Succession and nutrient dynamics following forest cutting and burning in Amazonia.

The study plot was dominated by forbs during the 1st yr and then by the pioneer tree species Cecropia ficifolia during year 2. Tree mortality exceeded establishment during the 3rd yr because the C. ficifolia trees died nearly in unison. During the 4th yr, tree density increased sharply as successional and forest tree species grew in the space vacated by C. ficifolia. The canopy was dominated at that time by the pioneers Vismia japurensis and V. lauriformis. By the 5th yr, all establishment space had been preempted. There were 56 tree species (= or >2 m tall) present on the 0.09 ha site after 5 yr. Over half of these were primary forest species. Primary forest species were most common in the understory. Biomass was only 66 g/m² at the end of the 1st yr, but -1000 g/m² were added in each subsequent year. The standing crop of biomass (shoot and root) at 5 yr was 4840 g/m², a value 16% that of the mature forest which occupied the site prior to cutting. Litter production increased each year from 39 g/m² (year 1) to 825 g/m² (year 5) and tended to be inversely related to rainfall. Total aboveground production was highest for the 5th yr (1940 g/m²) and was probably close to a maximum for the site. Total live-plant nutrient stocks after 5 yr, as a percentage of the precut forest stocks, were 15% for N, 23% for P, 39% for K, 48% for Ca, and 45% for Mg. Overall, nutrient losses were not great enough to destroy the site's ability to return eventually to a state similar to that which existed prior to disturbance.-from Authors