THE IMPACT OF DEFORESTATION ON THE MINERAL NITROGEN AVAILABLE DURING RESTORATION OF THE HOLM OAK (QUERCUS-ILEX L) COPPICE

The impact of deforestation on the biological activity of a mediterranean red soil was studied from January 1984 to April 1986 within a holm oak (Quercus ilex L) stand after clearcut. Part of the study involved the estimation of the amount of nitrogen available for vegetation both in the mature holm oak coppice and in the 1-2-yr-old recovery stand. The study indicates that the new shoots essentially took up nitrate nitrogen; however, the mature site used both nitrate and ammonium nitrogen as nitrogen source. The availability of mineral nitrogen, essentially nitrate, ranged from 47.4 to 118.6 kg.ha-1.yr-1 in the rebuilding site and 25.6 to 63.9 kg.ha-1.yr-1 in the mature stand. At the control site, ammonium nitrogen represented 43% of the total nitrogen available.