The effect of the interplay between fire frequency and grassland structure on tick abundances in the Hluhluwe-iMfolozi Park, South Africa

Abstract: Fire in ecology is a very variable factor and its effects are best described as a complex feedback system with other biotic and abiotic factors. These feedback systems need to be understood to enable generalized conclusions about the influence of fire regimes. The concept of pyrodiversity describes the variability in the characteristics of fire, such as fire intensity or frequency. This study investigated how the feedback mechanism between grassland structure in the form of grazing lawn abundance and distribution, and fire frequency affect the abundance of ticks (Class: Arachnida, Subclass: Acari), which are highly connected to both factors. I sampled tick abundances in 30 plots in the Hluhluwe‐iMfolozi Park (South Africa) via tick drags. While neither of the parameters had an effect in itself, the interaction between grazing lawn coverage and long‐term fire frequency significantly affected tick abundances leading to lower abundances with increasing lawn coverage in areas of low, but not at high, fire frequencies. The heterogeneity of their distribution was dependant on the heterogeneity of grass biomass, herbivore density and an interaction between the average grass biomass and the short‐term fire frequency in the last 17 years. Tick distribution was more heterogeneous in areas of high grass biomass or zero short‐term fire frequency, but more variable in areas with low fire frequencies above zero. This indicates that the effect of pyrodiversity on certain species could vary with other environmental factors important for the species. It also suggests that the disappearance of grazing lawns could lead to an increase in tick abundance if fire management plans are not adapted accordingly, potentially leading to higher herbivore tick infestations.