Main content area

Complementarity in the use of nitrogen forms in a temperate broad-leaved mixed forest

Jacob, Andreas, Leuschner, Christoph
Plant ecology & diversity 2015 v.8 no.2 pp. 243-258
Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia cordata, biomass, fine roots, interspecific variation, mixed forests, nitrates, nitrogen, soil, trees
Background: The complementary use of different forms of soil nitrogen (N) might lead to a higher productivity of mixed forests than monocultures, but convincing evidence for temperate mixed forests is scarce. Aims: We searched for species differences in N uptake rates and the preference for NH ₄⁺, NO ₃⁻ or glycine among five temperate broad−leaved tree species (Acer pseudoplatanus, Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia cordata) in a mature mixed stand. Methods: ¹⁵N tracer was added to the soil and its accumulation in fine root biomass was analysed after 10 min, 1 h and 1 d. Results: The estimated root uptake rates of the species were in the range of 5–46 µg N g ⁻¹ root h ⁻¹ for NH ₄⁺, 6–86 µg N g ⁻¹ h ⁻¹ for NO ₃⁻ and 4–29 µg N g ⁻¹ h ⁻¹ for glycine during the first hour after tracer application. Carpinus, Tilia and Acer tended to prefer NH ₄⁺ over NO ₃⁻, while Fraxinus showed equal preference for both N forms and Fagus seemed to prefer NO ₃⁻. Conclusions: The five co-existing tree species differed in uptake rates and partly in their N form preference, but complementarity in the use of different N forms seems to be of minor importance in this forest because tree species appear to be rather flexible in their N form use.