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

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Commodities

• Additional Plants: native plants
• Animal Products: meat

Practices

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

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 spicata), and rough fescues (Festuca campestris Rydb). 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 Range.

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).

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.