Construcción de una tarifa de cubicación con clasificación de productos para Pinus radiata D. Don en Galicia basada en una función de perfil del tronco

Seventeen taper functions from six different groups of models (single polynomial, segmented polynomial, power, exponential, variable exponent and trigonometric taper fucntions) were fitted to diameter at different heights data from a sample of 280 trees of Pinus radiata D. Don in Galicia (Northwestern Spain). The equations obtained were compared to evaluate its performance and were validated using an independent sample of 85 trees to determine the best model. A total and merchantable volume equation was calculated by integration of the taper function. This equation is useful to estimate the yield of the stand for the different log qualities.Un total de 17 funciones de perfil del tronco pertenecientes a seis categorías de modelos distintos (polinómicos simples, polinómicos segmentados, potenciales, exponenciales, de exponente variable y trigonométricos) se han ajustado a los datos de diámetros medidos a diferentes alturas obtenidos de una muestra de 280 árboles de Pinus radiata D. Don en Galicia. Las ecuaciones obtenidas se han comparado y validado empleando una muestra independiente de 85 árboles, con el fin de determinar el modelo que mejor se adapta al perfil real del tronco para la especie en esta Comunidad Autónoma. Posteriormente se ha construido una tarifa de cubicación con clasificación de productos mediante integración de la mejor función de perfil. Esta tarifa permite la estimación del volumen del árbol correspondiente a los distintos destinos industriales de la madera y por tanto una mejor valoración económica de la producción de las masas de esta especie

Growth and yield models in Spain: historical overview, contemporary examples and perspectives

Producción CientíficaIn this paper we present a review of forest models developed in Spain in recent years for both timber and non timber production and forest dynamics (regeneration, mortality,..). Models developed are whole stand, size (diameter) class and individual-tree. The models developed to date have been developed using data from permanent plots, experimental sites and the National Forest Inventory. In this paper we show the different sub-models developed so far and the friendly use software. Main perspectives of forest modelling in Spain are presented

Modelización de la relación altura-diámetro para Pinus pinaster Ait. en Galicia mediante la función de densidad bivariante SBB

The bivariate density function SBB has been fitted to height and diameter data of maritime pine (Pinus pinaster Ait.) from 24 sample plots established in even-aged stands of this specie in Galicia (Northwestern Spain). The height-diameter model in maritime pine was estimated using a property of the SBB bivariate distribution. In order to get this, a median regression of SBB function was established between heights and diameters data of each one of the 24 sample plots. The estimated values obtained in the fit has also been used to obtain the curves corresponding to the percentiles of the 5 and 95 % of the height distribution. Finally, a generalized height-diameter function has been developed for Pinus pinaster in Galicia from the equations fitted to each plot, relating the SBB function with the principal stand variables.Se ha ajustado la función de densidad bivariante SBB a datos de altura y diámetro de una muestra de pies de pino marítimo (Pinus pinaster Ait.) pertenecientes a 24 parcelas de ensayo instaladas en masas regulares de dicha especie y repartidas por toda la Comunidad Autónoma de Galicia. Utilizando una propiedad de la distribución bivariante SBB se ha estimado la relación altura-diámetro en pino pinaster. Para ello se realizó un ajuste por regresión de medianas de la función SBB entre los datos de las alturas y los diámetros de los pies de cada una de las 24 parcelas inventariadas. Los estimadores obtenidos en el ajuste también han servido para obtener las curvas correspondientes a los percentiles del 5 y 95%de la distribución de alturas. Posteriormente, y a partir de la ecuación modelizada, se ha construido una función altura-diámetro generalizada, relacionando los parámetros de la función SBB con las principales variables de masa

Accumulation of northern krill (Meganyctiphanes norvegica) in a convergence zone at the Cap Breton Canyon (southern Bay of Biscay)

Publicado

The HADES RV Programme with HARPS-N@TNG IV. Time resolved analysis of the Ca ii H&K and H{\alpha} chromospheric emission of low-activity early-type M dwarfs

M dwarfs are prime targets for planet search programs, particularly of those focused on the detection and characterization of rocky planets in the habitable zone. Understanding their magnetic activity is important because it affects our ability to detect small planets, and it plays a key role in the characterization of the stellar environment. We analyze observations of the Ca II H&K and H{\alpha} lines as diagnostics of chromospheric activity for low-activity early-type M dwarfs. We analyze the time series of spectra of 71 early-type M dwarfs collected for the HADES project for planet search purposes. The HARPS-N spectra provide simultaneously the H&K doublet and the H{\alpha} line. We develop a reduction scheme able to correct the HARPS-N spectra for instrumental and atmospheric effects, and to provide flux-calibrated spectra in units of flux at the stellar surface. The H&K and H{\alpha} fluxes are compared with each other, and their variability is analyzed. We find that the H and K flux excesses are strongly correlated with each other, while the H{\alpha} flux excess is generally less correlated with the H&K doublet. We also find that H{\alpha} emission does not increase monotonically with the H&K line flux, showing some absorption before being filled in by chromospheric emission when H&K activity increases. Analyzing the time variability of the emission fluxes, we derive a tentative estimate of the rotation period (of the order of a few tens of days) for some of the program stars, and the typical lifetime of chromospheric active regions (a few stellar rotations). Our results are in good agreement with previous studies. In particular, we find evidence that the chromospheres of early-type M dwarfs could be characterized by different filaments coverage, affecting the formation mechanism of the H{\alpha} line. We also show that chromospheric structure is likely related to spectral type

Greenhouse effect gases emission implications on sustainability of the Campus of Vegazana, University of León

En este trabajo se presentan los resultados del estudio de emisiones de CO2, uno de los gases más importantes de efecto invernadero, debido a la actividad desarrollada en el Campus de Vegazana de la Universidad de León, para el año 2006. El estudio se enmarca en un proyecto más amplio de cálculo del indicador Huella Ecológica (HE), desarrollado para conocer en qué medida se alcanzan los objetivos de sostenibilidad establecidos para el Campus, así como para el desarrollo de propuestas encaminadas a la reducción de las emisiones de CO2. Los resultados obtenidos reflejan como el área de superficie biológicamente productiva necesaria para absorber las emisiones del Campus constituyen cerca del 99% del área total de HE. La mayor parte de estas emisiones proceden del gasto energético para electricidad (38%) y uso térmico (24%, seguido del transporte (19%) y la construcción del propio complejo universitario (16%, el cual hace referencia únicamente al año 2006, considerando una vida útil de 27 años para los edificios e instalaciones del Campus, inaugurado en 1979. Una vez analizadas cualitativa y cuantitativamente las emisiones producidas, se ha buscado conocer el total de superficie forestal necesaria para absorber dichas emisiones, considerando los datos del Tercer Inventario Forestal Nacional (2003) sobre cobertura de las masas forestales para el territorio nacional, y los aportados por Bravo (2007) en relación a las tasas de fijación del gas por parte de éstas. Como conclusión, puede estimarse que del total de la superficie forestal de la provincia de León, un 0.46% es necesaria como depósito y sumidero del CO2 emitido por el Campus de Vegazana (8.470.168 toneladas. Esta estimación se ha realizado considerando que las masas forestales son las únicas depositarias de CO2, tarea compartida en la naturaleza, no obstante, con el suelo, el agua y los cultivosIn this work, we present the results obtained about the CO2 emissions, one of the most important greenhouse gases, due to the normal activity developed in the Campus of Vegazana of the University of León for the year 2006. This study is all part of a wider project for evaluating the Fingerprint ecological indicator (HE, initially developed for assessing if the sustainability objectives established by the University policies for the Campus of Vegazana have been achieved, as well as the development of proposals and ideas directed towards the reduction of the emissions of CO2. Results obtained showed that the biologically productive area necessary for absorbing all emissions are close to the 99% of the total value of HE. The majority of these emissions come from the energy consumed for producing electricity (38%) and heating (24%), followed by the transport (19%) and the constructions of the buildings and infrastructures of the University (16%, which related just for the year 2006, considering a living period of 27 years as it was inaugurated in 1979. Once analyzed qualitatively and quantitatively the emissions produced, it was developed a method for estimating the total area covered necessary for absorbing them by considering data available from the Third National Forestry Inventory of Spain (2003), related with the forest cover of the territory, and data provided by Bravo(2007, about the absorption rate of the tree species. As a conclusion, we estimated that form the total area covered by forests of the Province of León, a 0.46% is necessary as sink of the CO2 produced in the Campus of Vegazana (8.470.168 ton. This assessment has been achieved considering that forests are the only warehouse of CO2, when actually soil, water and crops are in nature.Peer Reviewe