Comparison of soil nitrogen dynamics under beech, Norway spruce and Scots pine in central Germany

Vergleich der Bodenstickstoffdynamik unter Buche, Fichte und Kiefer in Mitteldeutschland

Berlin

2004

3 Abb., 4 Tab., 48 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

638

200136664

To investigate the effect of tree species on soil N dynamics in temperate forest ecosystems, total N (Nt), microbial N (Nmic), net N mineralization, net nitrification, and other soil chemical properties were comparatively examined in beech (64-68 years old) and Norway spruce (53-55 years old) on sites 1 and 2, and beech and Scots pine (45 years old) on site 3. The initial soil conditions of the two corresponding stands at each site were similar; soil types were dystric Planosol, stagnic Gleysols, and Podzols. In organic layers (LOf1, Of2, Oh), Nmic and Nmic/Nt, averaged over three sampling times (Aug., Nov., Apr.), were higher under the beech stands than under the corresponding coniferous ones. However, the Nmic in the organic layers under beech had a greater temporal variation. Incubation (10 weeks, 22 degrees C, samples from November) results showed that the net N mineralization rates in organic layers were relatively high with values of 8.1 to 24.8 mg N 1/kg 1/d. Between the two corresponding stands, the differences in net N mineralization rates in most of the organic layers were very small. In contrast, initial net nitrification rates (0.2-17.1 mg N 1/kg 1/d) were considerably lower in most of the organic layers under the conifer than under the beech. In the mineral soil (0-10 cm), Nmic values ranged from 4.1-72.7 mg 1/kg, following a clear sequence: August>November>April. Nmic values under the beech stands were significantly higher than those under the corresponding coniferous stands for samples from August and April, but not from November. The net N mineralization rates were very low in all the mineral soils studied (0.05-0.33 mg N 1/kg 1/day), and no significant difference appeared between the two contrasting tree species.