The Weibull and the Chaudhry-Ahmad probability density functions were used to model resin product... more The Weibull and the Chaudhry-Ahmad probability density functions were used to model resin production distributions for maritime pine stands. Maximum likelihood was used for parameter estimation. Data were collected during one season in two sets of plots. Set 1 consisted of two 50-tree and one 100-tree plots. Bootstrap re-sampling showed that the Weibull parameters had smaller estimation errors for small sample sizes. Set 2 consisted of thirty-seven 10-tree plots. No significant differences in the fit of the density functions were detected. Parameters of both models were found to be well correlated with the mean plot production as well as with the within plot coefficient of variation. The results did not reveal any major differences between the Weibull and the Chaudhry-Ahmad probability functions. The most appropriate model should be chosen at later stages when parameters of both functions are regressed against easily measured stand attributes. resin production distribution / Pinus pinaster / Weibull / Chaudhry and Ahmad / modelling Résumé -Modélisation de la distribution de production de résine pour Pinus pinaster Ait au moyen de deux lois de probabilité. La distribution de la production de résine de peuplements de pin maritime est modélisée par les fonctions de densité de probabilité de Weibull et de Chaudhry-Ahmad La méthode du maximum de vraisemblance est utilisée pour l'estimation des paramètres. Les données ont été mesurées dans deux groupes de placettes pendant une saison de récolte. Pour le premier groupe qui est composé de deux placettes de 50 arbres et d'une autre de 100 arbres, le re-échantillonnage « bootstrap » a montré que les paramètres de la fonction de Weibull ont une erreur plus faible pour les petits échantillons que celle de la fonction de Chaudhry-Ahmad. Le second groupe est constitué de 37 placettes de 10 arbres. Aucune différence significative entre l'ajustement des deux fonctions de probabilité n'est mise en évidence. Les paramètres des deux modèles sont corrélés avec les productions moyennes des placettes et avec les coefficients de variation intra-placettes. Les résultats ne montrent pas de différences significatives entre les fonctions de probabilité de Weibull et de Chaudry-Ahmad. Le modèle définitif sera choisi ultérieurement après la mise en relation entre les paramètres des deux fonctions et des variables dendrométriques facilement mesurables. distribution de la production de résine / Pinus pinaster / Weibull / Chaudhry et Ahmad / modélisation
In this study, the capacity of contingency tables and correspondence analysis (CA) to determine g... more In this study, the capacity of contingency tables and correspondence analysis (CA) to determine graphically what categories of edaphic variables vary with Site Index (SI) is analysed. The categories that show association with SI are those related to textural type and water holding capacity. Furthermore, 66 discriminant rules are tested for their ability to classify plots into SI classes using edaphic data. A discriminant rule for classifying observations into two SI classes according to elevation and soil texture (represented by the silt and clay content) is presented for stone pine (Pinus pinea L.). This model was chosen based on a cross-validation. The error rate was 29.4% for the best quality group and 21.7% for the lowest quality group. correspondence analysis / discriminant analysis / site index / edaphic variable / categorical data / Pinus pinea L. Résumé -Site index en relation avec les variables du sol pour les peuplements de pin pignon (Pinus pinea L.) dans le sud-ouest de l'Espagne. On a étudié l'intérêt des tables de contingence et l'analyse de correspondance pour définir, d'une façon graphique, quelles sont les variables du sol les plus reliées aux caractéristiques des stations. Les variables qui sont corrélées avec SI (site index) sont celles qui sont en relation avec le type de texture et la capacité de rétention en eau. Différentes équations discriminantes basées sur des données édaphologiques ont été testées pour classer les parcelles selon la qualité de station. L'équation discriminante résultante pour le sud-ouest de l'Espagne est basé sur l'altitude et la teneur en limon et argile. L'erreur totale a été de 29,4 % dans le cas de la meilleure qualité et de 21,7 % dans le cas de la qualité la moins bonne. table de contingence / analyse de correspondance / analyse discriminante / site index / variable du sol / Pinus pinea L.
The historical formation of holm oak (Quercus ilex L.) dehesa woodlands has often resulted in eit... more The historical formation of holm oak (Quercus ilex L.) dehesa woodlands has often resulted in either rapid deforestation episodes by means of clear cuts or slower depletion of oak woodlands due to tree natural mortality and the absence of tree natural regeneration. Consequently, holm oak woodlands have been progressively converted into rough pasturelands, cereal croplands and scrublands. Whilst this tendency of holm oak exhaustion was not socially questioned, scientists and conservationists defending oak woodland conservation providing long run economic and environmental arguments were regarded as romantics ignoring the necessity for social progress and development. Today, these romantics are perceived as nature conservation pioneers and many of their arguments and concepts have been included in science and politics. This paper shows that cereal cropping and permanent grassland uses are more profitable to Extremadura's landowners than holm oak artificial plantations and monitored holm oak natural regeneration. Increasing social demand for recreational and conservation services have been taken into account by Spanish and European public authorities. Along last decade, the European Union and the Spanish government have financed oak reforestation over extensive-use croplands of West and Southwest Spain, resulting in an unprecedented net increase in holm oak woodlands. The presented extended cost-benefit analysis shows that even after incorporating estimated income derived from public and private consumption of environmental services, uses associated to treeless cropland, pastureland and scrubland are still preferred to traditional extensive multiple use associated to dehesa holm oak woodlands.
Stone pine (Pinus pinea L.) is one of the most useful trees in the Mediterranean basin, offering ... more Stone pine (Pinus pinea L.) is one of the most useful trees in the Mediterranean basin, offering a variety of products and functions. In northeast Spain (Catalonia) it represents about 41,500 ha of woodland (DGCN, 2001) and is of recognised value, both economic (timber and fruit production) and ecological (dune fixation, soil restoration and biodiversity). Pinus pinea forests also contribute to landscape quality in the coastal areas and offer valued recreational and soil conservation uses. These features, together with the economic yield of its two principal productions, wood and pine kernels, have for decades justified the commercial exploitation of this species. Yet despite their economic utility little information is available on Pinus pinea forests in this area and no work has been done on structure, production or yield. However, in recent years interest in the management of this tree species has sharply increased
Este trabajo consta de tres partes diferentes aunque muy relacionadas entre sí. En la primera par... more Este trabajo consta de tres partes diferentes aunque muy relacionadas entre sí. En la primera parte se hace un análisis de las principales características de la selvicultura, en el 'lue se pone de manifiestO, una vez más, el doble carácter ecológico y p:coduccivo de esta técnica, para o cual se aporcan abundantes * Trabajo presentado en el curso La Gestión de los Re en masas naturales y artificiales de Pintts sylvestris cursos Forestales. Teruel, 16-21 de julio de 1990.
Silvopastoralism and sustainable land management. Proceedings of an international congress on silvopastoralism and sustainable management held in Lugo, Spain, April 2004, 2005
This chapter presents a preliminary characterization of Quercus pyrenaica Willd. open woodlands i... more This chapter presents a preliminary characterization of Quercus pyrenaica Willd. open woodlands in Madrid province. From data from the second and third National Forest Inventory we compare main stand variables (N, Dg, Hm, Ho, G, V and Hart-Becking index) at the two inventories for open woodlands with low density (N<100 trees/ha). A trend in recruitment of new trees from natural regeneration or growth of coppices under the main stand has been found, as well as a reduction in density of old dehesas of large trees.
Accurate estimates of tree biomass are strongly required for forest carbon budget estimates and t... more Accurate estimates of tree biomass are strongly required for forest carbon budget estimates and to understand ecosystem dynamics for a sustainable management. Existing biomass equations for Mediterranean species are scarce, stand-and site-specific and therefore are not suitable for large scale application. In this study, biomass allometric equations were developed for stone pine (Pinus pinea L.), a Mediterranean tree species with relevant ecologic and economic interest. A dataset of 283 harvested trees was compiled with above-and belowground biomass from 16 sites in three countries (Italy, Spain, Portugal) representative of the species' geographical Mediterranean distribution. A preliminary approach comparing the ordinary least squares method and the mixed model approach was performed in order to evaluate the most appropriate method for nested data in the absence of calibration data. To quantify the sources of error associated with applying biomass equations beyond the geographical range of the data used to develop them, a residual analysis was conducted. The allometric analysis showed low intra-specific variability in aboveground biomass relationships, which was relatively insensitive to the stand and site conditions. Significant differences were found for the crown components (needles and branches), which may be attributed to local geographical adaptation, site conditions and stand management. The root biomass was highly correlated with diameter at breast height irrespective of the geographical origin. Biased estimates were found when using site-specific equations outside the geographical range from where they were developed. The new biomass equations improved the accuracy of biomass estimates, particularly for the aboveground components of higher dimension trees and for the root component, being highly suitable for use in regional and national biomass forest calculations. It is, up to the present, the most complete database of harvested stone pine trees worldwide. therefore an essential tool for defining international agreements regarding the mitigation and adaptation process to climate change. Forest inventory estimates usually rely on species-specific biomass equations and/or biomass expansion factors developed from empirical data. Forest life cycle assessments and carbon footprints accounting are other applications that heavily rely on biomass equation and expansion factors (Demertzi et al., 2016). Therefore, it is of upmost importance to improve the quality of biomass and carbon estimates in order to verify its applicability on large spatial scales (Temesgen et al., 2015). The development of biomass equations requires harvesting a sample
This study compares two site index estimations for Mediterranean maritime pine (Pinus pinaster Ai... more This study compares two site index estimations for Mediterranean maritime pine (Pinus pinaster Ait.) stands in the Iberian Peninsula. The first prediction was performed under the assumption of constant climate conditions, whereas the second one used foreseen climate according to an energy-use increment and high population growth (IPCC's A2 emission scenario). We used an existing climate-based dominant height model that incorporates temperature, seasonal precipitation in winter and autumn, and drought length as driver variables for dominant height growth. Climate attributes were retrieved from eight regional climate models nested in the same atmospheric-ocean global circulation model. Forest stand data from 188 experimental plots in four natural regions were used to compare regional climate change trends. Results indicated a climate-related diminishing trend of site index values, although some regional differences were evident. In the northern stands, the negative effects were not observed, and in some cases, forest productivity increased on low site index classes. Conversely, in the southernmost stands, there is a significant decrease in the site index across all productivity classes. Western and eastern stands also showed a decreasing trend but to a lesser extent. Our results confirm the vulnerability of stands to warmer and drier climate conditions in the southern Mediterranean region in relation to wood productivity. Résumé : Cette étude compare deux méthodes d'estimation de l'indice de qualité de station pour des peuplements de pin maritime méditerranéen (Pinus pinaster Ait.) de la péninsule ibérique. La première méthode est basée sur l'hypothèse de conditions climatiques constantes alors que la deuxième méthode utilise des prévisions climatiques provenant d'un scénario d'accroissement de l'utilisation de l'énergie et d'une forte croissance de la population (scénario d'émission A2 du GIEC). Nous avons utilisé un modèle existant de hauteur dominante basé sur le climat qui tient compte de la température, des précipitations saisonnières en hiver et en automne et de la durée des périodes sèches comme variables déterminantes de la croissance en hauteur des arbres dominants. Les variables climatiques ont été tirées de huit modèles de climat régional imbriqués dans le même modèle de circulation générale, atmosphérique et océanique. Nous avons utilisé les données de peuplements forestiers de 188 parcelles expérimentales établies dans quatre régions naturelles pour comparer les tendances de changement des climats régionaux. Les résultats indiquent une tendance décroissante des valeurs d'indice de qualité de station en fonction du climat bien que certaines différences régionales soient évidentes. Dans les peuplements situés au nord, ces effets négatifs n'ont pas été observés et, dans quelques cas, la productivité forestière augmente dans les faibles classes d'indice de qualité de station. À l'inverse, dans les peuplements situés les plus au sud, il y a une diminution significative de l'indice de qualité de station dans toutes les classes de productivité. Dans les peuplements situés à l'ouest ou à l'est, il y a une tendance décroissante, mais à un degré moindre. Nos résultats confirment que les peuplements sont vulnérables aux conditions climatiques plus chaudes et plus sèches dans le sud de la région méditerranéenne en ce qui a trait à la productivité ligneuse.
Environmental variability and site productivity relationships, estimated by means of soil-site eq... more Environmental variability and site productivity relationships, estimated by means of soil-site equations, are considered a milestone in decision making of forest management. The adequacy of silvicultural systems is related to tree response to environmental conditions. The objectives of this paper are to study climatic and edaphic variability in Mediterranean Maritime pine (Pinus pinaster) forests in Spain, and the practical use of such variability in determining forest productivity by means of site index estimation. Principal component analysis was used to describe environmental conditions and patterns. Site index predictive models were fitted using partial least squares and parsimoniously by ordinary least square. Climatic variables along with parent material defined an ecological regionalization from warm and humid to cold and dry sites. Results showed that temperature and precipitation in autumn and winter, along with longitudinal gradient define extreme site qualities. The best qualities are located in warm and humid sites whereas the poorest ones are found in cold and dry regions. Site index values are poorly explained by soil properties. However, clay content in the first mineral horizon improved the soil-site model considerably. Climate is the main driver of productivity of Mediterranean Maritime pine in a broad scale. Site index differences within a homogenous climatic region are associated to soil properties.
A stand growth model for Mediterranean maritime pine in the Iberian Peninsula (Pinus pinaster Ait... more A stand growth model for Mediterranean maritime pine in the Iberian Peninsula (Pinus pinaster Ait.) is presented. The model consist of a site index submodel developed from 281 stem analysis and validated with the data from 92 permanent sample plots. Three height growth equations in difference form are tested and the Bailey and Clutter (1974) function is considered appropriate due to its good performance with both fitting and validation data. A compatible growth and yield submodel is then elaborated with the data from the Forest Research Centre (CIFOR-INIA) permanent sample plots network. The future state of the stand is determined by the current state, characterized by basal area, age and density. The model is completed with a control function that predicts the diameter after thinning and a mortality rate for non-thinned intervals. The global model was validated with data of 13 independent permanent thinning plots from two experimental sites. The simulation of the long-term projection of volume, basal area and DBH after thinning shows certain overestimation in diameter after thinning and in volume. However, the results show errors lower than 5% and little bias.
En esta investigacion se presenta en primer lugar la metodologia aplicada en RECAMAN, que incluye... more En esta investigacion se presenta en primer lugar la metodologia aplicada en RECAMAN, que incluye el sistema de cuentas agroforestales simplificado (se omiten las actividades animales y agricolas), el metodo de valor de cambio simulado y los metodos de valoracion empleados para cada una de las actividades consideradas. El sistema de contabilidad de los ecosistemas presentado amplia el concepto de proceso productivo manufacturado admitido por el actual sistema de cuentas nacionales, al incorporar los procesos productivos naturales de las actividades publicas y las ganancias de capital. El objetivo es medir la renta total social, la renta ambiental y los capitales sociales privados y publicos. La renta ambiental se obtiene residualmente y representa la contribucion de los servicios del ecosistema que se producen sin la intervencion humana a su renta total social. Los valores comerciales se estiman directamente del mercado. Para las actividades actualmente fuera del mercado se aplican ...
Se han obtenido modelos explicativos de los parametros de la funcion Weibull biparametrica para m... more Se han obtenido modelos explicativos de los parametros de la funcion Weibull biparametrica para modelizar las distribuciones diametricas en masas regulares de Pinus pinea L. en la provincia de Valladolid (Espana). A partir de datos experimentales tomados en 131 parcelas (20 arboles/parcela), se han determinado inicialmente los parametros de la distribucion teorica ajustada a las distribuciones reales mediante el metodo de los percentiles y regresion no lineal. A continuacion se han ajustado modelos lineales predictivos de los parametros calculados, que incluyen variables de masa. El parametro «b» se asocia muy estrechamente con el diametro medio cuadratico (dg), mientras que el parametro «c» presenta una mayor dificultad de ajuste, relacionandose con dg y una segunda variable (edad o fraccion de cabida cubierta).
Se ha realizado una estimacion de la biomasa y del dioxido de carbono que hay acumulado en las ma... more Se ha realizado una estimacion de la biomasa y del dioxido de carbono que hay acumulado en las masas de Pinus sylvestris y Quercus pyrenaica de los montes «Matas de Valsain» y «Pinar de Valsain» (Segovia). Para ello se han utilizado los datos de muestreos realizados por el CIFOR-INIA para ambas especies. Se eligen al menos tres pies por clase diametrica, se apearon y se separaron en fracciones de biomasa (fuste, ramas de diametro mayor de 7 cm, ramas de diametro entre 2 y 7 cm, ramas menores de 2 cm) que se pesaron en campo. Se extrajo el tocon de un pie por clase diametrica y se peso en verde. En laboratorio se determino el peso seco de las muestras y se hallaron modelos para las distintas fracciones que relacionasen la biomasa seca y con el diametro. Con estos modelos se calcularon unos valores modulares que se aplicaron a los datos del numero de pies, obtenidos de los inventarios, para estimar la biomasa total de los montes. El CO2 se estima mediante la relacion entre el porcenta...
Cones of the Mediterranean stone pine (Pinus pinea L.) constitute one of the most relevant non-wo... more Cones of the Mediterranean stone pine (Pinus pinea L.) constitute one of the most relevant non-wood forest products collected in the Mediterranean forests, providing high value edible kernels. In the last years it has been observed a severe decline in the kernel-per-cone yield (kg of kernels obtained from a kg of fresh cones) through the whole area of the species. This decline has been associated with both ongoing climate change and the recent expansion over the Mediterranean Basin of the Western Conifer Seed Bug, Leptoglossus occidentalis Heideman, an exotic pest which predates seeds of conifer species. In the present work we aimed to confirm and quantify the impact of this recent decline on pine nut and kernel production, identify the main factors provoking this reduction, and give evidence over causality by a potential biotic agent. We analysed recent and historical series of pine nut and kernel production obtained in the four main regions where Pinus pinea occurs in Spain. Our results showed a significant drop in the final kernel-per-cone yield on three of the four regions analysed, reaching reductions over 50% in the most affected areas. We observed that this reduction is mainly associated with a significant and generalised drop in the kernel-per-nut yield (kg of kernels per kg of pine nuts in shell), triggered by an increment in the rate of damaged pine nuts and, to a lesser extent, a reduction in the number of pine nuts per cone. The prevalence of this reduction on kernel-per-cone yield over different years and provenances with contrasting climate reinforces the hypothesis of the implication of a biotic factor which can be aggravated on extreme drought years.
Cork oak (Quercus suber L.) seedlings of two Iberian provenances (PA-SR and SM-Lp) were grown for... more Cork oak (Quercus suber L.) seedlings of two Iberian provenances (PA-SR and SM-Lp) were grown for one growing season in non-treated containers or in containers treated on their interior surfaces with white exterior latex paint containing 80 g CuCO3/liter. Copper carbonate-treated containers effectively prevented root deformation and decreased the amount of circled, kinked and matted roots formed at the container wall-medium interface. Root morphology was altered by the copper coating, so elongation of lateral roots contacting CuCO3-treated surfaces was more reduced than that of the tap root (82.7% vs 1.5%). These lateral roots showed higher branching frequency than roots contacting untreated container walls. CuCO3 treatment decreased root collar diameter, but did not influence seedling height, leaf area and tap root length. No sign of copper toxicity was observed in any seedling treated with CuCO3. Provenance had a significant effect on height, root collar diameter, tap root length ...
The Weibull and the Chaudhry-Ahmad probability density functions were used to model resin product... more The Weibull and the Chaudhry-Ahmad probability density functions were used to model resin production distributions for maritime pine stands. Maximum likelihood was used for parameter estimation. Data were collected during one season in two sets of plots. Set 1 consisted of two 50-tree and one 100-tree plots. Bootstrap re-sampling showed that the Weibull parameters had smaller estimation errors for small sample sizes. Set 2 consisted of thirty-seven 10-tree plots. No significant differences in the fit of the density functions were detected. Parameters of both models were found to be well correlated with the mean plot production as well as with the within plot coefficient of variation. The results did not reveal any major differences between the Weibull and the Chaudhry-Ahmad probability functions. The most appropriate model should be chosen at later stages when parameters of both functions are regressed against easily measured stand attributes. resin production distribution / Pinus pinaster / Weibull / Chaudhry and Ahmad / modelling Résumé -Modélisation de la distribution de production de résine pour Pinus pinaster Ait au moyen de deux lois de probabilité. La distribution de la production de résine de peuplements de pin maritime est modélisée par les fonctions de densité de probabilité de Weibull et de Chaudhry-Ahmad La méthode du maximum de vraisemblance est utilisée pour l'estimation des paramètres. Les données ont été mesurées dans deux groupes de placettes pendant une saison de récolte. Pour le premier groupe qui est composé de deux placettes de 50 arbres et d'une autre de 100 arbres, le re-échantillonnage « bootstrap » a montré que les paramètres de la fonction de Weibull ont une erreur plus faible pour les petits échantillons que celle de la fonction de Chaudhry-Ahmad. Le second groupe est constitué de 37 placettes de 10 arbres. Aucune différence significative entre l'ajustement des deux fonctions de probabilité n'est mise en évidence. Les paramètres des deux modèles sont corrélés avec les productions moyennes des placettes et avec les coefficients de variation intra-placettes. Les résultats ne montrent pas de différences significatives entre les fonctions de probabilité de Weibull et de Chaudry-Ahmad. Le modèle définitif sera choisi ultérieurement après la mise en relation entre les paramètres des deux fonctions et des variables dendrométriques facilement mesurables. distribution de la production de résine / Pinus pinaster / Weibull / Chaudhry et Ahmad / modélisation
In this study, the capacity of contingency tables and correspondence analysis (CA) to determine g... more In this study, the capacity of contingency tables and correspondence analysis (CA) to determine graphically what categories of edaphic variables vary with Site Index (SI) is analysed. The categories that show association with SI are those related to textural type and water holding capacity. Furthermore, 66 discriminant rules are tested for their ability to classify plots into SI classes using edaphic data. A discriminant rule for classifying observations into two SI classes according to elevation and soil texture (represented by the silt and clay content) is presented for stone pine (Pinus pinea L.). This model was chosen based on a cross-validation. The error rate was 29.4% for the best quality group and 21.7% for the lowest quality group. correspondence analysis / discriminant analysis / site index / edaphic variable / categorical data / Pinus pinea L. Résumé -Site index en relation avec les variables du sol pour les peuplements de pin pignon (Pinus pinea L.) dans le sud-ouest de l'Espagne. On a étudié l'intérêt des tables de contingence et l'analyse de correspondance pour définir, d'une façon graphique, quelles sont les variables du sol les plus reliées aux caractéristiques des stations. Les variables qui sont corrélées avec SI (site index) sont celles qui sont en relation avec le type de texture et la capacité de rétention en eau. Différentes équations discriminantes basées sur des données édaphologiques ont été testées pour classer les parcelles selon la qualité de station. L'équation discriminante résultante pour le sud-ouest de l'Espagne est basé sur l'altitude et la teneur en limon et argile. L'erreur totale a été de 29,4 % dans le cas de la meilleure qualité et de 21,7 % dans le cas de la qualité la moins bonne. table de contingence / analyse de correspondance / analyse discriminante / site index / variable du sol / Pinus pinea L.
The historical formation of holm oak (Quercus ilex L.) dehesa woodlands has often resulted in eit... more The historical formation of holm oak (Quercus ilex L.) dehesa woodlands has often resulted in either rapid deforestation episodes by means of clear cuts or slower depletion of oak woodlands due to tree natural mortality and the absence of tree natural regeneration. Consequently, holm oak woodlands have been progressively converted into rough pasturelands, cereal croplands and scrublands. Whilst this tendency of holm oak exhaustion was not socially questioned, scientists and conservationists defending oak woodland conservation providing long run economic and environmental arguments were regarded as romantics ignoring the necessity for social progress and development. Today, these romantics are perceived as nature conservation pioneers and many of their arguments and concepts have been included in science and politics. This paper shows that cereal cropping and permanent grassland uses are more profitable to Extremadura's landowners than holm oak artificial plantations and monitored holm oak natural regeneration. Increasing social demand for recreational and conservation services have been taken into account by Spanish and European public authorities. Along last decade, the European Union and the Spanish government have financed oak reforestation over extensive-use croplands of West and Southwest Spain, resulting in an unprecedented net increase in holm oak woodlands. The presented extended cost-benefit analysis shows that even after incorporating estimated income derived from public and private consumption of environmental services, uses associated to treeless cropland, pastureland and scrubland are still preferred to traditional extensive multiple use associated to dehesa holm oak woodlands.
Stone pine (Pinus pinea L.) is one of the most useful trees in the Mediterranean basin, offering ... more Stone pine (Pinus pinea L.) is one of the most useful trees in the Mediterranean basin, offering a variety of products and functions. In northeast Spain (Catalonia) it represents about 41,500 ha of woodland (DGCN, 2001) and is of recognised value, both economic (timber and fruit production) and ecological (dune fixation, soil restoration and biodiversity). Pinus pinea forests also contribute to landscape quality in the coastal areas and offer valued recreational and soil conservation uses. These features, together with the economic yield of its two principal productions, wood and pine kernels, have for decades justified the commercial exploitation of this species. Yet despite their economic utility little information is available on Pinus pinea forests in this area and no work has been done on structure, production or yield. However, in recent years interest in the management of this tree species has sharply increased
Este trabajo consta de tres partes diferentes aunque muy relacionadas entre sí. En la primera par... more Este trabajo consta de tres partes diferentes aunque muy relacionadas entre sí. En la primera parte se hace un análisis de las principales características de la selvicultura, en el 'lue se pone de manifiestO, una vez más, el doble carácter ecológico y p:coduccivo de esta técnica, para o cual se aporcan abundantes * Trabajo presentado en el curso La Gestión de los Re en masas naturales y artificiales de Pintts sylvestris cursos Forestales. Teruel, 16-21 de julio de 1990.
Silvopastoralism and sustainable land management. Proceedings of an international congress on silvopastoralism and sustainable management held in Lugo, Spain, April 2004, 2005
This chapter presents a preliminary characterization of Quercus pyrenaica Willd. open woodlands i... more This chapter presents a preliminary characterization of Quercus pyrenaica Willd. open woodlands in Madrid province. From data from the second and third National Forest Inventory we compare main stand variables (N, Dg, Hm, Ho, G, V and Hart-Becking index) at the two inventories for open woodlands with low density (N<100 trees/ha). A trend in recruitment of new trees from natural regeneration or growth of coppices under the main stand has been found, as well as a reduction in density of old dehesas of large trees.
Accurate estimates of tree biomass are strongly required for forest carbon budget estimates and t... more Accurate estimates of tree biomass are strongly required for forest carbon budget estimates and to understand ecosystem dynamics for a sustainable management. Existing biomass equations for Mediterranean species are scarce, stand-and site-specific and therefore are not suitable for large scale application. In this study, biomass allometric equations were developed for stone pine (Pinus pinea L.), a Mediterranean tree species with relevant ecologic and economic interest. A dataset of 283 harvested trees was compiled with above-and belowground biomass from 16 sites in three countries (Italy, Spain, Portugal) representative of the species' geographical Mediterranean distribution. A preliminary approach comparing the ordinary least squares method and the mixed model approach was performed in order to evaluate the most appropriate method for nested data in the absence of calibration data. To quantify the sources of error associated with applying biomass equations beyond the geographical range of the data used to develop them, a residual analysis was conducted. The allometric analysis showed low intra-specific variability in aboveground biomass relationships, which was relatively insensitive to the stand and site conditions. Significant differences were found for the crown components (needles and branches), which may be attributed to local geographical adaptation, site conditions and stand management. The root biomass was highly correlated with diameter at breast height irrespective of the geographical origin. Biased estimates were found when using site-specific equations outside the geographical range from where they were developed. The new biomass equations improved the accuracy of biomass estimates, particularly for the aboveground components of higher dimension trees and for the root component, being highly suitable for use in regional and national biomass forest calculations. It is, up to the present, the most complete database of harvested stone pine trees worldwide. therefore an essential tool for defining international agreements regarding the mitigation and adaptation process to climate change. Forest inventory estimates usually rely on species-specific biomass equations and/or biomass expansion factors developed from empirical data. Forest life cycle assessments and carbon footprints accounting are other applications that heavily rely on biomass equation and expansion factors (Demertzi et al., 2016). Therefore, it is of upmost importance to improve the quality of biomass and carbon estimates in order to verify its applicability on large spatial scales (Temesgen et al., 2015). The development of biomass equations requires harvesting a sample
This study compares two site index estimations for Mediterranean maritime pine (Pinus pinaster Ai... more This study compares two site index estimations for Mediterranean maritime pine (Pinus pinaster Ait.) stands in the Iberian Peninsula. The first prediction was performed under the assumption of constant climate conditions, whereas the second one used foreseen climate according to an energy-use increment and high population growth (IPCC's A2 emission scenario). We used an existing climate-based dominant height model that incorporates temperature, seasonal precipitation in winter and autumn, and drought length as driver variables for dominant height growth. Climate attributes were retrieved from eight regional climate models nested in the same atmospheric-ocean global circulation model. Forest stand data from 188 experimental plots in four natural regions were used to compare regional climate change trends. Results indicated a climate-related diminishing trend of site index values, although some regional differences were evident. In the northern stands, the negative effects were not observed, and in some cases, forest productivity increased on low site index classes. Conversely, in the southernmost stands, there is a significant decrease in the site index across all productivity classes. Western and eastern stands also showed a decreasing trend but to a lesser extent. Our results confirm the vulnerability of stands to warmer and drier climate conditions in the southern Mediterranean region in relation to wood productivity. Résumé : Cette étude compare deux méthodes d'estimation de l'indice de qualité de station pour des peuplements de pin maritime méditerranéen (Pinus pinaster Ait.) de la péninsule ibérique. La première méthode est basée sur l'hypothèse de conditions climatiques constantes alors que la deuxième méthode utilise des prévisions climatiques provenant d'un scénario d'accroissement de l'utilisation de l'énergie et d'une forte croissance de la population (scénario d'émission A2 du GIEC). Nous avons utilisé un modèle existant de hauteur dominante basé sur le climat qui tient compte de la température, des précipitations saisonnières en hiver et en automne et de la durée des périodes sèches comme variables déterminantes de la croissance en hauteur des arbres dominants. Les variables climatiques ont été tirées de huit modèles de climat régional imbriqués dans le même modèle de circulation générale, atmosphérique et océanique. Nous avons utilisé les données de peuplements forestiers de 188 parcelles expérimentales établies dans quatre régions naturelles pour comparer les tendances de changement des climats régionaux. Les résultats indiquent une tendance décroissante des valeurs d'indice de qualité de station en fonction du climat bien que certaines différences régionales soient évidentes. Dans les peuplements situés au nord, ces effets négatifs n'ont pas été observés et, dans quelques cas, la productivité forestière augmente dans les faibles classes d'indice de qualité de station. À l'inverse, dans les peuplements situés les plus au sud, il y a une diminution significative de l'indice de qualité de station dans toutes les classes de productivité. Dans les peuplements situés à l'ouest ou à l'est, il y a une tendance décroissante, mais à un degré moindre. Nos résultats confirment que les peuplements sont vulnérables aux conditions climatiques plus chaudes et plus sèches dans le sud de la région méditerranéenne en ce qui a trait à la productivité ligneuse.
Environmental variability and site productivity relationships, estimated by means of soil-site eq... more Environmental variability and site productivity relationships, estimated by means of soil-site equations, are considered a milestone in decision making of forest management. The adequacy of silvicultural systems is related to tree response to environmental conditions. The objectives of this paper are to study climatic and edaphic variability in Mediterranean Maritime pine (Pinus pinaster) forests in Spain, and the practical use of such variability in determining forest productivity by means of site index estimation. Principal component analysis was used to describe environmental conditions and patterns. Site index predictive models were fitted using partial least squares and parsimoniously by ordinary least square. Climatic variables along with parent material defined an ecological regionalization from warm and humid to cold and dry sites. Results showed that temperature and precipitation in autumn and winter, along with longitudinal gradient define extreme site qualities. The best qualities are located in warm and humid sites whereas the poorest ones are found in cold and dry regions. Site index values are poorly explained by soil properties. However, clay content in the first mineral horizon improved the soil-site model considerably. Climate is the main driver of productivity of Mediterranean Maritime pine in a broad scale. Site index differences within a homogenous climatic region are associated to soil properties.
A stand growth model for Mediterranean maritime pine in the Iberian Peninsula (Pinus pinaster Ait... more A stand growth model for Mediterranean maritime pine in the Iberian Peninsula (Pinus pinaster Ait.) is presented. The model consist of a site index submodel developed from 281 stem analysis and validated with the data from 92 permanent sample plots. Three height growth equations in difference form are tested and the Bailey and Clutter (1974) function is considered appropriate due to its good performance with both fitting and validation data. A compatible growth and yield submodel is then elaborated with the data from the Forest Research Centre (CIFOR-INIA) permanent sample plots network. The future state of the stand is determined by the current state, characterized by basal area, age and density. The model is completed with a control function that predicts the diameter after thinning and a mortality rate for non-thinned intervals. The global model was validated with data of 13 independent permanent thinning plots from two experimental sites. The simulation of the long-term projection of volume, basal area and DBH after thinning shows certain overestimation in diameter after thinning and in volume. However, the results show errors lower than 5% and little bias.
En esta investigacion se presenta en primer lugar la metodologia aplicada en RECAMAN, que incluye... more En esta investigacion se presenta en primer lugar la metodologia aplicada en RECAMAN, que incluye el sistema de cuentas agroforestales simplificado (se omiten las actividades animales y agricolas), el metodo de valor de cambio simulado y los metodos de valoracion empleados para cada una de las actividades consideradas. El sistema de contabilidad de los ecosistemas presentado amplia el concepto de proceso productivo manufacturado admitido por el actual sistema de cuentas nacionales, al incorporar los procesos productivos naturales de las actividades publicas y las ganancias de capital. El objetivo es medir la renta total social, la renta ambiental y los capitales sociales privados y publicos. La renta ambiental se obtiene residualmente y representa la contribucion de los servicios del ecosistema que se producen sin la intervencion humana a su renta total social. Los valores comerciales se estiman directamente del mercado. Para las actividades actualmente fuera del mercado se aplican ...
Se han obtenido modelos explicativos de los parametros de la funcion Weibull biparametrica para m... more Se han obtenido modelos explicativos de los parametros de la funcion Weibull biparametrica para modelizar las distribuciones diametricas en masas regulares de Pinus pinea L. en la provincia de Valladolid (Espana). A partir de datos experimentales tomados en 131 parcelas (20 arboles/parcela), se han determinado inicialmente los parametros de la distribucion teorica ajustada a las distribuciones reales mediante el metodo de los percentiles y regresion no lineal. A continuacion se han ajustado modelos lineales predictivos de los parametros calculados, que incluyen variables de masa. El parametro «b» se asocia muy estrechamente con el diametro medio cuadratico (dg), mientras que el parametro «c» presenta una mayor dificultad de ajuste, relacionandose con dg y una segunda variable (edad o fraccion de cabida cubierta).
Se ha realizado una estimacion de la biomasa y del dioxido de carbono que hay acumulado en las ma... more Se ha realizado una estimacion de la biomasa y del dioxido de carbono que hay acumulado en las masas de Pinus sylvestris y Quercus pyrenaica de los montes «Matas de Valsain» y «Pinar de Valsain» (Segovia). Para ello se han utilizado los datos de muestreos realizados por el CIFOR-INIA para ambas especies. Se eligen al menos tres pies por clase diametrica, se apearon y se separaron en fracciones de biomasa (fuste, ramas de diametro mayor de 7 cm, ramas de diametro entre 2 y 7 cm, ramas menores de 2 cm) que se pesaron en campo. Se extrajo el tocon de un pie por clase diametrica y se peso en verde. En laboratorio se determino el peso seco de las muestras y se hallaron modelos para las distintas fracciones que relacionasen la biomasa seca y con el diametro. Con estos modelos se calcularon unos valores modulares que se aplicaron a los datos del numero de pies, obtenidos de los inventarios, para estimar la biomasa total de los montes. El CO2 se estima mediante la relacion entre el porcenta...
Cones of the Mediterranean stone pine (Pinus pinea L.) constitute one of the most relevant non-wo... more Cones of the Mediterranean stone pine (Pinus pinea L.) constitute one of the most relevant non-wood forest products collected in the Mediterranean forests, providing high value edible kernels. In the last years it has been observed a severe decline in the kernel-per-cone yield (kg of kernels obtained from a kg of fresh cones) through the whole area of the species. This decline has been associated with both ongoing climate change and the recent expansion over the Mediterranean Basin of the Western Conifer Seed Bug, Leptoglossus occidentalis Heideman, an exotic pest which predates seeds of conifer species. In the present work we aimed to confirm and quantify the impact of this recent decline on pine nut and kernel production, identify the main factors provoking this reduction, and give evidence over causality by a potential biotic agent. We analysed recent and historical series of pine nut and kernel production obtained in the four main regions where Pinus pinea occurs in Spain. Our results showed a significant drop in the final kernel-per-cone yield on three of the four regions analysed, reaching reductions over 50% in the most affected areas. We observed that this reduction is mainly associated with a significant and generalised drop in the kernel-per-nut yield (kg of kernels per kg of pine nuts in shell), triggered by an increment in the rate of damaged pine nuts and, to a lesser extent, a reduction in the number of pine nuts per cone. The prevalence of this reduction on kernel-per-cone yield over different years and provenances with contrasting climate reinforces the hypothesis of the implication of a biotic factor which can be aggravated on extreme drought years.
Cork oak (Quercus suber L.) seedlings of two Iberian provenances (PA-SR and SM-Lp) were grown for... more Cork oak (Quercus suber L.) seedlings of two Iberian provenances (PA-SR and SM-Lp) were grown for one growing season in non-treated containers or in containers treated on their interior surfaces with white exterior latex paint containing 80 g CuCO3/liter. Copper carbonate-treated containers effectively prevented root deformation and decreased the amount of circled, kinked and matted roots formed at the container wall-medium interface. Root morphology was altered by the copper coating, so elongation of lateral roots contacting CuCO3-treated surfaces was more reduced than that of the tap root (82.7% vs 1.5%). These lateral roots showed higher branching frequency than roots contacting untreated container walls. CuCO3 treatment decreased root collar diameter, but did not influence seedling height, leaf area and tap root length. No sign of copper toxicity was observed in any seedling treated with CuCO3. Provenance had a significant effect on height, root collar diameter, tap root length ...
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