The Influence of Precipitation, Vegetation and Soil Properties on the Ecohydrology of Sagebrush Steppe Rangelands on the INL Site (2011)

The Influence of Precipitation, Vegetation and Soil Properties on the Ecohydrology of Sagebrush Steppe Rangelands on the INL (2011)

 

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
  • Jocylene Benao, B.S. candidate, Idaho State University, Pocatello, Idaho
  • Richard Martinez, A.S. candidate, College of Southern Idaho, Twin Falls, Idaho
  • Carrier Jilek, B.S. candidate, Boise State University, Boise, Idaho
  • Cassandra Gause, B.S./M.S. candidate, Idaho State University, Pocatello, Idaho

 

Funding Sources:

  • Idaho Experimental Program to Stimulate Competitive Research (EPSCoR), National Science Foundation
  • U.S. Geological Survey
  • In-kind facilities and infrastructure support from DOE INL, logistics support through ESER Program and 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 (Idaho State University) and the 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.


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 2011

In 2011 we inserted new Time Domain Reflectometry (TDR) water content sensors in an effort to reduce our reliance on manual neutron-probe measurements, an effort that will continue. We made detailed measurements of vegetation cover, using the standard methods of the previous principal investigators in combination with some adjusted techniques that we will seek to rely on in the future. We performed a substantial amount of soil sampling and evaluated biogeochemical and soil physical measurements.

Results

Preliminary results suggest that irrigation, particularly when added in winter on deep soils, increases sagebrush but also cheatgrass. Soil microbial activity, particularly chitinases, is enhanced by irrigation, and increased microbial activity may explain observations of reduced soil carbon in irrigated plots. Increased aggregation of soils has also been observed in response to irrigation, particularly under sagebrush plants. Additionally, the heterogeneity between perennial plant patches (“islands of fertility”) in nitrogen cycling and other biogeochemical properties is strongly affected by the precipitation treatments. The results will be useful in understanding how use of crested wheatgrass plantings compared to native perennial vegetation affects the resistance of restoration sites to cheatgrass invasion.

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 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.


Publications, Reports, and Theses

Germino MJ and Reinhart K. Ecohydrological impacts of vegetation conversion from diverse sagebrush steppe to exotic grassland: insight from a long-term experiment. American Geophysical Union Annual Meeting, Dec 2011, San Francisco, CA.

Huber DP, Hardenbrook S, Lohse KA, Germino MJ, Reinhardt K. Climate Shifts and Plant- Community Transformations Affect Nitrogen Cycling in Semi-Arid Rangelands. American Geophysical Union Annual Meeting, Dec 2011, San Francisco, CA.

De Graaff MA, vanderVeen J, Germino MJ. Changes in soil aggregate dynamics following 18 years of experimentally increased precipitation in a cold desert ecosystem. American Geophysical Union Annual Meeting, Dec 2011, San Francisco, CA.

Feris KP, Jilek C, Huber DP, Reinhardt K, de Graaff MA, Lohse K, Germino MJ. Influence of Precipitation Regime on Microbial Decomposition Patterns in Semi-Arid Ecosystems. American Geophysical Union Annual Meeting, Dec 2011, San Francisco, CA.

Reinhardt K, Germino MJ. Desert shrub responses to seasonal timing of precipitation revealed from long-term experimental evidence. Botanical Society of America Annual Meeting, Jul 2011, St Louis, MO.

Reinhardt K, Germino M. Desert shrub responses to seasonal timing of precipitation are contingent on soil depth: long-term experimental evidence, from leaves to populations. In session on “Carbon and nitrogen dynamics in semi-arid ecosystems: Responses to climate change from mechanisms to landscape processes. NSF EPSCoR Tri-State Meeting, Apr 2011, Albuquerque, NM.

Feris K, Sorensen P, Germino MJ. Experimental manipulation of precipitation regime affect soil microbial community structure and carbon storage in the semi-arid sagebrush steppe. NSF EPSCoR Tri-State Meeting, Apr 2011, Albuquerque, NM.