Modelos de crecimiento y producción en España: historia, ejemplos contemporáneos y perspectivas

En el presente trabajo se presenta una revisión sobre los modelos forestales desarrollados en España durante los últimos años, tanto para la producción maderable como no maderable y, para la dinámica de los bosques (regeneración, mortalidad). Se presentan modelos tanto de rodal completo como de clases diamétricas y de árbol individual. Los modelos desarrollados hasta la fecha se han desarrollado a partir de datos procedentes de parcelas permanentes, ensayos y el Inventario Forestal Nacional. En el trabajo se muestran los diferentes submodelos desarrollados hasta la fecha, así como las plataformas informáticas que permiten utilizar dichos modelos. Se incluyen las principales perspectivas de desarrollo de la modelización forestal en España.In 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 modeling in Spain are presented.The models described in this paper were funded by different regional, national and European projects, and some of them were elaborated by the authors. This work was funded by the Spanish Government by the SELVIRED network (code AGL2008-03740) and the strategic project «Restauración y Gestión Forestal» (code PSE-310000-2009-4)

Emerging stability of forest productivity by mixing two species buffers temperature destabilizing effect

The increasing disturbances in monocultures around the world are testimony to their instability under global change. Many studies have claimed that temporal stability of productivity increases with species richness, although the ecological fundamentals have mainly been investigated through diversity experiments. To adequately manage forest ecosystems, it is necessary to have a comprehensive understanding of the effect of mixing species on the temporal stability of productivity and the way in which it is influenced by climate conditions across large geographical areas. Here, we used a unique dataset of 261 stands combining pure and two-species mixtures of four relevant tree species over a wide range of climate conditions in Europe to examine the effect of species mixing on the level and temporal stability of productivity. Structural equation modelling was employed to further explore the direct and indirect influence of climate, overyielding, species asynchrony and additive effect (i.e. temporal stability expected from the species growth in monospecific stands) on temporal stability in mixed forests. We showed that by adding only one tree species to monocultures, the level (overyielding: +6%) and stability (temporal stability: +12%) of stand growth increased significantly. We identified the key effect of temperature on destabilizing stand growth, which may be mitigated by mixing species. We further confirmed asynchrony as the main driver of temporal stability in mixed stands, through both the additive effect and species interactions, which modify between-species asynchrony in mixtures in comparison to monocultures. Synthesis and applications. This study highlights the emergent properties associated with mixing two species, which result in resource efficient and temporally stable production systems. We reveal the negative impact of mean temperature on temporal stability of forest productivity and how the stabilizing effect of mixing two species can counterbalance this impact. The overyielding and temporal stability of growth addressed in this paper are essential for ecosystem services closely linked with the level and rhythm of forest growth. Our results underline that mixing two species can be a realistic and effective nature-based climate solution, which could contribute towards meeting EU climate target policies

Emerging stability of forest productivity by mixing two species buffers temperature destabilizing effect

The increasing disturbances in monocultures around the world are testimony to their instability under global change. Many studies have claimed that temporal stability of productivity increases with species richness, although the ecological fundamentals have mainly been investigated through diversity experiments. To adequately manage forest ecosystems, it is necessary to have a comprehensive understanding of the effect of mixing species on the temporal stability of productivity and the way in which it is influenced by climate conditions across large geographical areas. Here, we used a unique dataset of 261 stands combining pure and two-species mixtures of four relevant tree species over a wide range of climate conditions in Europe to examine the effect of species mixing on the level and temporal stability of productivity. Structural equation modelling was employed to further explore the direct and indirect influence of climate, overyielding, species asynchrony and additive effect (i.e. temporal stability expected from the species growth in monospecific stands) on temporal stability in mixed forests. We showed that by adding only one tree species to monocultures, the level (overyielding: +6%) and stability (temporal stability: +12%) of stand growth increased significantly. We identified the key effect of temperature on destabilizing stand growth, which may be mitigated by mixing species. We further confirmed asynchrony as the main driver of temporal stability in mixed stands, through both the additive effect and species interactions, which modify between-species asynchrony in mixtures in comparison to monocultures. Synthesis and applications. This study highlights the emergent properties associated with mixing two species, which result in resource efficient and temporally stable production systems. We reveal the negative impact of mean temperature on temporal stability of forest productivity and how the stabilizing effect of mixing two species can counterbalance this impact. The overyielding and temporal stability of growth addressed in this paper are essential for ecosystem services closely linked with the level and rhythm of forest growth. Our results underline that mixing two species can be a realistic and effective nature-based climate solution, which could contribute towards meeting EU climate target policies.Emerging stability of forest productivity by mixing two species buffers temperature destabilizing effectpublishedVersio

Modelo de crecimiento individual para Pinus silvestris, con datos de los Inventarios Forestales Nacionales 2º y 3º, en la provincia de Madrid

Se presenta un modelo de crecimiento individual en área basimétrica, construido a partir de los datos de las parcelas permanentes de los Inventarios Forestales Nacionales Segundo y Tercero. El incremento del área basimétrica se calcula para cada árbol por comparación de los diámetros medidos en ambos inventarios. Las variables independientes que intervienen en el modelo se pueden dividir en tres grupos: variables que explican la situación inicial del árbol (tamaño, competencia, etc.), variables que caracterizan la calidad de estación (pendiente, orientación, tipo de suelo�) y variables descriptoras de la masa, tales como el área basimétrica eliminada entre ambos inventarios, el área basimétrica remanente y la altura dominante, etc. Se evita el uso de la edad como variable independiente, puesto que el objetivo es que el modelo de crecimiento pueda servir tanto para masas regulares como para masas irregulares. La metodología descrita, que en el trabajo se aplica a Pinus sylvestris L., en la provincia de Madrid, permite la creación de modelos similares a partir de los datos del Inventario Forestal Nacional

Actualización de los volúmenes proporcionados por los Inventarios Forestales Nacionales

Para monitorizar el estado y los cambios en los recursos forestales, organizaciones internacionales, tales como FAO o UNFCCC, solicitan información a los distintos países. Entre los parámetros solicitados uno de los más habituales es el volumen forestal. Para dar respuesta a los requerimientos la mayoría de los países utilizan los datos de sus Inventarios Forestales Nacionales (IFN). Sin embargo, dada la creciente frecuencia en la demanda de información, que en algunos casos llega a ser anual, existen discrepancias temporales entre las fechas de los IFN y de los datos requeridos. Para solventar dichas diferencias algunos países recurren a modificar los protocolos de medición para contar con datos anuales a nivel nacional, mientras otros recurren a la actualización de los datos mediante modelos. En cualquiera de los casos es necesaria una metodología específica para proporcionar estimaciones adecuadas con un error aceptable. En este trabajo se presentan dos metodologías diferentes. La primera de ellas es la utilizada en Estados Unidos donde se toman datos anualmente en todo el país. La segunda metodología permite actualizar los volúmenes medidos en el IFN español, con periodo de remedición de 10 años. Se hace especial hincapié en describir la metodología española, la cual se basa en la modelización del balance anual del volumen en las parcelas del IFN, y en la estimación de valores medios y la incertidumbre asociada (intervalos de confianza) mediante técnicas de inferencia híbrida. Se destacan en todos los casos la importancia del uso de imágenes provenientes de sensores remotos como información auxiliar

El uso del escáner láser aerotransportado para la estimación de la biomasa foliar del "Pinus sylvestris" L. en Canencia (Madrid)

La estimación de la biomasa foliar es uno de los problemas actuales que se presenta en los inventarios forestales, entre otras razones por su relación con la fijación del carbono atmosférico, y consecuentemente con la disminución del efecto invernadero. Para poder llevar a cabo una estimación adecuada de la biomasa foliar es necesario recurrir a un muestreo destructivo, que requiere el apeo de los árboles, la separación de cada uno de sus componentes así como el pesaje de los mismos. Para el cálculo de la biomasa foliar por unidad de superficie, se suelen crear modelos que relacionan la biomasa foliar del árbol con variables de fácil medición en los inventarios forestales, tales como el diámetro normal. Generalmente no se emplean en estos modelos otras variables que también están altamente correlacionadas, como la altura de copa o el diámetro de la copa, ya que dificultan la utilización posterior del modelo resultante. Mediciones obtenidas a partir de un escáner láser aerotransportado (lidar), y su alta correlación con valores de biomasa foliar por unidad de superficie, permiten el cálculo de la biomasa foliar en superficies extensas sin necesidad de la realización de un inventario exhaustivo. En este trabajo se presenta un modelo que permite la obtención de un mapa de la biomasa foliar a partir del sensor lidar en masas de Pinus sylvestris L. en Canencia (Madrid)

DOMO: una aplicación informática para el diseño de Inventarios Forestales

En este trabajo se presenta una aplicación informática que permite, en primer lugar, la simulación de rodales forestales, con una distribución diamétrica dada por el usuario y con distintos grados de agregación espacial: desde una plantación a marco hasta una agregación fuerte de los pies. El programa permite asimismo simular sobre parcelas mapeadas (bien procedentes de una medición en campo, bien procedentes de una simulación anterior) distintos tipos de inventario, que incluye diferentes alternativas de muestreo con parcelas circulares de tamaño fijo. A partir de este inventario se obtienen valores por hectárea del número de pies, área basimétrica y, con ayuda de tarifas de cubicación, del volumen por hectárea, así como los errores de muestreo correspondientes. Finalmente es posible utilizar el programa para calcular el diseño óptimo del muestreo a partir de una función de coste y de los rendimientos de los operarios en la toma de datos

Comparison of height-diameter models based on geographically weighted regressions and linear mixed modelling applied to large scale forest inventory data

Aim of the study: The main objective of this study was to test Geographically Weighted Regression (GWR) for developing height-diameter curves for forests on a large scale and to compare it with Linear Mixed Models (LMM).Area of study: Monospecific stands of Pinus halepensis Mill. located in the region of Murcia (Southeast Spain).Materials and Methods: The dataset consisted of 230 sample plots (2582 trees) from the Third Spanish National Forest Inventory (SNFI) randomly split into training data (152 plots) and validation data (78 plots). Two different methodologies were used for modelling local (Petterson) and generalized height-diameter relationships (Cañadas I): GWR, with different bandwidths, and linear mixed models. Finally, the quality of the estimated models was compared throughout statistical analysis. Main results: In general, both LMM and GWR provide better prediction capability when applied to a generalized height-diameter function than when applied to a local one, with R2 values increasing from around 0.6 to 0.7 in the model validation. Bias and RMSE were also lower for the generalized function. However, error analysis showed that there were no large differences between these two methodologies, evidencing that GWR provides results which are as good as the more frequently used LMM methodology, at least when no additional measurements are available for calibrating.Research highlights: GWR is a type of spatial analysis for exploring spatially heterogeneous processes. GWR can model spatial variation in tree height-diameter relationship and its regression quality is comparable to LMM. The advantage of GWR over LMM is the possibility to determine the spatial location of every parameter without additional measurements. Keywords: Spatial analysis; Pinus halepensis Mill; forest modelling.Abbreviations: GWR (Geographically Weighted Regression); LMM (Linear Mixed Model); SNFI (Spanish National Forest Inventory)

Stand-level biomass models for predicting C stock for the main Spanish pine species

16 Páginas.Background: National and international institutions periodically demand information on forest indicators that are used for global reporting. Among other aspects, the carbon accumulated in the biomass of forest species must be reported. For this purpose, one of the main sources of data is the National Forest Inventory (NFI), which together with statistical empirical approaches and updating procedures can even allow annual estimates of the requested indicators. Methods: Stand level biomass models, relating the dry weight of the biomass with the stand volume were developed for the five main pine species in the Iberian Peninsula (Pinus sylvestris, Pinus pinea, Pinus halepensis, Pinus nigra and Pinus pinaster). The dependence of the model on aridity and/or mean tree size was explored, as well as the importance of including the stand form factor to correct model bias. Furthermore, the capability of the models to estimate forest carbon stocks, updated for a given year, was also analysed. Results: The strong relationship between stand dry weight biomass and stand volume was modulated by the mean tree size, although the effect varied among the five pine species. Site humidity, measured using the Martonne aridity index, increased the biomass for a given volume in the cases of Pinus sylvestris, Pinus halepensis and Pinus nigra. Models that consider both mean tree size and stand form factor were more accurate and less biased than those that do not. The models developed allow carbon stocks in the main Iberian Peninsula pine forests to be estimated at stand level with biases of less than 0.2 Mg∙ha− 1. Conclusions: The results of this study reveal the importance of considering variables related with environmental conditions and stand structure when developing stand dry weight biomass models. The described methodology together with the models developed provide a precise tool that can be used for quantifying biomass and carbon stored in the Spanish pine forests in specific years when no field data are available.This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.Peer reviewe