Three phases of changes in carabid assemblages during secondary succession in a pine forest disturbed by windthrow - results from the first 10 years of observations

1. A windthrow disturbance alters the functioning and structure of a forest ecosystem and causes substantial economic losses. 2. A 10-year pitfall study of carabid assemblages (Coleoptera, Carabidae) was carried out in pine stands disturbed by windthrow (Pisz Forest, North Poland) in the first year after the disturbance, with different classes of severity: severely disturbed stands (canopy cover up to 30%), moderately disturbed stands (canopy cover of 40-60%) and least disturbed stands (canopy cover of 70-90%). 3. Based on the number of carabid species and their ecological traits, I confirmed the hypothesis that the amplitude of changes in carabid assemblages inhabiting severely and moderately disturbed stands would be greater than in the least disturbed stands. Variation in carabid assemblages was also linked to soil pH and to carbon and nitrogen content in the soil. 4. The study confirmed my hypothesis regarding the delayed replacement of late successional carabid fauna by early successional fauna, which was linked to the broken pines lying on the soil, allowing late successional fauna to survive in the first few years after the windthrow. 5. The principal response curve analysis identified three phases of post-disturbance succession in carabid assemblages: (i) slight changes in the number of species and their ecological traits, lasting for 4years; (ii) rapid' changes, lasting for 3years, involving an increase in the number of species and rapid replacement of late successional carabid fauna by early successional fauna; and (iii) the slow recovery of late carabid successional fauna.