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Fire shapes the world's terrestrial ecosystems and has been influencing biodiversity patterns for millennia. Anthropogenic drivers alter fire regimes. Wildfires can amplify changes in the structure, biodiversity and functioning of the fast‐warming tundra ecosystem. However, there is little evidence available, how these fires affect species diversity and community composition of tundra ecosystems over the long term. We studied long‐term fire effects on community composition and diversity at different trophic levels of the food web in the subarctic tundra of Western Siberia. In a space‐for‐time approach we compared three large fire scars (>44, 28 and 12 years old) to unburnt controls. We found that diversity (measured as species richness, Shannon index and evenness) of vascular and non‐vascular plants and birds was strongly affected by fire, with the greatest species richness of plants and birds for the intermediate‐age fire scar (28 years). Species composition of plants and birds still differed from that of the control >44 years after fire. Increased deciduous shrub cover was related to species richness of all plants in a hump‐shaped manner. The proportion of southern (taiga) bird species was highest in the oldest fire scar, which had the highest shrub cover. We conclude that tundra fires have long‐term legacies with regard to species diversity and community composition. They may also increase landscape‐scale species richness and facilitate range expansions of more southerly distributed species to the subarctic tundra ecosystem. [ABSTRACT FROM AUTHOR]

Wildfires affect biodiversity at multiple levels. While vegetation is directly changed by fire events, animals are often indirectly affected through changes in habitat and food availability. Globally, fire frequency and the extent of fires are predicted to increase in the future. The impact of fire on the biodiversity of temperate wetlands has gained little attention so far. We compared species richness and abundance of plants and birds in burnt and unburnt areas in the Amur floodplain/Russian Far East in the year of fire and 1 year after. We also analysed vegetation recovery in relation to time since fire over a period of 18 years. Plant species richness was higher in burnt compared to unburnt plots in the year of the fire, but not in the year after. This suggests that fire has a positive short-term effect on plant diversity. Bird species richness and abundance were lower on burnt compared to unburnt plots in the year of the fire, but not in the year after. Over a period of 18 years, high fire frequency led to an increase in herb cover and a decrease in grass cover. We show that the effects on biodiversity are taxon- and species-specific. Fire management strategies in temperate wetlands should consider fire frequency as a key driving force of vegetation structure, with carry-over effects on higher trophic levels. Designing fire "refuges", i.e., areas that do not burn annually, might locally be necessary to maintain high species richness. [ABSTRACT FROM AUTHOR]