Variation in DOB is much larger than the variation in soil salinity, and is an underlying reason for the poor relationship between tree size and soil salinity on an individual tree basis. This may not always be the case. Aragues et al. (2010) detected stronger relationships for tree height (r2 = 0.52–0.65) and for trunk growth (r2 = 0.49–0.83) and mean soil salinity for olive trees at 5 years of age.