ID do Resumo: 617

How sustainable are tropical forest managements in Amazonia?

The sustainable management of tropical forests is a promising way to protect the multiple functions and services of ecosystems and to guarantee the use of timber resources for the future. A fundamental indicator for a sustainable forest management is the wood increment of tree species. Timber resources in central Amazonian non-flooded upland forests (terra firme), nutrient-rich (várzea) and nutrient-poor (igapó) floodplain forests are managed by selective logging (polycylic systems) with cutting cycles of 25-30 years and a minimum logging diameter (MLD) of 50 cm. However, these time and diameter limitations are estimations or legal restrictions rather than being derived from scientific data. Wood growth in diameter and volume were modeled from 19 tree species of terra firme, igapó and várzea forests using tree-ring analyses. Cumulative diameter growth curves indicate periods between 15 years and 261 years for species to pass over the MLD of 50 cm. But volume growth models indicate that the majority of commercial tree species reaches their highest volume increment rates at diameters above 50 cm. Species-specific MLDs were derived at diameters when timber species reach their highest current volume increments. Cutting cycles, estimated as the mean passage time through 10-cm diameter classes until reaching the MLD, indicate large variations between tree species and also between different forest ecosystems. Tropical forest managements operating with only one MLD and cutting cycle are not sustainable, because they do not differentiate between the growth rates of the timber species. Forest management concepts must therefore be species-specific and site-specific to guarantee a sustainable timber resource management.

Sessão:  Mudanças de Uso e Cobertura das Terras e suas Dimensões Sociais - Manejo sustentável de florestas.

Tipo de Apresentação:  Oral