Hans Erens

Termites facilitate methane oxidation and shape the methanotrophic community.

ABSTRACT Termite-derived methane contributes 3 to 4% to the total methane budget globally. Termites are not known to harbor methane-oxidizing microorganisms (methanotrophs). However, a considerable fraction of the methane produced can be consumed by methanotrophs that inhabit the mound material, yet the methanotroph ecology in these environments is virtually unknown. The potential for methane oxidation was determined using slurry incubations under conditions with high (12%) and in situ (∼0.004%) methane concentrations through a vertical profile of a termite (Macrotermes falciger) mound and a reference soil. Interestingly, the mound material showed higher methanotrophic activity. The methanotroph community structure was determined by means of a pmoA-based diagnostic microarray. Although the methanotrophs in the mound were derived from populations in the reference soil, it appears that termite activity selected for a distinct community. Applying an indicator species analysis revealed that putative atmospheric methane oxidizers (high-indicator-value probes specific for the JR3 cluster) were indicative of the active nest area, whereas methanotrophs belonging to both type I and type II were indicative of the reference soil. We conclude that termites modify their environment, resulting in higher methane oxidation and selecting and/or enriching for a distinct methanotroph population.

Effects of spreading out termite mound material on ferralsol fertility, Katanga, D.R. Congo

ABSTRACT Around Lubumbashi, the introduction of large-scale pivot-irrigated agriculture entails leveling of large termite mounds during field preparation. The effect on soil fertility and crop yield (Solanum tuberosum and Alium cepa) is evaluated along 11 transects extending from a former termite mound location to reference soil that received no termite mound material. Spreading mound material was found to increase the pH, calcium carbonates CaCO3 content, and the amount of resin-extractable phosphorus (P), other possible effects being undone by fertilizer application. On the other hand, poor physical properties of the mound material seem to have adverse effects on crop production. While the benefits of spreading out mound material seem limited for large-scale farmers with access to fertilizers, the use of mound material may present an opportunity to resource-poor farmers throughout the miombo eco-region, provided that the application of mound materials is optimized and that any adverse effect on soil physical properties can be mitigated.