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The annual growth and the thickness of cork are known to be highly variable between trees located in the same geographical location. Researching how climate variables affect different trees within the same site is a step forward for the management of cork production since current knowledge focusses only on the average tree response. Quantile regression methodology was applied for the first time to a large data set containing measurements of cork growth, sampled in 35 stands across the cork oak distribution area in Portugal. This methodology proved to be useful for testing the hypothesis raised: does climate affect differently the annual cork growth, and ultimately cork thickness of individual trees located in the same stand? Estimating the amount of cork produced by one stand that has the required thickness for the production of natural cork stoppers is essential to support cork oak management. However, no model, before this work, had been developed to provide managers with this information. A downward parabolic relationship between annual cork growth and annual precipitation was determined for all quantiles, with optimum annual average precipitation value ranging from 1103 to 1007 mm. April to August monthly temperatures, spring average temperature or summer average temperature, showed a negative relationship with annual cork growth, in particular for lower quantiles. Maximum annual temperature was shown to negatively affect annual cork thickness, in particular for the trees under the 6th quantile. The ratio between annual precipitation and average temperature, that define the Lang index (LI), showed a downward parabolic relationship with annual cork growth. Best cork growth conditions are found for Lang index values around 60, corresponding for the transition between semi-arid climate and humid climate. The application of the final model developed for estimating cork thickness of an eight years’ cork growth period allowed the prediction and mapping of the percentage of cork suitable for natural cork stopper production. It showed that higher values are expected in the Southern and Central coastal regions and along the Tagus River basin. The Northern coastal and mountain regions, characterised by Lang index values higher to 60 (humid climates), present lower estimated values for the percentage of cork suitable for natural cork stopper production. The estimated values are expected to be reduced under climate change scenarios in the Southern and Central coastal regions.

Scheduling the first thinning in young cork oak stands is an important decision in management that is usually subjectively defined by each manager. An analysis of competition in cork oak plantations is extremely relevant as a support for this important decision. This study aimed to understand the relationship between stand characteristics and tree growth efficiency, and subsequently help identify the presence or absence of an inter-tree competition pattern in cork oak stands that were never debarked. The inter-tree competition was assessed by looking to several stand characteristics: (1) comparison with the self-thinning line; (2) stand density measures, such as stand spacing coefficient and relative spacing; (3) stand structure measures evaluated through the skewness and variability; and (4) tree relative growth rate pattern over tree size. Data used for this analysis were gathered from permanent plots that were established in even-aged stands located across the cork oak distribution area in Portugal. The study shows that the most common stand densities on young cork oak plantations might not lead to serious inter-tree competition before the first cork extraction. This information is relevant to support the potential timing and severity of the first thinning in order to retain more trees until the second cork extraction when cork quality can be taken into account in the selection of the trees to be removed.

Purpose The aim of the present study is to assess the influence of two different attributional life cycle assessment (LCA) approaches, namely static LCA (sLCA) and dynamic LCA (dLCA), through their application to the calculation of the carbon footprint (CF) of the entire cork sector in Portugal. The effect of including biogenic carbon sequestration and emissions is considered as well. Methods sLCA is often described as a static tool since all the emissions are accounted for as if occurring at the same time which may not be the case in reality for greenhouse gases. In contrast, dLCA aims to evaluate the impact of life cycle greenhouse gas emissions on radiative forcing considering the specific moment when these emissions occur. Results and discussion The results show that the total CF of the cork sector differs depending on the approach and time horizon chosen. However, the greater it is the time horizon chosen, the smaller the difference between the CF results of the two approaches. Additionally, the inclusion of biogenic carbon sequestration and emissions also influences significantly the CF result. The cork sector is considered a net carbon source when biogenic carbon is excluded from the calculations and a net carbon sink when biogenic carbon is included in the calculations since more carbon is sequestered than emitted along the sector. Conclusions dLCA allows an overview of greenhouse gas emissions along the time. This is an advantage as it allows to identify and plan different management approaches for the cork sector. Even though dLCA is a more realistic approach, it is a more time-consuming and complex approach for long life cycles. The choice of time horizon was found to be another important aspect for CF assessment. published

Understory management practices and stand density characteristics allow one to distinguish a cork oak traditional silvopastoral system (known as a montado) from a cork oak forest system. Although understanding the manner in which different management practices affect cork growth is imperative, there are still only a few outputs from experimental research that contribute to this knowledge. The effect of potential drivers on annual cork growth was analyzed using a linear mixed model approach. Two dimensions of drivers were considered: intraspecific competition, assessed by tree level distance-dependent indices, and interspecific competition, assessed by variables characterizing understory management. The present dataset was collected from an experimental trial established on a cork oak stand in Podzolic soil on the Tagus river basin, covering two different cork growth cycles over the period from 2003 to 2015. The adjusted models considered two understory management alternatives: spontaneous shrubs maintenance and forage application. In both models, annual precipitation displayed a positive effect on annual cork growth, as expected. However, no significant effect of intraspecific competition was found. Additionally, there was a positive effect on annual cork growth associated with the spontaneous shrubs growth and a negative effect associated with lupine presence, both effects linked to different cork ring ages&rsquo, thresholds. The study main contributions are the following: (i) the introduction of the interaction between cork growth cycle stage and understory management practices, only possible with cork sample collections from different cork rotation cycles, (ii) the finding that there was no significant effect of intraspecific competition on cork growth.

Research Article Aim of study: Cork oak is one of the main forest tree species in Portugal that typically occurs in montado, where operational practices oriented to the tree, crop or animal management may influence several of the ecosystem components. This study aimed at contributing to fulfil the a lack of knowledge on the effect of these practices on the cork and wood growth, by comparing the wood diameter growth and the annual cork increment under two different understory management options. Material and methods: An experimental trial implemented on an uneven-aged cork oak pure stand during a cork rotation period of 9 years, was established with the specific goal of comparing understory management options: a yellow lupine pasture versus spontaneous vegetation. Cork samples were taken at the beginning and end of the period and were used to measure cork thickness and annual cork rings. The differences between treatments were assessed performing a non-parametric test and a more robust approach using linear mixed model. Precipitation and treatment levels were jointly considered on the analysis. Main results: A slight effect was found on the cork thickness regarding the treatment with lupine application. However, no distinct effect was found, regarding wood and the annual cork increment pattern. Additionally, annual cork ring width showed a positive correlation with precipitation and a negative correlation with ring age. Research highlights: The results of this study indicate no distinct pattern regarding the annual cork and wood increment when comparing the understory effect of yellow lupine pasture versus spontaneous vegetation info:eu-repo/semantics/publishedVersion

Cork oak stands are one of the major sources of income from Portuguese Mediterranean forests. Future climate is projected to increase temperatures, reduce precipitation and decrease current forests’ productivity and therefore, adapting management, is a key strategy to mitigate impacts of future climate on cork supply. The central objective of this research was to compare conventional and adaptive management regimes under scenarios of climate change. The adaptive management focussed on adopting optimal harvest schedules while considering different management objectives. The study focused on the Chamusca region, one of the most productive areas of cork, and considered four distinct spatial scales for analysis. For each scale, the management objective was defined according to field information and considered the maximization of cork production while targeting different cork harvesting flows: (a) more frequent and regular or (b) less frequent and concentrated. A forest growth model was used to simulate climate change impact on future yield of cork oak stands under different forest management alternatives. A mixed integer programming model was developed to find the most adequate cork debarking cycle calendar for cork oak stands. Our results suggest that (1) business as usual management under climate change scenarios could decrease cork supply and carbon stock in the tree component of the forests by up to 20 and 30 %, respectively, (2) the development of adaptive management strategies, including cork extraction schedule optimization, to address climate change has advantages over traditional practices and (3) may contribute further to increase cork production (up to double productivity in mid-long term) while addressing concerns with the regulation of cork extraction flows through the adaptation of debarking periods. The mixed integer programming allowed the spatial visualization of the debarking cycle delay. Furthermore, results underline the relevance of an approach to develop adaptive management strategies that can consider different management goals, with different constraints to address climate change.

The European Commission expects the use of biomass for energy in the EU to increase significantly between 2010 and 2020 to meet a legally binding target to cover at least 20% of EU's total energy use from renewable sources in 2020. According to estimates made by the member states of the EU, the direct supply of biomass from forests is expected to increase by 45% on a volume basis between 2006 and 2020 in response to increasing demand (Beurskens LWM, Hekkenberg M, Vethman P. Renewable energy projections as published in the national renewable energy action plans of the European Member states. ECN and EEA; 2011. http://https://www.ecn.nl/docs/library/report/2010/e10069.pdf [accessed 25.04.2014]; Dees M, Yousef A, Ermert J. Analysis of the quantitative tables of the national renewable energy action plans prepared by the 27 European Union Member States in 2010. BEE working paper D7.2. Biomass Energy Europe project. FELIS Department of Remote Sensing and landscape information Systems, University of Freiburg, Germany; 2011). Our aims were to test the hypotheses that European private forest owners' attitudes towards supplying woody biomass for energy (1) can be explained by their responses to changes in prices and markets and (2) are positive so that the forest biomass share of the EU 2020 renewable energy target can be met. Based on survey data collected in 2010 from 800 private forest owners in Sweden, Germany and Portugal our results show that the respondents' attitudes towards supplying woody biomass for energy cannot be explained as direct responses to changes in prices and markets. Our results, furthermore, imply that European private forest owners cannot be expected to supply the requested amounts of woody biomass for energy to meet the forest biomass share of the EU 2020 renewable energy target, at least if stemwood is to play the important role as studies by Verkerk PJ, Anttila P, Eggers J, Lindner M, Asikainen A. The realisable potential supply of woody biomass from forests in the European Union. For Ecol Manag 2011;261: 2007-2015, UNECE and FAO. The European forest sector outlook study,II 2010-2030. United Nations, New York and Geneva; 2011 [abbreviated to EFSOS II] and Elbersen B, Staritsky I, Hengeveld G, Schelhaas MJ, Naeff H, Bottcher H. Atlas of EU biomass potentials; 2012. Available from: http://www.biomassfutures.eu [accessed 14.10.2013] suggest. (C) 2014 Elsevier Ltd. All rights reserved.

Recent studies projecting future climate change impacts on forests mainly consider either the effects of climate change on productivity or on disturbances. However, productivity and disturbances are intrinsically linked because 1) disturbances directly affect forest productivity (e.g. via a reduction in leaf area, growing stock or resource-use efficiency), and 2) disturbance susceptibility is often coupled to a certain development phase of the forest with productivity determining the time a forest is in this specific phase of susceptibility. The objective of this paper is to provide an overview of forest productivity changes in different forest regions in Europe under climate change, and partition these changes into effects induced by climate change alone and by climate change and disturbances. We present projections of climate change impacts on forest productivity from state-of-the-art forest models that dynamically simulate forest productivity and the effects of the main European disturbance agents (fire, storm, insects), driven by the same climate scenario in seven forest case studies along a large climatic gradient throughout Europe. Our study shows that, in most cases, including disturbances in the simulations exaggerate ongoing productivity declines or cancel out productivity gains in response to climate change. In fewer cases, disturbances also increase productivity or buffer climate-change induced productivity losses, e.g. because low severity fires can alleviate resource competition and increase fertilization. Even though our results cannot simply be extrapolated to other types of forests and disturbances, we argue that it is necessary to interpret climate change-induced productivity and disturbance changes jointly to capture the full range of climate change impacts on forests and to plan adaptation measures., published version, peerReviewed

Site productivity, assessed through site index, was modelled using partial least squares regression as a function of soil and climatic variables. Two alternative models were developed: a full model, considering all available explanatory variables, and a reduced model, considering only variables that can be obtained without digging a soil pit. The reduced model was used for mapping the site index distribution in Portugal, on the basis of existing digital cartography available for the whole country. The developed models indicate the importance of water availability and soil water holding capacity for site index value distribution. Site index was related to climate, namely evaporation and frost, and soil characteristics such as lithology, soil texture, soil depth, thickness of the A horizon and soil classification. The variability of the estimated values within the map (9.5–16.8 m with an average value of 13.4 m) reflects the impact of soil characteristics on the site productivity estimation. These variables should be taken into consideration during the establishment of new plantations of cork oak, and management of existing plantations. Results confirm the potential distribution of cork oak in coastal regions. They also suggest the existence of a considerable area, located both North and South of the Tagus river, where site indices values of medium (]13;15]) to high (]15;17]) productivity classes may be expected. The species is then expected to be able to have good productivity along the northern coastal areas of Portugal, where presently it is not a common species but where, according to historical records, it occurred until the middle of the sixteenth century. The present research focused on tree growth. Cork growth and cork quality distribution needs to be further researched through the establishment of long term experimental sites along the distribution area of cork oak, namely in the central and northern coastal areas of the country info:eu-repo/semantics/publishedVersion

High spatial resolution imagery provided by unmanned aerial vehicles (UAVs) can yield accurate and efficient estimation of tree dimensions and canopy structural variables at the local scale. We flew a low-cost, lightweight UAV over an experimental Pinus pinea L. plantation (290 trees distributed over 16 ha with different fertirrigation treatments) to determine the tree positions and to estimate individual tree height (h), diameter (d), biomass (wa), as well as changes in these variables between 2015 and 2017. We used Structure from Motion (SfM) and 3D point cloud filtering techniques to generate the canopy height model and object-based image analysis to delineate individual tree crowns (ITC). ITC results were validated using accurate field measurements over a subsample of 50 trees. Comparison between SfM-derived and field-measured h yielded an R2 value of 0.96. Regressions using SfM-derived variables as explanatory variables described 79% and 86–87% of the variability in d and wa, respectively. The height and biomass growth estimates across the entire study area for the period 2015–2017 were 0.45 m ± 0.12 m and 198.7 ± 93.9 kg, respectively. Significant differences (t-test) in height and biomass were observed at the end of the study period. The findings indicate that the proposed method could be used to derive individual-tree variables and to detect spatio-temporal changes, highlighting the potential role of UAV-derived imagery as a forest management tool We thank the Portuguese Science Foundation (SFRH/BD/52408/2013) for funding the research activities of Juan Guerra and the Galician Government and European Social Fund (Official Journal of Galicia—DOG No. 52, 17/03/2014 p. 11343, exp: POS-A/2013/049) for funding the postdoctoral research stays of Eduardo González-Ferreiro. This research was supported by SuFoRun project “Models and decision Support tools for integrated Forest policy development under global change and associated Risk and Uncertaint” funded by the European Union’s H2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 691149. The research was carried out in the Centro de Estudos Florestais: a research unit funded by Fundação para a Ciência e a Tecnologia (Portugal) within UID/AGR/00239/2013 SI

Forests play an important role in the global carbon balance because they offset a large portion of the carbon dioxide emitted through human activities. Accurate estimates are necessary for national reporting of greenhouse gas inventories, carbon credit trading and forest carbon management but in Portugal reliable and accessible forest carbon measurement methodologies are still lacking for some species. The objective of this study was to provide forest managers with a comprehensive database of carbon factors and equations that allows estimating stand-level carbon stocks in Pinus pinea L. (P. pinea), regardless of the tree inventory information available. We produced aboveground biomass and stem volume equations, biomass expansion factors (BEF) by component as well as wood basic density (WBD) and component carbon fraction in biomass. A root-to-shoot ratio is also presented using data from trees in which the root system was completely excavated. We harvested 53 trees in centre and south Portugal covering different sizes (6.5 to 56.3 cm), ages (10 to 45 years) and stand densities (20 to 580 trees ha-1). The results indicate that aboveground allometry in P. pinea is not comparable with other pines and varies considerably with stand characteristics, highlighting the need to develop stand-dependent factors and equations for local or regional carbon calculations. BEFaboveground decreases from open (1.33±0.03 Mg m-3) to closed stands (1.07±0.01 Mg m-3) due to a change in biomass allocation pattern from stem to branches. Average WBD was 0.50±0.01 Mg m-3 but varies with tree dimensions and the root-to-shoot ratio found was 0.30±0.03. The carbon fraction was statistically different from the commonly used 0.5 factor for some biomass components. The equations and factors produced allow evaluating carbon stocks in P. pinea stands in Portugal, contributing to a more accurate estimation of carbon sequestered by this forest type., Los bosques juegan un papel importante en el balance global del carbono porque desplazan una gran porción del dióxido de carbono emitidos por actividades humanas. Se necesitan estimaciones precisas para los informes nacionales de los inventarios de los gases de efecto invernadero, mercados de créditos de carbono, y manejo de carbono en los bosques. Pero en Portugal todavía faltan, para algunas especies, metodologías de mediciones fiables y accesibles de carbono en los bosques. El objetivo de este estudio es proporcionar a los gestores forestales una base de datos completa de los factores y ecuaciones del carbono que permitan estimar los stocks de carbono a nivel de rodal, en Pinus pinea, independientemente de la información disponible de los inventarios de árbol. Producimos ecuaciones de biomasa del matorral, y del volumen del troco, factores de expansión de biomasas (BEF) por componente así como densidad básica de la madera (WBD) y fracción de los componentes de carbono en la biomasa. Un ratio raíz-tallo se presenta también utilizando datos de los arboles en los que los sistemas radicales se extrajeron completamente. Se cosecharon 53 árboles en el centro y sur de Portugal, cubriendo tamaños diferentes (6,5 a 56,3 cm), edades (10 a 45 años), y densidad del rodal (20 a 580 árboles ha–1). Los resultados indican que la alometria del sistema radical en P. pinea no es comparable con otros pinos y varía considerablemente con las características del rodal destacando la necesidad de desarrollar factores dependientes del rodal y ecuaciones para cálculos de carbono a nivel local o regional. BEFradical disminuye de rodales abiertos (1,33 ± 0,03 Mg m–3) a cerrados (1,07 ± 0,01 Mg m–3) debido a cambios en la asignación de biomasa de tronco a ramas. La media de WBD es 0,50 ± 0,01 Mg m–3 pero varía con la dimensión de los árboles y el ratio de raíz a tallo se encuentra entre 0,30 ± 0,03. La fracción de carbono fue estadísticamente diferente del factor comúnmente utilizado de 0,5 de algunos componentes de biomasa. Las ecuaciones y los factores producidos permiten la evaluación de los stocks de carbono en rodales de P. pinea en Portugal, contribuyendo a una información más precisa del carbono secuestrado por este tipo de bosque.

In the last decades there has been an increasing number of forest models developed for the main species of the Portuguese forest. Forest models support management decisions by predicting long term stand development under alternative scenarios and taking into account all the components of the ecosystem. However, in most cases, there is a gap between the models developed and their application by decision-makers. The platform for Portuguese Forest Simulators (sIMfLOR) tries to overcome this gap integrating a wide variety of forest models into simulators and providing a baseline tool for forest managers in Portugal. As an integrated modular platform, sIMfLOR makes available forest simulators for the Portuguese forest with user-friendly interfaces to facilitate the introduction of the information for the simulators. The platform displays stand and regional simulators, interfaces to generate required inputs and also auxiliary tools. As the platform focus on end-users, it allows visualization of the simulators outputs in default graphics which can easily be edited by users. The sIMfLOR platform can be permanently accessed at http://www.isa.utl.pt/cef/forchange/fctools.