Elsevier, Forest Ecology and Management, 5-6(255), p. 1525-1535
DOI: 10.1016/j.foreco.2007.11.008
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The influence of soil type, slope and drainage on tree growth patterns (density, tree size, crown canopy cover and cork yield) was assessed in a cork oak montado, located in Central-western Portugal, based on a GIS approach followed by field survey. Five soil groups, that is, Arenosols, Regosols, Podzols, Luvisols and Gleysols, combined in three slope classes (flat, undulating and steep) under two different hydromorphic conditions (normal or deficient) were compared based on five cork oak stand parameters using ANOVA and PCA tests. The results showed a clear influence of soil type on cork oak growth patterns (cork yield, basal area, number of trees per hectare, crown canopy cover and circumference at breast height). In Arenosols all parameters showed maximum values and, in contrast, in Gleysols were found the minimum values. For instance, the average of the annual cork production for Gleysols (153kgha−1year−1) was only 70% of the expected annual cork production of Arenosols (219kgha−1year−1) and the average exploited tree density decreased from 56treesha−1 in Arenosols to 44treesha−1 in Gleysols, for an average exploited tree density of 53treesha−1 for the study area. Slope also seems to influence the cork oak growth patterns, as significant statistical differences were found for cork oak growth parameters between slope classes: steep slopes decreased the cork production, the tree size (circumference at breast height) and the tree density. An overall PCA test showed that three main soil groups could be identified: (i) Arenosols and Podzols; (ii) Regosols and (iii) Luvisols and Gleysols, showing that the former, which could allow the tree root development, have a positive influence on the cork oak growth. A two-way analysis of variance, for soil type and slope, showed that the cork yield and the exploited tree density are clearly affected by these two factors interaction.