Viability of thinning sessile oak stands by girdling

The effects of girdling were analysed in a sessile oak (Quercus petraea Matts. Leibl.) forest with an 80-year-old coppice with standard structure in northern Spain. The study evaluated the viability of girdling as an alternative to felling trees during crown thinning. Eighty-four direct competitors of selected future crop trees were girdled by double notching and peeling. Three years after girdling, 100% of the treated trees had died. Approximately half of the girdled trees did not resprout. The occurrence of basal sprouting was very low, and more than 35% of the sprouts had very low vigour. No correlation was found between sprouting and the diameter of the girdled trees or the distance to their nearest neighbour. A negative relationship between the diameter of the girdled tree and the stage of decline was recognized. Girdling is an economic alternative to non-commercial thinning in oak stands and can be seen as an effective structural enrichment treatment.