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Mound architecture and season affect concentrations of CO2, CH4 and N2O in nests of African fungus-growing termites

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Title Mound architecture and season affect concentrations of CO2, CH4 and N2O in nests of African fungus-growing termites
 
Creator Vesala, Risto
Räsänen, Matti
Leitner, Sonja
Mulat, Daniel Girma
Mwangala, Lucas
Rikkinen, Jouko
Arppe, Laura
 
Subject biomass
carbon
carbon dioxide
ecology
greenhouse gases
measurement
methane
models
nitrous oxide
population
precipitation
sampling
seasons
species
wet season
 
Description Termites are a significant natural source of greenhouse gases (GHGs), but quantifying emissions especially from large termite mounds is problematic as they rarely fit in measurement chambers. Predicting fluxes based on internal and atmospheric concentrations could provide an indirect way to assess mound emissions, but developing such models necessitates better understanding of the concentration levels and their variance. We used gas chromatography to measure carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentrations within nests of two co‐occurring species of fungus‐growing termites in both dry and wet seasons in Kenya, with termite Macrotermes michaelseni building mounds with a closed and Macrotermes subhyalinus with an open ventilation system. Gas concentrations were 3–100 times higher in mounds than the global averages in atmosphere, implying that termite mounds are sources of all three GHGs. Carbon dioxide concentrations were higher in closed than in open mounds. Methane concentrations remained constant in open mounds, whereas closed mounds exhibited considerable variation between nests and across seasons. Concentrations of both CH4 and N2O correlated positively with mound volume during the wet season, whereas interactions with mound size were not observed in CO2 concentrations or during the driest sampling period. These findings underline that among fungus‐growing termites, mound size, ventilation type and precipitation affect nest gas concentrations and with this likely the magnitude of mound GHG emissions. Potential reasons behind the observed relationships are discussed, including differences in population size, biomass of fungus gardens and CH4 oxidation.Termites are a significant natural source of greenhouse gases (GHGs), but quantifying emissions especially from large termite mounds is problematic as they rarely fit in measurement chambers. Predicting fluxes based on internal and atmospheric concentrations could provide an indirect way to assess mound emissions, but developing such models necessitates better understanding of the concentration levels and their variance.We used gas chromatography to measure carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) concentrations within nests of two co‐occurring species of fungus‐growing termites in both dry and wet seasons in Kenya, with termite Macrotermes michaelseni building mounds with a closed and Macrotermes subhyalinus with an open ventilation system.Gas concentrations were 3–100 times higher in mounds than the global averages in atmosphere, implying that termite mounds are sources of all three GHGs. Carbon dioxide concentrations were higher in closed than in open mounds. Methane concentrations remained constant in open mounds, whereas closed mounds exhibited considerable variation between nests and across seasons. Concentrations of both CH4 and N2O correlated positively with mound volume during the wet season, whereas interactions with mound size were not observed in CO2 concentrations or during the driest sampling period.These findings underline that among fungus‐growing termites, mound size, ventilation type and precipitation affect nest gas concentrations and with this likely the magnitude of mound GHG emissions. Potential reasons behind the observed relationships are discussed, including differences in population size, biomass of fungus gardens and CH4 oxidation.
 
Date 2023-08-10
2023-10-31T12:27:32Z
2023-10-31T12:27:32Z
 
Type Journal Article
 
Identifier Vesala, R. et al. 2023. Mound architecture and season affect concentrations of CO2, CH4 and N2O in nests of African fungus-growing termites. Ecological Entomology
0307-6946
1365-2311
https://hdl.handle.net/10568/132577
https://doi.org/10.1111/een.13267
 
Rights CC-BY-4.0
Open Access
 
Publisher Wiley
 
Source Ecological Entomology