The effects of fire frequency on vegetation structure and mammal assemblages in a savannah-woodland system

Abstract

Fire frequency affects vegetation structure and composition in savannah- woodlands, with the potential indirect consequence of affecting the habitat choice and space use of large mammals. Understanding these responses can assist with the development of appropriate fire management policies to conserve co-existing species with different habitat requirements. In a natural experiment in Majete Wildlife Reserve, Malawi, we compared vegetation composition, woody plant structure and large (>5 kg) mammal assemblages on 10 frequently and 10 infrequently burnt 30-ha plots, that had fire return intervals of <2.5 and >6 years, respectively, between 2001 and 2019. Fire frequency had little effect on woody plant composition, but did affect grass species composition. Frequent burning reduced mean tree height from 4 to 3 m, woody plant cover from 59% to 35%, and resulted in the dominance of short-statured, lesspalatable grasses. Many mammal species showed clear preferences for either frequently burnt (e.g. buffalo, zebra, kudu, impala and sable) or infrequently burnt (e.g. nyala, bush pig, baboon, common duiker and vervet monkey) areas, while others (e.g. elephants and black rhinoceros) were not selective. We conclude that establishing a mosaic of patches exposed to different fire frequencies would allow for the persistence of all mammal species in the area by creating an optimal range of habitat types.