muskox bulls           arctic fox   


Eric Post

Associate Professor of Biology, Penn State University
Visiting Professor, Department of Arctic Environment, Aarhus University, Denmark


In general, I am interested in ecological dynamics at many levels of organization and across multiple scales of space and time.    I am a broadly trained ecologist, with a mixed background of experience in population genetics, behavioral ecology, population ecology, and terrestrial and benthic community ecology.  I am primarily interested in life history evolution and dynamics, population dynamics, species interactions, conservation, and the role of animals in ecosystem dynamics.  Most of my research is tied together under the theme of climate change, and is conducted almost exclusively in far-northern and arctic environments. 

In my research group, we employ an array of approaches, including mathematical and statistical modeling, observation, and experimentation.


My primary major research interests include:

Variation in the distribution and abundance of organisms.  How is spatial and temporal variation in population size influenced by intrinsic factors, such as density dependence, and extrinsic factors, such as predation, interspecific competition, and environmental variability in time and space?  Along this line of research, my colleagues and I have worked for the past several years to develop linear and non-linear models of single and multi-species population dynamics and apply them to long-term data on birds and mammals.  


                                snow bunting 

                                Caribou bulls                                                          Muskox bull                                                   Male snow bunting



Community structure and dynamics in relation to species interactions and climate change.  How are trophic interactions among predators and herbivores, and among herbivores and plants, influenced by climatic variation and change?  How are the distribution and productivity of plants influenced by herbivory and abiotic conditions?  To answer these questions, my colleagues and I have conducted extensive analyses of long-term data and simulation modeling. 

Beginning in 2002, I adopted an empirical approach to investigating these subjects by initiating a large-scale, long-term field experiment in West Greenland involving the use of multiple exclosures and passive warming devices.  My students, assistants, and I erected 6, 800m2 permanent exclosures designed to eliminate herbivory by caribou and muskoxen in order to quantify the impact of these herbivores on productivity and species composition of arctic plant communities. 

                       

Erecting an exclosure at the study site in June, 2002.           The same exclosure in June, 2003.


Additionally, inside and outside of these exclosures we employ open-topped, passive warming chambers designed according to the protocols of the International Tundra Experiment (ITEX) to quantify short- and long-term vegetation community composition and productivity responses to warming and herbivory.

                              muskox ITEX cone

ITEX open-top chambers.                              Christian Pedersen quantifying                                           Muskoxen grazing adjacent to two of our exclosures and an ITEX chamber.
                                                                        biomass with the non-destructive
                                                                        point-intercept method.



Life history variation in relation to environment and conspecifics.  What factors influence the seasonal timing of reproduction, age at first reproduction, production of offspring, and variation in fitness-related traits such as body size of organisms in northern environments, where the growing season is short but also variable on inter-annual and longer-term scales?  On this subject, my colleagues and I have devoted considerable effort to analyzing long-term data on plant phenology and timing of migration by several species of birds.  We have also developed models of the timing of reproduction in relation to climate change and biotic interactions. 

At my study site in West Greenland, I have also initiated a multi-annual, observational study on the timing of calving by caribou in relation to plant phenology.  Our intent is to eventually use these data to model potential changes in trophic synchrony, and consequences for reproductive success, in a changing climate.  Within the large-scale exclosure experiment described above, plant phenology is also monitored annually inside and outside of several ITEX cones to quantify the influence of warming on the spatio-temporal dynamics of plant emergence and flowering.

       caribou       muskox calves

                                                        Female caribou and calves at the study site in West Greenland                                                                                 Muskox calves