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For more than a century, planted shelterbelts in Saskatchewan, Canada have protected farmyards from the elements, decreased soil erosion, sequestered atmospheric carbon, as well as provided many other ecological functions. It is estimated that there are >60,000 km of planted shelterbelts throughout the province, and considerably more in all of the Canadian Prairies. This paper details the overall process of quantifying and mapping the carbon stocks in white spruce ( Picea glauca ) shelterbelts planted in Saskatchewan. Shelterbelt data collected from field sampling sites, which were identified by a unique site selection approach, were used to parameterize two models for use in shelterbelt systems; an independent data set was used to validate model predictions. Shelterbelt tree growth was modeled with the Physiological Principles in Predicting Growth (3PG) model, and carbon flux and stocks in shelterbelts were modeled with the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3). Annual total ecosystem carbon (TEC) flux in white spruce shelterbelts increased one order of magnitude, from −0.33 to 4.4 Mg C km −1 yr −1 , for age 1–25 years, and reached a peak of 5.5 Mg C km −1 yr −1 (age 39 years). An initial soil carbon loss from the shelterbelt, caused by the land-use change, was offset in full by tree growth by age 17, 18, and 21 years for trees planted at 2.0, 3.5, and 5.0 m spacing within a row, respectively. Increase in carbon stocks, after 60 years of growth, was predicted in the litter layer (21.8 Mg C km −1 ), belowground biomass (26.1 Mg C km −1 ), and aboveground biomass (117.6 Mg C km −1 ). Across all the different provincial soils, carbon additions were 106–195 Mg C km −1 in 60-yr-old white spruce shelterbelts. Cumulatively, accounting for eight decades of white spruce shelterbelt planting and tree growth, carbon additions totaled 50,440 Mg C province-wide in 991 km of white spruce shelterbelts. The C additions represented 38% of the province-wide TEC stocks, which totaled 131,750 Mg C. The cumulative carbon storage in all components of planted white spruce shelterbelts far exceeded the initial carbon levels present at the time of shelterbelt planting. [ABSTRACT FROM AUTHOR]

The scientific community, forest managers, environmental organizations, carbon-offset trading systems and policy-makers require tools to account for forest carbon stocks and carbon stock changes. In this paper we describe updates to the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) implemented over the past years. This model of carbon-dynamics implements a Tier 3 approach of the Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance for reporting on carbon stocks and carbon stock changes resulting from Land Use, Land-use Change and Forestry (LULUCF). The CBM-CFS3 is a generic modelling framework that can be applied at the stand, landscape and national levels. The model provides a spatially referenced, hierarchical system for integrating datasets originating from different forest inventory and monitoring programs and includes a structure that allows for tracking of land areas by different land-use and land-use change classes. Ecosystem pools in CBM-CFS3 can be easily mapped to IPCC-defined pools and validated against field measurements. The model uses sophisticated algorithms for converting volume to biomass and explicitly simulates individual annual disturbance events (natural and anthropogenic). Several important scientific updates have been made to improve the representation of ecosystem structure and processes from previous versions of CBM-CFS. These include: (1) an expanded representation of dead organic matter and soil carbon, particularly standing dead trees, and a new algorithm for initializing these pools prior to simulation, (2) a change in the input data requirement for simulating growth from biomass to readily available merchantable volume curves, and new algorithms for converting volume to biomass, (3) improved prediction of belowground biomass, and (4) improved parameters for soil organic matter decay, fire, insect disturbances, and forest management. In addition, an operational-scale version of CBM-CFS3 is freely... [Copyright &y& Elsevier]

Net ecosystem productivity (NEP) is a key ecological variable in forestry and carbon sequestration sciences. Advances in eddy-covariance instrumentation in recent years have improved the accuracy to which productivity in ecosystems can be measured. However, equipment failure, power outages, system maintenance shutdowns, and inclement weather frequently introduce gaps in the measurement data stream, which can reduce the integrity, usefulness, and interpretation of the data. To compensate for these limitations, a simple NEP model with few automatically adjustable parameters is developed to improve gap filling of discontinuous time series. Initial model formulation and parameter-value determination are founded on 2004 growing-season NEP measurements collected at eight Fluxnet-Canada (FCRN) stations (i.e., eight ecosystems) from across Canada's southern commercial forest zone. A preliminary inter-equation comparison of three commonly used flux equations, all with photosynthetically active radiation (PAR) as the independent variable, revealed that the three equations provided similar mean description of NEP. In this paper, we use Landsberg''s equation [Landsberg, J.J., 1977. Some useful equations for biological studies. Exp. Agric. 13, 272–286] in modelling NEP. Initial parameter values of the Landsberg''s equation were shown to depend on forest species composition, stand age, and existing site conditions. Further analysis indicated that on average for a 9-day period for the Atlantic Maritime balsam fir site in New Brunswick, Landsberg''s equation represented mean NEP very well for cloudy days, but performed poorly when light conditions deviated from average conditions. We hypothesized that variation in the level of diffuse and direct radiation contributed to differences in light response. As Landsberg''s equation does not explicitly address (i) light quality, i.e., level of diffuse to direct illumination, and (ii) vertical canopy structure, a simple NEP model combining Landsberg''s equation with a two big-leaf (sunlit versus shade leaf model concept) and multiple-layer canopy light transmission formulation was developed for modelling the day-to-day variation in NEP and for gap filling. Results from these enhancements captured more of the NEP peaks (coefficient of determination, r 2 =0.70) than were previously modelled with the unaltered form of Landsberg''s equation (r 2 =0.63). Model sensitivity analysis suggested partitioning the canopy in four canopy layers provided the best overall improvement in NEP calculations; beyond four layers, model improvement was minor. [Copyright &y& Elsevier]