Comparing fast- and slow-growing provenances of Picea koraiensis in biomass, carbon parameters and their relationships with growth

Tree genetic selection programs are primarily focused on improving stem volume plantation productivity. Due to changes in climate and emergence of carbon (C) market, plantations are also being credited for total biomass productivity and C sequestration. Does growth selection adversely affect total above- and belowground biomass and C sequestration? We investigated this by comparing two fast-growing provenances (LS and CH) to a slow-growing provenance (KT) from a 31-year-old Picea koraiensis experiment. Results showed that (1) the fast-growing provenances could enhance both above- and belowground biomass productivity and carbon sequestration. On average, trees of LS and CH provenances produced 16.1% and 31.8% more biomass and had 17.2% and 31.8% more C stock, respectively, than KT provenance, although these differences were statistically non-significant (P < 0.10). The fast-growing provenances displayed a comparable to or even slightly higher C concentration than KT provenance; (2) growth selection influenced biomass and C partitioning. Compared to KT, the CH and LS allocated relatively more to stem wood but less to the needles and branches aboveground and partitioned more to the stump and coarse roots but less to the fine and medium size roots belowground. The fast-growing provenances had a very similar or lower above- to belowground biomass partitioning slope. Thus, the superiority of the aboveground growth of LS and CH was not achieved at the expense of belowground compartments; and (3) the best function to predict biomass and C content was 'a(DBH2H)b'. Fitting provenance-specific relationship parameter (a or b) improved prediction precision. This was particularly true for b and for the biomass of branches, aboveground and whole tree. Overall our results suggest the possibility of improving biomass productivity and C sequestration via planting growth-improved seed sources. Implications to tree improvement are discussed.