This thesis aims at improving the knowledge on the post-fire vegetationregeneration. For that, forests and shrublands were studied, after forest fires andexperimental fires.Maritime Pine (Pinus pinaster) recruitment after fire was studied. Fire severitywas evidenced as a major effect on this process. High crown fire severity cancombust the pines, destroying the seed bank and impeding post fire pinerecruitment. However, crown combustion also influences the post-fire conditionson the soil surface, since high crown combustion (HCC) will decrease the postfireneedle cast. After low crown combustion (LCC) (scorched rather than torchedcrowns), a considerable needle cover was observed, along with a higher densityof pine seedlings. The overall trends of post-fire recruitment among LCC andHCC areas could be significantly attributed to cover by needles, as well by theestimation of fire severity using the diameters of the burned twigs (TSI).Fire increased the germination from the soil seed bank of a Pinus pinaster forest,and the effects were also related with fire severity. The densities of seedlings ofthe dominant taxa (genus Erica and Calluna vulgaris) were contrastingly affectedin relation to the unburned situation, depending on fire severity, as estimatedfrom the degree of fire-induced crown damage (LCC/HCC), as well as using aseverity index based on the diameters of remaining twigs (TSI). Low severitypatches had an increase in germination density relatively to the control, whilehigh severity patches suffered a reduction.After an experimental fire in a heathland dominated by Pterospartum tridentatum,Erica australis and E. umbellata, no net differences in seedling emergence wereobserved, in relation to the pre-fire situation. However, rather than having noeffect, the heterogeneity of temperatures caused by fire promoted causeddivergent effects over the burned plot in terms of Erica australis germination – aprogressive increased was observed in the plots were maximum temperaturerecorded ranged from 29 to 42.5ºC and decreased in plots with maximumtemperature ranging from 51.5 to 74.5ºC. In this heathland, the seed density oftwo of the main species (E. australis and E. umbellata) was higher under theircanopies, but the same was not true for P. tridentatum.The understory regeneration in pine and eucalypt stands, 5 to 6 years post fire,has been strongly associated with post-fire management practices. The effect offorest type was, comparatively, insignificant. Soil tilling, tree harvesting and shrubclearance, were linked to lower soil cover percentages. However, while all thesemanagement operations negatively affected the cover of resprouters, seederswere not affected by soil tilling. A strong influence of biogeographic region wasidentified, suggesting that more vulnerable regions may suffer higher effects ofmanagement, even under comparatively lower management pressure than moreproductive regions. This emphasizes the need to adequate post-firemanagement techniques to the target regions.
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