Nathan R De Jager, PhD
I serve as a principal investigator and non-supervisory team leader for landscape ecological studies at the USGS Upper Midwest Environmental Sciences Center, where I have been since 2008. My research group uses a combination of field research and computer modelling to study how ecosystem processes respond to disturbances across large landscapes.
In the floodplain of the Upper Mississippi River, we study how spatial and temporal variation in flooding impacts plant and soil processes. Results from field studies are used to parameterize a spatially explicit simulation model that can be used to better understand and forecast effects of altered hydrological regimes and other disturbances (e.g., emerald ash borer, herbivory by white-tailed deer) on forest succession and nutrient cycling.
At Isle Royale National Park, we study how spatial and temporal variability in browsing by moose impacts plant and soil processes. Results from field studies are used to parameterize a spatially explicit simulation model that can be used to better understand and forecast effects of different moose population dynamics on forest succession in the context of climate change and predation by wolves.
In addition to these two primary study areas, I provide leadership and support for graduate students and other researchers working on a diverse array of topics, most of which require the use of GIS or other modelling approaches to link fine-scale measurements with landscape-scale phenomena. I frequently serve on regional to national scale working groups led by the USGS or other conservation groups and am an associate editor with the Natural Areas Journal.
Education and Certifications
2008 PhD in Ecology, Evolution, and Behavior with a minor in Conservation Biology, University of Minnesota, St. Paul, Minnesota
2005 MSc in Biology
Science and Products
Effects of flood inundation, invasion by Phalaris arundinacea, and nitrogen enrichment on extracellular enzyme activity in an Upper Mississippi River floodplain forest
Indicators of ecosystem structure and function for the Upper Mississippi River System
Developing a shared understanding of the Upper Mississippi River: the foundation of an ecological resilience assessment
Habitat Needs Assessment‐II for the Upper Mississippi River Restoration Program: Linking science to management perspectives
Effects of flood inundation and invasion by Phalaris arundinacea on nitrogen cycling in an Upper Mississippi River floodplain forest
Modelling moose–forest interactions under different predation scenarios at Isle Royale National Park, USA
Simulating ungulate herbivory across forest landscapes: A browsing extension for LANDIS-II
Spatial and temporal relationships between the invasive snail Bithynia tentaculata and submersed aquatic vegetation in Pool 8 of the Upper Mississippi River
Changes in aquatic vegetation and floodplain land cover in the Upper Mississippi and Illinois rivers (1989–2000–2010)
Patchiness in a large floodplain river: Associations among hydrology, nutrients, and fish communities
Landscape ecology of the Upper Mississippi River System: Lessons learned, challenges and opportunities
Measuring spatial patterns in floodplains: A step towards understanding the complexity of floodplain ecosystems: Chapter 6
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Effects of flood inundation, invasion by Phalaris arundinacea, and nitrogen enrichment on extracellular enzyme activity in an Upper Mississippi River floodplain forest
The community structures and ecosystem functions of floodplains are primarily driven by variation in flood inundation. However, global changes, such as invasive species and nutrient enrichment, may alter the effects of flooding in these systems. We added nitrogen (N) to correspond with twice the annual atmospheric deposition rate of the south-west Wisconsin, USA region within mature floodplain forAuthorsNathan R. De Jager, Whitney Swanson, Daniel L. Hernandez, Julia Reich, Richard A. Erickson, Eric A. StraussIndicators of ecosystem structure and function for the Upper Mississippi River System
This report documents the development of quantitative measures (indicators) of ecosystem structure and function for use in a Habitat Needs Assessment (HNA) for the Upper Mississippi River System (UMRS). HNAs are led periodically by the U.S. Army Corps of Engineers’ Upper Mississippi River Restoration (UMRR) Program, which is the primary habitat restoration program on the UMRS. The UMRR Program helAuthorsNathan R. De Jager, James T. Rogala, Jason J. Rohweder, Molly Van Appledorn, Kristen L. Bouska, Jeffrey N. Houser, Kathi Jo JankowskiDeveloping a shared understanding of the Upper Mississippi River: the foundation of an ecological resilience assessment
The Upper Mississippi River System (UMRS) is a large and complex floodplain river ecosystem that spans the jurisdictions of multiple state and federal agencies. In support of ongoing ecosystem restoration and management by this broad partnership, we are undertaking a resilience assessment of the UMRS. We describe the UMRS in the context of an ecological resilience assessment. Our description articAuthorsKristen L. Bouska, Jeffrey N. Houser, Nathan R. De Jager, Jon S. HendricksonHabitat Needs Assessment‐II for the Upper Mississippi River Restoration Program: Linking science to management perspectives
The Upper Mississippi River Restoration (UMRR) Program vision statement is for a healthier and more resilient Upper Mississippi River ecosystem that sustains the river’s multiple uses. To address this vision, the UMRR Program recently developed a suite of 12 indicators that quantify aspects of ecosystem health and resilience (i.e., connectivity, redundancy and diversity, and controlling variables)AuthorsKat McCain, Sara Schmuecker, Nathan R. De JagerEffects of flood inundation and invasion by Phalaris arundinacea on nitrogen cycling in an Upper Mississippi River floodplain forest
Although floodplains are thought to serve as important buffers against nitrogen (N) transport to aquatic systems, frequent flooding and high levels of nutrient availability also make these systems prone to invasion by exotic plant species. Invasive plants could modify the cycling and availability of nutrients within floodplains, with effects that could feedback to promote the persistence of the inAuthorsWhitney Swanson, Nathan R. De Jager, Eric A. Strauss, Meredith ThomsenModelling moose–forest interactions under different predation scenarios at Isle Royale National Park, USA
Loss of top predators may contribute to high ungulate population densities and chronic over-browsing of forest ecosystems. However, spatial and temporal variability in the strength of interactions between predators and ungulates occurs over scales that are much shorter than the scales over which forest communities change, making it difficult to characterize trophic cascades in forest ecosystems. WAuthorsNathan R. De Jager, Jason J. Rohweder, Brian R. Miranda, Brian R. Sturtevant, Timothy J. Fox, Mark C. RomanskiSimulating ungulate herbivory across forest landscapes: A browsing extension for LANDIS-II
Browsing ungulates alter forest productivity and vegetation succession through selective foraging on species that often dominate early succession. However, the long-term and large-scale effects of browsing on forest succession are not possible to project without the use of simulation models. To explore the effects of ungulates on succession in a spatially explicit manner, we developed a Browse ExtAuthorsNathan R. De Jager, Patrick J. Drohan, Brian M. Miranda, Brian R. Sturtevant, Susan L. Stout, Alejandro Royo, Eric J. Gustafson, Mark C. RomanskiSpatial and temporal relationships between the invasive snail Bithynia tentaculata and submersed aquatic vegetation in Pool 8 of the Upper Mississippi River
Bithynia tentaculata is an invasive snail that was first reported in Lake Michigan in 1871 and has since spread throughout a number of freshwater systems of the USA. This invasion has been extremely problematic in the Upper Mississippi River as the snails serve as intermediate hosts for several trematode parasites that have been associated with waterfowl mortality in the region. This study was desAuthorsAlicia M. Weeks, Nathan R. De Jager, Roger J. Haro, Greg J. SandlandChanges in aquatic vegetation and floodplain land cover in the Upper Mississippi and Illinois rivers (1989–2000–2010)
Quantifying changes in the cover of river-floodplain systems can provide important insights into the processes that structure these landscapes as well as the potential consequences to the ecosystem services they provide. We examined net changes in 13 different aquatic and floodplain land cover classes using photo interpreted maps of the navigable portions of the Upper Mississippi River (UMR, aboveAuthorsNathan R. De Jager, Jason J. RohwederPatchiness in a large floodplain river: Associations among hydrology, nutrients, and fish communities
Large floodplain rivers have internal structures shaped by directions and rates of water movement. In a previous study, we showed that spatial variation in local current velocities and degrees of hydrological exchange creates a patch-work mosaic of nitrogen and phosphorus concentrations and ratios in the Upper Mississippi River. Here, we used long-term fish and limnological data sets to test the hAuthorsNathan R. De Jager, Jeffrey N. HouserLandscape ecology of the Upper Mississippi River System: Lessons learned, challenges and opportunities
The Upper Mississippi River System (UMRS) is a mosaic of river channels, backwater lakes, floodplain forests, and emergent marshes. This complex mosaic supports diverse aquatic and terrestrial plant communities, over 150 fish species; 40 freshwater mussel species; 50 amphibian and reptile species; and over 360 bird species, many of which use the UMRS as a critical migratory route. The river and flAuthorsNathan R. De JagerMeasuring spatial patterns in floodplains: A step towards understanding the complexity of floodplain ecosystems: Chapter 6
Floodplains can be viewed as complex adaptive systems (Levin, 1998) because they are comprised of many different biophysical components, such as morphological features, soil groups and vegetation communities as well as being sites of key biogeochemical processing (Stanford et al., 2005). Interactions and feedbacks among the biophysical components often result in additional phenomena occuring overAuthorsMurray W. Scown, Martin C. Thoms, Nathan R. De Jager