Termites and ungulates affect arbuscular mycorrhizal richness and infectivity in a semiarid savanna

Abstract

In savanna ecosystems, mound-building termites and ungulate herbivores profoundly affect the abundance and diversity of aboveground organisms. Yet, surprisingly little is known about how these two groups interact to impact belowground communities. Using the Kenya Long-term Exclosure Experiment (KLEE), where ungulate herbivores have been excluded for over 15 years, we examined how the presence of termites and ungulate herbivore exclusion affected species richness, community composition, and infectivity of arbuscular mycorrhizal fungi (AMF). We also measured plant richness and soil nutrients to examine how the effects of termites and ungulate exclusion may indirectly impact AMF communities. AMF richness and infectivity and plant richness were significantly lower on termite mounds than in off-mound areas. AMF infectivity and plant richness were significantly higher in off-mound areas, especially where herbivores had access. Our results revealed a strong suppressive effect of termites on AMF communities that was not enhanced or ameliorated by the presence of ungulate herbivores. Herbivores, by contrast, enhanced the relationship between plants and their fungal symbionts but only in the absence of the suppressive effects of termites. Our results underscore the importance of multiple drivers affecting the patterns of both above- and below-ground communities.