Ecosystem Responses to Altered Precipitation Properties (2014)

Ecosystem Responses of Sagebrush Steppe to Altered Precipitation, Vegetation and Soil Properties (2014)

Return to Research 2014


Investigators and Affiliations

  • Matthew J. Germino, Ph.D., Research Ecologist, United States Geological Survey, Forest and Rangeland Ecosystem Science Center, Boise Idaho
  • Co-PI: Keith Reinhardt, Ph.D., Postdoctoral Fellow, Idaho State University, Pocatello, Idaho


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

Funding Sources

  • Idaho Experimental Program to Stimulate Competitive Research (EPSCoR), National Science Foundation
  • U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center
  • U.S. Geological Survey, Northwest Climate Science Center
  • In-kind facilities and infrastructure support from DOE-Idaho, logistics support through Gonzales-Stoller Surveillance, LLC.



The INL and other landscapes having sagebrush steppe vegetation are experiencing a simultaneous change in climate and floristics that result 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 establiashed and initially maintained for many years as the “Protective Cap Biobarrier Experiment” by Dr. Jay Anderson and the Stoller ESER program, and 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 to 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.


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 2014:

In 2014 we ended three major data collection efforts that provide key insight on biogeochemical responses to the main treatments of the experiment, and finished another study on the demographics of sagebrush responses to treatments. David Huber performed a stable isotope tracer study that will provide insight on how precipitation changes affect nitrogen transformation (e.g., denitrification, leaching) for his dissertation under Kathleen Lohse. Xochi Campos finished a multi-year study of decomposition rates using litter bags and soil incubations to assess impacts to respiratory efflux of carbon dioxide for her thesis under Marie Anne de Graff. Kate McAbee completed 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. We also completed a detailed study of growth and survival of adult sagebrush as it relates to herbivory, and assessed seedling demographics, and assessed cheatgrass responses. We published a paper on sagebrush responses in Journal of Ecology and a project report with the US Geological Survey.


Our preliminary data suggest differences in sagebrush growth and seedling establishment are occurring as a result of the precipitation treatments, and are accompanied by shifts in litter deposition and biogeochemical patterns. Winter precipitation increases net ecosystem exchange of carbon dioxide and carbon storage, although the response is largely in increases in biomass and not in soil carbon.

Plans for Continuation:

We are currently focused on sustaining the treatments for up to several more years, and in the upcoming year we will consider final measurements and consider a plan for either terminating the treatments or downscaling them for a second-generation set of research questions (eg, on response of the communities to extended drought caused by ceasing irrigation). We expect the theses for Ms. Campos and McAbee and Dissertation for Mr. Huber to be published in 2015, when conclusive findings will be available.


Publications, Theses, Reports:


  • Germino M.J., Reinhardt K. 2014. Desert shrub responses to experimental modification of precipitation seasonality and soil depth: relationship to the two-layer hypothesis and ecohydrological niche. Journal of Ecology. 102:989-997
  • Germino M.J., Reinhart K., Pilliod D., Debinski D. 2014. Sagebrush responses to climate – Final report to USGS NW-CSC, 52 pages. []
  • Germino MJ. 2014, Climate, wildfire, and Great Basin Ecosystems. Next Steppe Conference. Boise ID, Nov 5.
  • Kathryn McAbee, Keith Reinhardt, Matt Germino. 2015. How do long-term changes in precipitation seasonality affect ecosystem carbon dynamics? Evidence from a 21-year, manipulative climate-change experiment. Great Basin Consortium (4th Annual), Boise ID, Feb 17-19.
  • Xochi Campos, Matthew Germino, Marie-Anne de Graaff, Precipitation effects plant litter quality and decomposition. Great Basin Consortium (4th Annual), Boise ID, Feb 17-19.