The influence of cork oak pruning on the yield and growth of cork

Bearing in mind the importance of pruning as a silvicultural treatment in cork oak (Quercus suber L.) open woodland of the dehesa type, an experiment was designed to assess the effect of pruning on cork yield. This work was carried out in two ways: synchronically, compa- ring pruned sites with others which were either unpruned or pruned at different times, and diachronically, comparing pruned and unpruned trees within the same site. The five test sites (with forty trees in the synchronic and eighty in the diachronic plots) were selected in south-west Spain. In all cases measurements of the cork production were made in kilos per square metre of surface stripped, total cork yield per tree, and the mean thickness of stripped cork. Analysis was carried out using a paired data comparison test. The effect of pruning on yearly cork growth was also analysed by examining the annual growth rings. In the five plots analysed there were no significant differences (95% confidence intervals) bet- ween pruned and unpruned trees in terms of kilos of cork produced per square metre of surface stripped, nor for total cork yield per tree. Neither were there significant differences in annual cork growth rings, even when the pruning was carried out during the cork-stripping period.