Grasslands: Reservoirs of Biodiversity for Climate Resilience

Did you know that you can find over 30 plant species in a single quarter-square meter plot of grasslands, and that these habitats support over 90% of the endangered plants and animals in California? Grasslands are very dynamic; they have what’s called high interannual variation, which means they do not stay the same from year to year. That’s why, every spring at Pepperwood, our research team spends a half-month conducting grassland monitoring. We’ve been doing this at the same exact time every year for thirteen years. We are tracking the long-term health of our grassland communities under the impacts of climate change and the success of our land stewardship (which includes conservation grazing, invasive species management, and prescription and cultural burning).

Belted Galloway cattle managed by Markegard Family Grass-Fed LLC., are part of Pepperwood’s conservation grazing strategy to maintain ecological health and fire resilience. Photo courtesy of Ian Nelson.

CONSERVATION GRAZING

In our conservation or targeted grazing strategy, we use livestock to maintain and increase the biodiversity of natural grasslands and other habitats. After six years of grazing cattle at Pepperwood, we found that native non-grass flowering plant diversity increased from 67 species in 2012 to 87 species in 2017 (prior to the wildfires).

Photo by Ian Nelson.

FIRE RESILIENCE

Based on our observations from monitoring, we can reduce fuel loads by strategically modifying our conservation grazing (e.g., increasing herd size and/or rotating cattle through target areas) and by putting good fire on the ground to strengthen fuel breaks – all while enhancing the grassland community. We work to reduce thatch (a tight layer of dead stems and leaves between growing grass and soil that forms in the absence of fire/grazing) because it suppresses access to light and reduces seed germination, thus reducing plant growth (or productivity) and biodiversity.


Thatch Attack (based on data from 2013-2022) – Our Findings:

  • The average above-ground thatch biomass was reduced by more than half in just four seasons of conservation grazing
  • There was a slight increase in plant productivity despite a historic drought
  • The least thatch and greatest plant productivity in our study period occurred after the Tubbs Fire in fall 2017. Data showed the fire had burned off dead material and released nutrients into the system, which encouraged plant growth the following year.’However, this boom of plant growth resulted in greater thatch levels the following year, similar to their peak, despite the grazing program to reduce thatch.

This cycle highlights the importance of continued and well-planned grazing management alongside fire to control fuels over time – both for reducing the amount of thatch as well as enhancing biodiversity and plant productivity.

INVASIVE SPECIES MANAGEMENT

We found that in plots dominated by the invasive Harding grass (Phalaris aquatica), those that were not grazed but burned during the Tubbs Fire, increased from 16% Harding grass cover in 2017 to 28% in 2022. This demonstrated that fire alone is not a reliable suppressor of this invasive grass species. In four plots dominated by Harding grass and grazed we saw a 78% reduction of the species, showing that even with intermittent fire, grazing is key to controlling this invasive.

BIODIVERSITY MONITORING

We track how our stewardship affects grassland-dependent birds like western meadowlarks and grasshopper sparrows, which nest on the ground in grasslands, or predatory birds like kestrels, white-tailed kites, and burrowing owls that visit in winter months and forage on rodents. Although western meadowlarks are shown to be declining in coastal California regions, our bird monitoring data indicate that Pepperwood has continued to support healthy populations since monitoring began in 2007. This indicates that our grassland stewardship is working for Pepperwood’s western meadowlarks.

Fostering biodiversity is all about balance. Small voles and mice rely on sufficient ground cover to hide and maintain their populations, which are offset by predators – including birds, snakes, coyotes, bobcats, foxes, and more. With respect to the use of grazing to restore ecological balance, if we overgraze we are putting the food web at risk, but if we under-graze we are also putting the food web at risk. The same fine balance applies to our prescriptive use of good fire. Maintaining variability in our strategic use of grazing and good fire, as well as balancing their intensity and timing, supports greater biodiversity.

California’s native grasslands are highly prized for their ecological roles in groundwater infiltration and storage, carbon sequestration, erosion control, pollinator support, forage for wildlife after summer fires, and for delivering the beauty we can all enjoy. By applying regenerative agriculture, good fire, and conservation science to our grasslands, Pepperwood is supporting their key role in creating a more sustainable, resilient future for all.

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