title: Fire severity, residuals and soil legacies affect regeneration of Scots pine in the Southern Alps.
abstract: Regeneration of non fire-adapted conifers following crown fires on the European Alps is often delayed or unsuccessful. Fire may limit establishment by eliminating seed trees, altering soil properties, or modifying microsite and soil conditions via disturbance legacies. However, the effect of soil legacies on post-fire establishment has rarely been discussed. We analyzed the abundance of Scots pine regeneration in a 257 ha wildfire in an inner-alpine forest. Our aims were (1) to model fire intensity at the soil surface and topsoil heating along a gradient of increasing fire severities; (2) to assess the differences in soil properties along the fire severity gradient; (3) to model the effect of disturbance and soil legacies on the density of pine seedlings. We reconstructed fire behavior and soil heating with the First Order Fire Effects Model (FOFEM), tested the effect of fire severity on soils by nonparametric distributional tests, and modeled seedling density as a function of site, disturbance and soil legacies by fitting a GLM following a variable selection procedure. Topsoil heating differed markedly between the moderate and high severity fires, reaching temperatures high enough to strongly and permanently alter soil properties only in the latter. High fire severity resulted in decreased soil consistency and wet aggregate stability. Burned soils had lower organic matter and cations than those unburned. Pine seedlings favored low-fertility, eroded, and chemically poor sites. Establishment was facilitated by the presence of coarse woody debris, but hampered by increasing distance from the seed source. These results suggest that in dry, inner-alpine valleys, fire residuals and soil legacies interact in determining the success of Scots pine re-establishment. High severity fire can promote favorable soil conditions, but distance from the seed source and high evaporation rates of bare soils must be mitigated in order to ensure a successful restoration.
authors: Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Via da Vinci 44, 10095 Grugliasco (TO), Italy. Electronic address: giorgio.vacchiano@unito.it.
authors: Giorgio
authors: G
authors: Vacchiano
authors: Università degli Studi di Torino:NatRISK - Research Centre on Natural Risks in Mountain and Hilly Environments, 10095 Grugliasco (TO), Italy.
authors: Silvia
authors: S
authors: Stanchi
authors: Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Via da Vinci 44, 10095 Grugliasco (TO), Italy.
authors: Giulia
authors: G
authors: Marinari
authors: Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Via da Vinci 44, 10095 Grugliasco (TO), Italy.
authors: Davide
authors: D
authors: Ascoli
authors: Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Via da Vinci 44, 10095 Grugliasco (TO), Italy.
authors: Ermanno
authors: E
authors: Zanini
authors: Dipartimento di Scienze Agrarie, Forestali e Alimentari, Università degli Studi di Torino, Via da Vinci 44, 10095 Grugliasco (TO), Italy.
authors: Renzo
authors: R
authors: Motta
mesh_terms: D017753:Ecosystem; D004777:Environment; D005390:Fires / Q000706:statistics & numerical data*; D041605:Pinus sylvestris / Q000254:growth & development*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013557:Switzerland
chemical_list: D012987:Soil; D012989:Soil Pollutants
keywords: Crown fire; Disturbance ecology; FOFEM; Pinus sylvestris L.; Soil aggregate stability; Soil quality