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Abstract

Impact of harvesting and prescribed burning disturbances on physical and chemical characteristics of boreal forest soils in western Newfoundland.

Prescribed burning technology is used together with other forestry practices such as tramping residue before burning, mechanical site preparation after burning, and seedling establishment (Weber & Taylor 1992). The aim of this study is to investigate the short term impact of clearcutting and prescribed burning on soil physical and soil chemical properties and nutrient contents in a boreal forest ecosystem in Newfound-land, Canada.
After burning, the weight of the humus layer (F+H) was reduced by 24%. Prescribed burning decreased the acidity (increased pH) of the humus layer. Burning increased total amounts of Ca, Mg, P, contents of extractable Ca, Mg, available P, CECeff and the Corg/Nt ratios. Extractable and total amounts of K, organic carbon contents and total nitrogen remained unaffected by burning.
The decrease in thickness and weight of the humus layer (F+H) following burning may be related to a combination of direct effects of the fire, as well as compaction. The reduced acidity in the F-, H- and mineral soil layer of the burned treatments as well as the increased cation exchange capacity (CECeff) in the organic layer was due mainly to basic ash input subsequent to burning. Reasons for the absence of any clear treatment effect of prescribed burning on total as well as extractable K in all soil layers are unclear. Magnesium and calcium are major structural component of plant tissue. It can be assumed, that in the year of burning both cations are generally not leached from the charred organic layer in significant amounts into the mineral soil, since calcium and magnesium adhere well to humus (Viro 1974). Burning induces losses of organic carbon and organically bound nitrogen via volatilization. The calcu-lated values for Corg/Nt ratio for F and H layers are typical for mor humus, and indi-cate low biological turnover processes and mineralization.



Scheuner, E.T.; Makeschin, F.; Wells, E.D. 2001. Impact of harvesting and prescribed burning disturbances on physical and chemical characteristics of boreal forest soils in western Newfoundland. Mitteilungen der Deutschen Bodenkundlichen Gesellschaft 96, 449-450.