Drought and Suboptimal Habitats Shape Norway Spruce Vulnerability to Bark Beetle Outbreaks in Białowieża Forest, Poland

In Białowieża Forest, Poland, Norway spruce decline is primarily driven by drought and suboptimal habitats, increasing its vulnerability to bark beetle outbreaks. The study found that 75% of spruce-dominated stands in 2015 were in unsuitable habitats, with outbreak years showing significantly lower precipitation, reduced hydro-climatic indices (Selyaninov k), and more negative SPEI-12 values compared to non-outbreak years. Drought acts as both a predisposing and triggering factor for outbreaks, with one-year lag effects observed. The research analyzed spruce share from 1902–2018, habitat suitability, and climate records using hydro-climatic indices and statistical tests (Welch’s t-test, point-biserial correlation). These findings underscore the critical role of habitat suitability and drought in spruce decline, advocating for adaptive management strategies to retain spruce in optimal habitats while transitioning suboptimal stands to more drought-tolerant species.

Kędziora, W., Szyc, K., Silva, J. S., & Wójcik, R. (2025). Drought and Suboptimal Habitats Shape Norway Spruce Vulnerability to Bark Beetle Outbreaks in Białowieża Forest, Poland. Land, 14(10), 2014. https://doi.org/10.3390/land14102014