Wild ungulates and salvage logging modulate disturbance effects on moth communities in spruce‐dominated forests

Abstract In Central Europe, natural forest disturbances are increasing due to climate change and management legacies. The consequences of the resulting habitat changes on biodiversity, with a higher availability of open and sparse forest stages shaped by varying post‐disturbance forest management, remain poorly understood. We aimed to disentangle the effect of stand‐replacing forest disturbance and associated post‐disturbance management on moths, a hyper‐diverse insect order with high ecological indicator value, in a spruce‐dominated low mountain range in Germany. We also assessed how these effects are modulated by structural heterogeneity and wild ungulate density. In 2021 and 2022, we sampled 40 sites each for macro‐moths using non‐lethal light traps. We compared unlogged and salvage‐logged sites disturbed by bark beetle outbreaks and windthrow 2–5 and 12–15 years ago. We used undisturbed spruce plantations as controls. We caught 52,090 specimens of 393 macro‐moth species. Taxonomic and functional diversity were higher on disturbed sites but varied little with post‐disturbance management. Species of conservation concern benefited from forest disturbance. Higher wild ungulate densities enforced the positive effect of disturbance, especially 12–15 years after disturbance. Disturbance‐induced structural heterogeneity was positively associated with taxonomic and functional diversity. Community composition diversified by post‐disturbance management. Disturbance also triggered community changes, with an increase in the number of open forest species that outweighed a decrease in closed‐forest species. Synthesis and application. In an area of massive forest disturbance, taxonomic and functional moth diversity currently benefit from a re‐opening of dense, dark forests. At a landscape scale, management should aim at diverse management strategies creating vegetation heterogeneity, that is, combining unlogged and salvage‐logged sites. Ungulate management should allow access to disturbed areas for browsing and grazing.