Abstract

FONSECA, Felícia; GUERRA, Alzira  and  NOGUEIRA, Clotilde. The Effect of the Substitution of Forest Species in the Organic Horizons, and Chemical Characteristics of the Soil. Silva Lus. [online]. 2004, vol.12, n.2, pp.183-190. ISSN 0870-6352.

The aim of this study was to evaluate the influence of substituting areas of Quercus pyrennaica, which constitute the autochthonous vegetation of Serra da Nogueira in the North of Portugal, with Pseudotsuga menziesii on the chemical characteristics of the soil. For this evaluation, three sampling areas were selected in adjacent zones with similar soil and climatic conditions. The first zone, containing Quercus pyrennaica (QP), which represents the soil in its initial state.  The second, a 40 year-old Pseudotsuga menziesii (PM40) zone, and the last a 15 year-old Pseudotsuga menziesii (PM15) zone. In each sampling area, 10 plots were randomly selected.   In each of these the organic material from a 0.25 m² area, and soil samples from depths of 0-5 cm, 5-10 cm and 10-20 cm were collected. The results revealed that the accumulation of organic residues in the soil is elevated more with the resinous PM40 and PM15 than with the deciduous QP. Having compared the concentration of mineral elements of the organic horizon residues a lower concentration was detected in the PM15 species.  These are reflected in the chemical characteristics of the soil with a greater acidity and less carbon, nitrogen, potassium and exchangeable basis. The differences between the soil that developed under the PM40, and the soil in the initial state (QP), are less evident. It seems that with time, the characteristics of the soil, which developed under the Pseudotsuga menziesii species tends to become similar to that of the soil in its initial state.

Keywords : Quercus pyrennaica; Pseudotsuga menziesii; litterfall; nutrients.

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