It would be helpful to know the ecological life zone and habitat in which these very large trees have grown. I would guess their age to be in the 50-200 years range.
many thanks for this! The trees we measured grow in tropical dry forest in the Colombian Valle de Cauca department. The below website seems to suggest that these trees may be much older (a tree with a girth of 3.2m from Hinduras was estimated to be more than 400 years old, but no reference to how this was done). Do you happen to know of any other attemps to measure the age of guanacaste trees? http://www.monumentaltrees.com/en/trees/enterolobiumcyclocarpum/records/