Tree regeneration after fire in a hemiboreal mire in the Nature Reserve “Stiklu purvi” in Latvia

Fire is one of the major human-caused and natural disturbances in boreal forests. Ecosystems have adapted to this disturbance, but salvage logging is often employed to hasten the establishment and productivity of new stands. Knowledge of the natural regeneration of the tree layer and its relationship with fire intensity, surviving tree cover, the amount of dead wood and soil factors such as the depth of the organic layer may facilitate the identification of the best post-fire management strategy. Information on tree regeneration is quite copious for dry forest types but insufficient for mire complexes. In 2018, a large fire burned an area of 1353 ha with variable intensity in the protected “Stiklu purvi” mire complex, located in the hemiboreal forest zone in Latvia. The aim of this study was to survey tree regeneration in relation to living and standing dead tree basal areas, log volume, tall shrub density, ground vegetation cover and the depth of the organic layer. It was hypothesized that tree colonization would be greater at sites with deeper peat due to a higher water level and less competition by shading. There was a weak effect of habitat type on tree regeneration, but NMS ordination revealed a positive relationship between birch regeneration and the shallow organic layer. Pine regeneration decreased with increasing basal area of surviving trees, indicating a shading effect. The survival of trees was greater in deeper organic soils.