Interspecific variation in the resprouting responses of Acacia species following simulated herbivory in a semi-arid southern African savannah

Plants have evolved a diverse suite of tolerance traits against herbivory, including compensatory growth, increased photosynthesis and activation of dormant meristems. We studied the responses of five Acacia species to simulated herbivory in a semi-arid southern African savannah. We clipped terminal shoots of five juvenile Acacia species (Acacia rehmanniana, A. nilotica, A. karroo, A. arenaria and A. gerarrdii) to simulate herbivory. We then determined biomass change after 5 months and also counted the number of resprouts and measured their length and diameter. All clipped shoots produced resprouts, with all the Acacia species compensating for the lost biomass. We found considerable interspecific variation in the compensation for biomass lost to herbivory in the five Acacia species. Resprouts biomass ranged from two times in A. arenaria to four times that removed in A. karroo. Acacia karroo produced many resprouts, while A. arenaria produced very few resprouts (4 vs 15 resprouts). The relationship between the number of resprouts and their growth also varied among the different Acacia species. We conclude that the response of Acacias to herbivory ranges from prolific resprouters (such as A. karroo) to poor resprouters (e.g. A. arenaria).