© 2003 Heron Publishing—Victoria, Canada
Growth and nutrient uptake of ectomycorrhizal Pinus sylvestris seedlings in a natural substrate treated with elevated Al concentrations
Ulla Ahonen-Jonnarth (1, 2), Anders Göransson (3) and Roger D. Finlay (1, 4)
1. Department of Forest Mycology and Pathology, SLU, Box 7026, SE-750 07 Uppsala, Sweden / 2. Department of Mathematics, Natural and Computer Science, University College of Gävle, SE-801 76 Gävle, Sweden / 3. Department for Production Ecology, SLU, Box 7042, SE-750 07 Uppsala, Sweden / 4. Author to whom correspondence should be addressed (roger.finlay@mykopat.slu.se) / Received October 4, 2001; accepted July 16, 2002; published online January 31, 2003
Summary
Models of the effects of elevated concentrations of aluminum (Al) on growth and nutrient uptake of forest trees frequently
ignore the effects of mycorrhizal fungi. In this study, we present novel data indicating that ectomycorrhizal mycelia may
prevent leaching of base cations and Al. Mycorrhizal and non-mycorrhizal Pinus sylvestris L. seedlings were grown in sand obtained from the B-horizon of a local forest. In Experiment 1, non-mycorrhizal seedlings
and seedlings inoculated with Hebeloma cf. longicaudum (Pers.: Fr.) Kumm. ss. Lange or Laccaria bicolor (Maire) Orton were provided with nutrient solution containing 2.5 mM Al. Aluminum did not affect growth of non-mycorrhizal
seedlings or seedlings inoculated with L. bicolor. Seedlings colonized by H. cf. longicaudum had the highest biomass production of all seedlings grown without added Al, but the fungus did not tolerate Al. Shoots of
seedlings colonized by L. bicolor had the lowest nitrogen (N) concentrations but the highest phosphorus (P) concentrations of all seedlings. The treatments
had small but significant effects on shoot and root Al concentrations. In Experiment 2, inoculation with L. bicolor was factorially combined with the addition of a complete nutrient solution, or a solution lacking the base cations K, Ca
and Mg, and solutions containing 0 or 0.74 mM Al. Seedling growth decreased in response to 0.74 mM Al, but the effect was
significant only for non-mycorrhizal seedlings. Mycorrhizal seedlings generally had higher P concentrations than non-mycorrhizal
seedlings. Aluminum reduced P uptake in non-mycorrhizal plants but had no effect on P uptake in mycorrhizal plants. Mycorrhizal
colonization increased the pH of the soil solution by about 0.5 units and addition of Al decreased the pH by the same amount.
We conclude that the presence of ectomycorrhizal mycelia decreased leaching of base cations and Al from the soil.
Keywords:
aluminum, base cations, ectomycorrhiza, Hebeloma, Laccaria, nitrogen, phosphorus, Scots pine, tree growth.
