Miles Merwin, Lyn Townsend, Greg Johnson, and Roel Vining. USDA-NRCS, 1201 Lloyd Blvd., Suite 1000, Portland, OR 97232
There are a number of agroforestry practices that are a part of the portfolio of conservation planning activities officially encouraged by the USDA-Natural Resources Conservation Service (NRCS). Recognizing the need for carbon sequestration estimates from such practices the NRCS has embarked on a project to develop such estimates and integrate these into their existing CarbOn Management Evaluation Tool for Voluntary Reporting (COMET-VR). Presently, COMET-VR provides estimates of soil carbon storage in farm and rangeland settings under user-specified management scenarios. An extension to COMET-VR which will allow users to estimate changes over time in carbon storage (CS) in above- and below-ground components of agroforestry practices is being developed. The intended audience includes private landowners, farmers, ranchers, non-industrial private forest owners, NRCS field staff, and technical service providers. Different methods are used to estimate changes in woody biomass and CS in two general types of agroforestry practices: 1) row-type and 2) forest-like. For row-type agroforestry practices (alley cropping, windbreaks, and silvopasture), individual tree biomass is calculated using diameter-based allometric equations generalized for species groups. For forest-like practices (forest farming and riparian buffers), the COLE Lite online tool (USFS) is used to calculate CS in above- and below-ground biomass components. The Century soil carbon model in COMET-VR is used to estimate CS in soil for agroforestry practices which have an understory crop component. Biomass growth and reportable CS flux over the 10-year reporting period are based on data from both windbreak and forest plots in different regions of the US. Output from the tool will be an estimate of the annual change in CS suitable for the US Department of Energy 1605(b) Voluntary Greenhouse Gas Reporting Program. It will also allow users to compare potential CS in agroforestry versus other land use alternatives.