Sapling survival in a frequently burnt savanna: mobilisation of carbon reserves in Acacia karoo

B.J. Wigley, Michael Cramer, W.J. Bond

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    59 Citations (Scopus)


    In frequently burnt savannas, saplingsface the formidable challenge of both recoveringfrom, and eventually growing tall enough to escapefrom, frequent fire damage. The aim of this study wasto explore how saplings allocate carbon to achievethese ends through carbon partitioning, storage andremobilization. Lignotuber total non-structural carbohydrate(TNC) concentrations and d13C values ofAcacia karroo (Fabaceae; Mimosoideae) were determinedin plants from two different juvenile stages.These were one year after a fire when the plantconsisted of numerous leafy shoots or coppices(‘‘coppicing’’ stage), and three years after a fire whenthe plant consisted of one pole-like stem (‘‘Gulliver’’stage). Gulliver lignotubers were found to havesignificantly larger TNC pools (150 g vs. 97 g) andlarger TNC concentrations (33% vs. 24%, w/w) thancoppice lignotubers showing that post-coppice Gulliversrecharged TNC in the lignotuber. d13C valuesfrom the stems of plants in the Gulliver stage weresignificantly enriched ([1%) in 13C compared to bothcoppicing (P\0.01) and adult (P\0.05) plants.Changes in both the amount of stored carbon and inthe d13C values indicated dependence on storedcarbon reserves, and partially heterotrophic growthfor initial resprouting. The plants appeared to use bothcurrent photosynthate and stored carbon reserves forgrowth of the Gulliver stem. The use of stored carbonis hypothesized to promote fast stem growth rates to aheight where saplings escape fire injury.
    Original languageEnglish
    Pages (from-to)1-11
    JournalPlant Ecology
    Issue number1
    Publication statusPublished - 2009


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