Growth, soil properties and foliage chemical analysis comparison

Ecosystems 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.