Sancho, the oldest known Iberian shrub

Abstract

Abstract Cliffs are refuges for old trees and shrubs. In the Mediterranean Basin most dendroclimatic reconstructions have focused on high-elevation forests where tree radial growth is constrained by low temperatures in addition to drought stress. Old shrubs may provide longer ring-width series of hydroclimate proxies in low-elevation, drought-prone Mediterranean ecosystems where old trees are rare. To fill this research gap we investigated the maximum age and climate sensitivity of young, old, and recently dead Phoenician junipers (Juniperus phoenicea L.), growing on calcareous cliffs and nearby plains, in the Guara Natural Park (northeast Spain). The oldest living juniper was 14C-dated to be 927 years old, and it was named “Sancho” after Don Quixote’s squire. Based on ring counts, the maximum age was 655 years. The difference in age estimates between the 14C-dates and ring counts was 39 years indicating that ring counts underestimate age. This was due to missing and wedging rings making the cross-dating of old junipers unfeasible. Cool and wet conditions from May to July enhanced radial growth of young junipers. Old shrubs have a high dendroecological potential in Mediterranean sites where their growth is constrained by warm-dry conditions during the growing-season. Further techniques combining dendrochronological and wiggle-match 14C dating may allow reconstructing long-term hydroclimate in low-elevation Mediterranean areas.