Role of Prairie Shelterbelts in Mitigating Greenhouse Gases in Saskatchewan.

Planted shelterbelts are an agroforestry system used in the Canadian Prairies to prevent soil erosion and reduce fertility loss but their role in mitigating greenhouse gases (GHGs) is poorly understood. Carbon storage was quantified, and its distribution was mapped across the province of Saskatchewan, for six common shelterbelt species planted from 1925 to 2009 - caragana (CG: Caragana arborescens), green ash (GA: Fraxinus pennsylvanica), Manitoba maple (MM: Acer negundo), Scots pine (SP: Pinus sylvestris), white spruce (WS: Picea glauca Monch), and hybrid poplar (HP: Populus spp.). The Physiological Principles in Predicting Growth (3PG) model was used to calculate tree biomass, and carbon stocks were modeled with the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). Total ecosystem carbon (TEC) stocks, which included the C stocks in aboveground and belowground biomass, litter layer, initial soil C pool, and new C added to the soil ranged from 7.86 to 0.13 Tg C in the descending order CG>HP>GA>MM>SP>WS. The cumulative TEC stocks for the six species was 10.81 Tg C (Tg=teragram), of which 4.85 Tg were C stocks additions from shelterbelt planting. About 78% of these total C stocks additions (=3.77 Tg C) occurred in the period after 1990, regardless of when shelterbelts were planted. Shelterbelts also increased soil carbon storage compared to adjacent agriculture crop fields. Emissions of GHGs varied between shelterbelt species; however, GHG emissions predicted from the Holos model were reduced when shelterbelts were included in the farming system. The results reported in this paper warrant similar carbon stocks analyses for all planted shelterbelts in the Canadian Prairies and the exploration of shelterbelt management as another potential mechanism to reduce greenhouse gas emissions in Canada.