Background
With respect to the consequences of possible future global warming for earth's trees, Hamrick notes there are concerns that "expected changes may be of such an extent that tree species will not have adequate genetic variation to adapt to the modified conditions (Critchfield, 1984; Davis and Zabinski, 1992)," that "environmental changes may occur at such a rapid rate that trees, with their long generation times, could not adapt quickly enough to keep pace with predicted changes (Davis and Shaw, 2001)," and that trees "may not be capable of dispersing into newly available habitats quickly enough to match the rate of environmental change (Clark, 1998)."

What was done
The author reviews the findings of a number of studies that focus on the responses of trees to conditions analogous to those of computer-generated simulations of rapid global warming.

What was learned
Hamrick finds that "trees combine life-history traits and levels of genetic diversity that will allow them to adapt relatively quickly to environmental changes," and that they have high genetic mobility, especially via pollen.  The plant biology and genetics professor also notes that "tree species have faced large-scale global environmental changes many times during their evolutionary histories," and that even though these changes "have occurred quite quickly, most tree species have survived."

What it means
In conclusion, Hamrick states that "the goal of this paper is to emphasize characteristics of tree species that are often overlooked in discussions of the effects of global climatic changes," and that "these traits may allow many tree species to survive predicted global climatic changes while preserving much of their genetic diversity."

References
Clark, J.S.  1998.  Why trees migrate so fast: confronting theory with dispersal biology and the paleorecord.  American Naturalist 152: 204-224.

Critchfield, W.B.  1984.  Impact of the Pleistocene on the genetic structure of North American conifers.  In: Tanner, R.M. (Ed.), Proceedings of the Eighth North American Forest Biology Workshop.  Logan, Utah, USA, pp. 70-118.

Davis, M.B. and Shaw, R.G.  2001.  Range shifts and adaptive responses to Quaternary climate change.  Science 292: 673-679.

Davis, M.B. and Zabinski, C.  1992.  Changes in geographical range resulting from greenhouse warming: effects on biodiversity in forests.  In: Peters, R.L. and Lovejoy, T.E. (Eds.), Global Warming and Biological Diversity.  Yale University Press, pp. 297-308.