionó, en gran medida, el impacto del fuego sobre el suelo y, por otra, que los dos tratamientos ensayados, la siembra y el acolchado de paja, particularmente este último, redujeron de forma significativa las pérdidas de suelo por erosión., Trabajo financiado por el Ministerio Español de Economía y Competitividad (AGL2012-39686-C02-01). A. Barreiro y A. Lombao son becarios FPU del Ministerio Español de Educación.

The impact of a wildfire on some selected physicochemical, biochemical and microbiological properties was assessed in an ecosystem located in the Fragas do Eume Natural Park (NW Spain). Soil samples were collected from the topsoil (0-2.5 and 2.5-5 cm) of the unburnt and burnt soil under the autochthonous (Quercus) and non autochthonous (Eucalyptus) vegetation. The results indicated that, independently of the vegetation considered, a short-term impact of the wildfire on most soil properties analyzed was detected; the effect being more pronounced for the biochemical properties than for the physical and chemical ones. As expected soil properties varied with soil depth, and the fire effect was more noticeable in the 0-2.5 cm layer than in the 2.5-5 cm layer., This study was supported by the Ministerio Español de Economía y Competitividad (AGL2012-39686-C02-01) and by Fundación MAFRE. A. Barreiro and A. Lombao are recipients of FPU grants from Spanish Ministry of Education.

Trabajo presentado en el VII Simposio Nacional sobre el control de la Degradación y Restauración de Suelos, celebrado en Bilbao (España), del 23 al 26 de junio de 2015, Se estudió la respuesta de la población microbiana del suelo frente al calentamiento en laboratorio (100ºC y 200ºC) y la recurrencia del mismo, mediante el análisis de la actividad y la biomasa de determinados grupos microbianos. Se realizaron dos calentamientos consecutivos, utilizando un suelo no afectado y afectado por un incendio de alta intensidad. Los resultados indicaron que el historial del suelo (quema en campo y laboratorio) condicionó la respuesta de la microbiota frente al calentamiento y que las propiedades analizadas mostraron una diferente sensibilidad frente al impacto térmico., Este estudio fue financiado por el Ministerio de Ciencia e Innovación (AGL2012-39686-C02-01). A. Barreiro y A. Lombao son beneficiarias de becas FPU del Ministerio Español de Educación.

Trabajo presentado en la European Geosciences Union General Assembly, celebrada en Viena (Austria), del 12 al 17 de abril de 2015, It is well known that soil properties determining the thermal transmissivity (moisture, texture, organic matter, etc.) and the duration and temperatures reached during soil heating are key factors driving the fire-induced changes in soil microbial communities. However, despite its interest, the information about this topic is scarce. The aim of the present study is to analyze, under laboratory conditions, the impact of the thermal shock (infrared lamps reaching temperatures of 100 ºC, 200 ºC and 400 ºC) on microbial communities of three acid soils under different moisture level (0 %, 25 % and 50 % per soil volume). Soil temperature was measured with thermocouples and the impact of soil heating was evaluated by means of the analysis of the temperature-time curves calculating the maximum temperature reached (Tmax) and the degree-hours (GH) as an estimation of the amount of heat supplied to the samples (fire severity). The bacterial growth (leucine incorporation) and the total microbial biomass (PLFA) were measured immediately after the heating and one month after the incubation of reinoculated soils. The results showed clearly the importance of moisture level in the transmission of heat through the soil and hence in the further direct impact of high temperatures on microorganisms living in soil. In general, the values of microbial parameters analyzed were low, particularly immediately after soil heating at higher temperatures; the bacterial activity measurements (leucine incorporation technique) being more sensitive to detect the thermal shock showed than total biomass measurements (PLFA). After 1 month incubation, soil microbial communities tend to recover due to the proliferation of surviving population using as substrate the dead microorganisms (soil sterilization). Thus, time elapsed after the heating was found to be decisive when examining the relationships between the microbial properties and the soil heating parameters (GH, Tmax). Analysis of results also showed that the measurement of the heat supplied to the soil (GH) rather than Tmax is a useful parameter to interpret microbial changes induced by soil heating., This work was supported by Spanish Ministry of Economy and Competitiveness (AGL2012-39686-C02-01) and for the for the MAPFRE foundation. A. Barreiro and A. Lombao are recipients of FPU grant from Spanish Ministry of Education

The BIOLOG and Phospholipid Fatty Acid (PLFA) techniques were used to evaluate the short- and medium- term effects produced by an experimental fire and different stabilisation treatments (seeding, mulching) on soil microbial community. The study was performed in a shrubland ecosystem from Galicia (NW Spain) affected by an experimental fire of low-severity and two different post-fire treatments (seeding and mulching). Soil samples were collected from the top layer (0-5 cm) of the A horizon immediately and 90, 180 and 365 days after the fire and the microbial community was determined using both the BIOLOG and the PLFA methods. The results indicated that, independently of the method used, the experimental fire induced marked changes on the soil microbial community, which persisted even after 1 year and that there was no evidence of noticeable microbial changes between the two different post-fire treatments and the corresponding burnt treatment. In addition, a clear significant effect of the sampling time on the soil microbial community structure was observed, the impact being even most important than that observed for the experimental fire., This study was supported by the Ministerio Español de Economía y Competitividad (AGL2012-39686-C02-01) and by Fundación MAFRE. A. Barreiro and A. Lombao are recipients of FPU grants from Spanish Ministry of Education

1 póster donde se muestran los resultados de su investigación.-- Póster presentado al XV Congress of the Spanish Society of Nitrogen Fixation, and the IV Portuguese-Spanish Congress on Nitrogen Fixation. En León (España). 16, 17 y 18 de junio de 2015, Soil is a pivotal component of the environment and the maintenance of soil quality is critical for ensuring the sustainability of the biosphere. The use of fertilizers has increased at a faster rate than global food production. Modern agriculture is dependent on phosphorus derived from phosphate rock, which is a non‐renewable resource. It is needed to improve P acquisition efficiency for both low input and intensive agroecosystems. However, few studies have focused on cereal‐legume interactions with regard to soil P. The objective of this work was to study the effects of grass‐legume mixtures and phosphorus fertilization on soil microbial community structure and biomass [determined by fatty acid methyl ester (FAME) profiling] as well as on the soil nitrogen (N) mineralisation rate.

Trabajo presentado en la 7th International Conference on Forest Fire Research, celebrada en Coimbra (Portugal), del 17 al 20 de noviembre de 2014, The effect of two post-fire stabilization treatments (seeding and mulching) on some selected physical, chemical, biochemical and microbiological properties as well as the efficacy of these treatments on post-fire erosion control was investigated. The study was performed in two scrubland areas of Galicia (N.W. Spain), susceptible to suffer post-fire erosion (slope 30-50%) after an experimental fire and a wildfire, respectively. Soil samples were taken from the A horizon at different sampling times over one year after the fire event as well as from the corresponding unburnt soil located in an adjacent plot used as control; the sediments from the burnt soils, with and without different post-fire stabilisation treatments, were periodically collected after precipitation events. The results showed that initially the wildfire induced important changes in most properties measured and that these effects persisted 12 months after the fire; in contrast, the experimental fire provoked slight changes in the physic-chemical and chemical properties but moderate changes in the biochemical properties. They also indicated that both stabilisation treatments had no effects on the soil properties analysed and then on soil quality, but reduced significantly the sediments yield compared to the control burnt soil. The mean efficiency of the seeding and mulching treatments in preventing soil erosion was 21-31% and 85-88%, respectively, showing that, in the short- and medium-term (12 months), the straw mulching was the most effective treatment for reducing the post-fire erosion in both burnt areas.