Biomass removals during harvesting or site preparation cause major changes in C and nutrient stores and potentially affect long-term site productivity. We assessed C and N stores in a highly productive coastal Washington site before and after imposing biomass removal treatments to a 46-year old Douglas-fir/western hemlock stand. Treatments included removal of commercial bole (B0), bole only up to 5-cm top diameter (BO5), total tree (TT), and total tree plus all legacy woody debris (TT+). The stand contained similar amounts of C above the mineral soil (294 Mg ha-1) as within the mineral soil to 80-cm depth including roots (297 Mg ha-1). Carbon stores above the mineral soil by size were live trees (194 Mg ha-1), forest floor (27 Mg ha-1), coarse woody debris (11 Mg ha-1), dead trees/snags (7 Mg ha-1), and understory vegetation (0.1 Mg ha-1). Carbon in the mineral soil amounted to 249 Mg ha-1 while roots added 49 Mg ha-1. Total N in mineral soil and roots was more than ten-fold greater (13.6 Mg ha-1) than the N store above the mineral soil (1.3 Mg ha-1). After harvest, C stores above the mineral soil decreased to 130 Mg ha-1 in BO, 121 Mg ha-1 in BO5, 64 Mg ha-1 in TT and 51 Mg ha-1 in TT+. Post-harvest forest floor C averaged 24 Mg ha-1 in TT and TT+, against 45 Mg-1ha in BO and BO5, and 27 Mg ha-1 in the pre-harvest stand. Total N above the mineral soil averaged 779 Mg ha-1 in BO and BO5, and decreased to 414 and 347 Mg ha-1 in TT and TT+, respectively, while soil N remained mostly unchanged. Proportion of C stores above and within the mineral soil was markedly altered by removals while total N was only reduced by 6% in the most intensive treatment.
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