Drivers of Pinus sylvestris L. regeneration following small, high-severity fire in a dry, inner-alpine valley

In dry, inner-alpine valleys, regeneration of Scots pine after large, high-severity fires is limited by seed dispersal distance. When dispersal limitations are relaxed (small fires), colonization dynamics of Scots pine remain unclear. Our aims were (1) to assess the regeneration niche of Scots pine seedlings following small fires in a dry, inner-alpine valley and (2) to measure the influence of competition, drought, fertility, and soil pH on pine colonization. We sampled pine seedlings in six high-severity fires (1962–2006), where distance from the unburned edge was < 60 m. We modeled seedling density as a function of topography and soil cover by means of generalized linear models. Ellenberg indicator values (EIVs) for light, moisture, soil pH, and fertility were computed from vegetation sampling at each plot, and used as additional predictors of seedling density. Pine colonization was initially slow due to drought, and peaked 16 years after fire. The inclusion of EIV provided +31% of explained deviance in models of seedling density. Herb cover and soil moisture were the most important predictors. Scots pine regenerates successfully following small, high-severity fires, albeit slowly due to unfavorable water balance. Hence, restoration by artificial regeneration may not be necessary when seed dispersal is not limiting.