View Danielle's Full CV.
711 Independent Ave.
Grand Junction, CO 81505
(970) 255- 6117
Ph.D., Ecology— Colorado State University, June 2006
B.A., Biology — Rice University, January 1999
Current or Recent Positions
Wildlife Habitat Researcher— Colorado Parks and Wildlife, June 2007-Present
Researcher— Natural Resource Ecology Laboratory, Fort Collins, CO, June 2006- May 2007
Current or Recent Research Projects
Restoring energy fields for wildlife. This project began in 2008 with the goal of finding improved wildlife habitat restoration techniques for oil and gas disturbances in the Piceance Basin of northwest Colorado. The study is unusual in that 6 linked experiments were conducted at 12 locations spanning nearly 4,000 ft of elevation changes. The invasive grass cheatgrass (Bromus tectorum) was a problem, or became one, at 10 of the 12 sites. Techniques that controlled the density or dispersal of cheatgrass seeds were successful over a broad range of conditions. Techniques that sought to alter the competitive environment to hinder cheatgrass had more limited success. Imazapic (Plateau®) herbicide produced results ranging from beneficial to devastating depending on application rate and site conditions. A seed mix containing 75% forbs produced excellent wildlife habitat and controlled cheatgrass as well as a more traditional grass-heavy seed mix.
Two seed dispersal projects were spin-offs of Restoring energy fields for wildlife. Through these projects we found that disturbances which remove vegetation, such as well pads or fire, greatly increase dispersal of cheatgrass seeds.
Rangeland restoration with pothole seeding. One of the most promising techniques in Restoring energy fields for wildlife was creating a rough surface of mounds and holes. This surface was very helpful in controlling cheatgrass, probably because it greatly limits cheatgrass seed dispersal. We produced a prototype of a seeder/modified disk to produce the rough surface and broadcast seed in a single pass. We used this ‘pothole seeder’ in 2012 at Horsethief State Wildlife Area near Fruita, CO. Today, an area which was once a cheatgrass near-monoculture has a diverse, native plant community of grasses, forbs, and shrubs.
Evaluation of habitat treatments for mule deer in the Piceance Basin (Component 1). To improve habitat for deer, pinyon and juniper trees may be removed to increase the productivity of palatable understory vegetation. Mechanical techniques for tree removal include hydro-axing (which grinds trees to a fine mulch), roller chopping (which pushes trees over and cuts them up) and chaining (which pulls trees over and leaves them intact). We evaluated understory responses to these 3 methods in a head-to-head, replicated field experiment implemented in 2011. After 5 years, all methods increased grass cover over untreated plots, but differences among treatment types were minimal.
Evaluation of habitat treatments for mule deer in the Piceance Basin (Component 2). Several hundred acres of hydro-ax treatments were performed for the study Population response of mule deer to natural gas resource extraction and associated mitigation approaches (PI: Chuck Anderson, CPW). Shrubs such as bitterbrush and serviceberry are important forage species in the area which are expected to respond to the treatments. Estimating the increase in forage is tricky because only a portion of each shrub is palatable. We have developed equations relating quick shrub canopy measurements to palatable biomass for focal species and are using them to track treatment productivity over time.
Investigating use of super-absorbent polymer (SAP) to mitigate climate change during habitat restoration. (Co-PI: Cynthia S. Brown, graduate student Magda Garbowski, Colorado State University.) SAP retains water and gradually releases it, helping soils stay moist for longer. We wanted to test if SAP could help native plants and/or reduce the competitive advantage of cheatgrass. We tested SAP amendment under ambient and artificial drought conditions at Waverly Ranch (near Fort Collins, CO) and Dry Creek Basin State Wildlife Area (near Naturita, CO). Preliminary results indicate that SAP helped native annuals establish, but only under ambient precipitation at Waverly.
Areas of Interest, Expertise
Invasive plant ecology; arid lands restoration techniques; plant-herbivore interactions; seed dispersal; shrub measurement techniques; plant water relations
Decker, K., A. Pocewicz, S. Harju, M. Holloran, M. Fink, T. Toombs, and D. B. Johnston. Provisionally accepted. Landscape disturbance models consistently explain variation in ecological integrity across large landscapes. Ecosphere.
Stephens G. J., Johnston D.B., Jonas, J.L., and M.W. Paschke. 2016. Understory responses to mechanical treatment of pinyon-juniper in northwest Colorado. Rangeland Ecology and Management 69:351-359.
Johnston D.B. 2015. Downy brome (Bromus tectorum) control for pipeline restoration. Invasive Plant Science and Management 8:181-192.
Johnston D.B. and P.L.Chapman. 2014. Rough surface and high-forb seed mix promote ecological restoration of simulated well pads. Invasive Plant Science and Management. 7:408-424.
Monty, A., Brown, C.S., and D.B. Johnston. 2012. Fire promotes downy brome (Bromus tectorum L.) seed dispersal. Biological Invasions 15:1113-1123.
Johnston D.B., Cooper DJ and Hobbs NT 2011. Relationships between groundwater use, water table, and recovery of willow on Yellowstone's northern range. Ecosphere 2(2):art20: doi:10.1890/ES10-00150.1
Johnston D.B. 2011. Movement of weed seeds in reclamation areas. Restoration Ecology 19:446-449.
Bilyeu D.M., D.J. Cooper, and N.T. Hobbs NT. 2008. Water tables constrain height recovery of willow on Yellowstone's Northern Range. Ecological Applications 18:80-92.
Bilyeu D.M., D.J. Cooper, and N.T. Hobbs NT. 2007. Assessing impacts of large herbivores on shrubs: tests of scaling factors for utilization rates from shoot-level measurements. Journal of Applied Ecology 44:168-175
Johnston D.B., D.J. Cooper, and N.T. Hobbs NT. 2007. Elk browsing increases aboveground growth of water-stressed willows by modifying plant architecture. Oecologia 154: 467-478