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Abstract(s)
Este trabalho pretende dar um contributo sobre o efeito da natureza das espécies
Florestais na pedogénese. O presente estudo decorreu na Serra da Nogueira, Nordeste de
Portugal, coberta por um bosque de Quercus pyrenaica, que constitui a vegetação climácica,
mas onde se tem vindo a assistir à introdução de outras espécies nomeadamente Pseudotsuga
menziesii e Pinus nigra. Para obter informação sobre a influência desta substituição de
espécies na pedogénese, foram seleccionadas três áreas de amostragem, uma de Pseudotsuga
menziesii (PM) outra de Pinus nigra (PN) e outra, que representa o solo original, de Quercus
pyrennaica (QP), em zonas adjacentes e com características edafo-climáticas idênticas. Em
cada área de amostragem foram seleccionados, de forma aleatória, 15 locais onde se procedeu
à recolha do material orgânico numa área de 0,49 m2 por local, e à recolha de amostras de
solo nas profundidades 0-5, 5-10, 10-15, 15-20, 20-30 cm.
Os horizontes orgânicos apresentam desenvolvimento máximo, compreendendo as
camadas L, F e H. Os resultados mostram que a acumulação de resíduos orgânicos à
superfície do solo é mais elevada para a espécie PM (31,8 t ha-1) quando comparada com as
espécies PN (27,1 t ha-1) e QP (18,4 t ha-1). Os resíduos orgânicos de PM mostram maiores
concentrações em fósforo, cálcio e magnésio; os de PN em carbono e finalmente os de QP
são mais ricos em Potássio. De um modo geral, as concentrações de elementos aumentam ao
longo do processo de mineralização/humificação, isto é, de L para H.
Em todos os solos analisados, observa-se que as concentrações de elementos minerais
diminuem consideravelmente dos horizontes orgânicos para os horizontes minerais. Sobre o
complexo de troca, regista-se uma baixa concentração de bases de troca no solo sob as três
espécies, sendo que a incorporação de bases de troca é superior no solo sob PM. Todos os
solos situam-se na zona considerada ácida com o valor de pH (H2O) mais elevado (5,4) no
solo sob PM e o mais baixo (4,7) no solo sob PN. A densidade aparente é geralmente
superior a 1 e idêntica entre espécies, em todas as profundidades consideradas. As diferenças
entre solos tendem a anular-se ao longo do perfil edáfico em todas as situações estudadas.
This work aims to contribute on the effect of the nature of forest species in pedogenesis. This study took place in the Serra da Nogueira, northern Portugal, covered by Quercus pyrennaica, which is the climax forests vegetation, but which has been witnessing the introduction in small areas, other species including the Pseudotsuga menziesii and Pinus nigra. For information about the influence in pedogenesis of Pseudotsuga menziesii and Pinus nigra, were selected three sampling areas, one of Pseudotsuga menziesii (PM) other of Pinus nigra (PN) and another representing the initial situation, Quercus pyrennaica (QP) in adjacent areas with similar characteristics of soil and climate. In each sampling area 15 points were selected at random. In each point we colleted the organic material in a 0,49 m2 area and soil samples at depths 0-5, 5-10, 10- 15, 15-20 and 20-30cm. The organic horizons have maximum development, comprising the layers L, F and H. The results show that the accumulation of organic residues at the soil surface is higher in PM species when compared with PN and QP species. The PM forest floor is rich in mineral elements (P-phosphorus, Ca-calcium, Mg-magnesium); PN the forest floor are rich in mineral element carbon (C) and the residue of QP are rich in mineral element potassium (K). In general, the concentrations of elements increases during the mineralization process, that is from, L to H. In all soils, it was observed that concentrations of mineral components decrease considerably from the organic horizon to the mineral horizon. It was registered a low concentration in exchangeable bases on the soil in the three species, and the incorporation of exchangeable bases is superior in soil under PM. All soils are considered acid with the highest pH (H2O) value (5.4) in soil under PM and lower (4.7) in soil under PN. The bulk density is generally higher than 1 for all three species, along the soil depth. The values do not differ significantly between soils. The differences among soils tend to fade along the edaphic profile.
This work aims to contribute on the effect of the nature of forest species in pedogenesis. This study took place in the Serra da Nogueira, northern Portugal, covered by Quercus pyrennaica, which is the climax forests vegetation, but which has been witnessing the introduction in small areas, other species including the Pseudotsuga menziesii and Pinus nigra. For information about the influence in pedogenesis of Pseudotsuga menziesii and Pinus nigra, were selected three sampling areas, one of Pseudotsuga menziesii (PM) other of Pinus nigra (PN) and another representing the initial situation, Quercus pyrennaica (QP) in adjacent areas with similar characteristics of soil and climate. In each sampling area 15 points were selected at random. In each point we colleted the organic material in a 0,49 m2 area and soil samples at depths 0-5, 5-10, 10- 15, 15-20 and 20-30cm. The organic horizons have maximum development, comprising the layers L, F and H. The results show that the accumulation of organic residues at the soil surface is higher in PM species when compared with PN and QP species. The PM forest floor is rich in mineral elements (P-phosphorus, Ca-calcium, Mg-magnesium); PN the forest floor are rich in mineral element carbon (C) and the residue of QP are rich in mineral element potassium (K). In general, the concentrations of elements increases during the mineralization process, that is from, L to H. In all soils, it was observed that concentrations of mineral components decrease considerably from the organic horizon to the mineral horizon. It was registered a low concentration in exchangeable bases on the soil in the three species, and the incorporation of exchangeable bases is superior in soil under PM. All soils are considered acid with the highest pH (H2O) value (5.4) in soil under PM and lower (4.7) in soil under PN. The bulk density is generally higher than 1 for all three species, along the soil depth. The values do not differ significantly between soils. The differences among soils tend to fade along the edaphic profile.
Description
Keywords
Propriedades físicas do solo Propriedades químicas do solo