Slow growth rates of Amazonian trees: Consequences for carbon cycling

Abstract

Quantifying age structure and tree growth rate of Amazonian forests is essential for understanding their role in the carbon cycle. Here, we use radiocarbon dating and direct measurement of diameter increment to document unexpectedly slow growth rates for trees from three locations spanning the Brazilian Amazon basin. Central Amazon trees, averaging only Ϸ1 mm͞year diameter increment, grow half as fast as those from areas with more seasonal rainfall to the east and west. Slow growth rates mean that trees can attain great ages; across our sites we estimate 17-50% of trees with diameter >10 cm have ages exceeding 300 years. Whereas a few emergent trees that make up a large portion of the biomass grow faster, small trees that are more abundant grow slowly and attain ages of hundreds of years. The mean age of carbon in living trees (60 -110 years) is within the range of or slightly longer than the mean residence time calculated from C inventory divided by annual C allocation to wood growth (40 -100 years). Faster C turnover is observed in stands with overall higher rates of diameter increment and a larger fraction of the biomass in large, fast-growing trees. As a consequence, forests can recover biomass relatively quickly after disturbance, whereas recovering species composition may take many centuries. Carbon cycle models that apply a single turnover time for carbon in forest biomass do not account for variations in life strategy and therefore may overestimate the carbon sequestration potential of Amazon forests.radiocarbon ͉ forest dynamics ͉ dendrometry ͉ tree age

Biometria de frutos e sementes da castanheira-do-Brasil da região Médio-Norte do Mato Grosso

“…A planta é perene, de crescimento lento, pode alcançar até 50 metros de altura e diâmetro superior a 300 cm, a copa frondosa com galhos encurvados que atingem 20 metros de comprimento (MULLER et al,1995;LORENZI, 2008;SALOMÃO, 2009), plantas adultas podem viver até 996 anos de acordo com a datação por radiocarbono (VIEIRA et al, 2005). O fruto é esférico, lignificado e bem rígido, formado por exocarpo, mesocarpo e endocarpo, pedúnculo, funículo e sementes.…”

Kumukumu 1, a hilltop site in the Aird Hills: Implications for occupational trends and dynamics in the Kikori River delta, south coast of Papua New Guinea

“…It is unknown whether this phase consists of intermittent or continuous site use. Because it is well established that, through the 'old wood' phenomenon (that is, the inbuilt age of wood in a living tree, as opposed to the storage age of a dead tree; e.g., Kurokawa et al, 2003;Vieira et al, 2005), all wood charcoal determinations will predate by an unknown amount of time the archaeological context of interest (e.g. Anderson, 1991;Spriggs and Anderson, 1993), we have opted to apply an outlier correction for charcoal dates, as informed by Bronk-Ramsey (2009b).…”

Avances y perspectivas del manejo forestal para uso múltiple en el trópico húmedo

“…La tasa de crecimiento lento (Vieira et al, 2005) significa que la mayoría de los individuos serán cosechados al poco tiempo de llegar al diámetro apto para la cosecha. De hecho, los individuos de C. guianensis toman un promedio de 20 años para crecer de 40 a 50 cm de DAP y de 50 a 60 cm, pero la desviación estándar del crecimiento fue alta (55 años) (Figura 1).…”

“…Se usaron estimaciones conservadoras de los ingresos de la extracción de madera, dadas estas tasas de crecimiento lentas y variables. Si bien estas tasas conservadoras de las mediciones de radiocarbono del crecimiento de los árboles de C. guianensis (Vieira et al, 2005) y el crecimiento que se midió en el lugar de estudio (Figura 1) son adecuadas para el presente modelo, se hace hincapié en que el área de estudio no es ni un bosque inundado, ni el ambiente más propicio para el crecimiento de C. guianensis. De hecho, Vieira et al (2005) encontraron que las tasas de C. guianensis en esta región eran más bajas que en las zonas más septentrionales de Brasil.…”