Cork-oak reforestation – effects of preplanting root treatments and treeshelters on survival and growth seven years after plantation

Abstract

Four-month old containerized cork-oak seedlings grown in nursery with different root conditioning were planted in a fenced area near Évora, southern Portugal. The effects of six precondioning root treatments and two different treeshelters on the survival and growth were evaluated seven years after plantation. Pre-planting root treatments, consisting in the combination of three different containers and two different substrates did not clearly affect survival but plants grown with a mixture of ground pine bark and vermiculite grew better than plants which received a superfosphate enriched mixture of soil and peat. Different shelters affect differently both survival and growth of the plants. The 1.20 m high, translucent light brown corrugated polypropylene shelter (Sheltatree) did not significantly affect survival, increased growth in height but trunk growth in diameter was delayed in comparison with non sheltered plants. The 0.75 cm high transparent PVC shelter (Gro-Cone) had no effects on height and significantly reduced trunk radial growth as well as plant survival but only when compared with the other shelter. The use of treeshelters appears as a promising technique which, depending on the local conditions, may conciliate the multiple use of the montado with cork-oak regeneration. The use of a seedling growth substrate like ground pine bark revealed high potential for plant growth in the usually nutrient scarce soils of cork-oak stands.