Andrea H. Lloyd

Abbreviated Curriculum vitae

Dynamics of black spruce (Picea mariana) at its northern limit in the Brooks Range, Alaska

This research project, funded by the Bonanza Creek LTER Program, investigates the dynamics of black spruce forests at the species' northern limit in the Brooks Range, Alaska. Black spruce forests are the most widespread forest type in interior Alaska, but black spruce becomes increasingly less common as treeline is approached, and treeline forests are dominated almost completely by white spruce.

We are seeking to understand:

• the relative importance of climatic/non-climatic controls over black spruce distribution
• the fire regime of northernmost black spruce forests
• competitive interactions between white and black spruce at the northern limit of black spruce.

Black spruce are co-dominant with white spruce near their northern limit. This site, near milepost 200 on the Dalton Highway, is approximately 60% black spruce and 40% white spruce. Evenly mixed stands like this are much more unusual in the central part of black spruce's range.

Initial results from this research are summarized in the following :

Wilson, A. E. 2003. The population dynamics of Picea mariana at the northernmost range limit in the Brooks Range, Alaska: A matrix population model. Honors Thesis, Middlebury College, VT. To download a PDF version of this thesis, click here. (File is approximately 1.2 MB.)

Lloyd, A.H., A. E. Wilson, and C. L. Fastie. 2003. Population dynamics of black spruce at its northern limit in Alaska. Poster presentation at the Ecological Society of America Annual Meeting. For link to Abstract, click here.

Response of the Alaskan boreal forest to climate change
(Funded by the Bonanza Creek Long-Term Ecological Research Program and the National Science Foundation's Land-Atmosphere-Ice Interactions program in the Office of Polar Programs).

This research project is focused on the following questions:

• Is global warming likely to cause the northward expansion of boreal forests?
• How do climate and disturbance (especially by fire) interact to control spruce recruitment at the forest-tundra boundary?
• Has warming in the last 100 years caused changes in the structure/distribution of treeline forests?

Treeline at Twelvemile Summit, along the Steese Highway.

Visit our outreach web site, constructed by John Mauro as part of his senior honors thesis work in 1999.

Recent publications from this project:

• Lloyd, A.H. and C.L. Fastie. 2002. Spatial and temporal variability in tree growth and climate response of treeline trees in Alaska. Climatic Change. 52:481-509.
• Lloyd, A.H., T. S. Rupp, C.L. Fastie, and A. M. Starfield. (2003). Patterns and dynamics of treeline advance on the Seward Peninsula, Alaska. Journal of Geophysical Research-Atmospheres. 108 (D2): 8161, doi: 10.1029/2001JD000852.
• Lloyd, A.H. and C.L. Fastie (2003). Recent changes in treeline forest distribution and structure in interior Alaska. Ecoscience. 10(2):176-185.
• Lloyd, A.H., K. Yoshikawa, C. L. Fastie, L. Hinzman, and M. Fraver. (2003). Effects of permafrost degradation on woody vegetation at arctic treeline on the Seward Peninsula, Alaska. Permafrost and Periglacial Processes. vol. 14. doi: 10.1002/ppp.446.

Any opinions, findings, conclusions, or recommendations expressed in the material on this site are those of the author(s) and do not necessarily reflect the views of the supporting agencies.

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