Field data for carbon storage within woody biomass were collected at each of the forested properties. There were no plots established at St. Pierre Wetland because there were not enough large trees to warrant the use of woody biomass calculations. Within each property, a series of 10 m x 10 m plots was established in order to cover a representative sampling of cover types across each property (Fig. A-3 to A-7). Before each site visit, rough placements of the plot locations were selected from aerial imagery. Each property contained 8 - 12 plots divided between deciduous and coniferous cover types. In the field, plots were randomly established by blindly throwing a flag to establish the southwest (SW) corner of the plot. The location of the SW corner was recorded with a Garmin GPS unit. Within the plot, every tree larger than 10 cm in diameter at breast height (dbh) was counted. Species and dbh were then recorded. Field data collection took place between November 2019 and February 2020.
Species group and DBH were used to calculate the biomass of each tree using allometric equations (Jenkins et al 2003). Species groups were classified as Hard Maple/Oak/Hickory/Beech, Mixed Hardwoods, Soft Maple/Birch, Aspen/Alder/Cottonwood, Spruce, Cedar/Larch, and Pine. Root biomass was estimated through an allometric equation using the natural log of the aboveground biomass. Biomass was then converted to the carbon content in the trees using an estimate of carbon as 50% of woody biomass. Carbon content was then converted to mass of CO2 using the molecular weight of C and CO2.
The LULC classifications were then converted to polygons using ArcGIS Pro and the area of each cover type was calculated. When calculating the estimate of carbon storage on each property the summed total area of deciduous forest cover and coniferous forest cover were used to extrapolate the field data calculations to the property as a whole using the equation: Ct=Cf*(At/Af) where Cf is the carbon estimate calculated from field data, At is the total area of the given cover type present at the property, and Af is the area of the field sites. The total carbon stored in aboveground woody biomass was calculated by summing each of these cover types. Belowground biomass was calculated using the equation: BGB=e(-1.0587+(0.8836*ln(AGB)+0.2840) which was developed for use by the U.S. Forest Service by Cairns et al. (1997).
Soil carbon is a large percentage of carbon storage in natural areas. Using the USDA Web Soil Survey soil map layer, the team clipped the boundaries of each of the SEAS properties and recalculated the area of each soil type. Then the USDA Natural Resource Conservation Survey’s soil lab results (National Cooperative Soil Survey) were analyzed and average soil carbon percentage and bulk density numbers were calculated to use for estimating each property’s soil carbon. These data were converted to tons/hectare and multiplied by the total area, in hectares, of each soil type.
Minimum and maximum carbon sequestration rates for each property were estimated from published rates from the Great Lakes region (Tables A-1 and A-2). The lowest and highest published numbers were used and the carbon sequestration rate for each property was calculated using the areas of each land cover from the LULC maps for each property.