## 3 Results and Discussion
### Sensitivity Analyses  
Sensitivity analyses were performed for both the wood-only and wood + carbon scenarios to determine the effect of economic uncertainty on model results. Table 3 summarizes the sensitivity analyses of the wood-only scenario for a range of \(r\), \(C\), and Stumpage Price (\(P\)) values. When \(r\) was increased from 4% to 8%, the optimal rotation period was shortened by about 6 years for all three GCMs. Furthermore, because of this, NPV was significantly lower at the new adjusted optimal harvest ages. The largest relative drop in NPV was observed in the southern region of the study area, whereas the smallest reduction was seen in the northeastern region. Conversely, when \(r\) was decreased from 4% to 2%, rotation periods lengthened by 7-8 years and NPVs increased by up to $1086/ha across the three GCMs. Again, NPV changes were greatest in southern Ontario, reflecting the higher growth potential in this region.  
Establishment costs (\(C\)) were adjusted from $500 to $0, $200 and $1000 per hectare. When \(C\) was reduced to $0, the rotation periods were shorter: from 39 years to 33 years for CanESM2, from 38 years to 34 years for MIROC, and from 38 years to 33 years for MPI. Furthermore, NPVs increased by approximately $300. When \(C\) was reduced to $200, a similar pattern emerged, with rotations periods shortening by two to four years depending on the GCM and increased NPVs. Conversely, when \(C\) was increased to $1000, the rotation periods lengthened by 7 to 8 years and NPVs declined making the overall investment questionable for all three GCMs. This has been shown in other studies as well, where the economic attractiveness of plantations increases in areas where opportunity costs (e.g., land values) are low [9]. Finally, when \(P\) was adjusted from $20 to $50, the result was a shorter rotation period by 2 to 5 years depending on the GCM. Increasing \(P\) turns NPV from negative to positive, making the investment more attractive. Although the increases in NPV vary by region, the highest values occur primarily in the southern portion of the study area, with the lowest values in northeastern Ontario. While perhaps counterintuitive, these shortened rotation periods are due to the increased value of future rotations, hence causing the rotation ages to decline to capture these increases in value.  
Table 4 illustrates the results of the sensitivity analyses of the wood + carbon scenario, where \(r\), \(C\), \(P\) and \(P_{\text{cs}}\) were adjusted to observe the effects of parameter uncertainty on the resulting NPVs. Decreasing \(r\) from 4% to 2% resulted in longer rotation periods by 3 to 7 years depending on the GCM; NPV also increased by as much as $1,000 in the southern region of the study area. When \(r\) was increased from 4% to 8%, shorter rotation periods were identified for all three GCMs, and NPVs were reduced. When \(C\) was adjusted, the results were similar to those described above for the wood-only scenario: as \(C\) increases, the rotation periods become longer and NPVs decrease. When \(P\) was adjusted from $20 to $50, the rotation periods shortened by 4 to 9 years depending on the GCM; however, NPVs increased by almost 3 fold in southern Ontario, making the investment significantly more attractive. The results highlight the importance of future price and yield expectations and establishment costs in evaluating forest investments. Forest managers will have to make judgements about their ability to adjust costs and still attain desirable future yields. In this study, we have not adjusted yields based on establishment costs given the lack of empirical information on this issue. This will be a subject of future research.