PhD Research - Ian McCullough

MS Ecology & Environmental Science, University of Maine; BA Environmental Studies, Colby College

Ian McCullough's research focuses on the effects of climate change on California's forests. Climate change is expected to affect the growth patterns and geographic distributions of trees, threatening key provisions of ecosystem services, timber and wildlife habitat. As droughts and warming temperatures place additional stress on forests, trees, like other species, are expected to seek milder conditions by migrating to higher latitudes and elevations. However, trees can only "migrate" by producing seedlings in new, previously unoccupied locations. Reproduction in tree species is generally slow and unpredictable, so it is conceivable that many species will be unable to keep up with the rate of climate change. Mountainous terrain, however, contains a wide range of habitats and microclimates that may allow species to remain locally even when regional climate becomes increasingly unfavorable. Consequently, examining how trees can potentially make use of these different microclimates throughout landscapes is an important step in understanding the response of forests to climate change. McCullough uses tree-rings, field experiments and fine-resolution climate models to examine direct effects of continued climate change on California's iconic mountain forests.

Dissertation Abstract
My research focuses on responses of forests to climate change. In my first chapter, I developed a conceptual framework for climate change exposure, which I applied to a mountainous landscape at Tejon Ranch, CA. I found that high elevations are disproportionately exposed to future climate change due to projected losses in snowpack. In my second chapter, I examined long-term relationships between climate, particularly drought, and ponderosa pine tree rings at Tejon Ranch to place the recent multi-year California drought in an ecological, historical context. According to a range of climate change projections, there will likely be similar extreme droughts in the future, so this case study provides a possible window into future forest responses to climate change. In my final chapter, I examined the sensitivity of ponderosa pine to historical climate across the western United States, also using tree rings. Climate sensitivity is highly variable across the species' range as a function of local climate and adaptation. Therefore, future conservation efforts for ponderosa pine and other wide-ranging species should consider within-species variability in climate sensitivity.

Year Admitted : 2012
Research areas: biogeography, landscape ecology, conservation, limnology
Faculty Advisor: Frank Davis

Frank Davis Lab
Research Website


Global Lake Ecological Observatory Network Graduate Student Fellowship (Jan 2015-)

Summer Research Fellowship, Earth Research Institute, UC Santa Barbara (Jun 2014)


Nov 2015 McCullough, I. M., Davis, F. W., Dingman, J. R., Flint, L. E., Flint, A. L., Serra-Diaz, J. M., Syphard, A. D., Moritz, M. A., Hannah, L. and J. Franklin. High and dry: high elevations disproportionately exposed to regional climate change in Mediterranean-climate landscapes. Landscape Ecology. DOI: 10.1007/s10980-015-0318-x.

Oct 2015 Serra-Diaz, J. M., Franklin, J., Sweet, L, McCullough, I. M., Syphard, A. D., Regan, H., Flint, L., Flint, A., Dingman, J., Moritz, M. A., Redmond, K., Hannah, L. and F. W. Davis. Averaged 30 year climate change projections mask opportunities for species establishment. Ecography. DOI: 10.1111/ecog.02074.

May 2015 Hannah, L., Flint, L. E., Syphard, A. D., Moritz, M. A., Buckley, L. B. and McCullough, I. M. Place and process in conservation planning for climate change: a reply to Keppel and Wardell-Johnson. Trends in Ecology and Evolution 30(5): 233-234.

Feb 2015 Aceves-Bueno, E., Adeleye, A. S., Bradley, D., Brandt, W. T., Callery, P., Feraud, M., Garner, K. L., Gentry, R., Huang, Y., McCullough, I. M., Pearlman, I., Sutherland, S. A., Wilkinson, W., Yang, Y, Zink, T., Anderson, S. E. and C. Tague. Citizen science as a tool for overcoming insufficient monitoring and inadequate stakeholder buy-in in adaptive management: Criteria and evidence. Ecosystems 18(3): 493-506.

July 2014 Hannah, L., Flint, L., Syphard, A. D., Moritz, M. A., Buckley, L. B. and McCullough, I. M. Fine-grain modeling of the response of species to climate change:
holdouts, stepping-stones and microrefugia. Trends in Ecology and Evolution 29 (7): 390-397.

Oct 2013 Dingman, J. R., Sweet, L. C., McCullough, I. M., Davis, F. W., Flint, A., Franklin, J. and L. E. Flint. Cross-scale modeling of surface temperature and seedling establishment to improve projections of tree distribution shifts under climate change. Ecological Processes 2-30.

Sep 2013 McCullough, I. M., Loftin, C. S. and S. A. Sader. Landsat imagery reveals declining clarity of Maine’s lakes during 1995-2010. Freshwater Science 32(3): 741-752.

March 2013 McCullough, I. M., Loftin, C. S. and S. A. Sader. Lakes without Landsat? An alternative approach to remote lake monitoring with MODIS 250 m imagery. Lake and Reservoir Management 29: 89-98.

Jan 2013 McCullough, I. M., Loftin, C. S. and S. A. Sader. A manual for remote sensing of Maine lake clarity. Maine Agricultural and Forest Experimentation Station, University of Maine. Technical Bulletin 207. ISSN: 1070-1054.

Sep 2012 McCullough, I. M., Loftin, C. S. and S. A. Sader. High-frequency remote monitoring of large lakes with MODIS 500 m imagery. Remote Sensing of Environment 124: 234-241.

Aug 2012 McCullough, I. M., Loftin, C. S. and S. A. Sader. Combining lake and watershed characteristics with Landsat TM data for remote estimation of regional lake clarity. Remote Sensing of Environment 123: 109-115.