Kenna O. Karjala, University of Montana, Missoula
The North American Beaver (Castor Canadensis), being an ecosystem engineer, played a key role in shaping the North American riparian landscape until they were trapped into near extinction to meet the demands of the fur trade. Their absence has been felt on degraded riparian ecosystems through the incision of streams, which disconnects the channel from the floodplain, as well as through the loss of pool habitat and woody material in incised streams. In the last thirty years, restoration practitioners have sought to bring the benefits of beavers back into these systems through beaver mimicry. Beaver mimicry is the restoration technique of replicating the structure and function of beavers in a landscape through the use of human-constructed beaver dams called beaver dam analogues (BDAs) in order to restore degraded ecosystems. While this technique is relatively cheap, mimics natural events, and might encourage the return of beavers to streams, there is little known about the impacts of BDAs on the organic matter inherent in all streams, despite organic matter making up the base of the riparian food web. In an effort to correct that oversight, I engaged in a study on the impacts of BDAs on dissolved organic matter (DOM) in streams as part of a larger project on BDAs run by PhD student Andrew Lahr in collaboration with the Clark Fork Coalition and The Nature Conservancy. We implemented a BACI (Before, After, Control, Impact) test on three pairs of low-order streams in Western Montana. To answer the question of how these structures impact DOM above and below the dams, I collected and analyzed DOM samples, using levels of protein and humic acid within the samples to indicate the freshness of the DOM present. My results show significant change in these levels over time when looking at individual streams (p0.1). This could suggest that the installation of BDAs on these streams has no impact on the quality of DOM but rather the differences seen are byproducts of the natural progression of these streams. The results from this study come only one year post-treatment, so hopefully with long-term monitoring a more robust pattern will emerge.
Whitetail Deer (Odocoileus virginianus) and Mule deer (Odocoileus hemionus) In the Western United States present management challenges by browsing on ornamental plants and shrubs grown on private and public property. Deer eat a variety of species and their populations in urban settings are increasing. One approach to minimize damage by deer is to select ornamental plants that are deer resistant, however, there is a lack of knowledge about deer resistant native ornamental choices in this region. This region is also experiencing longer and more intense fire seasons, and so while deer pose a threat to ornamental plants, ornamental plants can also pose a threat to property by serving as fuels. In response to this, there has been a shift to the selection of native plants that are fire resistant to minimize the risk to homes and public spaces. The goal of this project is to test the extent to which urban deer will browse on fire resistant plants. To accomplish this, I will conduct a field trial on the University of Montana Campus where I have plantings of 10 species of plants. I will quantify deer presence in the area and browse on the plantings to compare the relative preference of deer for the different plant species. This information will provide guidance to homeowners seeking plants that pose a low risk from fire and are resistant to deer browsing.
Madison Grace Miller, University Of Montana
Reconstructing Historical Wildfire Temperatures by Analyzing Lake Sediment Charcoal Using Infrared Spectroscopy
Wildfire is a natural ecological process in the Northern Rockies that has shaped forest ecosystems for millennia. Anthropogenic climate change is altering fire regimes creating ecological, economic, and social challenges for people living in the West. Not all wildfires are the same. Moderate intensity fires burn at relatively low temperatures, combusting the understory vegetation and killing some trees, while hotter fires can kill most trees and lead to stand replacement. Lake sediments provide modern scientist with a record of historical fire activity spanning thousands of years. By extracting sediment cores and quantifying charcoal accumulation layer by layer, we are able to infer how frequently wildfires occurred in the past. A peak in charcoal accumulation indicates a fire event. However, these methods do not tell us anything about the intensity as which past fire burned, an important factor that in part determines fire impacts on ecosystems.
To infer the temperature of reconstructed fire events, I used infrared spectroscopy to analyze charcoal from lake sediment records. I created a set of modern charcoal samples from Northern Rockies native conifers, combusted at varying temperatures, and analyzed them using Fourier Transformed Infrared Spectroscopy (FTIR). FTIR measures vibrational state of molecules by quantifying the wavelengths of light the molecules absorb. At hotter temperatures, more complex molecules break down. Therefore, the spectrum obtained from a samples varies with the temperature at which the sample was combusted. I will compare the spectrums of charcoal from lake sediment to the modern samples to determine the range of temperatures at which historical fires burned. This will provide insights into changes in fire intensity over time.
With changing climate, drought is becoming a problem for many species across the globe. Scientists are predicting widespread water stress in some regions where precipitation has previously been plentiful and understanding the effects of water stress on vegetation has become a primary research need. Since most studies do not report the efficacy of experimental drought treatments, however, the scientific community lacks information on the most effective ways to create experimental drought -- a real limitation to understanding drought effects on plants. To improve knowledge about drought treatments, I conducted an experiment to assess the effect of drought treatments and pot sizes on volumetric water content (VWC, the ratio of water volume to soil volume). In order to determine how VWC in soil changes over time under different temperatures regimes (20° C = control; and 26° C = drought treatment) and with different sized pots (2” deep, 2” shallow, and 4” shallow), I set up an experiment in two growth chambers at the University’s Environmental Controlled Organismal Research (ECOR) Facility. After filling the pots with soil, I watered to field capacity and left the pots in the chambers to dry-down for 4 days, continuously recording VWC during this time. I replicated the experiment 9 times. I found that all pots in the drought experiment dried down at a faster rate then those in the control, and the results clearly show pot size matters when attempting to maintain a particular VWC in drought studies.