Ecosystem Responses of Sagebrush Steppe to Altered Precipitation, Vegetation and Soil Properties

Ecosystem Responses of Sagebrush Steppe to Altered Precipitation, Vegetation and Soil Properties (2015)

Return to Research 2015

 

Investigators and Affiliations

  • PI: Matthew J. Germino, Ph.D., Research Ecologist, USGS, Forest and Rangeland Ecosystem Science Center, Boise, ID
  • Co-PI: Keith Reinhardt, Ph.D., Assistant Professor, Idaho State University, Pocatello, ID

Collaborators

    • Lar Svenson, M.S., US Geological Survey, USGS, Forest and Rangeland Ecosystem Science Center, Boise, ID
    • Kevin Feris, Ph.D., Assistant Professor, Boise State University, Boise, ID
    • Kathleen Lohse, Ph.D., Assistant Professor, Idaho State University, Pocatello, ID
    • Marie-Anne deGraff, Ph.D., Assistant Professor, Boise State University, Boise, ID
    • David Huber, Ph.D. candidate, Idaho State University, Pocatello, ID
    • Patrick Sorenson, M.S., Boise State University, Boise, ID
    • Patricia Xochi Campos, M.S. candidate, Boise State University, Boise, ID
    • Kate McAbee, M.S. candidate, Idaho State University, Pocatello, ID
    • Andrew Bosworth, Science Teacher, Ririe High School, Ririe, ID

    Funding Sources

    • Idaho Experimental Program to Stimulate Competitive Research, NSF
    • US Geological Survey, Forest and Rangeland Ecosystem Science Center
    • Great Basin Landscape Conservation Cooperative
    • In-kind facilities and infrastructure support from DOE INL, logistics support through Stoller-Gonzales LLC

     

    Background:

    The INL Site and other landscapes with sagebrush steppe vegetation are experiencing a simultaneous change in climate and floristics that results from increases in exotic species. Determining the separate and combined/interactive effects of climate and vegetation change is important for assessing future changes on the landscape and for hydrologic processes.

    This research uses the 72 experimental plots established and initially maintained for many years as the “Protective Cap Biobarrier Experiment” by Dr. Jay Anderson and the DOE ESER program—the experiment is also now referred to as the “INL Ecohydrology Study.” We are evaluating long-term impacts of different plant communities commonly found throughout Idaho subject to different precipitation regimes and different soil depths. Treatments of amount and timing of precipitation (irrigation), soil depth, and either native/perennial or exotic grass vegetation allow researchers to investigate how vegetation, precipitation, and soil interact to influence soil hydrology and ecosystem biogeochemistry. This information will be used to improve a variety of models as well as provide data for these models.


    Objectives:

    The goal of this study is to assess the interactive and reciprocal effects of hydroclimate shifts and plant community composition on ecohydrological and biogeochemical processes, with the specific objectives to:

    • Determine response of vegetation to timing of irrigation and soil depth, and conversely the influence of plant communities and vegetation type on deep soil water infiltration
    • Investigate microbial communities and soil microbial enzymatic activity and soil aggregation/porosity to assess whether fundamental ecosystem changes to treatments are occurring and could feed back on water flow patterns
    • Investigate changes in plant and soil nutrient pools and fluxes due to vegetation and precipitation differences.


    Accomplishments through 2015:

    In 2015, our focus was on wrapping up studies led by (1) Kate McAbee (M.S. received under Keith Reinhardt), who did a year-long assessment of in-situ chamber measurement of soil and net-ecosystem flux of carbon dioxide as it relates to standing crop (biomass and productivity) for her thesis under Keith Reinhardt; and (2) Xochi Campos (M.S. received under Marie Anne DeGraff), who finished a multi-year assessment of soil physical and biological responses.


    Results:

    Data from McAbee (2015) suggest that supplemental watering/precipitation increased net carbon uptake whether added in the winter or summer and increased standing crop of biomass when added in winter only. Respiratory carbon efflux was increased by summer precipitation under some circumstances (e.g., on summer evenings, especially in plots planted with native vegetation vs. crested wheatgrass). Net ecosystem carbon exchange without supplemental water was otherwise nearly null, indicating that increases in precipitation may stimulate carbon sequestration by this vast rangeland type.

    Data from Campos (2015) demonstrate that the plant and soil treatments have impacted soil physical properties via altering soil particle aggregation, in turn feeding back on the hydrology of plots. Additionally, Campos (2015) revealed that decomposition rates were differentially affected by the hydrology vs. vegetation type changes, and that this reflects microbial changes that underlie carbon respiratory effluxes from the treatments.

    Plans for Continuation:

    We are considering that 2016 could be the last year we attempt to maintain the experiment, given uncertainties in funding, condition of pumping and irrigation equipment, and of the neutron probe, which is an irreplaceable means for us to measure soil water responses.

    We expect the theses for Campos and McAbee and the dissertation for Huber to be published in 2016–2017, when conclusive findings will be available.


    Publications, Theses, Reports:

    Publications

    • McAbee, K., 2015, Exotic grass species toggles the response of aboveground carbon balance to long-term precipitation shifts in cold-desert rangelands: results from a 21-year climate change experiment. MSc Thesis, Department of Biological Sciences, Idaho State University, Pocatello, ID.
    • McAbee, K., K. Reinhard, M. J. Germino, and A. Bosworth, Submitted. Exotic grass species toggles the response of aboveground carbon balance to long-term precipitation shifts in cold-desert rangelands: results from a 21-year climate change experiment. Oecologia.
    • Campos, P. X., 2015, Precipitation induced changes in decomposition processes and soil carbon stabilization. MSc Thesis, Department of Biological Sciences, Boise State University, Boise, ID.

    Presentations

    • McAbee, K., K. Reinhard, M. J. Germino, and A. Bosworth, 2015, Exotic grass species toggles the response of aboveground carbon balance to long-term precipitation shifts in cold-desert rangelands: results from a 21-year climate change experiment, Great Basin Consortium #4, Boise, ID Feb 17–19 (poster).