The role of seed banks in the management of Bromus tectorum in the western Great Basin

Authors: Harmon, Daniel; Clements, Darin

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/30/2024
Publication Date: 2/11/2025
Citation: Harmon, D.N., Clements, D.D. 2025. The role of seed banks in the management of Bromus tectorum in the western Great Basin. Society for Range Management Meeting Abstracts. 78:58.

Interpretive Summary:

Technical Abstract: Persistent soil seed banks and reliable seed production are two significant advantages that cheatgrass (Bromus tectorum) utilizes to dominate arid Great Basin Rangelands. Cheatgrass produces hundreds of seeds per plant in favorable years, and the seed can persist in the soil for up to 4 years. Even in the most drought effected years, cheatgrass can produce enough seed on diminutive plants that will ensure the next years population. Data was collected on monitored seed banks at multiple research locations in the western Great Basin, under various land management treatment outcomes. Our data found that the ability of pre-emergent herbicides to control cheatgrass and other annual weeds can significantly reduce the weed seed bank temporarily providing 1-2 years of reduced weed competition. This control allows an opportunity to establish competitive perennial grasses through seeding efforts, that can suppress cheatgrass and other annual weed seed production long-term. By competitively limiting soil resources, established perennial grasses can suppress cheatgrass seed production leading to minimal weed seed banks in these ecosystems. This effect is sustainable long-term, unlike herbicide use alone, which is a short-term seed bank reduction. Our results determined that after herbicide reduction of cheatgrass seed banks, if a high density of perennial grass is not established, the cheatgrass seed bank will quickly return to pre-treatment levels. Similarly, we found that if a high density of perennial grasses is established after herbicide/seeding treatments, the cheatgrass seed banks remain low (<200 seeds/m2) compared to untreated plots where thousands of seeds per m2 (>3,000 seeds/m2) are recorded. We have measured these positive cheatgrass seed bank reductions from as short as 3 years after perennial grass establishment to as long as 20 years after successful seeding efforts.