Carbon sequestration : trade-offs of planting trees on agricultural land

For some time, climate change has been considered by many to be one of the world's greatest, and most critical, environmental concerns of our age. In 1997 these concerns led to the creation of the Kyoto Protocol, which was designed to limit greenhouse emissions in an attempt to mitigate climate change. Canada's commitment under this agreement is a reduction in emissions to 6% below its 1990 levels, and one of the options that is under consideration to enable Canada to partially meet its commitments is carbon sequestration by planting trees on marginal land. The sequestered carbon can then be counted as a credit in Canada's net emissions budget. Hybrid poplar (Populus hybrids) has been identified as the tree species for this purpose in the study region of this thesis, due to its high growth rates. Landowners, however, prefer a mix of trees. In this thesis I explore some of policy implications involved in the undertaking of a largescale tree planting program by developing a non-linear programming model that examines the tradeoffs between carbon sequestration, tree species diversity and net profits in terms of net present value (NPV). In the context of the model developed, tree species diversity is used as a proxy for biodiversity and landscape diversity, and a landowner survey is used to determine the mix of tree species that landowners would prefer. Eight tree species are considered in the context of the model, using two different discount rates, and a series of tree planting scenarios are developed, which show the tradeoffs that result from planting varying amounts of each tree species in the Peace River regions of Alberta and British Columbia. Land availability in this region is estimated using a land supply function that is based on predicted crop yields from the landowner survey. The full range of trade-offs are illustrated, in part, through a series of production possibility relationships, which plot the three main policy objectives against each other. The results indicate that NPV can range from -$18.4 million over the 120 year planning period to just over $10.4 million, depending on the species mix planted and the discount rate utilized. Similarly, carbon sequestered can range from some 233 thousand tonnes to around 2.4 million tonnes over the same period, and the trade-offs with diversity can be significant.Land and Food Systems, Faculty ofGraduat