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Sammanfattning

Recent analyses of Swedish National Forest Inventory (NFI) data have reported changes in forest growth, including indications of declining increment for some tree species. To examine whether such trends are detectable at the level of individual tree, we developed new functions and applied residual analysis across major biogeographical regions of Sweden. We developed new individual-tree basal area increment models for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), and birch (Betula spp.) using Swedish NFI data from permanent plots measured between 1983 and 2022. Weighted nonlinear regression was applied with a limited set of tree-, stand-, and site-level predictors to simplify model validation and application. Model performance was evaluated against an independent NFI subset, existing functions implemented in the Heureka decision support system, and long-term thinning experiments (for Scots pine only). Overall predictive accuracy was comparable to established models, with slightly reduced bias at the stand level. No consistent long-term decline was detected for Scots pine or birch in residual analysis. In contrast, Norway spruce exhibited a systematic decline in basal area increment during the last decade in central and southern regions, indicated by increasingly negative residuals. These findings support recent inventory-based evidence of reduced spruce growth and suggest species-specific responses to changing climatic conditions in Sweden.

Nyckelord

Nonlinear regression; Forest growth; Scots pine; Betula spp

Publicerad i

Forest Ecology and Management
2026, volym: 610, artikelnummer: 123673
Utgivare: ELSEVIER

SLU författare

UKÄ forskningsämne

Skogsvetenskap

Publikationens identifierare

  • DOI: https://doi.org/10.1016/j.foreco.2026.123673

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/146534