Soil seed bank composition and spatial distribution in a cheatgrass (Bromus tectorum L.)–dominated rangeland in Colorado, USA

Authors

Ryan W. R. Schroeder, Systems Ecology Program, University of Montana, Missoula, MT; Graduate Degree Program in Ecology, Colorado State University, Fort Collins, COFollow
Jayne L. Jonas, Department of Biology, University of Nebraska at Kearny, Kearny, NE; Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, COFollow
M. Nikki Grant-Hoffman, Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, CO; U.S. Department of the Interior, Bureau of Land Management, Grand Junction Field Office, Grand Junction, COFollow
Mark W. Paschke, Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO; Department of Forest and Rangeland Stewardship, Colorado State University, Fort Collins, COFollow

Abstract

Invasion by nonnative annual plants that form prolific seed banks, including Bromus tectorum L. (cheatgrass), throughout western North America is a major natural resource concern. Even with known economic and ecological implications, soil seed banks and their potential to impact ecological restoration in arid and semiarid ecosystems are poorly understood. Quantifying the regenerative potential of the soil seed bank—the living seeds in the soil profile and on the soil surface—can help natural resource managers make decisions to increase the likelihood of restoration success. We analyzed the germinable soil seed bank composition and distribution of a rangeland site in western Colorado that experienced a wildfire in 1994 and is dominated by cheatgrass. We collected soil seed bank samples from 118 points in a 100 × 110 m grid to a depth of 5 cm. Each sample was split by depth from 0 to 2 cm and from 2 to 5 cm, and the seed bank was quantified using greenhouse emergence methods. We found that seeds of native species were more dense and evenly distributed (3391 seeds ⋅ m⁻²than seeds of nonnative species were (1880 seeds ⋅ m⁻²) in the 0–5 cm seed bank across the site. We also found that seeds of both native and nonnative species were concentrated in the 0–2 cm layer of the seed bank but that native and nonnative seeds were present in substantive densities in the 2–5 cm layer. These findings suggest that the soil seed bank of the site is resilient, and a targeted approach to specifically deplete the seed bank of nonnative annuals could facilitate restoration by the in situ native seed bank.


La invasión de plantas anuales no autóctonas que forman prolíficos bancos de semillas, entre ellas Bromus tectorum L. (pasto espiguilla), en todo el oeste de Norteamérica es una preocupación muy importante de recursos naturales. A pesar de sus conocidas implicaciones económicas y ecológicas, los bancos de semillas del suelo y su potencial para influir en la restauración ecológica de los ecosistemas áridos y semiáridos son poco conocidos. Cuantificar el potencial regenerativo del banco de semillas del suelo—las semillas vivas en el perfil y la superficie del suelo—puede ayudar a los gestores de recursos naturales a tomar decisiones para aumentar las probabilidades de éxito de la restauración. Analizamos la composición y distribución del banco de semillas germinables del suelo de un pastizal del oeste de Colorado que sufrió un incendio forestal en 1994 y en el que predomina el pasto espiguilla. Recogimos muestras del banco de semillas del suelo en 118 puntos de una cuadrícula de 100 × 110 metros a una profundidad de 5 cm. Cada muestra se dividió por profundidad de 0–2 cm y 2–5 cm y el banco de semillas se cuantificó utilizando métodos de emergencia en invernadero. Encontramos que las semillas de especies nativas fueron más densas y estaban distribuidas uniformemente (3391 semillas ⋅ m⁻²) que las semillas de especies no nativas (1880 semillas ⋅ m⁻²) en el banco de semillas de 0–5 cm en todo el lugar. También encontramos que tanto las semillas de especies nativas como las de no nativas se concentraban en la capa de 0–2 cm del banco de semillas, pero que las semillas nativas y no nativas estaban presentes en densidades sustanciales en la capa de 2–5 cm. Estos hallazgos sugieren que el banco de semillas del suelo del lugar es resiliente, y un enfoque específico para agotar el banco de semillas de plantas anuales no autóctonas podría facilitar la restauración por parte del banco de semillas autóctonas in situ.

Recommended Citation

Schroeder, Ryan W. R.; Jonas, Jayne L.; Grant-Hoffman, M. Nikki; and Paschke, Mark W. (2023) "Soil seed bank composition and spatial distribution in a cheatgrass (Bromus tectorum L.)–dominated rangeland in Colorado, USA," Western North American Naturalist: Vol. 83: No. 2, Article 5.
Available at: https://scholarsarchive.byu.edu/wnan/vol83/iss2/5