Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales

Andrew B. Davies, Shaun R. Levick, Mark P. Robertson, Berndt J. van Rensburg, Gregory P. Asner, Catherine L. Parr

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Herbivores do not forage uniformly across landscapes, but select for patches of higher nutrition and lower predation risk. Macrotermes mounds contain higher concentrations of soil nutrients and support grasses of higher nutritional value than the surrounding savanna matrix, attracting mammalian grazers that preferentially forage on termite mound vegetation. However, little is known about the spatial extent of such termite influence on grazing patterns and how it might differ in time and space. We measured grazing intensity in three African savanna types differing in rainfall and foliar nutrients and predicted that the functional importance of mounds for grazing herbivores would increase as the difference in foliar nutrient levels between mound and savanna matrix grasses increases and the mounds become more attractive. We expected this to occur in nutrient-poor areas and during the dry season when savanna matrix grass nutrient levels are lower. Tuft use and grass N and P content were measured along transects away from termite mounds, enabling calculation of the spatial extent of termite influence on mammalian grazing. Using termite mound densities estimated from airborne light detection and ranging (LiDAR), we further upscaled field-based results to determine the percentage of the landscape influenced by termite activity. Grasses in close proximity to termite mounds were preferentially grazed at all sites and in both seasons, but the strength of mound influence varied between savanna types and seasons. In the wet season, mounds had a relatively larger effect on grazers at the landscape scale in the nutrient-poor, wetter savanna, whereas in the dry season the pattern was reversed with more of the landscape influenced at the nutrient-rich, driest site. Our results reveal that termite mounds enhance the value of savanna landscapes for herbivores, but that their functional importance varies across savanna types and seasons.

Original languageEnglish (US)
Pages (from-to)726-734
Number of pages9
JournalOikos
Volume125
Issue number5
DOIs
StatePublished - May 1 2016
Externally publishedYes

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termite mounds
termite
savanna
savannas
herbivore
herbivores
grass
nutrient
grasses
nutrients
grazing
Isoptera
matrix
forage
dry season
Macrotermes
lidar
grazing intensity
predation risk
soil nutrient

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

Cite this

Davies, A. B., Levick, S. R., Robertson, M. P., van Rensburg, B. J., Asner, G. P., & Parr, C. L. (2016). Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales. Oikos, 125(5), 726-734. https://doi.org/10.1111/oik.02742

Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales. / Davies, Andrew B.; Levick, Shaun R.; Robertson, Mark P.; van Rensburg, Berndt J.; Asner, Gregory P.; Parr, Catherine L.

In: Oikos, Vol. 125, No. 5, 01.05.2016, p. 726-734.

Research output: Contribution to journalArticle

Davies, AB, Levick, SR, Robertson, MP, van Rensburg, BJ, Asner, GP & Parr, CL 2016, 'Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales', Oikos, vol. 125, no. 5, pp. 726-734. https://doi.org/10.1111/oik.02742
Davies, Andrew B. ; Levick, Shaun R. ; Robertson, Mark P. ; van Rensburg, Berndt J. ; Asner, Gregory P. ; Parr, Catherine L. / Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales. In: Oikos. 2016 ; Vol. 125, No. 5. pp. 726-734.
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