Distribution of juniper stands and the impact of environmental parameters on growth in the drought-stressed forest-steppe zone of Central Anatolia

Abstract

Juniper is one of the three main tree species in Central Anatolia, where it grows under extreme environmental conditions. Although dendrochronological studies of juniper are challenging because of cross-dating problems, these types of studies on long-lived tree species have the potential to provide long time series, which reflect changes in climatic conditions. Juniper has been neglected as a scientific research subject in Turkey due to degraded populations and low economic expectations. This study analysed the distribution and present state of Juniperus spp. (Juniperus excelsa M. Bieb., Juniperus oxycedrus L., and Juniperus foetidissima Willd.) stands and used dendrochronological data to examine relationships between growth and environmental parameters. We hypothesised that there may be differences in the radial growth of juniper in areas of different exposure in drought regions. During a field survey, we sampled 31 plots of 25 m × 20 m and data, including information on wood cores, were collected. For dendrochronological investigation, 95 wood cores were manually measured and cross-dated. Residual chronologies of tree-ring width series of juniper from four wind directions and regional chronology of Kirikkale and Ankara Province were provided and similarities between the chronologies were tested using Gleichläufigkeits test. The relationships between climate parameters and growth were examined using a simple correlation analysis and multiple linear regression model analysis in SAS 9.0 program and response function analysis in the DENROCLIM2002 program. The results of this study indicated that Juniperus spp. in Central Anatolia are sensitive to environmental parameters and mainly respond to changes in precipitation. Juniper show differences in radial growth in areas of different exposure in drought regions. We conclude that juniper may offer an excellent opportunity for large-scale dendrochronological and dendroecological studies in drought regions.