RELATIONSHIP BETWEEN SOIL CHANGES AND PLANT SUCCESSION IN POSTFIRE REGENERATION OF QUERCUS-PYRENAICA ECOSYSTEMS

Changes in the chemical characteristics of soil and postfire plant suc cession were studied in eight oak (Quercus pyrenaica) ecosystems in th e Province of Leon (NW Spain) during the first 3 years following the p re. An increase in organic matter, C/N ratio, available K, and P resul ting from the fire was observed. It was also observed that with time, these parameters tended to decrease. However, there is a great differ difference in values in sites with the same regeneration age (e.g., 92 5-975 kg ha(-1) of available K 1 month following the fire, but 225-935 kg ha(-1) 2 years following the fire). It was therefore appropriate t o compare the values for each site in successive years. A study into t he relationship between vegetation and the edaphic conditions by canon ical correspondence analysis shows the importance of initial condition s, given that the regeneration process is an autosuccession.