The fourth assessment of the recently published Intergovernmental Panel on Climate Change agrees that it is highly likely that global climate warming over that past half century is a function of human activity and that global temperature rises of between 2 degrees and 4.5 degrees Celsius will occur over the next century (Working Group 1, Intergovernmental Panel on Climate Change, 2007). It is likewise predicted that the climatic conditions of the Cariboo region of British Columbia will become significantly hotter and drier (Aitken 2005). Extensions in growing seasons, especially in springtime, have already been observed in many areas around the world, and it is expected that there will be increased species distribution shifts towards the poles and to higher elevations (Walther et al. 2002).The pace of change will likely outstrip the ability of vegetation to move by natural distribution (Walther et al. 2002; Iverson 2004). Modeling of migration rates of select eastern North American trees suggests an advance of 10 km in 100 years would occur naturally into new suitable habitat resulting from climate change (Iverson 2004). An abundance of parent trees would be required for this to occur, suggesting that tree species that are rare at the edge of their distribution, a condition that is often the case for any species at a range edge, will migrate even more slowly. Fragmentation, agricultural areas and urbanization can also be barriers to dispersal for trees (Noss 2001). Also, as climate is changing at an unprecedented pace, trees, with their long life-spans, may not adapt quickly enough to maintain current levels of forest cover. Opportunities to acclimatize, evolve genetically, or move to more suitable sites increases the resistance and resilience of forests to change (Noss 2001) and such adaptation requires time. It is thus likely that people will have to plant tree species outside of their current ranges to ensure sufficient stocking for future forestry operations.
Related to project 4655007.
Koot, Cathy. 2007. Performance of ponderosa pine and western larch planted north of natural ranges: RP #05-03 summary following the first and second growing seasons. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2007MR202