Kauri trees (Agathis australis) affect nutrient, water and light availability for their seedlings

E. Verkaik, W.G. Braakhekke

Research output: Contribution to journalArticleAcademicpeer-review

13 Citations (Scopus)

Abstract

Plants can change the soil that they grow on, for example by producing litter. If litter characteristics are such that their effect on the soil increases a plant's fitness, a positive feedback can develop between the plant and the soil. Several studies indicate that New Zealand kauri trees (Agathis australis) lower the availability of nutrients in the soil beneath their crown. Low nutrient availability would be positive for the survival of kauri seedlings as they are known to use nutrients more efficiently than angiosperm species. We tested the hypotheses that nutrient availability is lower and light availability is higher beneath kauri trees than beneath the surrounding angiosperm vegetation. We determined the availability of nutrients (using leaf nutrient concentrations as a proxy), soil moisture, and light in both situations. As a reference we did the same measurements in tea tree vegetation (Leptospermum scoparium and Kunzea ericoides) where kauri seedlings were abundant. The availability of nitrogen, phosphorus and calcium was lower under kauri than in the surrounding vegetation. Further, in a dry period the availability of water in the organic layer surrounding the kauri trunk was lower than in the mineral soil further away from the kauri trunk. We suggest that periodic drought explains why the density of kauri seedlings under mature kauri trees is less than in tea tree vegetation. Kauri seedlings are more tolerant of drought and low nutrient availability than other tree seedlings and we conclude that the conditions under mature kauri give kauri seedlings an advantage over seedlings of other tree species. The low nutrient availability under mature kauri trees supports the idea of a positive soil¿plant feedback driven by poor decomposability of kauri litter.
Original languageEnglish
Pages (from-to)39-46
Number of pages8
JournalNew Zealand Journal of Ecology
Volume31
Issue number1
Publication statusPublished - 2007

Keywords

  • don lindl kauri
  • new-zealand
  • population-dynamics
  • soil interactions
  • forest remnants
  • litter
  • growth
  • decomposition
  • biology
  • shade

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