Stand and soil changes along a mountain hemlock death and regrowth sequence

Stand characteristics, dead wood, and soil carbon (C) and nitrogen (N) pools were measured through a wave-regenerated sequence of mountain hemlock death and regrowth created by Phellinus weirii. Stem density increased along the 96-yr regrowth sequence, but was low in the 225-yr-old, mature stand. Total ecosystem C (TEC) dropped upon stand death and did not recover. Net ecosystem production (NEP) was negative just after stand death and zero thereafter. The O2 horizon and the forest floor (O1 / O2) had greater mass, organic matter, and N capital in the mature stand than in the bare or regrowth zones. From the mature stand to the bare zone, forest-floor organic matter decrease 27% and C and N 24%. The forest-floor N decrease was offset by an equal N increase in the mineral soil at 0-15 cm depth. Mineral-soil C, as well as C and N for the sum of the forest floor / mineral soil, were constant across the death and regrowth sequence. The C/N ratio peaked for O1 material, and reached its minimum for fine roots, in the bare zone.