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Keywords:

  • arbuscular mycorrhizal fungi;
  • plasticity;
  • root architecture;
  • roots;
  • soil heterogeneity

Summary

1 Nutrient-rich patches can occur in soils at a wide range of spatial and temporal scales. Differences in the root proliferation response between species may be due to differing abilities of root systems to locate and recognize patches of differing size and nutrient concentration.

2 We investigated the root proliferation responses of seven co-occurring herbaceous perennial British woodland species (Ajuga reptans, Glechoma hederacea, Oxalis acetosella, Silene dioica, Stachys sylvatica, Veronica montana and Viola riviniana) and the effect of mycorrhizal colonization on any response.

3 Plants were planted in nutrient-poor sand in the centre of rectangular pots, with a nutrient-rich patch to one side and a control (sand) patch on the other. Size and nutrient concentration of the patches were varied between treatments.

4 Species differed in the size of their root systems and in their ability to respond to localized nutrient-rich patches. Oxalis acetosella and Viola riviniana, which produced the smallest root systems, showed similar root growth in nutrient-rich and control patches. All other species responded to the presence of a nutrient-rich patch by various combinations of root proliferation, changes in root branching pattern and by an increase in specific root length.

5 In some species the response was affected by patch attributes: Silene dioica and Veronica montana were sensitive to the nutrient concentration of the patch, and Glechoma hederacea did not respond to the smallest sized patch.

6 Mycorrhizal colonization had little effect on root proliferation. Only one species (Oxalis acetosella) could be shown to benefit from colonization by increased phosphate uptake.

7 The soil is a heterogeneous environment in terms of nutrient availability; differences between species in the ability to exploit this heterogeneity may affect their distribution, and could be a mechanism that reduces interspecific root competition.