Different triggers, different stories: Bark-beetle infestation patterns after storm and drought-induced outbreaks

• DOI: 10.1016/j.foreco.2023.121255
• Publication Date: 2023-07-18T03:23:29Z
• Authors: S. Kärvemo; L. Huo; P. Öhrn; E. Lindberg; H.J. Persson
• Keywords: Felling

In the recent decades, Norway spruce forests (Picea abies Karst.) in Europe have been subject to large-scale tree mortality caused by bark beetle (Ips typographus L.). The outbreaks were induced storm-felling events and periods of drought, which are becoming increasingly frequent due climate change. Because storms droughts spatially affect differently, infestation patterns configuration beetles might differ between drought. this study, we examined local landscape factors associated with beetle-caused after one storm (2005) drought-induced outbreak (2018), both occurring southern Sweden. A total 13,192 infested one-ha pixels 6,425 drought (in 19,617) compared regarding differences occurrence size forest structures two different outbreaks, using a generalized linear model (GLM) approach. Based on our findings, discovered that allocation patch sizes (including four classes: 5–10, 11–25, 26–50 >50 trees) for quite similar large proportion (>0.6) small groups (≤10 trees). However, outcomes from study demonstrate drivers behind spatial infestations can considerably triggered droughts, main cause seems be linked distribution susceptible trees. most consistent storm-induced increased more volumes area protected (nature reserves) landscape; whereas infestations, clear-cuts heights across scales. Soil moisture mean index (SPEI; May-July) important but generally than may involve time-lagged effect. reasoning during when wind-felled trees removed or not suitable anymore, need find specific standing trees, while all less stressed, results selection dry warm landscapes as they resources favorable reproduction conditions. Finally, show previous influenced later negatively within 25 ha related depletion host These assessment predictions, should integrated future risk mapping outbreaks.