Results of the use of shelters in cork oak (Quercus suber L.) reforestation in Sardinia

Abstract: The artificial reforestations using Quercus suber L. are widely distributed in Sardinia and the authors have previously conducted a series of studies in a reforestation of Q. suber L., established in 2001, by using individual protection shelters of different types and heights. Results were positive; the shelters reduced the mortality and favoured the growth of seedlings.In autumn 2006, the individual protections were removed without any modification of the experimental plots in order to follow the evolution of the seedlings; the data for the period 2006-2012 were analysed in this paper. Pluviometric data showed that the trend of rainfall was nearly always higher than the historical average, with some years particularly rainy. The data analysis shows that the control seedlings, grown without individual protection shelters, continue to have a significantly higher mortality. The greater height values were observed in plants protected by shelters of 60 cm. After protection removing, the seedlings protected by shelters of 120 cm, have suffered from 2007 to 2009 stunting. The increase in diameter was higher in seedlings grown with Tubex 60 and Arboplus 60, while control plants exhibited the lowest growths, confirming the results obtained in 2006. The ipso-diametric ratio decreased in all the modalities, in particular for plants protected by shelters of 120 cm, highlighting the achievement of a balance between growth in height and in diameter. The use of individual protection shelters, originally created to avoid damage by animals, has demonstrated its effectiveness in reducing seedling mortality and improving their development, especially when using shelters of 60 cm.