Volume increment modeling and subsidies for the management of the tree Mora paraensis (Ducke) Ducke based on the study of growth rings

Abstract

First study that demonstrated the formation of annual growth rings in Amazonian Estuary trees. Growth patterns of Mora paraensis and specific management criteria, such as felling cycle, are presented. The aim of the present study was to contribute to increased sustainability in the timber management of Mora paraensis, through the estimation of minimum logging diameter (MLD) and felling cycle, using volume increment models based on tree-ring analysis and allometric relationships. We collected stem discs from 17 trees of five diameter classes. The diameters and heights of the trees were also measured. We estimated tree ages by ring-counting and the radial increment rates by measuring the ring widths with a digital analysis system. We built growth models based on relationships between age, diameter and tree height to estimate volume increment along the tree’s whole life cycle. The maximum current diameter increment in M. paraensis occurs at an age of around 26 years, reaching 4.91 mm year-1. The MLD was 46.4 ± 0.6 cm (standard error), which trees achieve at an age of about 115 years. The felling cycle, estimated by the mean passage time through 10 cm diameter classes until achieving the MLD, was 24.7 ± 1.3 years. These results corroborated the norms of the current Brazilian legislation that regulates forest management of high intensity in the Amazon basin. In future, more specific growth models are needed for other commercial tree species in the Amazonian Estuary to define the optimal harvest rate to maintain sustainable timber resource management practices. Through such practices, the conservation of these ecosystems and their multiple services and functions, as well as the welfare of the forest-dependent human populations can be secured.