Early post-fire regeneration in Pinus brutia forest ecosystems of Samos island (Greece)

Abstract

The recovery of the burnt pine (Pinus brutia) forests of Samos island was followed during the first three post-fire years. Samos is characterised by a Mediterranean-type climate with a mild, subhumid winter and a long xerothermic period. The natural regeneration of P. brutia is realised exclusively by seeds and is enhanced by a number of adaptations to fire: (i) the cones are serotinous and xerochasic, so most seeds survive inside the cones and are disseminated by the strong winds immediately after fire; (ii) the seeds are non-dormant and can germinate throughout the rainy season, though two frequency peaks were observed (a major one in spring and a minor one in late autumn); (iii) the heliophilous nature of both seed germination and seedling establishment is promoted by the opening of habitats produced by fire; (iv) from the survival curve it is evident that pine seedlings show a considerable drought tolerance and, once settled, their survival chance is quite high. The average density of pine seedlings measured after 15 months was 0.30 seedlings/m2, high enough to result in complete natural reforestation for most of the area burnt. The ecosystem recovery was additionally characterised by a prolific regeneration through both seed germination and resprouting. Among the reseeders, an eminent role was allocated to Cistus spp. and many leguminous plants. Resprouting was also very important and was especially impressive among the evergreen sclerophylls, the geophytes-hemicryptophytes and several phryganic shrubs.