Forest dynamics in flood plain forests in the Peruvian Amazon: effects of disturbance and implications for management

Forest dynamics were studied from 1993 to 1997 for individuals greater than or equal to 10 cm DBH in nine 1 ha permanent sample plots. They were estab lished in natural flood plain forests located on the lower Ucayali river in the Peruvian Amazon. After inventories of three plots in each of three for est types, a light and a heavy felling treatment were applied to each of th e two plots, while a third plot was kept untreated. Average annual stem mor tality and recruitment rates in the untreated plots were among the highest observed in neotropical rain forests: mortality 2.2-3.2% per year, recruitm ent 3.0-4.6% per year. Dead individuals deviated significantly from random dispersion towards clumping. The average annual basal area growth was aroun d 1 m(2)/ha per year, corresponding to average annual basal area growth rat es of 3.5-3.8% per year in the untreated plots. No decrease in basal area g rowth was observed even in the treated plots where annual basal area mortal ity rates up to 41% during the first year were observed. The average diamet er growth increased from 4.0-4.5 tnm per year in the untreated plots to 5.3 -6.8 tnm per year in the treated plots. The stocking of commercial timber s pecies was high with basal areas of 2.6-10.0 m(2)/ha and volumes of 59-240 m(3)/ha. The corresponding growth of basal area and volume of commercial ti mber species were also considerable, reaching values of 0.1-0.3 m(2)/ha per year and 2-9 m(3)/ha per year, respectively. These attributes suggested th at forest management for timber production in these forests can be flexible and provide relatively high yields on a sustained basis. It appeared that management interventions can be carried out within the range of naturally o ccurring perturbations, although it should be noticed that only limited pro portions of each habitat are disturbed at a time by nature. The patchy occu rrence of habitats may provide logistic problems to management. (C) 2001 El sevier Science B.V. All rights reserved.