Disc sections (cut using a bandsaw) and cores were then scanned at high resolution using an Epson Expression 11000XL scanner (Fig. As the rings were particularly narrow on the samples from Suriname, the microtome was used to cut thin sections (~10 µm thick) that were scanned with an Epson Perfection V700 Photo scanner (Fig. Rings on the samples from Suriname were observed to frequently follow a regular pattern of a narrow ring followed by a wide ring, possibly indicating the presence of non-annual rings (e.g. Where this pattern was identified, the narrow rings were assumed to be false and thus the wide and narrow rings were initially counted together as a single annual ring and dated accordingly.All rings were dated following the convention of Schulman (), where the assigned calendar date corresponds with the year that the tree started growing.at the onset of the thermonuclear tests), these signatures are mostly well distributed across the hemispheres (Hua et al.
Here, we use ‘bomb-peak’ radiocarbon ( trees from four sites across tropical South America.
We show that trees from Bolivia, Ecuador and Venezuela have reliably annual tree rings, while trees from Suriname regularly form two rings per year.
Tropical tree rings have the potential to yield valuable ecological and climate information, on the condition that rings are annual and accurately dated.
It is important to understand the factors controlling ring formation, since regional variation in these factors could cause trees in different regions to form tree rings at different times.
Stem discs were collected in 2011 (Bolivia), 2013 (Ecuador) and 2014 (Suriname) from trees felled for timber or during the installation of overhead power lines.