Foliar gypsum formation and litter production in the desert shrub, Acacia bivenosa, influences sulfur and calcium biogeochemical cycling in arid habitats

Thomas Robson, Jason Stevens, Kingsley Dixon, Nathan Reid

    Research output: Contribution to journalArticle

    2 Citations (Scopus)

    Abstract

    Aims: Some sulfur-accumulating species from arid habitats facilitate a little-understood foliar gypsum (CaSO4•2H2O) biomineralisation. This study seeks to increase our understanding of the ecophysiological and nutritional function of phytogenic gypsum, including how gypsum-formers influence soil S and Ca (S/Ca) cycling mineralogy and distribution. Methods: We studied leaf composition and mineralogy (ICP-OES, SEM-EDXS) through leaf senescence and litter degradation in Acacia bivenosa DC, together with detailed soil profile analysis (composition, S chemistry & stable isotopes). Results: Acacia bivenosa accumulated foliar gypsum even when growing in surface soils without high S/Ca concentrations, accreting tissue-encapsulated gypsum, which was relatively recalcitrant to degradation, within the litter beneath the crown. Though A. bivenosa regulated limiting or potentially harmful elements during leaf senescence, it did not remobilise S/Ca or preferentially accrete gypsum in senescing foliage to enhance S/Ca excretion with litter. Instead, A. bivenosa maintained high S concentrations through reabsorption from phytogenic accretion zones supplemented by alternative sources, most likely in the deeper regolith. Conclusions: Acacia bivenosa influences S/Ca cycling, mineralogy and spatial distribution with the soil environment by readily accumulating S/Ca, which it concentrates within the topsoil as phytogenic gypsum. These phytogenic accretion zones can provide a sink for S/Ca salts and other potential phytotoxins, which could assist with revegetating sulfate-saline substrates.

    Original languageEnglish
    Pages (from-to)53–68
    Number of pages16
    JournalPlant and Soil
    DOIs
    Publication statusPublished - 1 Aug 2017

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