PARENT SESSION
Oral Session # 42: Mammal Ecology: From Mice to Elephants.
Presiding: H Howe
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 104.
Net effects of large mammals on Acacia seedling survival in an African savanna.
Keesing, Felicia*,1, 3, Goheen, Jacob2, Ostfeld, Richard3, Allan, Brian4, Misurelli, Darcy5, 1 Bard College, Annandale, NY, USA3 Institute of Ecosystem Studies, Millbrook, NY2 University of New Mexico, Albuquerque, NM4 Rutgers University, New Brunswick, NJ5 Mpala Research Centre, Nanyuki, Kenya
ABSTRACT- Trees critically affect the functioning of savanna ecosystems through their effects on nutrient cycling, water availability, and patterns of space use by wildlife. Therefore, whatever factors influence successful recruitment of tree seedlings are important filters controlling savanna ecosystem function. In African savannas, large mammals, especially elephants, have been considered the most important agents of mortality for adult trees, but their impacts on tree seedlings are not well-known. We investigated the effects of large mammals on Acacia seedling survival by excluding large mammals from replicated, 4-ha plots. In areas where large mammals were excluded, rodents and invertebrates were more abundant and consumed approximately twice as many seedlings as on plots with large mammals. However, seedlings in areas with large mammals were more likely to die of desiccation. Overall, net seedling survival was approximately twice as high in the presence of large mammals. Our results indicate that large mammals may indirectly increase seedling survival for a dominant savanna tree, which in turn may influence tree recruitment and ecosystem function.
Key words: savanna, acacia, seedling predation, rodent