Plant Community Management: The Complex Science Behind Grassland Health, Carbon Storage, and Ranch Profitability on the Northern Great Plains
In recent years, there's been increasing discussion about plant diversity in grasslands, often with simplified claims like "more diversity is better" or "diverse plant communities produce extensive and deep root systems." While these statements contain kernels of truth, the reality of grassland ecology – especially in regions like the Northern Great Plains – is far more nuanced and complex.
Understanding Plant Communities: Beyond Simple Diversity
When we examine healthy native rangeland closely, we discover that it's not just about the number of species present, but rather their functional roles within the ecosystem. Each plant serves a purpose, contributing differently to both the ecological health of the land and the nutritional needs of grazing animals.
Montana range management expert Matt Ricketts has extensively documented how native plant communities contain multiple categories of plants that work together:
Decreaser species – These are typically taller, deeper-rooted plants like bluebunch wheatgrass, green needlegrass, and winter fat that dominate healthy rangelands (often comprising 50-80% of the potential native plant community). They provide reliable forage production and excellent drought resistance due to their extensive root systems.
Increaser species – Latent plants like needle and thread grass or prairie June grass, for example, may initially take hold as decreasers are reduced, but can't fully replace their ecological functions over the long term.
Nutritional diversity providers – Many native forbs and shrubs serve as "little protein blocks scattered across the range." Plants like dotted gayfeather (25-30% protein) or winter fat (13% protein in winter) provide critical nutrients when grasses are low in protein.
The key insight is that not all diversity is created equal. A degraded rangeland might show increased species diversity as native grasses diminish and are replaced by shallow-rooted increasers or invasive species – but this represents declining land health, not improvement.
The Critical Role of Standing Forage
One of the most overlooked aspects of rangeland health is the importance of leaving adequate standing forage after grazing. This standing forage serves multiple crucial functions:
Animal nutrition – As Ricketts' research demonstrates, having a mix of old and new growth is essential for proper livestock nutrition. New growth provides protein while old growth provides energy.
Plant health – When plants are grazed too heavily (often meaning more than 50% of top growth removed during growing season), root growth stops for up to 18 days, reducing the plant's ability to recover, capture water, and build extensive root systems.
Carbon storage – Properly grazed decreaser species develop extensive root systems that store carbon deep in the soil profile. As these roots naturally turn over (about 1/3 each year), they contribute to long-term soil carbon stock.
Soil protection – Standing forage protects soil from erosion, reduces evaporation, captures snow, and creates a more favorable microclimate for seedling establishment of desirable species.
When rangelands are repeatedly grazed too heavily, even with rotational systems, we often cross ecological thresholds where the original, deep-rooted native plant community is permanently altered. This shifts the land toward more shallow-rooted species and can drastically reduce its carbon storage potential.
The Biological Laws That Drive Rangeland Health
Four biological laws, as outlined by Ricketts, govern how grasslands function:
If you keep down the shoot, you kill the root – Heavy grazing during the growing season stops root growth, eventually killing plants.
Nature doesn't like bare spots – Something will grow where soil is exposed, but often these are less desirable, shallow-rooted plants.
Moisture is the limiting factor on rangelands – Plants that maximize moisture capture and efficient use have evolutionary advantages - part of why native grasses are often superior to any introduced species.
If given a chance, nature would like to put back the original best-adapted plants – But this only happens if we haven't crossed ecological thresholds and if we work with natural processes.
Understanding these laws helps us recognize that management decisions need to work with, not against, these natural principles.
Management Implications for Carbon Storage and Ranch Profitability
When we bring this understanding to questions of carbon sequestration and ranch economics, several key principles emerge:
For Healthy Rangelands:
Conservative stocking – Nothing has a greater impact on rangeland health than stocking rate. As one Montana rancher demonstrated over 27 years, simply employing conservative stocking allowed rough fescue and other native decreasers to return without any other interventions.
Timing of grazing – Grazing when plants are less vulnerable (avoiding heavy use during stem elongation) allows them to maintain health and productivity.
Matching livestock to the environment – As detailed in "Feed Less, Earn More," matching calving dates and cattle types to the forage quality environment can significantly increase profitability while reducing supplementation costs.
Valuing standing forage – Recognize that grass left standing isn't "wasted" – it's building soil, protecting against drought, and ensuring future productivity.
For Degraded Rangelands:
When rangelands have crossed ecological thresholds (dominated by invasive species like cheatgrass or crested wheatgrass), more intensive intervention may be needed:
Well-designed grazing management comes first – Even on degraded lands, getting the fundamentals right is essential.
Accelerating practices – Strategic use of targeted herbicides, proper seeding techniques, or other interventions may help jumpstart recovery when combined with proper management.
Realistic expectations – Recovery takes time, and some thresholds may be permanently crossed and recovery would require an expensive reclamation project.
Carbon Storage: The Long View
True, sustainable carbon storage in grasslands comes primarily from:
Maintaining and enhancing populations of deep-rooted decreaser species – These plants allocate more carbon belowground and deposit it deeper in the soil profile.
Soil protection – Preventing erosion through adequate ground cover preserves the carbon already stored in soils.
Balanced nutrition – The diverse plant community provides balanced nutrition that supports animal health without requiring extensive supplementation.
Unlike some popular grazing systems that claim to rapidly increase carbon storage through intense, short-duration grazing, the evidence suggests that respecting plant recovery periods and maintaining healthy plant communities provides the most reliable, long-term carbon benefits.
Conclusion: Knowledge-Based Management
The path to both ecological and economic sustainability in rangeland management requires a sophisticated understanding of native plant communities and their functional roles. Rather than pursuing diversity for diversity's sake or employing one-size-fits-all grazing prescriptions, successful rangeland managers develop management approaches based on:
Knowledge of the local plant community – Understanding which plants should dominate in your ecological sites.
Respect for biological laws – Working with, not against, the natural processes that govern plant growth and succession.
Careful monitoring – Watching for early signs of range degradation and adjusting management accordingly.
Economic integration – Finding the sweet spot where ecological health and economic profitability overlap.
By focusing on these principles, ranchers can build operations that are not only more profitable today but will remain productive and resilient for generations to come – all while making meaningful contributions to carbon storage and ecosystem health.