See more from this Division: General Discipline Sessions
See more from this Session: Paleontology III - Paleoecology, Geochronology, and Education
Abstract:
Away from termite mound hotspots' N2-fixation by Acacia trees is an important input of N into savanna ecosystems. We used stable isotopic analyses of plant tissues to investigate how termite mounds, and the preferential use of mounds by megaherbivores, generate spatial heterogeneity in N processes. We sampled Acacia, C4 grass and Aspelia sp. (non-fixing herb) foliage on and off termite mounds inside and outside of large herbivore exclosures at the Mpala Research Center in Kenya. The abundance of 15N in Acacia foliage, and therefore the amount of N not derived from N2-fixation, was significantly higher near termite mounds, and megaherbivore presence had no effect. Likewise, C4 grasses and Aspelia had higher d15N values on vs. off mounds (again no herbivore effect), indicating that Acacia trees are a source of biologically fixed N2 away from termite hotspots'. Our results show that termite mounds exert strong spatial controls on landscape-scale N cycling in forested savannas. Megaherbivore use of mound hotspots' did not enhance these patterns, indicating that termites can independently generate ecosystem-level heterogeneity.
See more from this Division: General Discipline Sessions
See more from this Session: Paleontology III - Paleoecology, Geochronology, and Education