Research

Nutrient Limitation and Carbon Export from the Portneuf River Watershed
With support from the Idaho NSF EPSCoR RII program and the ID DEQ, we are using nutrient diffusers to determine if nitrogen and/or phosphorus is limiting primary production in the Portneuf River at various locations and times. We are also using leaf packs to measure rates of decomposition at the same locations, some of which are where there is also continuous water quality monitoring equipment. 

Participants in this project include Dr. Colden Baxter (ISU Biological Sciences), Dr. Dan Ames (ISU Geosciences), Dr. Amy Marcarelli (post-doctoral researcher), and Heather Bechtold (PhD student).

Diversity and Anthropogenic Impacts in Sagebrush Steppe
I have established experimental plots to examine two changes in sagebrush steppe communities that are likely to result from human impacts. The first treatment is a shrub removal. One of the consequences of increased abundance of cheatgrass (Bromus tectorum) can be an increase in fire frequency, which in turn can result in the loss of shrub species that are not well adapted to fire. The second treatment involves two levels of nitrogen addition. One of the more widespread impacts that humans are having on ecosystems is a consequence of increased atmospheric nitrogen deposition. Adding nitrogen to an ecosystem over an extended period of time, even at low levels, has the potential to shift competitive interactions and cause changes in the relative and absolute abundance of species. These experiments are located at the Barton Road Ecological Research Area, which is adjacent to the ISU Business and Research Park. Treatments on these plots were started in 1997.

I'm beginning work, with Drs. Matt Germino (ISU Biological Sciences), Nancy Huntly (ISU Biological Sciences), John Marshall (UI), and Jonathan Horton (U. North Carolina, Ashville) on a USDA-funded project looking at the consequences of losing sagebrush on the availability and use of deep soil moisture by invasive weeds. This work will also be done at the Barton Road Ecological Research Area.

Bacterial Concentrations in the Portneuf River
We are monitoring concentrations of E. coli and other fecal coliform bacteria in the Portneuf River within the Pocatello city limits. Samples collected by General Ecology classes revealed concentrations of E. coli that were above the Idaho limits for primary and secondary contact. Samples collected from January through June 2003 all had concentrations of E. coli that were below the primary contact limit of 406 CFU/100 ml. Samples collect in early July 2003 had much higher concentrations of E. coli, with some samples at the downstream end of the concrete channel above both the secondary (576 CFU/100 ml) and primary contact limits. This pattern of elevated bacterial concentrations during the summer months, when discharge is lowest, was repeated in 2004 and in 2005.



Results of E. coli sampling in the Portneuf River. Water flow is from left to right, and spacing between sample locations reflects distances along the river channel. The black line shows average results for samples collected in the first 6 months of 2003. The red line shows average results for samples collected in July. The two dashed lines indicated the Idaho limits for primary (406) and secondary (576) contact.

The next graph shows results of samples collected in early August, 2003.

Samples were collected within the concrete channel on two dates, about 10 m downstream and 10 m upstream of each of the bridges that span the channel. Samples below the channel were collected on one day. Similar to samples collected in July,
there were elevated levels of E. coli within the channel. The concentration of E. coli tended to decline below the channel, with the exception of an increase from North City Park to the North Main Extension bridge.
 

Our best guess is that pigeons are the source of much of the E. coli within the concrete channel. There are large quantities of pigeon droppings on the support structures under many of the bridges that span the channel.

Fairview Constructed Wetland
We are examining the design, operation, and function of a small scale constructed wetland for reducing nonpoint source pollution from agricultural areas. This work, funded by the Idaho State Board of Education, is located on the west side of American Falls Reservoir, about 30 miles from Pocatello. Additional information about this project is available at the Fairview Wetland Web Site and at the Center for Ecological Research and Education (CERE) Web Site. Current work is focused on comparing treatment effectiveness of the various components of the system.

This constructed wetland system (CWS) provides numerous research opportunities for studies on aquatic plants, amphibians, insects, and nutrient uptake by plants. Currently, Bryan Stowe (MS candidate) is looking at nutrient uptake by plants during the growing season and also at rates of decomposition of plant material.