From
Farm to Forest: The Land-Use History and Carbon Stocks
of a Reforested Farm in Central New Hampshire
Rosalind Fredericks
The carbon stocks of a 100ha forested area in central New Hampshire, formerly comprising a family farm, were modeled from presettlement to the present day to examine the impact of land-use history on the biotic flux of carbon. The model involved a reconstruction of the temporal and spatial characteristics of disturbance patterns of the farm since initial settlement in the late 1700's, using aerial photography, historical data, and site characteristic data collected in situ. Present day carbon stocks were examined for the aboveground living biomass and the forest floor carbon pools. Carbon accumulation rates for land-uses were predicted from these data and other data from the White Mountains region. Aggregate estimates of the carbon flux for the farm over the last 200 years were made and the sensitivity of the outcome to the assumptions was tested. The pastures were assumed to act as ploughed land, and the woodlots acted more like clear-cuts. The model was sensitive to the categorization of the intermediate land-use categories (woodlots, seasonal pastures), and to assumptions of carbon accumulation rates, which changed the aggregate flux estimate within the farm by up to 20%. When compared to a global land-use model, (Houghton, 1983), the local model revealed some insufficient assumptions used in global models which, when used in extrapolations, could significantly affect global carbon estimates. The findings indicate that simplifying assumptions made in global carbon flux models must be supported by more detailed land-use history data to close the gaps we presently face in quantifying biotic carbon flux.