Pedro Álvarez-Álvarez

Effects of foliar nutrients and environmental factors on site productivity in Pinus pinaster Ait. stands in Asturias (NW Spain)

Abstract• BackgroundThe effects of foliar nutrients and environmental variables on site productivity in Maritime pine (Pinus pinaster Ait.) stands in Asturias (NW Spain) were studied.• MethodsSite productivity was evaluated by means of site index. The environmental characteristics considered included physiographic, edaphic and climatic variables. Two different statistical analyses were carried out to determine the key factors affecting site productivity: the CHAID procedure and parametric regression techniques.• ResultsThe regression trees obtained by applying the CHAID algorithm separately to each type of variable revealed the order of importance of the environmental factors. In addition, the variables corresponding to the first level of branches of the CHAID regression trees were consistent with those identified by parametric regression. According to the parametric regression model, a physical soil characteristic (soil depth) and a climatic characteristic (mean summer temperature) were the most important variables for explaining site productivity in the region. Foliar concentrations of phosphorus and elevation were not significant factors in the parametric regression analysis (although considered key factors when foliar nutrients and physiographic variables were analyzed separately).• ConclusionAlthough the percentage variability in SI explained by the best parametric model was not very high (45%), the model is parsimonious and provides robust estimates of the spatial distribution of this variable. The results obtained provide further information about the ecology of this species in Asturias, and represent an important tool in forest management, especially for afforested areas.

Landscape metrics for characterization of forest landscapes in a sustainable management framework: Potential application and prevention of misuse

Abstract• The use of landscape indices in the analysis of forest landscapes offers great potential for integration of spatial pattern information in management processes, but requires understanding of the limitations and correct interpretation of results. In this sense, awareness of scale effects on landscape indices is essential, especially when the data available is restricted to low-resolution maps.• In this study, developed within the framework of the FORSEE project, the objective was to define accurately the potential usefulness of applying landscape indices to low-resolution maps commonly used in forestry studies. Landscape indices were applied to two maps differing in spatial resolution, and subsets were defined for three spatial extensions. Correlation analysis and comparison of the results were carried out to enable identification of the most suitable indices for use with low resolution data.• The analysis enabled identification of the least scale-dependent indices, which are thus more useful for extrapolating results from low-resolution data. In general terms, diversity and edge indices provided the best results.• We conclude that some (but not all) of the landscape indices can be used to analyse low-resolution maps with acceptable results. Additional advice is made to prevent misuse of the application of landscape indices.Résumé• L’utilisation d’indices de paysage dans l’analyse des paysages forestiers offre un grand potentiel pour l’intégration d’informations de modèles spatiaux dans les processus de gestion, mais exige la compréhension des limitations et une interprétation correcte de résultats. Dans ce sens, la conscience des effets d’échelle sur les indices de paysage est essentielle, particulièrement quand les données disponibles sont limitées aux cartes de basse résolution.• Dans cette étude, développée dans le cadre du projet FORSEE, l’objectif était de définir précisément l’utilité potentielle d’application des indices de paysage aux cartes de basse résolution, généralement utilisées dans les études de sylviculture. Les indices de paysage ont été appliqués à deux cartes différant par la résolution spatiale et les sous-ensembles ont été définis pour trois extensions spatiales. Une analyse de corrélation et la comparaison des résultats ont été effectuées pour permettre l’identification des indices les plus appropriés pour une utilisation avec des données de basse résolution.• L’analyse a permis l’identification des indices les moins dépendants de l’échelle, qui sont ainsi plus utiles pour extrapoler les résultats de données de basse résolution. En termes généraux, la diversité et des indices de bord ont fourni les meilleurs résultats.• Nous concluons que certains (mais pas tous) indices de paysage peuvent être utilisés pour analyser les cartes de basse résolution avec des résultats acceptables. Un conseil supplémentaire est fait pour prévenir une mauvaise utilisation des indices de paysage.

Relating growth and nutrition to site factors in young chestnut plantations established on agricultural and forest land in northern Spain

The growth and nutritional status of 97 hybrid chestnut plantations on former agricultural land and forest land were studied in relation to site conditions (climatic variables and soil properties). A single family of curves was obtained for classifying the early height growth of hybrid and sweet chestnut. Soil limitations and nutrient deficiencies were evident in the former forest land, whereas the agricultural soils were found to be generally suitable for growing chestnut. The stands with highest growth rates were characterized by high foliar concentrations of K, P and Ca. Successful growth of the plantations was always related to high summer precipitation, low elevation and absence of long periods of risk of frost. The results confirm the adaptability of chestnut to most sites where it has been planted for timber production.

Stem taper function for sweet chestnut (Castanea sativa Mill.) coppice stands in northwest Spain

Abstract• ContextDespite the economic importance of Castanea sativa Mill. in northwest Spain, studies of its growth and yield are practically non-existent.• AimsA compatible system formed by a taper function, a total volume equation, and a merchantable volume equation was developed for chestnut (C. sativa Mill.) coppice stands in northwest Spain.• MethodsData from 203 destructively sampled trees were used for the adjustment. Outliers were removed with a non-parametric local adjustment, providing a final data set of measurements taken from 3,188 sections which was used to test five taper models (compatible and non-compatible). A second-order continuous autoregressive error structure was used to model the error term and account for autocorrelation. Presence of multicollinearity was evaluated with the condition number. Comparison of the models was carried out using overall goodness-of-fit statistics and graphical analysis.• ResultsResults show that the models developed by Fang et al. in For Sci 46: 1–12, 2000 and Kozak in For Chron 80, N 4: 507–515, 2004 were superior to other equations in predicting diameter for chestnut coppice stands.• ConclusionThe compatible volume system developed by Fang et al. in For Sci 46: 1–12, 2000 was finally selected as it provided the best compromise between describing stem profile and also estimating merchantable height, merchantable volume, and total volume and therefore provides the first specific tool for more effective management of chestnut coppice stands.

Management tools for Castanea sativa coppice stands in northwestern Spain

La importancia del monte bajo de castano en el noroeste de Espana, junto con la falta de estudios de crecimiento y produccion, hacen necesario el desarrollo de herramientas que faciliten su gestion. En este estudio se han desarrollado dos herramientas de gestion: tablas de produccion de densidad variable y diagramas de manejo de densidad (DMDs). Para la construccion de las tablas de produccion se ajustaron un modelo de altura dominante y uno de densidad de masa. El modelo de altura dominante proporciona el indice de sitio, es decir, estimar indirectamente la calidad de estacion. Se necesito un modelo de densidad porque los escenarios selvicolas eran muy heterogeneos. Tanto las tablas de produccion como los DMDs requieren el ajuste de modelos de prediccion de diametro medio cuadratico y stock de crecimiento (volumen total y comercial de masa y/o biomasa total o por componentes). Se construyeron ocho tablas de produccion considerando dos niveles de densidad de masa (alta y baja) y cuatro indices de sitio (8, 12, 16 y 20 m). El turno de maxima renta en especie vario entre 25 y 45 anos segun la clase de densidad y el indice de sitio. El crecimiento medio oscilo desde 38,1 m3 ha-1 ano-1 para las densidades mas elevadas y mejores calidades, hasta 5,2 m3 ha-1 ano-1 en las densidades mas bajas y peores calidades. Las herramientas de gestion desarrolladas permiten la estimacion del volumen total y comercial de masa, biomasa total y por componentes y tambien facilitan el diseno de esquemas selvicolas

Use of ecosystem information derived from forest thematic maps for spatial analysis of ecosystem services in northwestern Spain

A clear link between ecosystem services (ES) and human well-being has been established in the recent decades. Thus, forests are recognised as extremely important ecosystems in relation to their capacity to provide goods and services to society. Nevertheless, this capacity greatly depends on the type of forest and on the management applied. Some types of data often used for this type of analysis, such as land use/land cover maps produced for general purposes, are not always appropriate for representing forest ecosystems and the services they offer. In this study, we used a forest map (Spanish National Forest Map: scale 1:25,000) and information describing composition and structure to assess six services closely associated with forest ecosystems in a forest-dominated zone of northwestern Spain on a regional scale. The following ES were considered: provision of food (basically fruits), provision of materials (timber and pulp), provision of biomass for energy (firewood), climate regulation (carbon storage by above-ground biomass), erosion regulation (protection against erosion), and cultural (recreational use and nature tourism). By combining information about tree species and cover with forest harvest data and other statistics, we established representative spatial models for the six ES representing different categories of the potential supply of each one. The six models were analysed by different methods (Spearman’s correlation, Moran’s I and Getis-Ord Gi*), enabling detection of hotspots and coldspots and the characteristic spatial scales for ES supply. The combined use of highly detailed map data, nonspatial databases and spatial analysis yielded accurate ES supply assessment.