Variability in soil and foliar stable carbon and nitrogen isotope compositions in the winter rainfall biomes of South Africa. (May 2022)

• Record Type: Journal Article
• Authors: Carr, Andrew S.; Chase, Brian M.; Boom, Arnoud; Meadows, Michael E.; Sanchez, Javier Medina
• Is Part Of: Journal of arid environments. Volume 200(2022)
• Publication Date: 2022-05
• Subjects: CAM plant -- Climate -- Photosynthesis -- Organic matter -- Fynbos -- Succulent karoo; Arid regions ecology -- Periodicals; Arid regions -- Periodicals; Écologie des régions arides -- Périodiques; Régions arides -- Périodiques; 577.54
• DOI: 10.1016/j.jaridenv.2022.104726
• Languages: English
• ISSNs: 0140-1963

Abstract

Abstract: We present the stable carbon and nitrogen isotope compositions of 204 plants and 99 soils from South Africa's Fynbos and Succulent Karoo biomes, from which we assess variability in δ 13 C and δ 15 N within and between the biomes. Higher foliar δ 13 C in the Succulent Karoo (−22.4 ± 4.7‰) primarily reflects a greater abundance of CAM photosynthesis relative to Fynbos (−25.7 ± 3.5‰). For C3 plants within the Fynbos Biome, there is no statistically significant relationship between δ 13 C and climate, suggesting that within the present sampling framework, local-scale variability masks expected climatic controls on C3 plant δ 13 C. Soil and foliar δ 15 N are highly variable, but foliar δ 15 N is significantly higher in the Succulent Karoo (7.7 ± 3.9‰) compared to the Fynbos (4.4 ± 3.3‰). Soil and foliar δ 15 N correlate, with soils 3 ± 1‰ more enriched in 15 N. Both soil and foliar δ 15 N show stronger correlations with climate than δ 13 C, and they accord with the previously observed tendency for higher δ 15 N with greater aridity. The relationship between δ 15 N and mean annual rainfall is, however, relatively steep (2.4 ± 0.6‰ per 100 mm rainfall), potentially implying additional controls on δ 15 N variability. These data provide a benchmarking of contemporary isotopic variability, anticipated to support future archaeological, palaeoenvironmental and C and N cycling research. Highlights: Foliar and soil δ 13 C distinct between biomes Foliar δ 13 C for C3 plants in the Fynbos biome is un-correlated with climate Foliar δ 15 N is highly variable at the plot scale Plot average soil and foliar δ 15 N negatively correlated with rainfall Foliar isotopic signatures are mirrored in associated soils