Effect of fire on flowering of Hyparrhenia hirta (L.) Stapf (C4), Merxmuellera disticha (Nees) Conert (C3) and Themeda triandra Forsskal (C4) on the Signal Hill, Cape Town, South Africa

Abstract

Flowering in Merxmuellera disticha was more strongly stimulated by fire in summer. Flowering tillers produced between 9 and 11 months after fire were significantly more abundant than those produced 21 to 24 months thereafter. Growth in terms of size of individuals was considered insignificant for analysis. Neighbored Hyparrhenia hirta showed, to a certain degree, an out-of-season growth, production and reproduction, whilst M. disticha and Themeda triandra on the same plots did not. The xylem water potential of H. hirta [-10.9(±0.29)], M. disticha [-14.6(±0.80)] and T. triandra [-13.8(±0.29)] on one stand differed significantly from one another (p < 0.0001), and that of H. hirta [-19.7(±0.81] and M. disticha [-34.5(±1.26)] on the other stand also differed significantly from each other (p < 0.0001). One way analysis of variance (ANOVA) thereof produced the following (F-ratio = 13.893; degrees of freedom = 29, p < 0.0001), and for H. hirta versus M. disticha, (F-ratio = 97.605; degrees of freedom = 23, p < 0.0001). Multiple range analysis tests revealed a significant difference between xylem water potentials of H. hirta from that of M. disticha and T. triandra but not between M. disticha and T. triandra.

Fire stimulates grass flowering in the Cerrado independent of season

“…During the dry season, most of the above‐ground biomass dies off and they become dormant until the next rainy season or fire, which regularly removes dead leaves attached to the base of grass tussocks and promotes grasses to resprout and persist in the plant community (Frost, 1984). Most grasses of African savannas will flower during the wet season (Menaut & Abbadie, 2004), but fire can affect flowering time by stimulating blooming out of season, immediately after fire or in the next year (Ligavha‐Mbelengwa & Bhat, 2013), while some species, such as Eragrostis capensis (Thunb.) Trin., are described as being fire‐dependent (Frost, 1984).…”