Fine root biomass, production and its proportion of NPP in a fertile middle-aged Norway spruce forest: Comparison of soil core and ingrowth core methods

Fine root bio- and necromass, net primary production (NPP) of fine roots and its proportion of the NPP of trees, as well as turnover rate were investigated in a fertile middle-aged Norway spruce ( Picea abies (L.) Karst) stand by sequential core and ingrowth core methods. The stand's site type is Oxalis, the site quality class is I a and the soil type is Umbric Luvisol (FAO classification). Twenty soil cores (volumetric samples, core diameter 38 mm) were taken monthly during the period June-1996 to November 1996 and in June-1997. Ingrowth cores were collected, 15 at a time, during the growing seasons from 1997 to 1999, once after first year and three times in the second and third years. Spruce roots from samples collected by both methods were separated into living and dead roots (two diameter classes: