Potential effects of climate change on growth and the implications for conservation of the endangered Serbian spruce (Picea omorika (Pančić) Purk.)

Abstract

Understanding the impacts of climate change on the future growth of tree species is particularly important for conserving endemic species with limited geographic distributions, such as Serbian spruce (Picea omorika (Pančić) Purk.). This study describes an approach to assessing the effects of future climate conditions on the growth and the implications for future management to conserve this endangered species on the IUCN Red List. To investigate the climate-growth relationship, age structure and diameter growth trends, we have sampled 231 trees across 11 locations at National Park "Tara" in western Serbia. The existence of heterogeneous age structures suggests that Serbian spruce poses considerable potential for continual regeneration in stands with open canopy. Conducted dendroclimatological analysis exhibits exceptional coherence in growth patterns within populations (Rxy 0.67–0.78), allowing the established climate-sensitive mixed-effect model to achieve conditional R_c² ​= ​0.683. It is revealed that the radial increment of Serbian spruce is dominantly regulated by water deficit in the summer season. The rainfall amount during the spring is another meaningful climatic factor for growth trends, while minimal winter temperatures and previous autumn water balance show varying influences. Finally, the growth projections under climate change scenarios RCP4.5 and RCP8.5 foreseen reductions of up to one-third and almost half from the historical mean growth rate. The given estimations should be seen as a critical warning signal calling for immediate conversion from passive to active protection to preserve this unique species.