Location: Great Basin Rangelands Research
Project Number: 2060-22000-024-004-I
Project Type: Interagency Reimbursable Agreement
Start Date: May 15, 2015
End Date: Apr 30, 2020
Objective:
In a field experiment, we will:
• Determine the effects of warming and drought on invasive and native plant emergence, growth, and reproduction.
• Investigate what native species mixtures may compete with B. tectorum or B. rubens in future climate.
Approach:
In a field experiment, we will examine the effects of increased temperature and altered precipitation on native and invasive plant growth, reproduction, and community dynamics. In field plots, we will establish three-3x3m plots with the following four treatments: control, warming, drought, and warming + drought (12 plots total). Passive warming chambers will be constructed to increase soil temperatures approximately 5°C (Germino and Smith 1999). Rainout shelters will be constructed to reduce precipitation by 50% (Yahdijan and Sala 2002). Weather at the site will be monitored with a weather station and monitoring equipment under the shelters. The weather station will measure precipitation, relative humidity, air temperature, windspeed and direction, and incoming solar radiation. Additionally, we will measure soil moisture and temperature (2 and 5 cm depths), air temperature, relative humidity, and precipitation under the chambers/shelters.
We will plant eight different seed treatments into 15x15cm plots underneath each chamber/shelter; each treatment will have two subplots for a total of 16 plots in each chamber/shelter. We will use native species that occur at the Wyoming big sagebrush/mountain big sagebrush ecotone. Seed will be obtained from the BLM, commercial growers such as Benson Farms, and/or the Malheur Experiment Station. We will attempt to obtain species from similar seed zones to the greatest extent possible and avoid cultivars. Native species include: 1) native perennial grasses (Poa secunda; POSE / Elymus elymoides; ELEL5) 2) native annual grass (Vulpia octoflora; VUOC), and forbs (Achillea millefolium; ACMI2/ Machaeranthera canescens; MACA2). Native species will be planted with either of two invasive annual grasses: B. tectorum (BRTE) or B. rubens (BRRU2). Poa secunda and E. elymoides were chosen due to their competitive ability with B. tectorum, V. octoflora is in a similar functional group to the invasive Bromus species, and the two forbs are adequately produced plant materials that are both competitive with Bromus (Tilley et al. 2010, Tilley et al. 2014).
Seeding treatments will include the following: 1) POSE-forbs-BRTE, 2) ELEL5-forbs-BRTE, 3) VUOC-forbs-BRTE, 4) POSE-forbs- BRRU2, 5) ELEL5-forbs- BRRU2, 6) VUOC-forbs- BRRU2, 7) BRTE alone, and 8) BRRU2 alone. Species mixtures will be planted in grids to track individual plants and randomized within subplot and plot. For each species, we will measure plant emergence, height, specific leaf area, biomass, reproduction, d13C, d15N, and C:N. Results will be analyzed in ANOVAs; dependent variables will include temperature and precipitation as fixed factors.
