Growth response to thinning in a mixed pine-oak stand of Pinus pinaster and Quercus pyrenaica.

During the last decades the interest on mixed stands has increased in forestry due to their potential benefits, especially conifer-broadleaves mixtures. However, more knowledge is need about their dynamic and their response to silvicultural treatments. On the other hand, climate change can affect different species in different ways, so it is important to study the effect of climate in mixed stands with different silvicultures. In this work we present preliminary results of a thinning trial in a mixed stands of Pinus pinaster Ait. and Quercus pyrenaica Willd located in ?Montes de Toledo? (Central Spain). The main objectives of the experiment are to study the growth response of each species to thinning and to analyse if there are different climate-growth relationships between species and thinning treatments. The stand is a stratified mixture with a planted pine overstory and a natural regenerated oak lower stratum (understory). The experiment design is a Latin square of order three with the following treatments: heavy thinning from below (40% of basal area is removed), moderate thinning from below (25% of basal area is removed) and control or unthinned. The thinning was applied during the winter 2009-10. The position of all trees larger than 7.5 cm of diameter per plot was recorded. Diameter of all trees and heights of a sample were measured before the thinning. In each plot dendrometer bands were installed in 10 trees per species in order to study the effect of treatments on individual tree growth. Dedrometer bands were read every month to detect possible differences in growth pattern between treatments. These data were complemented with continued records registered with electronic dendrometer installed in one tree per species and treatment. Climatic variables and soil temperature and humidity were recorded with a weather station and soil sensors set up in the study site. Data from the first growing season after the thinning treatment (spring of 2010) will be presented in this work. The possible differences in total growth and in growth pattern between species and treatments will be analysed and discussed

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)

Modelización de sistemas ecológicos mediante redes neuronales

Las relaciones que existen en los sistemas ecológicos son objeto de estudio por parte de investigadores de todo el mundo. Los ecólogos han utilizado tradicionalmente en dichos estudios las relaciones lineales y las no lineales. En algunas ocasiones las relaciones no lineales no son obvias y presentan una gran dificultad a la hora de la modelización, dando lugar a complejos modelos cuya precisión no es siempre la deseada. En los últimos años, la inteligencia artificial se ha convertido en una técnica que permite tanto la gestión de grandes bases de datos como la utilización de algoritmos que, aunque complejos en su estructura, arrojan resultados fácilmente interpretables. El trabajo que sepresenta ofrece, por una parte, una introducción a la teoría de las redes neuronales y, por otra, la aplicación de las mismas en la modelización ecológica

Forest management and carbon sequestration in the Mediterranean region: A review

Aim of the study: To review and acknowledge the value of carbon sequestration by forest management in the Mediterranean area.Material and methods: We review the main effects of forest management by comparing the effects of silvicultural systems (even-aged vs. uneven-aged stands, coppice systems, agroforestry systems), silvicultural options (thinning, rotation period, species composition), afforestation, harvesting, fire impact or effects of shrub layer on carbon sequestration in the Mediterranean area.Main results: We illustrate as forest management can clearly improve forest carbon sequestration amounts. We conclude that forest management is an effective way to maintain and enhance high carbon sequestration rates in order to cope with climate change and provision of ecosystem services. We also think that although much effort has been put into this topic research, there are still certain gaps that must be dealt with to increase our scientific knowledge and in turn transfer this knowledge to forest practitioners in order to achieve sustainable management aimed at mitigating climate change.Research highlights: It is important to underline the importance of forests in the carbon cycle as this role can be enhanced by forest managers through sustainable forest management. The effects of different management options or disturbances can be critical as regards mitigating climate change. Understanding the effects of forest management is even more important in the Mediterranean area, given that the current high climatic variability together with historical human exploitation and disturbance events make this area more vulnerable to the effects of climate chang

EuMIXFOR Introduction: integrating scientific knowledge in sustainable management of mixed forests

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Maximum stand density strongly depends on species-specific wood stability, shade and drought tolerance

The abundance of stems in crowded populations and the subsequent self-thinning is a key issue in forest stand dynamics. However, the mechanisms that control self-thinning are challenging to model. Although some attempts to include climate and structural traits like specific gravity (SG) are promising, they remain confined to North American species. In this study we aimed to disentangle how SG along with two major abiotic stress tolerances, i.e. shade and drought tolerance, contribute to the maximum density of a forest stand across a climatic gradient in Europe, and thus test the validity of the species-specific trait control over stand density. We propose a modelling approach that incorporates the tolerance to drought and shade in the determination of maximum relative stocking. Here, relative stocking refers to the degree of tree crowding in forest ecosystems. A relative stocking base model where specific wood density is inversely related to stand density is modified, adding normalized indices of drought and shade stress tolerance. We used available species tolerance rankings modulated by stress intensity to analyse the effects of abiotic stress polytolerance or trade-offs in the study area which represent an environmental gradient from Alpine to Mediterranean climate in northern Spain. Results indicated that the role of drought tolerance in controlling maximum stand density is stronger in warmer sites. The simultaneous tolerance to shade and drought results in less carrying capacity of sites. In those sites where there is no water limitation but minimum temperature is very low the tolerance to bending stress (i.e. specific gravity) explains better the maximum tree occupancy.The Spanish Minister of Economy and Competitiveness (grant number: AGL2014–51964-C2–2-R); the New Hampshire Agricultural Experiment Station (Scientific Contribution Number 2768); the USDA National Institute of Food and Agriculture McIntire-Stennis (Project Accession Number 1007007); and Short Term Scientific Mission provided by COST Action EuMIXFOR (COST Action number FP1206) to A.B.-O.Peer Reviewe

Modeling dominant height growth including site attributes in the GADA approach for Quercus faginea Lam. in Spain

Aim of the study: To develop a site index model for Quercus faginea Lam. stands.Area of study: SpainMaterial and Methods: Data from 81 growth series collected in plots where Q. faginea was the main species were used for modelling. Different generalized algebraic difference equations (GADA) were fitted from traditionally used models. Richards model was selected and used to expand the parameters with environmental variables.Research highlights: Winter rainfall (WR), annual potential evapotranspiration (PET) and pH were introduced increasing the prediction ability of the GADA. It is strongly recommended to apply the model with ages lower than 80 years because the lack of data above that age makes bias increase and efficiency decrease.Keywords: Site index; Lusitanian oak; environmental variables