Evaluating the role of disturbance in determining forage root phenology in a Montana semi-arid rangeland

Commodities

• Agronomic: grass (misc. annual), grass (misc. perennial)
• Additional Plants: native plants

Practices

• Animal Production: feed/forage, feed management, range improvement, rangeland/pasture management
• Education and Training: on-farm/ranch research
• Natural Resources/Environment: habitat enhancement
• Production Systems: agroecosystems, dryland farming
• Soil Management: soil analysis

Fire and drought are key drivers of forage availability in western rangelands, shaping when forage emerges, how long it persists, and how much biomass is produced for cattle. For producers, the contrast between uncontrollable drought and manageable fire creates an urgent need to understand how these disturbances interact to shape forage availability and quality across the growing season. At the same time, the field of plant phenology, which studies the timing and seasonality of plant activity has traditionally focused on aboveground plant processes. Consequently, we currently lack understanding of belowground phenology and the extent to which root production may become decoupled from aboveground plant activity. We especially lack an understanding of how disturbances, such as fire and drought, alter belowground root phenology. This is important in rangelands where most biomass production occurs belowground and because roots serve as the basis for water and nutrient acquisition that drives aboveground forage amount and quality. To address this, we will conduct a field experiment using "minirhizotron" root cameras to (1) quantify the degree of temporal coupling between root and leaf production, (2) compare phenological patterns under fire and drought disturbance regimes, and (3) assess the underlying mechanism influencing such ecosystem processes. We will share this research with producers through extension publications, field days, digital media, scientific meetings, and peer-reviewed publications. The findings from this study will allow producers to better understand how disturbances will impact belowground root production, informing decisions related to forage availability and quality, grazing timing, and resilience of cattle operations.

The research goals of this project are to improve our understanding of the potential decoupling of aboveground forage production and belowground root phenology in semi-arid rangelands and evaluate how disturbances such as fire and drought may modify the timing and magnitude of root and leaf production. To assess our goals, we will address three objectives during the 2027 field season (March - September).

Objective 1: Quantify the degree of temporal coupling between aboveground (root) and belowground (leaf) forage production in a semi-arid rangeland.

Objective 2: Assess how two key rangeland disturbances - fire and drought - independently and interactively influence the timing, duration, and magnitude of above and belowground forage production and the coupling thereof.

Objective 3: Assess the underlying mechanisms influencing above and belowground phenological dynamics of forage production.

The educational goals of this project are to further educate Montana producers and land managers, scientists, students, and the general public about belowground productivity dynamics in semi-arid rangelands, especially how fire and drought influence above and belowground forage production. We aim to clearly communicate how these findings can be applied to real-world management decisions. To achieve these goals, we have one objective with three sub-objectives.

Objective 4: Share our results about the impact of fire and drought on above and belowground plant production and the underlying mechanisms influencing these processes.

a) Communicate practical, management-relevant results to producers and land managers.

b) Disseminate research to scientists who study rangeland ecology, plant-soil interactions, and disturbance processes.

c) Increase awareness and understanding of rangeland ecological processes among university students and broader public audiences.