Where Does the Carbon Go When We a Clear a Hectare of Forest?

Recent interests in land use change analysis and associated greenhouse gas (GHG) emissions, especially related to biofuel policies (US EPA 2010, Harris, Grimland and Brown 2009, Tyner, et al. 2010), has renewed efforts to improve GHG release/storage estimates from forest biomass removal due to land use change. Following forest clearance, wood is burned on-site, left to decay, or removed for use off-site. Of the wood removed, its fate and associated carbon disposition varies by country. Wood removals may end up in short- or long-term storage as fuel, paper, panels, or lumber--also known as harvested wood products (HWP). At the end of a product's useful life it will be recycled, disposed, or incinerated. Moreover, global trade of logs and forest products can result in the transfer of carbon across national and climatic boundaries. In this study, we characterize the contribution of HWPs to above-ground biomass carbon emissions/storage associated with land use change. More specifically, we create a set of carbon emission factors that temporally describe how much above-ground biomass carbon will be released to the atmosphere or remains stored in forest products after clearing a hectare of forest for 166 countries in the world. Forest growing stock data by country (Mg carbon per hectare) are taken from the 2010 Forest Resource Assessment. Production and trade data for six different forest product types originate from the Food and Agriculture Organization's ForeStat database. Recycling, disposal and inceration rates are modeled based on country-specific climatic and landfill conditions. We find that after 30 years a large amount of variation exists globally in the fraction of carbon stored as HWPs following land clearance (0 - 35%). Generally, countries in Europe and North America show higher carbon retention than Asian, African and South American countries. Higher storage rates mostly result from (1) a greater percentage of long-lived products such as panels and lumber and (2) more anaerobic conditions at landfills, along with less tropical climatic conditions which leads to slower wood decay rates. Lower storage rates tend to be associated with (1) more wood used for energy purposes (e.g. home cooking) and (2) more aerobic conditions at landfills, along with tropical climatic conditions leading to faster wood decay rates. Such factors should be useful for characterizing carbon emissions/storage from forest biomass removals, especially in models that estimate global land use change.