A new approach to measure reduction intensity on cores and tools on cobbles: the Volumetric Reconstruction Method

Knowing to what extent lithic cores have been reduced through knapping is an important step toward understanding the technological variability of lithic assemblages and disentangling the formation processes of archaeological assemblages. In addition, it is a good complement to more developed studies of reduction intensity in retouched tools, and can provide information on raw material management or site occupation dynamics. This paper presents a new methodology for estimating the intensity of reduction in cores and tools on cobbles, the Volumetric Reconstruction Method (VRM). This method is based on a correction of the dimensions (length, width, and thickness) of each core from an assemblage. The mean values of thickness and platform thickness of the assemblage’s flakes are used as corrections for the cores’ original dimensions, after its diacritic analysis. Then, based on these new dimensions, the volume or mass of the original blank are reconstructed using the ellipsoid volume formula. The accuracy of this method was experimentally tested, reproducing a variety of possible archaeological scenarios. The experimental results demonstrate a high inferential potential of the VRM, both in estimating the original volume or mass of the original blanks, and in inferring the individual percentage of reduction for each core. The results of random resampling demonstrate the applicability of VRM to non size-biased archaeological contexts.Introduction Methods - The Volumetric Reconstruction Method - Experimental design - Statistical procedures - Resamples Results - Geometric formulas - Reduction strategy and size - Resampling (randomly biased record) - Resampling (size bias) - Measuring the effect of number of generations Discussion and conclusion

Recovery of a soil under different vegetation one year after a high intensity wildfire

Studies on soil recovery in fragile ecosystems following high intensity wildfires are scarce. The aim of the present investigation is to evaluate the impact of a high intensity wildfire in an ecosystem under different vegetation (shrubland and pinewood) located at Vilardevós (Galicia, NW Spain) and highly susceptible to suffer soil erosion due to the steep relief and high erositivity of the rainfall. Soil samples were collected from the A horizon (0-5 cm) 1 year after the fire and soil quality was evaluated by analysis of several physical, chemical and biochemical properties measured in the fraction < 2 mm. The results showed marked effects of the wildfire on most properties analyzed even 1 year after the fire; however, a different effect both in the trend (positive, negative) and magnitude were observed, depending on the soil property analyzed. In general, the sensitivity to detect fire induced changes followed the order: biochemical properties > chemical properties > physical properties. The data also showed that the fire impact was different depending on the soil vegetation considered (shrubland and pinewood). Moreover, the data confirmed the slow soil recovery in this fragile ecosystem and, therefore, the need of adopting post-fire stabilisation and rehabilitation treatments in order to minimize the post-fire erosion and soil degradation

Mulching and seeding treatments for post-fire stabilization techniques in Laza (NW Spain): medium-term effects on soil quality and effectiveness

The impact of fire and different post-fire stabilisation treatments like mulching and seeding on some selected physical, chemical biochemical and microbiological properties as well as the efficacy of these treatments on control of post-fire erosion was evaluated in a burnt area affected by a high severity wildfire located in Laza (NW Spain). Soil samples were collected from the A horizon (0-2 cm) of the burnt soil 8 and 12 months after the wildfire as well as from the unburnt soil located in an adjacent plot used as control; sediments were periodically collected after precipitation events in the burnt soil with and without different post-fire stabilisation treatments. The results clearly showed that a significant medium-term impact of the wildfire on most soil properties analyzed was still observed 12 months after the fire event and that mulching and seeding treatments did not affect the overall soil quality (physical, chemical, biochemical and microbiological properties) of this burned soil. Sediments data indicated that both stabilisation treatments were effective to control post-fire erosion since, compared to the burnt control, soil losses were reduced by 85% in the mulching treatment and by 30% in the seeding treatment

Oldowan Technology Amid Shifting Environments ∼2.03–1.83 Million Years Ago

The Oldowan represents the earliest recurrent evidence of human material culture and one of the longest-lasting forms of technology. Its appearance across the African continent amid the Plio-Pleistocene profound ecological transformations, and posterior dispersal throughout the Old World is at the foundation of hominin technological dependence. However, uncertainties exist concerning the degree to which the Oldowan constitutes an environment-driven behavioral adaptation. Moreover, it is necessary to understand how Oldowan technology varied through time in response to hominin ecological demands. In this study, we present the stone tool assemblage from Ewass Oldupa, a recently discovered archeological site that signals the earliest hominin occupation of Oldupai Gorge (formerly Olduvai) ∼2.03 Ma. At Ewass Oldupa, hominins underwent marked environmental shifts over the course of a ∼200 kyr period. In this article, we deployed an analysis that combines technological and typological descriptions with an innovative quantitative approach, the Volumetric Reconstruction Method. Our results indicate that hominins overcame major ecological challenges while relying on technological strategies that remained essentially unchanged. This highlights the Oldowan efficiency, as its basic set of technological traits was able to sustain hominins throughout multiple environments.Introduction Ewass Oldupa Materials and methods - Stone Tool Techno-Typological Analysis - The Volumetric Reconstruction Method Results - Assemblage Overview - Techno-Typological Variation Over Time and Across Environments - The Volumetric Reconstruction Method Discussio

Soil organic carbon dynamics under burned and unburned forests in Galicia (N.W. Spain)

Trabajo presentado en el Congreso Managed forests in future landscapes: Implications for water and carbon cycles. COST Action Forman, celebrado en Santiago de Compostela (España), del 9 al 12 de mayo de 2011Peer reviewe

Medium term impact of fire and post-fire emergency rehabilitation treatments (mulching and seeding) on soil quality

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 2016Se 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.Peer reviewe

Impact of a high severity wildfire and two post-fire stabilization treatments on microbial biomass in a soil located in Laza (Ourense, NW Spain)

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 2012A field experiment was conducted in a burnt area affected by a high severity fire located in Laza (Ourense) to evaluate the impact of fire and different post-fire stabilisation treatments like mulching and seeding on microbial biomass. Samples were collected from the A horizon (0-2 cm) immediately and 4, 8 and 12 months after the wildfire. Total biomass and biomass of specific groups (bacteria, fungi, actinomycetes, Gram-positive bacteria and Gram-negative bacteria) were determined in the fraction < 2mm by analysis of phospholipid fatty acids. Results showed that total biomass and biomass of specific groups decreased immediately after the wildfire and although this effect is was attenuated over time it still persisted after 1 year. Fungal/bacterial and G -/G+ ratios as well as actinomycetes abundance increased in burnt soil samples due to changes in soil pH and carbon content. The ratio of cyclopropyl fatty acid/monoeic precursors (cyclo/prec) tended to be higher in the burned soils than in the unburned control, indicating that the fire caused stress in soil microorganisms. There was no evidence of any significant difference on total biomass, biomass of specifics groups and microbial fatty acids indices (fungal/bacterial, G-/G+, cyclo/pre) between the two different post-fire treatments (QS, QM) and the corresponding burned treatment (Q).Este estudio fue financiado por el Ministerio de Ciencia e Innovación (AGL2008-02823), España, por la Consellería de Medio Rural de la Xunta de Galicia (08MRU002400PR). A. Barreiro y A. Lombao son beneficiarias de becas FPU del Ministerio Español de Educación.Peer reviewe