Effects of changes in traditional management on height and radial growth patterns in a Juniperus thurifera L. woodland

In order to understand the effects of changes in traditional forest management on Spanish juniper (Juniperus thurifera L.) forest dynamics, height and radial growth patterns were studied in 107 juniper trees in Cabrejas del Pinar (Soria, Central Spain). Suppressions in height and radial growth were common until the second half of XIXth century. These suppressions occurred at relatively low tree heights, and affected 30% of the sampled trees. The individual suppressions ended abruptly with a sharp increase in height and radial growth. These results fit well into the browsing cessation model, suggesting that an intense browsing pressure shaped this forest. The timing in the reduction of the browsing pressure matches the regional decrease in transhumant livestock that occurred in Spain during the second half of XIXth century. No difference in height-growth rate between suppressed and non-suppressed trees was observed for post-suppression period, indicating a high recovery capacity for J. thurifera. We observed a high variability in height-growth rate during post-suppression periods. This variability was poorly related to site factors (competition, landform), being related to tree life (age and presence of past suppression events). Traditional logging based solely on trees morphological traits may be partially responsible of this pattern. (C) 2007 Elsevier B.V. All rights reserved.