Get access

Plant diversity is linked to nutrient limitation of dominant species in a world biodiversity hotspot

Authors

  • Burak K. Pekin,

    Corresponding author
    1. Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, USA
    • Ecosystems Research Group, School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    Search for more papers by this author
  • Matthias M. Boer,

    Corresponding author
    1. Hawkesbury Institute for the Environment, University of Western Sydney, South Penrith, NSW, Australia
    • Ecosystems Research Group, School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    Search for more papers by this author
  • Roy S. Wittkuhn,

    1. Science Division, Department of Environment & Conservation, Bentley Delivery Centre, WA, Australia
    Search for more papers by this author
  • Craig Macfarlane,

    1. CSIRO Sustainable Ecosystems, Centre for Environment and Life Sciences, Wembley, WA, Australia
    Search for more papers by this author
  • Pauline F. Grierson

    Corresponding author
    • Ecosystems Research Group, School of Plant Biology, The University of Western Australia, Crawley, WA, Australia
    Search for more papers by this author

Abstract

Questions

What is the role of nutrient limitation of dominant species in maintaining plant species diversity at small spatial scales, particularly in biodiversity hotspots?

Location

Southwest of Western Australia.

Methods

The extent of nutrient limitation was determined by measuring variation in the foliar nutrients of dominant plant species and total above-ground biomass in relation to soil N and P across 16 plots. Plant species richness and evenness for the same plots were then regressed against foliar N:P and δ15N of the dominant species.

Results

Foliar N and P content as well as above-ground biomass increased, while foliar N:P decreased with increasing soil N and P, suggesting that dominant species are limited by both N and P in southwest Australia. In contrast, foliar δ15N values only increased with decreasing soil P, indicating that δ15N enrichment reflects low P availability. Species richness increased at sites where foliar N:P was higher and δ15N more enriched, suggesting that a relatively greater number of rare plant species co-exist where the growth of dominant vegetation is more nutrient-limited.

Conclusions

The mechanisms that allow an exceptionally high number of plant species to co-exist at small spatial scales in a southwest Australian biodiversity hotspot are linked to the extent to which the dominant plant species are limited in N and P. In addition, on nutrient-impoverished soils, a foliar N:P ratio >16 can reflect N as well as P limitation. While foliar δ15N also reflects availability of soil P, it is not necessarily a reliable indicator of nutrient limitation in southwest Australia, and perhaps in other environments where plants are highly adapted to low-nutrient conditions.

Ancillary