Table 4 Comparison of various methods used to calculate biomass and NPP at the four sites

Leaves

2002–2008, littertraps. Pre-2002, allometric relationship.

Littertraps.

Littertraps, lagged for pines.

Diameter based allometric functions.

Wood

Diameter based allometric functions. Two functions were used depending on a diameter based cutoff.

Diameter and height based functions relationships, annual measurements of wood carbon density.

Diameter and height based allometric functions, annual measurements of wood density. Sub-sample of full plot.

Diameter based allometric functions.

Coarse-root

Linear function of above-ground tree mass and fine-root mass.

Diameter based allometric functions.

Function of above-ground biomass.

Soil cores, ground-penetrating radar, and allometric functions (when cores and GPR were not taken).

Fine-root

2002–2008, mini-rhizontrons. Pre-2002, allometric relationship.

Mini-rhizotrons.

Soil cores.

Mini-rhizotrons and soil cores.

Leaves

Equal to biomass.

Equal to biomass.

Peak Leaf Area Index divided by species specific SLA.

Biomass increment plus litterfall. Litterfall estimated from littertraps.

Wood

Biomass increment at the tree scale*.

Biomass increment at the tree scale*.

Plot scale biomass increment.

Biomass increment plus litterfall. Litterfall assumed zero.

Coarse-root

"

"

"

Same method as fine roots.

Fine-root

2002–2008, in-growth cores and mini-rhizontrons. Pre-2002, biomass increment plus estimated root litterfall from 2002–2008 mini-rhizotron data.

Mini-rhizotrons.

Biomass multiplied by proportion of annual length production from mini-rhizotrons.

Biomass increment plus litterfall. Litterfall estimated as biomass multiplied by C turnover rate. Turnover rate measured using an isotopic tracer approach.

for details see

Talhelm et al.³⁵

Norby et al.¹³

McCarthy et al.¹⁵

Hungate et al.^16,69