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2005 Fellows

Sarah EmerySarah Emery earned her B.S. as a double major in Biology and Studio Art at Denison University in Ohio in 2000. She earned her Ph.D. in a dual degree program in Plant Biology and Ecology, Evolutionary Biology, and Behavior from Michigan State University in 2005. Her dissertation work with Kay Gross focused on understanding the role of dominant species in regulating plant community invasibility in old-fields. She also has interests in population dynamics of invasive species and recently finished a brief post-doc examining old-field succession and non-native species invasions at the KBS LTER site. As a NPER Fellow, Sarah is working with Dr. Jennifer Rudgers in the Ecology and Evolutionary Biology Department at Rice University. Her research focuses on understanding the role of microbial mutualists such as endophytic and mycorrhizal fungi in regulating plant invasion and successional dynamics of Great Lakes sand dune communities. She is specifically addressing how these mutualists affect the dominance of a common native dune grass, Ammophila breviligulata , in natural and restored areas within Indiana Dunes, Sleeping Bear Dunes, and Pictured Rocks National Lakeshores in Indiana and Michigan.

Philip HigueraPhilip Higuera earned his B.A. in Biology and Environmental Studies from Middlebury College, Vermont (1998) where he worked with Andrea Lloyd and Grant Meyer. It was there that he was introduced to paleoecology and became interested in long-term forest dynamics. He earned his M.S. (2002) and Ph.D. (2006) in Forest Ecosystem Analysis from the University of Washington. His M.S. research, co-advised by Linda Brubaker and Douglas Sprugel, focused on the use of sediment charcoal records to reconstruct fire history in the Puget Lowland forests of Washington State. His dissertation work, under the guidance of Linda Brubaker, focused on reconstructing fire history to understand the impacts of centennial- and millennial-scale climatic and vegetational changes on fire regimes in and around Gates of the Arctic National Park, in the southern Brooks Range of Alaska. As a NPER Fellow, Philip is working with Cathy Whitlock at Montana State University studying the spatial and temporal evolution of fire regimes over the past 4000 years in subalpine forests of Rocky Mountain National Park, Colorado.

Emily MinorEmily Minor received her B.S. in Biology from the University of South Florida in 1999 and her Ph.D. in Ecology from Duke University in 2006. Her dissertation work with Dean Urban examined some of the effects of urban development on the behavior and distribution of forest songbirds in the North Carolina Piedmont. As a NPER fellow, she will be working with Katia Engelhardt and Todd Lookingbill at the University of Maryland Center for Environmental Science Appalachian Lab. Her research will focus on the spread of bird-dispersed invasive plant species in several battlefield parks in the National Capital Region. The parks contain very heterogeneous habitat, and the goal is to test hypotheses about the effects of spatial heterogeneity on the spread of these invasive plants. The project will make use of satellite imagery and long-term data sets to identify patterns of spread over the past few decades, and then apply graph theory to make predictions and management recommendations about future spread.

Kurt ReinhartKurt Reinhart received his B.S. from Appalachian State University in 1996 and his Ph.D. from the University of Montana in 2003. His doctoral work with Ragan Callaway examined the impact of an invasive non-native tree on terrestrial plant communities and aquatic systems. Additional research explored regeneration dynamics of the invader and prominent native species while more mechanistic research revealed how the invader impacted resident species while facilitating invasion. After completing his Ph.D. in 2003, Kurt began a Postdoctoral fellowship funded by the USDA at Indiana University with Keith Clay in fall 2003. His research explored t he role of belowground plant-microbe interactions in plant invasions. As a NPER Postdoctoral Fellow, Kurt is continuing to work with Keith Clay at Indiana University to explore the role of soil-borne disease on forest succession and diversity in deciduous forests in Mammoth Cave and Great Smoky Mountains National Parks. More information about Kurt's research interests is available online at

2004 Fellows

Nat Cleavitt began developing her skill in bryophyte taxonomy through an REU funded project in 1992. She earned her B.Sc. from the Department of Natural Resources at Cornell University in 1993. After her undergraduate time, she spent three years as a research assistant with Tim Fahey, John Battles and Joe Yavitt focusing largely on bryophyte taxonomy and plant ecology in the Delaware Water Gap National Recreation Area, upstate New York and New Hampshire . Her Ph.D. thesis work at the University of Alberta with Dale Vitt and JC Cahill compared the ecology of rare and common mosses in the Canadian Rocky Mountains, which offered considerable evidence of the importance of the establishment stage in determining bryophyte distributions. After completing her Ph.D. in 2002, Nat was a lecturer at the University of Alberta . She began a post-doctoral position at Cornell University with Tim Fahey in fall of 2002. Her task was to determine the dominant mechanism by which soil freezing affects tree roots, and she has found direct cell damage was more critical than indirect physical damage of ice lens formation and frost heave action. During this time, she was also privileged to mentor two undergraduate honors theses at Hubbard Brook Experimental Forest , NH . As a Postdoctoral Fellow, Nat will compare the physiology and community ecology of bryophytes and lichens between areas with high and low atmospheric deposition. This study based in Acadia National Park , Maine will provide an understanding of the ecological effects of atmospheric deposition, the potential for recovery of sensitive organisms after deposition reduction, and the reliability of these organisms as indicators of air quality.

Jeremy Long investigates the relationships betweens marine consumers and their prey, and how these interactions shape communities and ecosystems. Specifically, he studies the importance of chemical signals to these dynamic interactions. For his dissertation, Jeremy studied the effects of aquatic chemical signals between consumers and prey across a broad range of taxa (phytoplankton to fishes), organism sizes (microscopic to macroscopic), and habitats (pelagic to benthic). Chemical cues produced by these organisms or their activities provided information that allowed for surprisingly complex, induced responses in the receiving organisms. As a postdoctoral fellow, Jeremy continues to study aquatic chemical ecology under the guidance of Dr. Geoff Trussell at Northeastern University 's Marine Science Center . His project examines inducible responses of seaweeds to their consumers within Acadia NP in Maine . In addition to field and laboratory experiments, Jeremy will work with park managers to develop outreach and educational activities for the park. He received his B.A. in Marine Science from the University of San Diego (1998) and his Ph.D. in Biology from Georgia Tech (2004) while advised by Dr. Mark Hay.  

Shannon Murphy received her B.A. in Environmental, Population and Organismic Biology from the University of Colorado at Boulder in 1997. She then earned her Ph.D. from Cornell University in 2005 in the Department of Ecology and Evolutionary Biology. Her doctoral work with Paul Feeny investigated the dual roles of plant chemistry and differential predation in a host shift by two swallowtail butterflies. As a NPER Postdoctoral Fellow, Shannon is working with Dr. Bob Denno at the University of Maryland . Her research will study the effects of a short-term increase in nutrients (pulse) versus a long-term increase in nutrients (press) on the productivity of the cordgrass Spartina a lterniflora , an important component of the vegetation of Atlantic coastal marshes. Concurrent with her research on the direct effects of nutrient subsidies on Spartina marshes, Shannon will examine how these effects interact with herbivore load to either promote or hinder invasion by an aggressive reed. Shannon is conducting her research in both Assateague Island and Cape Hatteras National Seashores.

Peter Kennedy Peter Kennedy received his B.S. from The Evergreen State College in 1999 and his Ph.D. from the University of California , Berkeley in 2005. His doctoral work with Wayne Sousa examined the ecological factors affecting tree encroachment into coastal California grasslands, with particular interest in the role of ectomycorrhizal (EM) fungi. For his NPER fellowship, Peter is collaborating with Tom Bruns at UC Berkeley and studying the role of interspecific competition in structuring EM fungal assemblages. This work will focus on elucidating the nature of EM competitive hierarchies, how EM competitive ability changes in different habitats, and how EM competitive ability affects plant performance. Peter will be working in the Pinus muricata forests of Point Reyes National Seashore, CA. More information about Peter's interests and research is available online at

2003 Fellows

Jennifer Funk Jennifer Funk received her B.A. in Integrative Biology and Environmental Science from the University of California , Berkeley in 1996. She then earned her Ph.D. in Ecology and Evolution from Stony Brook University in 2004. Her research interests include how environmental factors influence plant physiological processes and, conversely, how plant ecophysiology influences ecosystem processes and biogeochemical cycles. Her dissertation work with Dr. Manuel Lerdau examined the physiological and environmental controls over isoprene emission from plants. In collaboration with Dr. Peter Vitousek of Stanford University, Dr. Funk’s NPER fellowship research will examine nitrogen use efficiency (NUE) as a mechanism for the success of exotic species in Hawai’i Volcanoes National Park. The project will focus on two types of NUE: photosynthetic nitrogen use efficiency and nitrogen retention, which includes species-specific patterns of leaf chemistry and compound resorption. Native and invasive species will also be studied along substrate and precipitation gradients to assess the degree of physiological plasticity in resource use.

Matthew Kauffman Matthew Kauffman received his B.A. in Biology from the University of Oregon in 1992 and his Ph.D. in Environmental Studies from the University of California, Santa Cruz in 2003. Matt is a conservation biologist with a broad organismal background. In his doctoral research with Dr. Dan Doak, Matt studied the effects of host and spatial heterogeneity on the spread of a nonnative forest pathogen, as well as the influence of spatial structure on the management and recovery of peregrine falcons. As a NPER Fellow, Matt is working with Drs. John Maron and Scott Mills at the University of Montana. His research will evaluate whether the recolonization of gray wolves has cascading indirect effects on aspen regeneration by altering either the number or foraging behavior of elk that heavily browse young aspen. This project seeks to understand where wolves kill elk on the landscape, how elk browsing differs spatially in response to predation risk, and whether these interactions between predator and prey translate to meaningful differences in the growth and survival of young aspen. Matt is conducting his research across several elk winter ranges in the Northern Rockies, including Yellowstone and Glacier National Parks, Gallatin National Forest (SW Montana), and Banff National Park.

Kathleen Kay Kathleen Kay received her B.S. in Environmental Biology and Management in 1995 from the University of California at Davis . She then earned her Ph.D. from Michigan State University in 2004 as a dual degree in Plant Biology and Ecology, Evolutionary Biology, and Behavior. Her dissertation research, under the direction of Doug Schemske, focused on speciation mechanisms in a diverse genus of tropical gingers. She has been particularly interested in the role of natural selection and plant-pollinator interactions in the formation of new plant species. As an NPER Postdoctoral Fellow, she joins the laboratory of Dr. Scott Hodges in the Department of Ecology, Evolution, and Marine Biology at the University of California at Santa Barbara , where she will continue to focus on the evolutionary mechanisms underlying plant diversity. She will investigate the ecological factors affecting gene flow and reproductive isolation in the columbines in the Sierra Nevada mountains of California , with field work spanning Yosemite , Sequoia, and Kings Canyon National Parks .

2002 Fellows

Nichole Barger Nichole Barger received her B.A. from the The Evergreen State College (1995), M.S. from the University of California, Berkeley (1998), and Ph.D. from Colorado State University (2003). Dr. Barger examined the constraints to colonization of an invasive African grass in Venezuela for her masters work, which was conducted under the supervision of Dr. Carla D’Antonio. Her dissertation research focused on nitrogen cycling in biological soil crusts in the Inner Mongolian Autonomous Region, China and Canyonlands National Park, Utah. This research was conducted in collaboration with Dr. Dennis Ojima from Colorado State University and Dr. Jayne Belnap with the USGS in Moab, Utah. The research conducted within Canyonlands National Park was supported by the Canon National Parks Science Scholars Program. Dr. Barger is continuing her work on the Colorado Plateau as a post-doctoral research scientist at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado, Boulder. She is working in collaboration with Dr. Connie Woodhouse , director of the INSTAAR Dendrochronology Laboratory. Dr. Barger will be exploring the role of land use change such as livestock grazing and the natural range in climate variability in pinyon-juniper woodland expansion on the Colorado Plateau. She will be conducting her work in Canyonlands National Park, Grand Staircase Escalante National Monument, and Zion National Park.

Jason Fridley Jason Fridley received his B.A. from Bennington College in 1997 and his Ph.D. from the University of North Carolina at Chapel Hill in 2002. His doctoral work, under the direction of Robert Peet, focused on the reationship between local plant diversity and ecosystem production in different environmental contexts. Dr. Fridley's NPER Fellowship project will shift his focus from small-scale plant diversity to the regional-scale floristic diversity of Great Smoky Mountains National Park. Using null models and new approaches to gradient analysis (developed in the Smokies over 50 years ago by Robert Whittaker), Dr. Fridley will examine the nature of spatial species turnover along broad environmental gradients (climate, soil, topography) to better understand the regional controls of floristic diversity. Floristic patterns from the Smokies will then be compared to those from other national parks throughout the country using vegetation data from the NPS Vegetation Mapping project and a high-resolution climate database. More information about Dr. Fridley's interests and research is online at

Jennifer Nagel Jennifer Nagel received her B.S. degree in Environmental Science and English in 1997 from Allegheny College in northwestern Pennsylvania. She then earned her Ph.D. from Columbia University in 2003 in the Department of Earth and Environmental Sciences. Her dissertation research with Dr. Kevin Griffin focused on elucidating physiological mechanisms that could influence the performance of invasive nonindigenous plant species in native communities under ambient environmental conditions and with changes in resource availability. As an NPER Post-Doctoral Fellow, she has joined the laboratory of Dr. Jake Weltzin in the Department of Ecology and Evolutionary Biology at the University of Tennessee. Dr. Nagel’s NPER Fellowship project focuses on examining how physiological properties, in particular the balance of energetic gains and costs, could influence plant community composition, processes of plant species’ invasion, and their responses to environmental changes in Great Smoky Mountains National Park. She will examine energetic properties of co-occurring invasive and native plant species in old-field communities within the Park and relate these properties to their relative community-level performance. This study will be linked to an ongoing project at the nearby Oak Ridge National Environmental Research Park designed to assess the responses of invasive and native old-field species to changes in multiple interacting environmental manipulations of atmospheric CO2, air temperature, and soil water availability.

Bibit Halliday Traut Bibit Halliday Traut received her B.A. in Biology and M.S. in Marine Sciences from the University of California, Santa Cruz. Her thesis focused on examining the natural history and feeding ecology of a large herbivorous kelp forest snail. Dr. Traut then received a M.S. in Botany and Plant Pathology from Oregon State University where her thesis focused on the effects of variation in ecosystem carryover on biodiversity and community structure of forest floor bryophytes and understory vascular plants. In 2003, Dr. Traut completed her PhD. in Ecology from the University of California, Davis. Her doctoral work focused on the structure and function of the high salt marsh ecotone and examined the influences of grazing and nitrogen addition on community dynamics. Dr. Traut’s NPER Fellowship project will continue to examine the marine/terrestrial transition zone at Point Reyes National Seashore, but will more specifically examine the relationship between plant diversity and ecosystem function. In collaboration with Whendee Silver and Carla D’Antonio at the University of California, Berkeley, her study will examine the relationship between plant composition and nitrogen cycling. They will also test the predictions that resistance to invasion will increase in more diverse plots, and that in those plots that are invaded (e.g. by a C4 annual invader) nitrogen retention will be reduced. Coastal transition zones provide essential ecological functions regulating fluxes of nutrients, water and organisms. Biological processes in these areas of transition mediate nitrogen retention and removal. As we are faced with rapid destruction of these crucial “filters,” it is imperative to increase our understanding of the consequences of biodiversity on ecosystem function. Results from this study will provide important information for the greater scientific community, as well as managers charged with conserving and restoring the marine/terrestrial transition zone.

2001 Fellows

Betsy Von Holle Betsy Von Holle received her B.S. degree in Ecology, Behavior and Evolutionary Biology at the University of California, at San Diego. She then received her Ph.D. from the University of Tennessee in 2002, in the Department of Ecology and Evolutionary Biology. Her dissertation research with Dr. Daniel Simberloff concerned ecological resistance to biological invaders. Dr. Von Holle’s NPER Fellowship project focuses on disturbance histories as a predictor of habitat invasibility in a mosaic landscape at Cape Cod National Seashore. Dr. Von Holle and her team have employed multi-scale techniques to determine landscape-level influences on nonnative plant invasion. Betsy is collaborating with Dr. David Foster and Glenn Motzkin of Harvard Forest in a landscape study of nonnative plant distribution that pairs historical, environmental, and biotic properties of Cape Cod National Seashore to determine habitat invasibility. This research has revealed that nonnative species distributions and abundances in this largely invasion-resistant landscape are largely driven by soil nutrient conditions, rather than current biota or historical disturbances. Models that emerge from this study are being tested for their generality by applying them to the rest of the Cape Cod/ Long Island coastal ecoregion. In a smaller-scale field-based study, nonnative species richness and abundance values decreased away from typical natural disturbances (wind, salt spray) of the outer Cape, while native species richness and abundance values typify the 'intermediate disturbance' response to natural disturbances. Betsy and her team have documented that the invasive, nitrogen-fixing black locust tree, Robinia pseudoacacia, facilitates invasion by other nonnative plant species, most likely owing to the nutrient-rich soils found beneath this nonnative species. Currently, they are investigating nutrient cycling properties of locust and native forests, initiating a restoration ecology experiment of heathland invasibility, and conducting manipulative experiments to investigate the factors that promote invasion into heathlands. For more information regarding Betsy’s research interests and activities, please see

Kristina M. Hufford Kristina M. Hufford's NPER Fellowship project will investigate the hypothesis that widespread, common plant species distributed among heterogeneous environments are likely to form different races or "ecotypes." Dr. Hufford's team will examine both ecological and genetic variation of populations of three native grass species on the California Channel Islands. They will compare data collected at the park with data collected from representative mainland sites in Santa Barbara County. A unique combination of genetic analyses and ecological field studies will allow them to characterize local adaptation within populations of a single species, and the extent to which breeding systems affect levels of local adaptation among species. As a result, this research will provide new insights in ecological genetics and the island biogeography of plant populations. Dr. Hufford received a B.A. in Environmental Sciences from the University of California, Berkeley and a Ph.D. in Botany from the University of Georgia. She conducted her dissertation research at the Smithsonian Tropical Research Institute on Barro Colorado Island in the Republic of Panama. Her Ph.D. project examined temporal variation in selection across life stages of a population of tropical rainforest trees. Dr. Hufford is currently conducting postdoctoral research with Dr. Susan Mazer in the Department of Ecology, Evolution, and Marine Biology at the University of California in Santa Barbara.

2000 Fellows

Brian Beckage Brian Beckage received an undergraduate degree in Civil and Environmental Engineering from Cornell University, and an M.S. degree in Biology at the University of Central Florida. For his thesis, he investigated the relationship between species diversity and fire frequency in xeric pinelands of central Florida. While pursuing a Ph.D. at Duke University, where he also completed an M.S. degree in statistics, Dr. Beckage worked with Dr. James Clark and studied the role of seedling recruitment in maintaining species diversity of Southern Appalachian forests. After attaining his Ph.D., he accepted a postdoctoral research position with Dr. William Platt at Louisiana State University where he became interested in pine demography. As a postdoctoral fellow, Dr. Beckage is studying the relationship between hurricane and fire disturbances on the dynamics of pine forests in Everglades National Park. While the effects of either fires or hurricanes have been studied in pinelands, much less is known about potential interactions among these disturbances. Currently, he is investigating the consequences of fires, hurricanes, and their interaction on the population dynamics of the pine savanna overstory using matrix and spatially explicit, individual-based models, parameterized from demographic data collected in the field. The resulting data and models encompass effects of Hurricane Andrew in combination with varied fire regimes and will be used to simulate pine dynamics and spatial structure in response to hypothetical disturbance regimes associated with global climate change. Dr. Beckage is currently an Assistant Professor in the Botany Department at the University of Vermont.

J. Nathaniel Holland J. Nathaniel Holland received his B.S. degree in Biology and Environmental Science in 1993 from Ferrum College in southwestern Virginia. He then attended the University of Georgia where he obtained an M.S. degree in 1995 in Entomology studying the effects of above-ground herbivory on plant carbon allocation and soil food webs. Dr. Holland completed his Ph.D., in the Department of Biology at the University of Miami, in 2001. Dr. Holland and his Ph.D. advisor, T.H. Fleming, co-discovered a pollinating seed-eating mutualism between senita cacti and senita moths, which are endemic to the Sonoran Desert of northwestern Mexico and Organ Pipe Cactus National Monument in south-central Arizona. His research is published in journals such as Ecology, Oecologia, American Naturalist, and Theoretical Population Biology. His theoretical research, in collaboration with D.L. DeAngelis and J.L. Bronstein, has lead to several insights, including how fruit abortion by cacti can limit moth population size and thereby increase the net benefits to cactus reproduction, by maximizing the difference between the benefits of moth pollination and the costs of the moth's larvae consuming seeds of cacti. As a postdoctoral fellow, he has joined the laboratory of J.L. Bronstein in the Department of Ecology and Evolutionary Biology at the University of Arizona, where he and Bronstein will empirically investigate the functional responses of benefits (pollination) and costs (seed consumption) to senita cacti at Organ Pipe Cactus National Monument. Dr. Holland is currently an Assistant Professor in the Department of Ecology and Evolutionary Biology at Rice University, Houston, Texas.

Steven Perakis Steven Perakis holds a BS from the University of Pennsylvania (1990), an MS from the University of Washington (1994), and his PhD from Cornell University (2000). His research centers on understanding biogeochemical cycles in terrestrial ecosystems, and he has particular interest in discerning how processes within ecosystems shape nutrient losses and whole-system nutrient balances. Steve received the Buell Award from the Ecological Society of America in recognition of his dissertation research into controls on nitrogen cycling in unpolluted, old-growth temperate forests of South America. His postdoctoral research with Peter Vitousek at Stanford University uses grasslands of Sequoia National Park as model systems to investigate how rainfall variations drive asynchrony in nutrient supply and demand, with implications for nutrient loss and limitation in a wide range of terrestrial ecosystems. In November 2002, Dr. Perakis took a position as staff scientist with the USGS Forest and Rangeland Ecosystem Science Center in Corvallis, Oregon. He is also an adjunct assistant professor in the Department of Forest Science at Oregon State University.

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