© 2003 by Institute of Chartered Foresters
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Fine root dynamics in gaps of Norway spruce stands in the German Ore Mountains
1 Institute of Silviculture and Forest Protection, Dresden University of Technology, Pienner Str. 8, 01737 Tharandt, Germany
Horizontal distribution of fine root density and fine root biomass net production were studied in six gaps and adjacent stands of pure Norway spruce using soil cores and in-growth cores. A statistical based model that does not require identifying the specific tree to each fine root was used to predict fine root distribution. This method calibrates fine root biomass functions of single trees by comparing fine root distributions with tree distributions via a least squares fit analysis. The variation of fine root density increases from 100 per cent within the stand to 250 per cent in gaps. The greatest root expansion distances regarding single tree positions were found in 35-year-old stands and in larger gaps. In-growth cores and root change maps based on model predictions show corresponding net growth rates. Net growth rates of fine root biomass differ significantly with distance to the gap edge (
-value of 0.10) with maximum values occurring in a circular strip 2.2 m from the gap edge. Our findings indicate that gaps with an average diameter <15 m should probably not be artificially regenerated because of rapid, below-ground gap closure.