Browsing by Author "Lopes, Domingos"
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- Aboveground production and c flux in three chestnut high forest stands in Northern PortugalPublication . Patrício, Maria Sameiro; Fernandes, Maria José; Pereira, Ermelinda; Lopes, DomingosLitterfall in three high forest chestnut stands in Marão, Padrela and Bornes (Northern Portugal), of 71, 64 and 53 years old, respectively, located on different soil types, was collected in the autumn of 2008. Circular littertraps which cover a surface area of 1 m2 each were installed in these chestnut stands. The litterfall was separated into leaves, branches, fruits and burs. All litter fractions were dried to constant weight at 70°C. The total amount of litter in the three stands was 4.2, 4.6 and 4.0 Mg DM ha-1 y-1 in Marão, Padrela and Bornes sites, respectively. Leaves are the main constituents of the total biomass return by litterfall contributing to 79.4% in Marão, 69.8% in Padrela and 78% in Bornes. The corresponding amounts of other litter fractions in these three locations were respectively: fruits 6.4%, 12.4% and 8.9%; branches 6.4%, 4.0% and 4.7%; burs 7.8%, 13.8% and 8.3%. C amount falling with litterfall was similar in the three stands, close to 2.3 Mg C ha-1 y-1. The aboveground net primary production ANPP was evaluated.
- Assessment of biomass and carbon litterfall in three chestnut high forest stands in Northern PortugalPublication . Patrício, Maria Sameiro; Fernandes, Maria José; Pereira, Ermelinda; Lopes, DomingosLitterfall in three high forest chestnut stands, located in different soil types, of 53, 71 and 64 years old, in Marão, Padrela and Bornes, respectively (northern Portugal), was collected last Autumn. Circular litter traps which cover a surface area of 1 m2 each were installed in these chestnut stands. The litterfall was separated into leaves, branches, fruits and burs. All litter fractions were dried to constant weight at 70ºC. The total amount of litter in the three stands was 4.2, 4.6 and 4.0 Mg ha-1 year-1 in Marão, Padrela and Bornes, respectively. Leaves are the main constituents of the total biomass return by litterfall contributing to 79.4% in Marão, 69.8% in Padrela and 78% in Bornes. The corresponding amounts of other litter fractions in these three locations were respectively: Fruits 6.4%, 12.4% and 8.9%; Branches 6.4%, 4.0% and 4.7%; Burs 7.8%, 13.8% and 8.3%. Carbon in the litterfall was similar in the three stands, about 2.3 Mg ha-1 year-1. This methodology will be continued during the present year. The net primary productivity PPN based on methodology proposed by Gower et. al (1997) will be evaluated. Parallel to this study we intend to analyse the progressive nutrient returned to the forest soil to evaluate the sustainability of the chestnut ecosystems.
- Assessment of biomass and carbon litterfall in three chestnut high forest stands in Northern PortugalPublication . Patrício, Maria Sameiro; Fernandes, Maria José; Pereira, Ermelinda; Lopes, DomingosLitterfall in three high forest chestnut stands, located in different soil types, of 53, 71 and 64 years old, in Marão, Padrela and Bornes, respectively (northern Portugal), was collected last Autumn. Circular litter traps which cover a surface area of 1 m2 each were installed in these chestnut stands. The litterfall was separated into leaves, branches, fruits and burs. All litter fractions were dried to constant weight at 70ºC. The total amount of litter in the three stands was 4.2, 4.6 and 4.0 Mg ha-1 year-1 in Marão, Padrela and Bornes, respectively. Leaves are the main constituents of the total biomass return by litterfall contributing to 79.4% in Marão, 69.8% in Padrela and 78% in Bornes. The corresponding amounts of other litter fractions in these three locations were respectively: Fruits 6.4%, 12.4% and 8.9%; Branches 6.4%, 4.0% and 4.7%; Burs 7.8%, 13.8% and 8.3%. Carbon in the litterfall was similar in the three stands, about 2.3 Mg ha-1 year-1. This methodology will be continued during the present year. The net primary productivity PPN based on methodology proposed by Gower et. al (1997) will be evaluated. Parallel to this study we intend to analyse the progressive nutrient returned to the forest soil to evaluate the sustainability of the chestnut ecosystems.
- Avaliação da capacidade de fixação de carbono em povoamentos mistos no Norte de PortugalPublication . Lopes, Domingos; Nunes, Leónia; Godinho, Paulo; Bento, João Manuel; Patrício, Maria Sameiro; Gonçalves, Ana Cristina; Oliveira, Ângelo; Monteiro, Maria do Loreto; Luís, Jaime F. Sales; Rego, FranciscoNo âmbito do projecto PTDC/AGR-CFL/68186/2006 da FCT, e com base em 45 parcelas de amostragem do Inventário Florestal Nacional de 2006 (19 de Pinus, 17 de Quercus e 10 de mistos de Quercus com Pinus), distribuidas por vários concelhos do distrito de Vila Real procedeu-se à quantificação da produção primária líquida (PPL. Para além da quantificação da produtividade total desses ecossistemas houve o cuidado de proceder à partição desta produtividade pelas diferentes componentes do ecossistema (árbórea,arbustiva e folhada/ outros resíduos). Esta informação pode e é fundamental para os gestores destes espaços e para uma mais completa compreensão destes ecossistemas. A quantificação da PPL permitiu à posteriori avaliar dinâmicas de fixação de carbono fundamentais para a compreensão das potencialidades destes ecossistemas numa óptica do protocolo de Quioto e num contexto de alterações climáticas. Numa segunda etapa pretende-se proceder e identificar variáveis que condicionam a fixação de carbono destes ecossistemas no sentido de apontar pistas para uma gestão que potencie a fixação de carbono destes ecossistemas.
- Avaliação da produção primária líquida em povoamentos puros e mistos de Quercus pyrenaica Willd. e Pinus pinaster L. no Distrito de Vila RealPublication . Nunes, Leónia; Magalhães, Marco; Patrício, Maria Sameiro; Luís, Jaime F. Sales; Rego, Francisco; Lopes, DomingosCom este trabalho procurou-se quantificar a Produção Primária Líquida (PPL) de povoamentos puros e mistos de Pinus pinaster e de Quercus pyrenaica. A quantificação baseou-se em parcelas de amostragem do último Inventário Florestal Nacional (IFN) localizadas exclusivamente no Distrito de Vila Real. Deste trabalho resultou, pela primeira vez, a avaliação de valores de PPL, logo a possibilidade de quantificar a capacidade que estes ecossistemas têm em fixar carbono. Procedeu-se à comparação entre a performance dos povoamentos puros e mistos. Os resultados obtidos apontam para uma maior potencialidade produtiva dos povoamentos mistos, comparativamente aos povoamentos puros, ainda que não estatisticamente significativa.
- Contributo da Robinia pseudoacacia para a valorização de espécies folhosas produtoras de madeira de qualidade: um caso de estudoPublication . Patrício, Maria Sameiro; Nunes, Luís; Monteiro, Maria do Loreto; Lopes, DomingosEm 1998, no âmbito do projecto PRAXIS XXI – 3/3.2/Flor/2127/95, foi estabelecido um ensaio de consociação de folhosas nobres: cerejeira, carvalho e castanheiro com a espécie acessória, robínia, numa série substitutiva, em Vimioso (Latitude 41º34'12''N; Longitude 6º30'7''W e altitude 700 m), antes da publicação do Decreto-Lei 565/99. O ensaio foi delineado em 30 parcelas de estudo permanentes estruturadas num desenho experimental aleatorizado com dez tratamentos e três repetições, sendo testados dois tipos de mistura (espécie objectivo alternada linha a linha com robínia e espécie objectivo alternada pé a pé com robínia). O objectivo deste estudo é avaliar os ganhos das espécies principais em mistura com uma fixadora de azoto. O teste da máxima verosimilhança demonstrou, para a cerejeira, uma elevada probabilidade de sobrevivência (77-80%). As restantes espécies estão associadas a baixa probabilidade de sobreviver devido, principalmente, ao insucesso verificado na fase de instalação (sobrevivência 46–55%). Comparou-se o crescimento para cada espécie, entre os diferentes tratamentos, usando o teste das diferenças mínimas significativas (LSD). O efeito da facilitação proporcionado pela espécie acessória é visível no caso da cerejeira. Para o castanheiro e para o carvalho verifica-se um efeito depressivo da robínia na mistura pé a pé sobre a espécie objectivo não sendo evidente o processo de facilitação.
- Growth dynamics and productivity of pure and mixed Castanea Sativa Mill. and Pseudotsuga menziesii (Mirb.) Franco plantations in Northern PortugalPublication . Nunes, Leónia; Gower, Stith T.; Monteiro, Maria do Loreto; Lopes, Domingos; Rego, FranciscoSince the late 1980's the productivity of monocultures vs. mixed-species forests has been the subject of studies by forest managers and ecologists. Mixed plantations have been established in different proportions to determine if mixtures could provide greater yields and more benefits than monocultures of the component species, as well as to understand if they could be an interesting economic option. An experimental design trial was set up in the north of Portugal in a replacement series with pure and mixed Castanea sativa Mill. and Pseudotsuga menziesii (Mirb.) Franco. The objective of this study was to assess growth dynamics and compare the aboveground biomass and net primary production of the two species in pure and mixed treatments in proportions 1:1 and 1:3. The growth was measured at 7, 11, 15, 17, 19, 27 and 28 years after planting and aboveground net primary production was estimated at age 28. As a component of the mixed treatments, P. menziesii exhibited greater height, diameter and aboveground biomass than C. sativa. Relative yield total indicated a higher productivity in the mixtures compared with the pure treatments. Early in the development, pure treatments and mixtures had similar aboveground biomass per hectare, but later the mixtures showed higher yield than pure treatments. The mixture productivity increase through time appears to be the result of both canopy stratification and better use of site resources. The aboveground net primary production was also higher in mixed than in the pure treatments.
- Growth, soil properties and foliage chemical analysis comparison between pure and mixed stands of Castanea sativa Mill. and Pseudotsuga menziesii (Mirb.) Franco, in Northern PortugalPublication . Nunes, Leónia; Coutinho, João; Nunes, Luís; Rego, Francisco; Lopes, DomingosEcosystems with mixed species compared to the ones with pure compositions provide a broader range of options in the fields of biodiversity, conservation, protection and restoration. Industrial plantations in Portugal are mostly monocultures with the predominance of coniferous forests, so the introduction of broadleaves could be important for the biodiversity and sustainability of Portuguese forests. This study aims to present and discuss field data from pure and mixed-species plantations of European chestnut (Castanea sativa Mill.) and douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] with different intercropping densities in a total of 5 treatments with two replicate blocks. In respect to growth, the results showed significant difference (P < 0.05, Scheffe) between treatments for survival and basal area. Diameter breast height (DBH), total and top height of the individual Castanea tree was positively affected by the presence of Pseudotsuga. In general, soil properties results showed a higher fertility for mixed treatments compared with pure ones. Statistically differences (P < 0.05, Scheffe) were observed in pH, P, Mn and in the exchangeable acidity. Results for foliar analysis in N, P, Ca and K concentrations are higher for mixed treatments. The obtained results from this study indicate that mixed plantations have a positive effect in the productivity of the Castanea.
- Mixed plantations: a silvicultural option for cherry high quality wood productionPublication . Patrício, Maria Sameiro; Nunes, Luís; Monteiro, Maria do Loreto; Lopes, DomingosSweet cherry (Prunus avium L.) is a promising species for high quality wood production. In Portugal, until the nineties the wild cherry was practically ignored in afforestations. After 1992, with the EU set-aside policies, the afforestation area with cherry was greatly increased due to the EU subventions. Actually, the oldest stands, mostly pure, are about fifteen years old and many of them are experiencing a high rate of mortality. A field trial was established in the northeast of Portugal (year 2000) to evaluate the behaviour of several broadleaves, including cherry, in mixed plantations with a fixing nitrogen species Robinea psedoacacia. This trial includes four broadleaves species with ten treatments and three replications. In this analysis we consider only the treatments were cherry is present (T2 – Pure cherry, T4 – Pure robinea, T6 – a line of cherry x a line of robinea, T9 – cherry x robinea in the line). Logistic regression was used to analyse the cherry’s survival. The analysis of maximum likelihood estimates pointed out that the cherry was associated to a high surviving probability when it was consociated with robinea, but the pure cherry treatment analysis was not conclusive (P>0.05). A HSD Tukey test was used to compare the height growth of cherry in the different treatments. It was observed that T2 did not differ from T9 concerning the height growth of cherry (P>0.05) but it differed between T2 - T6 and T6 – T9. The mean height of cherry was highest in the T6 followed by the T9. The apparent vigour of the cherry was superior when consociated with robinea, seeming that its presence directly benefits the objective species. The ecological principle of facilitation is evident at the level of the stand environment created by the robinia for the other species. The contribution of robinea for nitrogen fixation is being studied in a parallel research.
- The adjustment of global and partial dry biomass models for Pinus pinaster in the North-East of PortugalPublication . Lopes, Domingos; Almeida, Luís Roxo; Castro, João Paulo; Aranha, JoséEcosystems net primary production quantification can be done by means of allometric equations. Carbon sequestration studies also involve the quantification of growth dry biomass, knowing the carbon percentage of dry biomass. Fieldwork complexity to collect these kind of data are often limitative for obtaining these mathematical models. Allometric equations were adjusted to estimate dry biomass of individual Pinus pinaster trees, using data from 30 trees. Statisticals form the final equations have shown that biomass estimation could be made under an accuracy of around 95%. All mathematical models were calculated using diameter at breast height (dbh) as independent variable and enable to estimate biomass (in Kg) for: stem (R2adj=97.9); crown (R2adj=88.4) and roots (R2adj= 93. 5).