Staff research
Demonstrating benefits of conservation grasslands on water quality
Conservation grasslands are agricultural lands, planted in grass or other perennial cover as part of state and federal programs to minimize crop overproduction, to create wildlife habitat, and to reduce soil erosion and nutrient loss that otherwise would pollute lakes and streams. The research aims to quantify whether there is a critical amount or placement of grassland needed to produce a measurable reduction in erosion. Because lakes tend to trap most of the sediment that enters them, the rate of lake-sediment accumulation is a measure of erosion in the contributing watershed. Lakes in western and southern Minnesota have been selected according to the amount of conservation grasslands in their watersheds. Sediment cores from these lakes are being analyzed for accumulation rates of both sediment and phosphorus to see if these rates correlate with changes in land use. Funding for this project is provided by the Legislative and Citizen Commission on Minnesota Resources (LCCMR).
Continuation of the long-term mercury cycling study at the Marcell Experimental Forest
This project builds on a long-term ecosystem-scale experiment in which sulfate deposition to a boreal wetland was increased in order to examine the synergistic effects of atmospheric sulfate and mercury on production and export of the bioaccumulative neurotoxin, methylmercury. Previous work established a whole-wetland irrigation system for amending sulfate deposition through simulated rainfall. Results from the first six years of the experiment showed a consistent increase in mercury concentration and export from the wetland following sulfate addition, although the response differed markedly depending on the season of application and preceding climatic conditions. The focus of the investigation now shifts to the recovery of the wetland from chronic sulfate enrichment and the ultimate reduction in methylmercury production with the cessation of sulfate addition. Three specific questions concerning the rate of the response will be addressed: (1) what is the fate of the added sulfate and how is it recycled and ultimately sequestered in the peat, (2) how do water-table fluctuations and climate variability affect sulfur cycling and mercury methylation, and (3) what causes the observed seasonal differences in methylmercury production (following sulfate additions) – temperature, availability of labile carbon, speciation of inorganic Hg?
Centennial funding for the St. Croix
The St. Croix National Scenic Riverway is one of 76 national parks to receive funding through a new cost-share initiative, the Centennial Challenge. Funds from the Riverway, matched with funding from the Twin Cities Metropolitan Council and the Minnesota Pollution Control Agency, is supporting development of a watershed model that will help achieve nutrient reduction goals for the St. Croix River. The model, simulating nutrient loading, is being developed under the direction of Senior Scientist Jim Almendinger.
The watershed model, known as the Soil and Water Assessment Tool, or SWAT, will identify sources of tributary loading, the management practices that will be effective in reducing loads, and where those practices would be most effective. It can be used by communities, watershed districts, county conservation districts, private landowners, and others to help achieve water quality goals for the St. Croix.
Restoring habitat "For the Birds"
Populations of many grassland-nesting songbird species such as Eastern meadowlark, bobolink, and Henslow sparrow have declined significantly in the past few decades. Correspondingly, the habitat that these birds prefer for nesting has also decreased significantly over the last 50 years. This project, directed by Shawn Schottler in cooperation with Great River Greening and Standing Cedars Community Land Conservancy, restored old fields to prairie habitat, with the specific goal of creating and evaluating improved grassland habitat complexes for these species. Three separate plantings of native species have been planted on lands at Standing Cedars, overlooking the St. Croix south of Osceola, Wisconsin. Distinct seed mixes, using different species compositions, will create areas of differing "structures"—short to medium height prairie with high forb diversity; tall, dense forb-rich prairie; and short structure grass-dominated prairie. The importance of having high plant diversity in prairie reconstructions has gained acceptance; this project will demonstrate that structural diversity is equally important. Creating prairie with distinct structural difference (e.g. tall vs. short) is likely a key element in improving grassland songbird habitat. Locally-grown seed has been harvested in preparation for plantings in later 2008 and 2009, to create new structures "for the birds."
Landscape-level controls on terrestrial, aquatic, and wetland responses to climate change in the southern Canadian Arctic
Climate is changing rapidly in the Arctic as evidenced by a 0.4°C per decade rise in temperature over the past 40 years. Ecological responses to this warming include increases in lake productivity, permafrost thaw, shrub expansion, and northward shifts in the subarctic tree line. Paleoecological studies have played an important role in understanding modern and historic climate change in the Arctic, but relatively little is known about how landscape, in particular peat development and exposed till, constrains terrestrial, aquatic, and wetland responses to climate. In this project we will study six lakes across the forest-tundra ecotone of northern Manitoba. In lake sediment, peat, and soil cores we will variously analyze pollen/spores and charcoal, diatoms and silica, phosphorus, carbon and nitrogen (including isotopes), magnetic remanence, pollen/spores, and grain size. Our objectives are to (1) understand the role of landscape in mediating lake and terrestrial ecosystem responses to climate, and (2) investigate the impacts of changes in terrestrial and wetland ecosystems on adjacent lakes. Results will be broadly applicable to on-going efforts that model the impacts of warming on carbon dynamics in the arctic tundra and peatlands. The proposed research is multi-institutional and collaborative among four undergraduate institutions and the Science Museum of Minnesota. This three year project will include two field seasons and includes the training of at least 15 undergraduate students and one doctoral student.
Great Lakes Fisheries
The Great Lakes are undergoing an unprecedented ecological collapse, most notably in populations of a bottom-dwelling freshwater shrimp called Diporeia. Diporeia is a keystone species in the Lakes, linking energy flow from the deepest waters and sediment to the famed Great Lakes fishery. As Diporeia numbers have crashed, the health of the whitefish, yellow perch, and cisco fisheries have declined. The loss of Diporeia is coincident with the introduction of exotic species including the zebra and quagga mussel, and it has been hypothesized that the competition for food between the mussels and Diporeia is driving the changes. To test this hypothesis we are analyzing sediment cores from Lake Michigan to determine the quantity and quality of the algal food resources for Diporeia, particularly diatoms, and how changes in food resources are linked to population dynamics of zebra/quagga mussels and Diporeia. To corroborate these results, gut analyses of Lake Michigan Diporeia will be done, using preserved, historical collections taken from over 40 sites between 1981-2005. This project is a collaboration with the University of Michigan.
Sources of Suspended Sediment in Minnesota's Rivers
A series of projects is examining the sources of suspended sediment to rivers and streams in Minnesota's agricultural areas. Current projects involve studies of Lake Pepin on the Mississippi River, the South Fork of the Crow River, and Redwood and Seven Mile Creeks, and other tributaries to the Minnesota River. These projects use atmospherically-deposited radio isotypes to fingerprint eroding sediment sources, and compare these fingerprints to suspended sediments in rivers and lakes. Funded by and in collaboration with Minnesota Pollution Control Agency.
Watershed outlet monitoring program—Valley Creek
Streams are sensitive to land-use changes in their watersheds, and urbanization is a land-use change affecting nearly all streams in the Twin Cities metropolitan area. Because one of the responsibilities of the Metropolitan Council Environmental Services (MCES) is to develop target pollution loads for all Metropolitan Area watersheds, MCES has established the Watershed Outlet Monitoring Program (WOMP) to monitor loads of common pollutants such as suspended sediment, nitrogen, and phosphorus, among others. The project is intended to run for many years and generate long-term sets of water-quality data to better understand the effects of land-use change on these watersheds. Valley Creek is an important watershed in the monitoring network because it may serve as a relatively pristine end-member, a standard of comparison for the other, more urban-impacted streams.
Biomonitoring prospects for diatoms and paleolimnology in the Western Great Lakes National Parks
In Great Lakes Network (GLKN) National Park units, climate change, environmental contaminants, exotics, and land and resource uses including shoreline and urban development, recreation, water level management, logging, and agriculture have raised concerns about the state of the parks' resources and how to best manage them in a future certain to bring change. In this project we developed a strategy to integrate the use of paleolimnological techniques and diatom analysis in an inventory and monitoring framework. Results will provide a management foundation by determining the natural variability or reference condition of national park lakes. Because lake-sediment records integrate across both spatial and temporal scales, research results will be further used as a biomonitoring strategy by revisiting lakes on regular intervals (3-5 years) to quantify modern environmental conditions relative to historical conditions, to detect early ecological change and recent trends, and to evaluate success of management actions. Funded by National Park Service-GLKN. Collaborators: National Park Service
Recently Completed Projects
The Diatoms, Ostracodes, and Chironomids of Western Mongolia's saline lakes: biodiversity, ecology, and research applications
Sixty lakes in Mongolia's Valley of the Great Lakes that span gradients from fresh to hypersaline and brine types will be sampled for modern diatom, chironomid, and ostracode assemblages. Diatom and ostracode calibration sets will be prepared for future paleosalinity and paleoclimatic applications. Subsets of collections will be accessioned in curated collections in museums in Mongolia (NUM), America (SMM and UMinn), and Belgium (RBINS). The success and approach of the PRAIRIE research group will be further applied to mid-Asia's large closed basin region to decipher paleoclimatic records in this climatically responsive region. Funded by the National Science Foundation-Biodiversity Surveys and Inventories. Collaborators: University of Minnesota (Entomology, Geology), Royal Belgian Institute of Natural Sciences, National University of Mongolia, Mongolian Academy of Sciences (Paleontology), St. Olaf College.
Long-term impacts of lake-level alterations on water quality in Voyageurs National Park
The natural water levels of the large lakes in Voyageurs National Park - Rainy, Kabetogama, Namakan - have been altered and artificially manipulated for almost a century by a series of dams built to serve the logging industry. This project is exploring the biological consequences of lake-level changes through the analysis of fossil diatoms in dated lake-sediment cores. Multivariate numerical techniques including correspondence analysis and ordination along with environmental reconstruction based on a modern diatom/water-quality data set from Minnesota lakes will be used to rigorously evaluate limnological trends. Funded by USGS-NRPP program. Collaborators: National Park Service, U.S. Geological Survey, University of Minnesota (graduate student).
Using wetland environmental histories to develop management strategies for the St. Croix Riverway
Floodplains are a dominant feature in the Lower St. Croix National Scenic Riverway. Braided channels and wetlands harbor high diversity of plants and wildlife and are crucial nesting and nursery areas. Recreational uses include wildlife watching, fishing, and hunting. Floodplains are a crucial component in preventing unnatural water quality degradation, maintaining natural patterns and amounts of flow, and maintaining native organisms and their habitats. However, historical data indicate that floodplain wetlands have undergone significant changes possibly from exotic species introductions, land use changes in the watershed, and river management. This project will recover sediment cores from three floodplain wetlands in the Lower St. Croix River, analyze them to reconstruct the ecological history from geochemical and biological markers, and form a baseline for making management decisions regarding wetland protection and restoration. Funded by USGS-NRPP.
Protecting and propagating the genetic diversity of the Lower St. Croix Watershed through reconstruction of a 32 acre prairie on an abandoned agricultural field
A 32 acre site will be restored to prairie using St. Croix Ecotype seed. The site is divided into 17 separate plantings, testing methods to maximize floristic diversity. Variables include four seeding densities, two grass:forb ratios, and spring vs. fall planting (plus 1 control plot). Once established the restoration can be used as a site to examine the effect of floristic diversity on habitat value. Funded by National Park Service.
St. Croix Greenway sand prairie reconstruction: maximizing floristic diversity
Project will reconstruct 4 acres of prairie incorporating over 70 local ecotype plant species, designed to re-establish a stepping stone of high quality grassland wildlife habitat within the 4-mile St. Croix Greenway Corridor. Simultaneously, the project will be implemented using a suite of planting techniques that can subsequently be assessed to determine which methods create the maximum floristic diversity for the least amount of cost. Funded by MN DNR.
Manage nonpoint pollutants by watershed modeling of targeted subwatersheds in the St. Croix National Scenic Riverway
Construct computer watershed models of the Willow River in western Wisconsin and the Sunrise River in eastern Minnesota. The models will be applied to test the effectiveness of selected land-management scenarios in reducing the sediment and phosphorus loads from these watersheds into the St. Croix River. Funded by National Park Service.
Monitoring water quality in wadeable streams of national park units of the Great Lakes Inventory and Monitoring Network
The objective of this project is to develop a protocol for monitoring water quality in wadeable streams that will be consistent with and complement the protocols for lakes and large rivers. In addition to chemical and physical parameters, biota may be included in this protocol. Funded by National Park Service/CESU.
