Encontrados 19 documentos, a visualizar página 1 de 2
A data mining approach to improve multiple regression models of soil nitrate co...
Nunes, Jorge; Madeira, Manuel; Gazarini, Luiz; Neves, José; Vicente, HenriqueThe changes in the soil nitrate concentration were studied during 2 years in a ‘‘montado’’ ecosystem, in the South of Portugal. Total rainfall, air and soil temperature and soil water content under and outside Quercus rotundifolia canopy were also evaluated. A cluster analysis was carried out using climatic and microclimatic parameters in order to maximize the intraclass similarity and minimize the interclass s...
A data mining approach to improve multiple regression models of soil nitrate co...
Nunes, Jorge; Madeira, Manuel; Gazarini, Luiz; Neves, José; Vicente, HenriqueThe changes in the soil nitrate concentration were studied during 2 years in a ‘‘montado’’ ecosystem, in the South of Portugal. Total rainfall,air and soil temperature and soil water content under and outside Quercus rotundifolia canopy were also evaluated. A cluster analysis was carried out using climatic and microclimatic parameters in order to maximize the intraclass similarity and minimize the interclass si...
Conservation of Mediterranean oak woodlands: understorey dynamics under differe...
Canteiro, Cátia; Pinto-Cruz, Carla; Simões, M. Paula; Gazarini, LuizThe effect of experimental disturbances on the dynamics of a shrub community was studied on a ‘Montado’ ecosystem, in southern Portugal. The evolution of the community physiognomy, composition and diversity were monitored after shrub clearing followed by biomass removal, deposition on soil surface and incorporation with the soil, over a 9-year period. Maximum shrub density was recorded in the first year after t...
Leaf-level responses to light in two co-occurring Quercus (Quercus ilex and Que...
Vaz, Margarida; Maroco, J.; Ribeiro, Nuno; Gazarini, Luiz Carlos; Pereira, João Santos; Chaves, Maria ManuelaAbstract We studied morphological, biochemical and physiological leaf acclimation to incident Photon- Photosynthetic-Flux-Density (PPFD) in Quercus ilex (holm oak) and Quercus suber (cork oak) at Mediterranean evergreen oak woodlands of southern Portugal. Specific leaf area (SLA) decreased exponentially with increasing PPFD in both species. Q. ilex had lower SLA values than Q. suber. Leaf nitrogen, cellulose an...
Decomposition and nutrient release in halophytes of a Mediterranean salt marsh
Simões, Maria Paula; Calado, Maria da Luz; Madeira, Manuel; Gazarini, Luiz CarlosThis study dealt with the decomposition and nutrient release from the halophytes Atriplex portulacoides, Arthrocnemum macrostachyum, Limoniastrum monopetalum, and Spartina densiflora, the dominant species in the Castro Marim salt marsh, Portugal. Environmental effects on decomposition were also assessed. The study was carried out for one year using the in situ litterbag technique. S. densiflora showed a lower d...
Microclimatic specificity of a Mediterranean oak woodland (montado) in context ...
Nunes, Jorge; Andrade, José; Abreu, Francisco; Gazarini, Luiz; Madeira, ManuelThe effects of oak trees on microclimatic parameters in Quercus rotundifolia Lam. woodland in Alentejo, Southern Portugal, are reported. The results show that oak trees create a marked differentiation in the grass matrix between open and tree-canopied habitats. Compared to open areas, oak canopy cover is associated with lower soil moisture content, lower soil temperature and lower photosynthetically active radi...
Influence of Quercus ilex trees on herbaceous production and nutrient concentra...
Cubera, Elena; Nunes, Jorge; Madeira, Manuel; Gazarini, LuizIn an open woodland in Portugal, the nature of interactions between Quercus ilex trees and herbaceous plants was assessed during 2 years by studying how manipulation of incident solar radiation, water and nutrient supply affect the herbaceous biomass and N, K, P, Ca, Mg, and Mn concentrations. Measurements were carried out in three environments consisting of (1) open grassland, (2) beneath the tree canopy, and ...
Gas exchange in the salt marsh species Atriplex portulacoides L. and Limoniastr...
Neves, J.P.; Ferreira, L.F.; Vaz, M.M.; Gazarini, LuizSalt marshes are ecosystems subjected to a variety of environmental stresses like high salinity, water deficit, intense radiation or high temperatures. Field measurements were conduced in two halophyte species, Atriplex portulacoides L. and Limoniastrum monopetalum L., in the Reserva Natural do Sapal de Castro Marim, to compare their physiological response, i.e., water potential (w), net photosynthetic rate (A)...
The role of phenology, growth and nutrient retention during leaf fall in the
Simões, Maria Paula; Madeira, Manuel; Gazarini, LuizPhenological patterns, growth and internal nutrient cycling of the Mediterranean shrubs Cistus salviifolius and Cistus ladanifer were analysed during 2 years of contrasted precipitation to compare their life strategies and their competitive potential to cope with future climate changes, leading to increased drought. The phenophases of both study species occurred mostly in spring, the most favourable period of t...
Influência do posicionamento no solo na decomposição de folhas e raminhos de Ci...
Simões, M. Paula; Nunes, Jorge; Madeira, Manuel; Gazarini, LuizEstudou-se a influência do posicionamento no solo na dinâmica da decomposição de resíduos de arbustos mediterrânicos, numa comunidade característica de montados do Alentejo, durante um período de cerca de 2 anos. Para o efeito, monitorizaram- se as variações de matéria orgânica e de nutrientes em folhas e raminhos de Cistus salviifolius L. colocados na superfície do solo e incorporados a 10 cm de profundidade, ...
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