Comparing soil organic carbon, infiltration, and bulk density in various grass communities and management practices on Confederated Salish and Kootena

Project Overview

Project Type: Graduate Student
Funds awarded in 2024: $30,000.00
Projected End Date: 04/01/2026
Grant Recipient: Salish Kootenai College
Region: Western
State: Montana
Graduate Student:
Principal Investigator:
Virgil Dupuis
Salish Kootenai College
Principal Investigator:
Maureen McCarthy
Desert Research Institute


  • Additional Plants: native plants, other
  • Animal Products: meat


  • Animal Production: grazing management, range improvement, rangeland/pasture management, stocking rate
  • Natural Resources/Environment: carbon sequestration, wildlife
  • Pest Management: chemical control, weed ecology
  • Production Systems: other
  • Soil Management: organic matter, soil analysis, soil physics, soil quality/health

    Proposal abstract:

    The Bison Range is located on the Flathead Indian Reservation in
    Western Montana, the remaining homelands of the Selis, Qlipse,
    and Ksanka people. Invasive macrophytes pose significant threat
    to highly valued cool season Palouse type bunchgrass grasslands
    dominated by bluebunch wheatgrass (Pseudoroegneria
    ), and rough fescues (Festuca campestris
    ). Ventenata (Ventenata dubi), a recent annual
    invasive grass invader has become especially concerning, as it
    provides poor forage and creates a dense straw cover that
    smothers native vegetation (Wallace 2015, & Bradley, 2006).
    Ventenata was first noticed on the Bison Range around 2012, and
    is now throughout the 16,000-acre Bison Range.

    Bison are native to Montana, yet they are relatively recent
    additions to the Bison Range’s inter-mountain ecosystem. Although
    they are known for being easier on the land than cattle, little
    is actually known on how they influence soil health on the Bison

    To more fully understand annual invasive grasses and bison
    grazing effects on soil health, soil organic carbon (SOC),
    infiltration rates, and bulk density needs to be studied. This
    study preposes to compare SOC, infiltration rates, and bulk
    density in two sites with three vegetation functional groups that
    will be mapped and sampled using the line-point intercept method.
    One site has a long history of bison grazing while the other
    nearby site is in an exclosure.

    Invasive grasses and overgrazing can reduce organic carbon
    (Pendell et al., 2018, Koteen et al., 2011, & Harden, 1999). This
    study will help managers understand the relationship between soil
    carbon, vegetation, and grazing management on the Bison Range.
    Proxy measurements estimating total organic carbon, such as soil
    organic matter, bulk density, and infiltration rates will give
    insight into microsite variability (Franzluebbers, 2002).

    Project objectives from proposal:

    Research Objective

    • The first objective is to sample vegetation and soils in
      three mapped grassland functional groups in one season. We will
      compare SOC, infiltration, and bulk density and determine which
      functional group is the most beneficial to soil health.
    • The second objective is to sample soil and vegetation in a
      bison grazed and ungrazed grassland in one growing season. We
      will compare the SOC, infiltration, and bulk density to determine
      whether Bison Range stocking rates are maintaining soil health.


    Education Objective:

    1. After a field day with the producers and stakeholders, they
      will be able to discuss or describe the link between vegetation
      type and soil health as well as how management such as stock
      numbers and maintaining native grasses can influence soil
      health.  Land managers will be able to utilize data on the
      risks associated with annual invasive grasses to make informed
      management decisions in the following growing seasons.

    Following a classroom presentation, SKC students will be able to
    discuss the link between vegetation type and soil health as well
    as how management such as stock numbers and maintaining native
    grasses can influence soil health.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.