C and N transformations in forest soil after mounding for regeneration

2000

S. 17-28

9 Abb, 2 Tab., 20 Lit.

Unselbständiges Werk

200068071

Forest Ecology and Management 2000 ; 134 (1-3), S. 17-28

Carbon and nitrogen transformation were monitored in mounded and unmounded forest soil for 3 years after mounding. The mounding was done 1 year after the clear-cutting of a Norway spruce stand where a forest fertilization experiment had been carried out for 30 years with the following treatments: control, N fertilization, liming and combined N fertilization and liming. In the mounding plots, soil was sampled from the buried double humus layer of the mounds and from the undisturbed humus layer on the corresponding plots without soil preparation. Mounding decreased carbon mineralization in the humus layer, but had little effect on microbial biomass C and N, and net formation of mineral N and nitrification. Microbial biomass and activities were always higher in the humus layer than in the mineral soil layers. This was observed in both the mounded and unmounded plots. Net formation of mineral N and nitrification were, however, intensive also in the mineral soil layers of the unmounded, previously limed plots. Higher N concentrations, especially NO3-N and total N, in soil solutions were found in the mounded plots compared to the unmounded plots. The discrepancy between net formation of mineral N, nitrification and soil solution results can be explained to a great extent by the double amount of organic matter in the mounds. Mineral nitrogen concentrations of soil solution decreased during the 2 years after mounding, obviously due to the development of ground vegetation. The planting of birch seedlings increased microbial biomass C and carbon mineralization in the mineral soil of the mounds.