Some trees of the Amazon rainforests are much older than originally thought, according to a research published by Vieira et al. in 2005. Findings of the research are summarized in the article ‘Slow growth rates of Amazonian trees: Consequences for carbon cycling’ published by the Proceedings of the National Academy of Sciences (PNAS).
The research documented unexpectedly slow growth rates for trees in three locations of the Amazon Basin and found that trees of Central Amazon grow half as fast as those to the east and the west. With an average growth rate of only 1mm per year in diameter, trees of Central Amazonia can reach great ages. 17 to 50% of trees with diameter larger than 10cm were found to be older than 300 years. As many of the Amazon trees lack annual growth rings estimation of tree age is derived largely from permanent plot surveys and radiocarbon dating.
Vieira et al. note that their findings have important implications for the carbon cycling in Amazonian forests. They explain that as “most individuals in the forest are in the smallest size class, […] the mean age of trees reflects the dynamics of slower growing individuals”. On the other hand, they add, “most of the biomass (and therefore carbon) is in faster-growing, larger-size classes”. As a result, the mean age of trees may not correspond with the mean age of carbon.
Vieira et al. warns that if the diversity of tree carbon residence times is ignored models estimating the potential of tropical rainforests to emit or sequester carbon under different scenarios may provide inaccurate results. The article concludes that “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.“
 |
| Source: www.byronjorjorian.com |
No comments:
Post a Comment