Hossain MF*, Chen W, Zhang Yu, and Pavlic G

Natural Resources Canada, Canada Center for Remote Sensing, Environmental Monitoring Section, Applications Division, 588 Booth Street, Ottawa, Ontario, K1A 0Y7, Canada *Corresponding author: Faruque.Hossain@CCRS.NRCan.gc.ca Tel: +1 613 943 1179; Fax: + 1 613 947 1385

ABSTRACT

Global climate warming that is predicted for Canada's northern Territories will have a great impact on soil, which contains about 39% of the total soil organic carbon (SOC) of all Canadian soils. Accurate accounting of SOC is a challenging but necessary task in understanding carbon fluxes and ecological responses to global warming. Therefore, the objective of this study is to develop a SOC database to determine the quantity of SOC in Canada's north. An analytical database of 382 profiles and 1376 horizons of SOC were compiled from companies, government, and universities to represent the SOC conditions across northern Canada. Total carbon stores to 1 m depth ranged from 0.35 kg C m-2 to 158.49 kg C m-2 with an average of 24.07 kg C m-2, which is comparable to literature values (6.2 to 27.4 kg C m-2). Carbon stores in surface and mineral horizons varied, but when the carbon stores of the mineral horizons (18.14 kg C m-2) were considered along with those of the surface horizons (5.92 kg C m-2), carbon store estimates were nearly triple. On an average, SOC concentrations in organic horizons (LFH) range from 17.11% to 58.40% with an average concentration of 35.08%. In the mineral horizons mean average concentrations range from 0.59% to 7.22%, decreasing with depth in bottom layer C-horizons. The SOC concentrations for peat soil ranges from 22.5% to 58.35% with an average concentration of 38.75% and SOC content in organic horizons (20.76 kg C m-2) and total profiles (58 to 307 kg C m-2) are comparable to literature values (organic horizons 15 to 28 kg C m-2 and total profiles 60 to 181 kg C m-2). Soil OC storage to 1 m depth is double (19.82 to 28.32 kg C m-2) or even more than those reported in the literature, ranging from 8.1 to 16.1 kg C m-2 for different ecoclimatic provinces of Canada's north. The presented database provides an improved representation of the SOC content of Canada's north, to allow analyses from different points of view according to user needs. Since much work is still required to verify the current database, a reconnaissance soil survey along with bulk density measurement is proposed for future research. In addition, SOC and biomass relationships for total SOC estimation will be useful to produce a northern Canada soil C map.

Kew words: Soil organic carbon database, peat soil, northern Territory of Canada, organic horizons, mineral horizons, profiles, reconnaissance soil survey