Pathogen-induced structural simplification drives functional erosion and trophic decoupling in forest-floor arthropods

All data for analyses_Ecology.xlsx: Site-level dataset containing taxonomic (estimated richness, activity-density) and functional diversity metrics (FEve, Rao’s Q, FRic where available) for each arthropod group, spiders (spi), carabids (car), centipedes (cen), millipedes (mil), and woodlice (woo), together with environmental predictors including canopy openness (%), litter depth (cm), deadwood cover (%), herb-layer cover (%), shrub-layer cover (%), ash infestation intensity (%), and stand age category. Models_Ecology.R: R script used for model fitting, model selection, and plotting. For each response (stand structure: Canopy, Litter, Deadwood, Herb, Shrub; and community metrics for spiders (spi), carabids (car), centipedes (cen), millipedes (mil), and woodlice (woo)), we fitted a candidate set of GAMs testing effects of ash infestation intensity (Infestation, %) and stand age category (Young, Moderate, Mature), including additive terms and age-specific smooths s(Infestation, by = age); models were compared using AIC, and fitted relationships were visualized along the infestation gradient. Gamma(log) and negative binomial error structures were used where appropriate.