Effects of season of burn on shrub survival, regeneration and structure in the Natal Drakensberg.

Abstract

Four scrub species which tend to invade in burnt grassland were studied in field-burning trials at Cathedral Peak in the Natal Drakensberg. Results showed that neither hot winter burns, nor cool summer burns, affected the ability of Buddleia salviifolia, Leucosidea sericea, Widdringtonia nodiflora or Philippia evansii to survive fire. The first three species resprouted following damage to their shoot systems. The winter burns damaged more canopy, resulting in proportionally more basal resprouting and higher net gains in new stems. Summer burns, on the other hand, resulted in proportionally more defoliated stems developing aerial resprouts. P. evansii, in contrast, was sensitive to fire and the species regenerated from seed, with larger recruitment of seedlings following winter than summer burns. Season of burn was shown to be important insofar as it affected shrub structure and the nature and amount of regeneration. Management objectives would therefore influence the way in which fire is used in these shrublands.

Keywords: Aerial resprouting; Basal resprouting; Buddleia salviifolia; Canopy defoliation; cathedral peak; damage; Drakensberg; Field burning; Fire; Fire behaviour; grassland; KwaZulu/Natal; Leucosidea sericea; management; natal; natal drakensberg; philippia; Philippia evansii; recruitment; regeneration; season of burn; Seasons; Seed germination; Shrub regeneration; Shrub structure; Shrub survival; shrubland; Shrubs; summer; trails; widdringtonia; Widdringtonia nodiflora; winter

Journal of the Grassland Society of Southern Africa.