University of Colorado Denver College of Liberal Arts and Sciences

Bio

Primary research interests: 1) Seed dispersal and ecology of five-needle white pines; 2) Conservation of whitebark pine and related five-needle white pines.

For my doctoral research, I studied the ecological interaction between Clark’s nutcracker (Nucifraga columbiana), a relative of crows and jays, and the whitebark pine (Pinus albicaulis), a subalpine and treeline five-needle white pine that ranges widely throughout the higher mountains of the western United States and Canada. During my studies, I discovered that Clark’s nutcracker was the major seed disperser for whitebark pine and that bird and pine were coevolved mutualists. The seeds of the pine are large and wingless and the cones remain closed, even when the seeds are ripe; thus, the seeds cannot be dispersed by wind. Nutcrackers remove and store tens of thousands of the seeds in shallow subterranean caches to eat during times of food scarcity during the year. The unretrieved seeds may germinate after snowmelt or rain, leading to forest regeneration. In subsequent studies, my research has included several five-needle white pine relatives of whitebark pine.

My students and I work at the plant-animal interface, studying both the behavior and ecology of the seed dispersers and the ecology and population biology of the pines that they disperse, and more recently the potential decline of the whitebark pine-nutcracker interaction. Information on whitebark pine ecology has become particularly valuable, as a result of major population declines in the northern Rocky Mountains and Northwest of both the U.S. and Canada. These losses result from introduced, invasive disease--the fungal pathogen Cronartium ribicola, which causes white pine blister rust—as well as recent, widespread outbreaks of a native forest pest, mountain pine beetle (Dendroctonus ponderosae), coupled with fire exclusion policies in some regions. Management strategies, in response to our previous work, are being devised and implemented.

Several of my colleagues and I in 2001 started a 501 (c)(3) non-profit organization, the Whitebark Pine Ecosystem Foundation http://www.whitebarkfound.org , based in Missoula, MT, which is dedicated to the restoration of whitebark pine ecosystems and educating the public and resource management agencies about the importance of this pine. I have served as volunteer Director of this organization since its inception. Whitebark pine is considered both a foundation and keystone species for high-elevation ecosystems: its loss will diminish western biodiversity. As of July 2010, whitebark pine is being evaluated for possible listing as a threatened or endangered species by the US Fish and Wildlife Service. It is also under considered for endangered species status in Canada under the Species at Risk Act.

Select Publications

Tomback, D. F., and P. Achuff. 2010. "Blister rust and western forest biodiversity: Ecology, values, and outlook for white pines." Invited contribution for special issue. Forest Pathology 40:186-225.

McKinney, S. T., C. E. Fiedler, and D. F. Tomback. 2009. "Invasive pathogen threatens bird-pine mutualism: implications for sustaining high-elevation ecosystem." Ecological Applications 19:597-607.

Tillman-Sutela, E., A. Kauppi, K. Karppinen, and D. F Tomback. 2008. "Variant maturity in seed structures of Pinus albicaulis (Engelm.) and Pinus sibirica (Du Tour): key to an unusual soil seed bank?" Trees 22:225-236 (published online in 2007)

Resler, L. M., and D. F. Tomback. 2008. "Blister rust prevalence in krummholz whitebark pine: Implications for treeline dynamics." Arctic, Antarctic, and Alpine Research 40: 161-170.

Malanson, G. P., D.R. Butler, D. B. Fagre, S. J. Walsh, D. F. Tomback, L. D. Daniels, L. . Resler, W. K. Smith, D. J. Weiss, D. L. Peterson, A. G. Bunn, C. A. Hiemstra, D. Liptzin, P. S. Bourgeron, Z. Shen, and C. Millar. 2007. "Alpine treeline in western North America: linking organism-to-landscape dynamics." Invited contribution for special issue on alpine treeline. Physical Geography 28: 378-396.

Tomback, D. F., and L. M. Resler. 2007. "Invasive pathogens at treeline: consequences for treeline dynamics." Invited contribution for special section on alpine treeline. Physical Geography 28 (5):397-418.

McKinney, S. T., and D. F. Tomback. 2007. "The influence of white pine blister rust on seed dispersal in whitebark pine." Canadian Journal of Forest Research 37:1044-1057.

Tomback, D. F. 2005. "The impact of seed dispersal by Clark’s nutcracker on whitebark pine: multi-scale perspective on a high mountain mutualism." Pages 181-201 in: Mountain Ecosystems: Studies in Treeline Ecology. G. Broll and B. Keplin (eds.), Springer.

Tomback, D. F., A. S. Schoettle, K. E. Chevalier, and C. A. Jones. 2005. "Life on the edge for limber pine: seed dispersal within a peripheral population." Écoscience 12:519-529.

Samano, S., and D. F. Tomback. 2003. "Cone opening phenology, seed dispersal, and seed predation in southwestern white pine (Pinus strobiformis) in southern Colorado." Écoscience 10:319-326.

Courses Taught

BIOL 3411: Principles of Ecology

BIOL 4974/5974: Evolution

BIOL 4052/5052: Advanced Ecology

BIOL 4154/5154: Conservation Biology