1.1 Carbon Storage by the UMBS forest. Biometric carbon storage, or net ecosystem production (NEPB) compared to meteorological net primary production (NEPM) for the UMBS forest, 1999-2003. Dashed line shows 1:1 relationship (Gough et al., in press).

Accurately assessing C storage by forests remains a challenge because of the many uncertainties associated with measurements of ecosystem-level C storage. One way of evaluating the accuracy of these estimates is to concurrently measure C storage using independent methods. We used both biometric and meteorological methods to estimate annual C storage from 1999 – 2003 at UMBS. Carbon storage was estimated biometrically from surveys of wood, leaf, fine root, and coarse woody debris mass, mass losses to herbivory, and soil respiration. Eddy-covariance measurements made above the canopy were used to estimate C storage using meteorological techniques.

When NEPB and NEPM were compared within a given year, they differed from each other by 13 - 148 %. Mean annual C storage (averged over methods) was 1.53 Mg C ha-1 yr-1. However, annual C storage varied by more than 100%. Net primary production (NPP), or the difference between NEP and heterotrophic soil respiration, averaged 6.54 Mg C ha-1 yr-1.