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Root trait variation in African savannas

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Abstract

Aims

While patterns of variation in woody plant aboveground traits related to disturbance and resource availability in savanna ecosystems are fairly well understood, dimensions of variation in belowground traits remain poorly understood. We investigate how sapling coarse root (>2 mm diameter) traits and belowground storage organs vary with respect to differing disturbance regimes (i.e. fire or herbivore dominated) and soil fertility in Southern African savannas.

Methods

We examined how sapling rooting strategies (type of rooting system, storage organs, root allocation) as well as root total non-structural carbohydrate concentrations [TNC], root N and C:N of 69 common woody savanna and forest species at 16 sites vary with respect to differing disturbance regimes and soil fertility.

Results

We found that root [TNC] and the occurrence of storage organs were highest while root N was lowest for species growing at fire-driven sites, compared to herbivore-driven sites and competition-controlled forest species. Allocation to belowground biomass was higher at fire-dominated sites but root volume:stem basal area did not differ between disturbance regimes. None of the measured traits were found to differ between nutrient rich clayey soils and nutrient poor sandy soils.

Conclusions

Our results suggest that disturbance related controls are important drivers of savanna belowground traits.

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Acknowledgements

We are grateful to SANParks, Ezemvelo KZN Wildlife, the Zimbabwe Parks and Wildlife Authority and several anonymous private landowners for their support. Lab analyses for this study were partially supported by the Institute of Dendrology, Polish Academy of Sciences, Kórnik, Poland. We also want to thank the reviewers for their thoughtful inputs and comments on an earlier draft.

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Authors and Affiliations

  1. National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK, Bellary Road, Bangalore, 560 065, India

    Benjamin J. Wigley

  2. School of Natural Resource Management, Nelson Mandela University, George Campus, George, South Africa

    Benjamin J. Wigley & Corli Wigley-Coetsee

  3. Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, USA

    A. Carla Staver

  4. Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, PL-62-035, Kornik, Poland

    Roma Zytkowiak & Andrzej M. Jagodzinski

  5. Scientific Services, Kruger National Park, Private Bag X402, Skukuza, 1350, South Africa

    Corli Wigley-Coetsee

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  1. Benjamin J. Wigley
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  2. A. Carla Staver
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  3. Roma Zytkowiak
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Correspondence to Benjamin J. Wigley.

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Wigley, B.J., Staver, A.C., Zytkowiak, R. et al. Root trait variation in African savannas. Plant Soil 441, 555–565 (2019). https://doi.org/10.1007/s11104-019-04145-3

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