Temperature fluctuations inside savanna termite mounds: Do size and plant shade matter?

• Published in: Journal of thermal biology Vol. 74; pp. 23 - 28
• Main Authors: Ndlovu, M., Pérez-Rodríguez, A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-05-2018; Elsevier BV
• Subjects: Environment; Fungi; Fungus gardens; General additive mixed models GAMM; Generalized linear models; Kruger National Park; Macrotermes natalensis; Mounds; Shade; South Africa; Temperature; Temperature effects; Termites; Vegetation; South Africa; Macrotermes natalensis; South Africa; Temperature; Kruger National Park; General additive mixed models GAMM
• ISSN: 0306-4565; 1879-0992
• DOI: 10.1016/j.jtherbio.2018.03.004

Mound building termites are key ecosystem engineers of subtropical savanna regions. Mounds allow termites to maintain suitable conditions for termite reproduction and food cultivation ('fungus gardens'). We studied how the internal mound temperature of Macrotermes natalensis, a dominant mound-building termite of the subtropical savanna of southern Africa, responds to a number of environmental variables. We used general additive mixed models (GAMM) to determine how external temperature, mound size (volume) and the amount of vegetation shade affects mound internal temperature over a 24-h period. Internal mound temperature varied daily following changes of the external temperature, although the range of variation was much smaller. Active termite mounds maintained a higher internal temperature than inactive ones, and mound activity reinforced the positive effect of mound size and moderated the negative effect of vegetation shade on internal temperatures. In turn, external temperature fluctuations equally affected active and inactive mounds. Large mounds maintained near optimal internal temperatures compared to smaller sized mounds. We therefore conclude that termite mound size is a stronger determinant of internal mound temperature stability compared to plant shade cover.
•Temperature profiles inside 79 mounds were measured over a 24-h period.•We assessed how several variables affected termite mound temperature.•External temperature equally affected active and inactive mounds.•Large mounds maintained higher constant internal temperatures than smaller mounds.•Mound size was a stronger determinant of thermoregulation ability than shade.