Cattaneo, N. | Search bioRxiv

bioRxiv2025

A high-resolution, country-wide scenario analysis of forest susceptibility to spruce bark beetle damage in Norway

The European spruce bark beetle (Ips typographus (L.)) poses a growing threat to Norways forests under climate change, particularly in extensive spruce-dominated forests. Because controlling active outbreaks is notoriously difficult, reducing forest susceptibility through proactive management is essential. In this study, we used high-resolution simulations covering all of Norways forested land ([~]120,000 km2) to explore how different harvesting strategies affect long-term forest susceptibility to SBB damage. We compared a no-harvest baseline, a business-as-usual regime guided by economic criteria, and a risk-informed strategy that prioritizes harvesting of the most susceptible stands. Across two climate trajectories, we found that susceptibility-guided harvesting significantly reduced average forest susceptibility and fragmented high-risk areas, particularly in southern Norway. However, our results also reveal limitations to this approach: even with aggressive susceptibility-guided harvesting, long-term risk reductions plateau due to the homogenizing effects of even-aged forestry. Spatial connectivity analysis using electrical circuit theory further showed that susceptibility-guided harvesting disrupted landscape continuity among high-risk patches, suggesting a potential to constrain outbreak spread. These findings highlight the value of integrating susceptibility indicators and spatial connectivity metrics into forest planning to support adaptive, risk-informed management under climate uncertainty.

ecology↗

bioRxiv2023

Short-term thinning effect on inter- and intra-annual radial increment of Mediterranean Scots pine-oak mixed forest

Thinning treatment and mixed forest stands have been suggested as possible adaptation strategies to cope to climate change but there is still scarce knowledge about the combination of both subjects. In this study, we aim to better understand the thinning effect and the growth differences between two coexisting species on inter- and intra-annual cumulative radial increment patterns. We studied radial increment of a Scots pine-oak (Pinus sylvestris-Quercus pyrenaica) Mediterranean mixed forest during two climatically contrasted years (2016-2017) in north-western Spain. Data came from a thinning trial consisting in a randomized block experimental design with a control and two thinning treatments from below: a moderate and heavy thinning removing 25% and 50 % of initial basal area respectively focused on both species. Tree radial increment was analyzed based on bi-weekly readings from band dendrometers installed in 90 oak and pine trees. Non-linear mixed model based on double-Richards curve was fitted to show thinning and species differences in intra-annual cumulative radial increment patterns. Inter-annual basal area increment at species and stand levels were estimated using the model previously fitted at tree level and aggregating the results for exploring thinning effects at these levels. Scots pine leaded the tree and stand growth, and had also a better respond to early spring drought compared to oak. Heavy thinning increased tree radial increment for both species at the expense of decreased stand basal area. At species level, basal area increment decreased for Scots pine, however, heavy thinning generated the same oak basal area increment than control. Thus, heavy thinning may be good strategy towards a conversion from overaged coppice stands into high forests to conform a stable mixed forest stand. HighlightsO_LIScots pine leaded growth at tree and stand level C_LIO_LIScots pine trees may take advantage during early spring droughts C_LIO_LIHeavy thinning increased tree radial increment for both species C_LIO_LIHeavy thinning decreases stand basal area growth C_LI

ecology↗