Ecology and behavior of nine timber species in Pará, Brazil: links between species life history and forest management and conservation

Open Access
Schulze, Mark
Graduate Program:
Doctor of Philosophy
Document Type:
Date of Defense:
October 03, 2003
Committee Members:
  • Christopher Uhl, Committee Chair
  • Charles Raymond Fisher Jr., Committee Member
  • Claude W De Pamphilis, Committee Member
  • Jim C Finley, Committee Member
  • tropical forest dynamics
  • population ecology
  • tree life history
  • Brazil
  • Amazon
  • logging
  • tropical forest management
Under any definition of sustainability, forest management must maintain viable populations of timber species. I studied population dynamics of nine timber tree species in both undisturbed and logged stands at five sites in the eastern Amazon. In stands subjected to haphazard conventional logging and a reduced-impact harvest system, I investigated canopy tree mortality patterns, timber tree regeneration and recruitment in logging disturbance zones. I conducted experiments to investigate the regeneration management potential of important timber species. Adult growth rates varied dramatically among species and among individuals of a given species. Much of the individual variation in growth and mortality could be attributed to differences in crown damage, light availability and vine-loading. However, even among subsets of stems that under favorable growth conditions growth was highly variable. All study species displayed limited dispersal ranges: logging gaps that were more than 100 m from adults were rarely found to contain seedlings. High inter-annual variation in seed production poses challenges for management of timber species in logged stands through natural colonization of disturbed sites. After three years of logging gap succession, the majority of stems of all study species displayed signs of suppression. In eighteen-year-old gaps, suppression of juveniles was even more extreme. Estimated recruitment times from seedling to adult size in logging gaps were well-above sixty years for all study species. Planted seeds and seedlings of light-demanding study species performed well in medium to large (=250m²) logging gaps, as long as liberation thinning was conducted to reduce competition with pioneer species. Enrichment planting and tending of plants in logging gaps could prove to be a successful and necessary silvicultural technique. Variation in timber species life history characteristics lead to varied responses to logging disturbance. Populations of the three canopy-emergent study species were the most vulnerable to logging disturbance. Shade tolerant species appear more resilient under logging pressure. However, proposed rotation lengths of 30-40 years may be overly optimistic. Under current logging regimes, including reduced-impact logging, we are likely to see a shift from high value species in the first harvest to low value species with light wood in second and third harvests.