Carbon allocation in an East African ant-acacia: field testing a 13C-labeling method for evaluating biotic impacts on the carbon cycle

• Published in: Plant ecology 2023-11, Vol.224 (11), p.953-963
• Main Authors: Mizell, Gabriella M., Kim, Thomas, Sullivan, Benjamin W., Lemboi, John S., Mosiany, John, Palmer, Todd M., Pringle, Elizabeth G.
• Format: Article
• Language: English
• Subjects: Applied Ecology; Biodiversity; Biomedical and Life Sciences; Carbon; Carbon 13; Carbon cycle; Community & Population Ecology; Ecology; Herbivores; Labeling; Life Sciences; Plant Ecology; Terrestial Ecology; Trees; Vertebrates
• ISSN: 1385-0237; 1573-5052
• DOI: 10.1007/s11258-023-01350-0

Tree carbon allocation is a dynamic process that depends on the tree’s environment, but we know relatively little about how biotic interactions influence these dynamics. In central Kenya, the loss of vertebrate herbivores and the savanna’s invasion by the ant Pheidole megacephala are disrupting mutualisms between the foundational tree Acacia ( Vachellia ) drepanolobium and its native ant defenders. Here, we piloted a 13 Carbon (C) pulse-labeling method to investigate the influence of these biotic interactions on C allocation to ant partners by adult trees in situ. Trees withstood experimental conditions and took up sufficient labeled 13 CO 2 for 13 C to be detected in various C sinks, including ant mutualists. The δ 13 C in ants collected shortly after labeling suggested that trees exposed to herbivores allocated relatively more newly assimilated C to native ant defenders. Our results demonstrate the viability of the pulse-labeling method and suggest that C allocation to ant partners depends on the biotic context of the tree, but further investigation with replication is needed to characterize such differences in relation to invasion and herbivore loss.