Measures for sustainable forest management in the tropics – A tree-ring based case study on tree growth and forest dynamics in a Central Amazonian lowland moist forest

Abstract

The conservation of tropical forests is recognized as one of the most important challenges for forestry, ecology and politics. Besides strict protection, the sustainable management of natural forests should be enhanced as a key part of the foundation for the maintenance of tropical rain forest ecosystems. Due to methodological reasons it has been complicated to attain reliable growth data to plan sustainable felling cycles and rotation periods. Tree ring analyses enable the estimation of growth rates over the entire life span of trees and their age as well as giving hints from forest dynamics in previous centuries. For tree ring analysis, stem disk samples were taken from three important commercial tree species ( Cariniana micrantha , Caryocar villosum and Manilkara huber i) in the upland (terra firme) forests of the Precious Woods Amazon logging company near Itacoatiara, Brazil. Based on radiocarbon estimates of individual growth zones, the annual nature of tree rings was proven for the three species. Tree rings were measured and the results used together with height estimates to model diameter, height and volume growth. The age of the eldest tree, a C . micrantha , was 585 yrs with 165 cm in diameter. The species’ diameter increments range from 0.20±0.12 cm yr -1 to 0.29±0.08 cm yr -1 . At first sight, this is considerably lower than increments reported from other Amazonian or African timber species. Considering the respective wood density there is no significant difference in growth performance of dominant timber species across continents. The interpretation of lifetime tree ring curves indicate differences in shadow tolerance among species, the persistence of individuals in the understory for up to 150 years and natural stand dynamics without major disturbances. Management criteria should be adapted for the measured growth rates as they differed considerably from the Brazilian standards fixed by laws (felling cycle of 25–35 years and a common minimum logging diameter of 50 cm). Felling cycles should be increased to 32–51 years and minimum logging diameters to 63–123 cm depending on the species.

On tree longevity

“…see Kurokawa et al ., 2003), and may require additional confirmation from tree‐ring analysis (Box 1). Old hardwood trees normally do not exceed 300 yr of age, with a few genera that include individuals older than 500 yr (Di Filippo et al ., 2015; Worbes & Schöngart, 2019). Large olive trees ( Olea europea L.) are considered capable of living for millennia, but to date the oldest radiocarbon‐dated olive stems have maximum ages approaching, albeit not reaching, a millennium (Bernabei, 2015).…”

“…7). A similar mismatch with the sigmoidal model has been found for other temperate (Black et al ., 2008; Granda et al ., 2017) and tropical (Worbes & Schöngart, 2019) species. Climatic conditions are the main cause for temporary deviations from smooth growth curves, either by negatively impacting growth (Piovesan et al ., 2008) or by favoring it (Salzer et al ., 2009).…”

Ring width and vessel features of the mangrove Excoecaria agallocha L. depend on salinity in the Sundarbans, Bangladesh

“…Long-term data on tree growth is essential for understanding changes in natural forests and useful for forest management (Worbes and Schöngart, 2019). Detection of tree age and estimates of radial growth rate for woody species are usually carried out by applying indirect methods, including periodic measurements of tree diameter in forest inventories usually from permanent sample plots (PSPs, Groenendijk et al, 2014).…”

Dendroclimatologia e dendroecologia de árvores de >i<Cedrela odorata>/i< L. da Amazônia oriental Brasileira

“…Porém a coleta de discos do lenho depende dos recursos financeiros para coleta, quantidade de árvores de Cedrela no sítio amostral e liberação do seu corte, o que faz da parcerias com empresas de manejo florestal uma alternatva para trabalhar com discos do lenho (Andrade et al, 2019;Worbes & Schöngart, 2019).…”