The effects of parent density and season of burn on the regeneration of Leucadendron laureolum (Proteaceae) in the Kogelberg

The responses of Leucadendron laureolum (Lam.) Fourc. to season of burn were studied in a replicated plot experiment in the Kogelberg State Forest. The eight study plots were each about 40 by 40 m. One plot was not burnt, one was burnt in summer, three in spring and three in autumn. The mean number of seedlings per parent plant was lowest after spring and highest after autumn fires. The mean number of seedlings per parent plant on the three plots burnt in autumn ranged from 9,27 to 0,26. The number of seedlings per parent plant was inversely related to the parent plant density and directly related to the rainfall in the first 120 days after each fire. The parent density on all the plots burnt in spring was relatively high and this may have had a greater influence on the number of seedlings per parent plant than fire season per se. These results support the hypothesis that post-dispersal seed predation is an important factor determining the observed seasonal patterns in seedling regeneration. The alternative hypothesis that the variation in seedling regeneration is primarily due to the seasonal fluctuation in the canopy-stored seed reserves is not supported by this data. The importance of variations in seedling regeneration after fires in different seasons both between and within species is emphasized. Communities which have Proteaceae with canopy-stored seed should be burnt in summer or autumn in order to ensure that viable populations are maintained.