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- Forest owner motivations and attitudes towards supplying biomass for energy in EuropePublication . Blennow, Kristina; Persson, Erik; Lindner, Marcus; Faias, Sónia; Hanewinkel, MarcThe 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 e 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 fromforests in the European Union. For Ecol Manag 2011;261: 2007e2015, UNECE and FAO. The European forest sector outlook study II
- Relação hipsométrica geral para Eucalyptus globulus Labill. em PortugalPublication . Tomé, Margarida; Ribeiro, Fernanda; Faias, SóniaTree height is an important variable for determining the tree volume and the stand volume. Sometimes tree height is not measured in the field, and for predicting it an equation is used as a function of tree diameter and other stand variables. The existing equations that express hypsometric relationships have some limitations at the application level. In this work, a general equation has been developed with data that represent all the area of eucalyptus plantations in Portugal.
- Resource communication. sIMfLOR - platform for portuguese forest simulatorsPublication . Faias, Sónia; Palma, J.H.N.; Barreiro, S.; Tomé, MargaridaAbstract 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.
- Ajustamento simultâneo de equações de biomassa de pinheiro manso no sul de PortugalPublication . Correia, A.; Tomé, Margarida; Faias, Sónia; Freire, João; Carvalho, P.O.We present a system of alometric biomass equations for aboveground compartments for Pinus pinea L. that allows biomass estimation with information from conventional forest inventories. We harvested 40 trees located in south of Portugal and separated and weighed all the aboveground components: needles, stem bark, branches and stem. The equations were simultaneously fitted using seemingly unrelated regression. This method allows the compatibility of the partial allometric equations with the equation for total biomass aboveground that corresponds to the sum of those 4 equations. The models were better for stem (R2adj.=0.85) and bark (R2adj.=0.83) and worst for branches (R2adj.=0.79) and needles(R2adj.=0.71). Crown biomass was always high compared with aboveground biomass, independently on stand characteristics. However it may be exacerbated by artificial pruning that is carried out to increase crown expansion for pine nut production. The different stand management circumstances from where trees harvested were selected may explain the worst fitting for crown components.
- Estimation of stand crown cover using a generalized crown diameter model: application for the analysis of portuguese cork oak stands stocking evolutionPublication . Paulo, Joana Amaral; Faias, Sónia; Ventura-Giroux, Célia; Tomé, MargaridaA generalized non-linear tree crown diameter model was developed with the aim of allowing the computation of tree crown diameter over a large range of tree dimensions, and allowing its inclusion in forest growth and yield models. The model was formulated to provide biological meaning to the predicted values. Due to the nested structure of the data analyzed (trees within stands), both mixed- and fixed-effect models were developed. Since tree crown diameter is not frequently measured in forest inventories, the validation of the mixed model was carried out by considering the population specific response. The results demonstrate that when the measurements required for the mixed model calibration are not available, the use of the fixed effect model results in less biased and more accurate estimates. The fixed model was applied to the data from the two last Portuguese National Forest Inventories (NFI) to analyze the change in stand crown cover and assess the stocking evolution of cork oak stands in Portugal between 1996 and 2006. Results showed an increase in the frequency of stands with crown cover lower than 20%, as well as a decrease in the frequency of stands with crown cover between 20 and 40%. Average crown cover values were significantly different in the two NFI, with a decrease from 28.0 to 26.5% over the considered period
- Biomass allometry and carbon factors for a Mediterranean pine (Pinus pinea L.) in PortugalPublication . Correia, A.A.; Tomé, Margarida; Pacheco, C.A.; Faias, Sónia; Dias, A.C.; Freire, J.; Carvalho, P.O.; Pereira, J.S.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.
- Predicting site index from climate and soil variables for cork oak (Quercus suber L.) stands in PortugalPublication . Paulo, Joana Amaral; Palma, J.H.N.; Gomes, Alberto Azevedo; Faias, Sónia; Tomé, José; Tomé, MargaridaSite 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
- Forest models dissemination and knowledge transfer on cork oak based ecosystems: bridging the gap between research and practicePublication . Paulo, Joana Amaral; Faias, Sónia; Palma, J.H.N.; Tomé, Margarida
- Understory effect on tree and cork growth in cork oak woodlandsPublication . Faias, Sónia; Paulo, Joana Amaral; Palma, J.H.N.; Tomé, MargaridaAim 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
- Intra-annual tree diameter increment and seasonal leaves nutrients in cork oak species under three understory management alternativesPublication . Faias, Sónia; Firmino, Paulo Neves; Tomé, Margarida; Moreno, Gerardo; Paulo, Joana AmaralAn experimental trial implemented on a pure unevenaged cork oak stand, in Podzol soil, with the specific goal of comparing understory management alternatives, was monitored between 2003 and 2015. The stand understory layer is composed by spontaneous vegetation dominated by Cistus salvifolius, Lavandulla peduncalata and Ulex airensis. Cork samples from two distinct cork rotation cycles (2003 to 2012 or 2006 to 2015), taken at the beginning and end of the debarking period, were analyzed regarding cork ring width (Faias et al. 2018, Faias et al. 2019). Results suggest a different effect on cork annual growth depending on whether the operations are performed at the middle or at the beginning of the cork rotation cycle. Under the CorkNeighbors research project, this trial was continuously monitored and analyzed between 2016 and 2019 (Faias 2019).