The Influence of Precipitation, Vegetation and Soil Properties on the Ecohydrology of Sagebrush Steppe Rangelands on the INL Site

The Influence of Precipitation, Vegetation and Soil Properties on the Ecohydrology of Sagebrush Steppe Rangelands on the INL Site


Investigators and Affiliations


Matthew J. Germino, Ph.D., Research Ecologist, United States Geological Survey, Forest and Rangeland Ecosystem Science Center, Boise Idaho


Collaborators

  • Keith Reinhardt, Ph.D., Postdoctoral Fellow, Idaho State University, Pocatello, 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
  • Carrier Jilek, B.S. candidate, Boise State University, Boise, Idaho
  • Cassandra Gause, B.S./M.S. candidate, Idaho State University, Pocatello, Idaho
  • Jennifer Forbey Ph.D., Assistant Professor, Boise State University, Boise, Idaho
  • Lisa Lam, B.S. candidate, Boise State University, Boise, Idaho

Funding Sources

  • Idaho Experimental Program to Stimulate Competitive Research (EPSCoR), National Science Foundation.
  • US Geological Survey, Forest and Rangeland Ecosystem Science Center
  • US Geological Survey, Northwest Climate Science Center

In-kind facilities and infrastructure support from DOE-ID, logistics support through Gonzales Stoller Surveillance LLC.


Background: The INL Site 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 established 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 Site 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.

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 2012:

In 2012 we inserted an additional set of Time Domain Reflectometry (TDR) water content sensors in an effort to reduce our reliance on manual neutron-probe measurements, an effort that will continue. In 2011 we inserted Decagon Echo probes at 3 depths in shrub interspaces in about 1/3 of the plots, and in 2012 we inserted Campbell 616 probes into all 72 plots, with one sensor spanning 0-30 cm depth in interspace microsites. We installed litter traps to begin a formal evaluation of plant litter inputs, dug soil pits and analyzed the stratigraphy and pedogenesis of the soils, analyzed soil respiration, and made a number of soil biogeochemical measurements. We finished an extensive analysis of point-intercept data on vegetation cover of all plots, comparing the sampling method used from 1993 to 2006 with a revised method that will focus on aerial cover and leaf-area indices. We began a newly funded project on sagebrush demographic responses to the treatments, including detailed sampling of sagebrush responses. As part of this, we tested several approaches for measuring sagebrush growth, including marking stems and measuring stem elongation in the field compared to clipping stems to measure stem lengths along annual growth increments revealed by buds and the number of annual xylem (vascular) rings in the wood.

Results:
Preliminary results from soil pits reveal a surprisingly large amount of pegogenic activity since 1993 that has caused the soil profiles of experimental plots to resemble soil structure in the surrounding and natural sagebrush steppe. Features including the formation of calcic pedogenic minerals, silt layers that suggest vertical transport of fine soil particles, and these all vary by treatment. In a preliminary round of soil respiration, we did not detect appreciable differences among treatments, but did reveal strong differences between shrub and interspace microsites. Very large differences in sagebrush growth and seedling establishment are evident among the treatments, with winter irrigation continuing to promote greater sagebrush presence than other treatments. Preliminary data suggest large differences in growth estimated by measuring stem elongation in the field compared to clipping stems to measure stem lengths along annual growth increments revealed by buds and the number of annual xylem (vascular) rings in the wood (Figure 1). Sagebrush growth is an important variable to measure for assessing ecosystem change and function (e.g., for carbon storage, grazing impacts, hydrology, etc), and these data show much greater sensitivity of lab-based measurements, but also raise questions about sources of error in the field, assuming the laboratory measurement is more reliable.

Figure 1
Figure 1. Difference in annual stem growth estimated by marking stems and repeatedly measuring growth along them in the field, compared to clipping stems and measuring annual growth increments in the laboratory. Each datum is a plant, from all plots with native vegetation and 2 m deep soil.

This information is preliminary and is subject to revision. It is being provided to meet the need for timely best science. The information is provided on the condition that neither the U.S. Geological Survey nor the U.S. Government may be held liable for any damages resulting from the authorized or unauthorized use of the information.

Plans for Continuation:

We will continue making the same types of measurements as in the past year, generating multiple-years of data to substantiate our findings. New additions will continue to include 1) assessments of soil solution biogeochemistry done through installation of lysimeters via cores from the surface, 2) measurements of net primary productivity, 3) assessment of litter inputs and decomposition processes, along with root growth assessed by root-ingrowth tubes, 4) sagebrush demography.

Publications, Theses, Reports:

  • Germino, M., and K. Reinhardt. 2013. Experimental evidence for sagebrush responses to climate. Great Basin Consortium, 2nd annual meeting, Boise, ID, January 14, 2012.
  • Germino, M. 2012. Fire, wind, and water: landscape change and its relationship to development. Mountain West Water Institute Meeting, Idaho Falls, ID, May 15, 2012.
  • Joy S., D. Huber, A. Kathleen, K. Lohse, M. Germino, M. de Graaff, and K. Feris. 2012. Shifts in Timing and Magnitude of Precipitation Modulate Soil Carbon Pools in Semi-Arid Ecosystems. American Geophysical Union Annual Meeting, San Francisco, CA, December 10, 2012.
  • Germino, M., L. Svenson, and K. Reinhardt. 2012. Climate and Upland Ecosystems: Points of sensitivity and adaptation variability in sagebrush steppe viewed from a single species. 3rd Annual Pacific Northwest Climate Science Conference, Boise, Idaho, ID, October 1-2, 2012.
  • Germino, M. and B. Crosby. 2012. Plenary: The Changing Landscape of Science and Management of Land and Water: New Collaborative Initiatives and their Relevance. Tri-State (ID-NV-NM) NSF EPSCoR annual meeting, Sun Valley, ID, April 4, 2012.
  • Huber D., S. Hardenbrook, K. Lohse, M. Germino, K. Reinhardt. 2012. Effects of Climate Shifts and Plant-Community Transformations on Carbon and Nitrogen Cycling in Semi-Arid Rangelands. Tri-State (ID-NV-NM) NSF EPSCoR annual meeting, Sun Valley, ID, April 4, 2012.
  • Jilek C., K. Feris, and M. Germino. 2012. Influence of Precipitation Regime on Microbial Decomposition Patterns in Semi-Arid Ecosystems. Tri-State (ID-NV-NM) NSF EPSCoR annual meeting, Sun Valley, ID, April 4, 2012.
  • Reinhardt, K. and M. Germino. 2012. Effects of long-term experimental changes in precipitation seasonality on cover, ecophysiology, foliar crown properties, and carbon pools in big sagebrush. Northwest Science Association Annual Meeting, Boise, ID, March 29, 2012
  • de Graff, M., J. Vanderveen, and M. Germino. 2012. Changes in soil aggregate dynamics and carbon storage following 18 years of experimental increased precipitation in a cold- desert ecosystem. Northwest Science Association Annual Meeting, Boise, ID, March 29, 2012.