National‐scale estimates of forest root biomass carbon stocks and associated carbon fluxes in Canada

Abstract

Canada's forests play an important role in the global carbon cycle through carbon (C) storage and C exchange with the atmosphere. While estimates of aboveground biomass have been improving, little is known about belowground C storage in root biomass. Here we estimated the contribution of roots to the C budget of Canada's 2.3 × 106 km2 managed forests from 1990 to 2008 using the empirical modeling approach of the Carbon Budget Model of the Canadian Forest Sector (CBM‐CFS3) driven by detailed forestry data sets from the National Forest C Monitoring, Accounting and Reporting System. The estimated average net primary production (NPP) during this period was 809 Tg C yr−1 (352 g C m2 yr−1) with root growth and replacement of turnover contributing 39.8 % of NPP. Average heterotrophic respiration (Rh) was 738 Tg C yr−1 (321 g C m−2 yr−1), which resulted in a net ecosystem production (NEP) value of 31 g C m−2 yr−1(71 Tg C yr−1), and on average only 8.7% of NPP remained in the system as NEP. Estimated average root C stocks were 2.38 Pg (1235 g C m−2), mostly in coarse roots (≥ 5 mm diameter), and had an average root to shoot percentage (belowground to aboveground biomass) of 25.6%. Detailed monitoring of C exchange between forests and the atmosphere and an improved understanding of the belowground processes and their response to environmental changes are needed to improve our understanding of the terrestrial C budget.

Biomass carbon, nitrogen and phosphorus stocks in hybrid poplar buffers, herbaceous buffers and natural woodlots in the riparian zone on agricultural land

“…Our biomass C stock estimates for riparian woodlots also fall in the range of mean biomass C stock estimates for managed forests of the Mixedwood plains ecozone (Stinson et al, 2011). Furthermore, our belowground (root) biomass C stock amounts for poplar buffers (4.8e13 t/ha) and riparian woodlots (5.2e36.8 t/ha) (Table 3) are in the same order of magnitude than national scale estimates for managed forests of Eastern Canada, which are 10e17.5 t/ha (Smyth et al, 2013).…”

A survey of remote sensing-based aboveground biomass estimation methods in forest ecosystems

“…Process-based ecosystem models employ biogeochemical processes, including photosynthesis, absorption, and carbon allocation. The models generally couple biology, soil, climate, hydrology, and anthropogenic effects (Smyth et al 2013). Constraints in data source (e.g.…”

Moso bamboo (Phyllostachys pubescens) forests as a significant carbon sink? A case study based on 4‐year measurements in central Taiwan

“…We did not separate fine and coarse roots in this procedure. Because previous studies demonstrated that coarse roots, which have longer residence time than fine roots, made the predominant contribution to root biomass (IPCC 2006;Miller et al 2006;Bijak et al 2013;Smyth et al 2013), we assumed that disregarding fine and coarse roots is acceptable in terms of quantifying the total root biomass.…”