Research Highlights: Data indicated that fire severity modulates natural regeneration of Cytisus scoparius and Salix atrocinerea communities and drives much stronger effects on the germination of the dominant species. Background and Objectives: Previous studies demonstrated that fire severity induces different behaviours in plant species. Mother plant age is an important feature that must also be considered in plans of forest restoration. The objectives were to determine, in field studies, the effect of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities, to know the role of mother plant age on the germination of seeds of C. scoparius and S. atrocinerea, and to quantify their germination response at different levels of fire severity, in laboratory settings. Material and Methods: We have analysed the role of fire severity on the natural regeneration of C. scoparius and S. atrocinerea communities considering cover and height. Forty 30 × 30 m plots were randomly located in C. scoparius and S. atrocinerea communities. Fire severity on the germination of dominant species was tested through different levels of smoke, charcoal, ash, and heat. Results: High severity reduced the vertical cover and growth in height of the two communities and favoured the increase of cover of woody species in the C. scoparius community and herbaceous species in the S. atrocinerea community. Mother plant age determined germination percentages of C. scoparius seeds. Germination of C. scoparius was increased by moderate heat, and heat and smoke; and fire severity greatly reduced germination of S. atrocinerea. Conclusions: The regeneration responses after fire were largely controlled by interactions between the fire severity and the individual species regeneration strategies. For restoration purposes, C. scoparius seeds should be treated with 80 °C and smoke for 10 min, in order to increase germination; however, Salix seeds should be used without treatment and immediately after dispersion.

Serotiny degree may hypothetically depend on mother plant age and fire severity, and fire severity can strongly affect the regeneration of Pinus pinaster Aiton, which is an obligate seeder species with aerial seed banks stocked in cones showing a certain degree of serotiny. The main objective of this study was to evaluate the effect of serotiny and mother plant age on seed germination of P. pinaster in relation to fire severity. For this purpose, cones were collected in two stands from mother trees of different ages. Serotinous cones were opened in oven at increasing temperatures to determine the number of seeds released. The length of cones and the number and weight of seeds were measured. Seeds from both classes of mother plant age were subjected to 34 different treatments simulating different fire severity levels, and their germination was recorded. The results showed that serotiny was significantly higher in cones from young mother trees. Seed germination in the control groups from serotinous cones was always higher than that from non-serotinous cones without thermal shock. Fire severity decreased seed germination as fire severity increases in both mother age classes. Mother plant age was related to the serotiny level, which was higher in young than in old trees, suggesting a strong selection in the population due to a recent fire.

Acacia melanoxylon R.Br. (Leguminosae) is one of the most widely distributed tree species in the world. It has significant commercial use but can be a danger to natural ecosystems as an invader species. For these reasons it is necessary to have a deep knowledge about its germinative response to fire and the role the mother plant age plays in that response. In this work we assessed the effects of the interaction of the mother plant age with the main fire agents (smoke, charcoal, ash and heat) on the germinative response of A. melanoxylon. To reach this aim, germination tests were conducted with seeds from young, intermediate and mature mother plants, with 20 treatments each applied. Results show that fire can act as a great stimulator of the germination of A. melanoxylon but it can also strongly inhibit it. The mother plant age does not modify the final germination values, but it influences the time in which the first germinations occur after fire. This trait can be more important than the final germination percentage when looking at the success of post-fire regeneration. These results have important implications for A. melanoxylon management, for both species control and ecological restoration purposes.