Pre- and post-fire architectural guilds of subtropical dune thicket species in the southeastern Cape Floristic Region

Aim: South Africa's subtropical dune thicket represents an interesting case for investigating plant architecture since, unlike most other dry rain forest formations, dune thicket is subject to regular fire. We asked the following questions: (a) what are the different architectural guilds amongst subtropical dune thicket species in mature, closed canopy stands; (b) what are the architectural guilds of the same species but in the early stages of resprouting post fire; (c) do pre-fire guilds predict post-fire guilds; (d) what is the significance of our findings for explaining temporal (post-fire) and spatial patterns of subtropical dune thicket species? Location: Cape St Francis, southeastern Cape Floristic Region, South Africa. Methods: We used univariate and multivariate methods to identify architectural guilds amongst 11 commonly occurring dune thicket species in closed (light-limited), long unburnt vegetation and in recently burnt stands where vegetative regrowth (sprouts) is exposed to light. Results: We found three distinct architectural guilds in unburnt subtropical dune thicket, namely hedge formers, lateral spreaders and vertical growers. In burnt thicket we also identified three resprouting architectures, namely weak resprouters, moderate resprouters and strong resprouters. There was no strong congruence between the unburnt and resprouting architectures. Conclusion: Based on the ecologies of each guild, certain expectations originated from the results of the study. We expect frequently burnt landscapes to be dominated by strongly resprouting hedge formers and lateral spreaders, infrequently burnt landscapes to be dominated by strongly resprouting lateral spreaders, and fire-free landscapes to be dominated by weakly resprouting vertical growers.

Automated summary

This study investigated plant architecture in the subtropical dune thicket of South Africa's southeastern Cape Floristic Region. It found that there was no strong congruence between unburnt and resprouting architectures, and different resprouting architectures would dominate under different fire frequencies in the landscape.