Frequency and variability of missing tree rings along the stems of Pinus halepensis and Pinus pinea from a semiarid site in SE Spain

► P. halepensis and P. pinea in semiarid conditions frequently had missing tree rings. ► Nevertheless, most tree rings were missing only locally around and along the stem. ► Consequently, wood formation occurred every year in at least some part of a tree. ► In P. halepensis, the frequency of missing rings decreased from the bottom upward. ► Serial sectioning technique is recommended in tree ring and wood formation research.