Radial Growth Patterns of Juniperus Across Eurasia: A Multi-site Dendrochronological Comparison

Juniperus is one of the most widely distributed conifer genera in the Northern Hemisphere, yet its radial growth responses to climate have rarely been compared across contrasting environmental limits. This study examined three Eurasian populations: Juniperus przewalskii at Dulan on the northeastern Tibetan Plateau, and prostrate Juniperus communis at Kevo in northern Finland and Val Ventina in the Italian Alps. After quality control and crossdating, 59 ring-width series were retained: 9 from Dulan, 30 from Kevo, and 20 from Val Ventina. Site chronologies spanning 1475–2020, 933–2022, and 1718–2018, respectively, were standardised using age-dependent, 100-year, and 20-year splines. Climate–growth relationships were assessed through monthly, seasonal, and 35-year moving correlations using CRU TS 4.08 temperature and precipitation data. Kevo and Val Ventina produced robust chronologies with strong common growth signals, whereas the Dulan chronology was weaker because of its limited replication. Although detrending affected low-frequency variability, the principal climate signals were generally consistent among methods. At Dulan, radial growth was primarily associated with moisture availability, showing positive relationships with February–July precipitation (r = 0.57) and temperature from the previous November to the current January (r = 0.42). The July temperature response shifted from negative to positive through time, suggesting a changing balance between temperature and moisture limitation under the regional warm-and-wet trend. At Kevo, current July temperature was the dominant control (r = 0.51) and remained positive across almost all moving windows, representing the most temporally stable relationship. At Val Ventina, growth was positively related to May–October temperature (r = 0.42) and negatively related to precipitation from the previous October to the current January (r = −0.33). The strengthening of growing-season temperature sensitivity towards the present was interpreted as reflecting declining snow-cover duration and an earlier initiation of growth. These results demonstrate that Juniperus populations shift systematically along the gradient and that congeneric populations are unlikely to respond uniformly to continued warming. Their trajectories depend on whether growth is primarily constrained by temperature, moisture availability, or snow cover. Continued warming may promote growth in the near term, but longer-term responses are likely to diverge as local limiting factors change. They therefore contribute to understanding how Juniperus, and other widely distributed woody taxa, may behave across contrasting biomes as the climate changes.