Data from: Ecosystem carbon density and allocation across a chronosequence of longleaf pine forests

Forests can partially offset greenhouse gas emissions and contribute to
climate change mitigation, mainly through increases in live biomass. We
quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris
Mill.) forests ranging in age from five to 118 years located across the
southeastern USA and estimated above and belowground C trajectories.
Ecosystem C stock (all pools including soil C) and aboveground live tree C
increased nonlinearly with stand age and the modeled asymptotic maxima
were 168 Mg C/ha and 80 Mg C/ha, respectively. Accumulation of ecosystem C
with stand age was driven mainly by increases in aboveground live tree C,
which ranged from <1 Mg C/ha to 74 Mg C/ha and comprised <1%
to 39% of ecosystem C. Live root C (sum of below-stump C, ground
penetrating radar measurement of lateral root C, and live fine root C)
increased with stand age and represented 4% to 22% of ecosystem C. Soil C
was related to site index, but not to stand age, and comprised 39% to 92%
of ecosystem C. Live understory C, forest floor C, down dead wood C and
standing dead wood C were small fractions of ecosystem C in these
frequently burned stands. Stand age and site index accounted for 76% of
the variation in ecosystem C among stands. The mean root to shoot ratio
calculated as the average across all stands (excluding the grass stage
stand) was 0.54 (standard deviation of 0.19) and higher than reports for
other conifers. Long-term accumulation of live tree C, combined with the
larger role of belowground accumulation of lateral root C than in other
forest types, indicates a role of longleaf pine forests in providing
disturbance-resistant C storage that can balance the more rapid C
accumulation and C removal associated with more intensively managed
forests. Although other managed southern pine systems sequester more C
over the short-term, we suggest that longleaf pine forests can play a
meaningful role in regional forest C management.