Extractable soil nitrogen following clear-cutting and burning in a beech forest

Abstract

Nitrogen (N) mineralization was monitored in the humus layer and soil in an undisturbed and harvested beech (Nothofagus) spp. forest in the West Coast of the South Island of New Zealand. To assess the effects of different harvesting regimes and intensities of burning on N mineralization, treatments applied were (i) Podocarpus spp. clear-cutting; (ii) Podocarpus spp. clear-cutting and prescribed burning; (iii) harvesting to chipwood standard (10-cm dbh); and (iv) chipwood logging and prescribed burning. Nitrate was found to be negligible in fresh and field-incubated humus and soil samples in the undisturbed beech forest. Ammonium predominated in both the humus layer and soil. Clear-cutting, and clear-cutting and burning increased NH₄⁺-N. The burning effect was confined mainly to the humus layer.