Are larger termite mounds more resistant to fire? A study of two southern African termites (Isoptera: Termitidae)

Abstract

Termites are resistant to fire, a common disturbance in the world's savannas, but most explanations for how termites resist fire are speculative. Some researchers have suggested that the mounds of some termite species can serve as a structural defence against direct fire mortality. Because mound structure is related to thermoregulation, and larger mounds have more stable internal temperatures, larger mounds may confer greater fire resistance. Fire also causes indirect mortality to termites by removing food sources, which may give an advantage to larger mounds as they have superior food provisioning and storage ability. Using natural fires, we measured mound size and colony survival of two southern African termite species (Trinervitermes trinervoides and Amitermes sp.) in plots recently burnt (<4 months after fire), recovering from fire (1–2 years after fire), or unburnt (>3 years after fire). Burn status and mound size were each significant factors in colony survival. Recent fire was associated with the lowest survival, and larger mounds with greater survival. There is some evidence that larger mounds are generally more resistant to fire, especially the long term, indirect effects, but sample sizes were not adequate to confirm this.