By Stephanie Beard, Communications Coordinator &
Michelle Halbur, Preserve Ecologist
Every spring at Pepperwood, our research team spends a half-month out in the grasslands conducting grassland monitoring. We’ve been doing this at the same exact time every year for twelve years, and this May marks our thirteenth season. Why do we do this? Because we are monitoring the long-term health of our grassland communities under the impacts of climate change and our land stewardship (grazing, prescription burning and invasive species management).
We document things like species abundance and distribution – the long term picture of which shows us how these plant communities are changing from year to year and after disturbances like wildfire and drought – in short, climate change. To really get a good picture of what this work entails, we need to hear from our Preserve Ecologist, Michelle Halbur, who spearheaded and led these efforts from the get-go.
In the Weeds of Grassland Monitoring: Interview with Michelle Halbur, Preserve Ecologist
Stephanie: What does the monitoring process entail?
Michelle: We visit 32 transects (sampling lines) in areas that capture the variability of grasslands across the reserve’s 900-acres of open grassland. This means we have transects located in different grassland communities, such as predominantly native perennial grasses versus exotic perennial grasses, and in areas with different environmental conditions like slope, aspect, soil or substrate. Each transect is 55 meters long. At each five meter interval we lay down a one meter-squared “quadrat” (we use a PVC pipe square to show the area) that we sample every year. There are ten quadrats per transect meaning we sample 320 quadrats every year. Out of the 32 transects, seven are excluded from grazing to give us a “released from grazing” comparison. These are transects that were grazed until 2016. They still experience other disturbances such as wildfire, prescription fire, and drought, but they give us a sense of the impacts and benefits our conservation grazing program is having on the local conditions and community.
Stephanie: What sort of things are you measuring in each quadrat?
Michelle: We’re measuring things like…
- Percent cover of native perennial, native annual, exotic perennial, and exotic annual grasses
- Percent cover of bare ground, rock, dry material (litter and thatch), and disturbance like gopher or rodent activity, cow hoof punch, etc.
- Percent cover of forbs (non-grass species)
- Species composition (species list and percent cover for each)
- Species phenology (the timing of flowering and fruiting)
- Thatch depths
- Fine fuel heights
- Percent soil moisture
- Aboveground biomass for both thatch (old stuff) and the current season’s material
- We also incorporate our grazing data into this dataset, which includes stocking rate (the number of animals per acre for a specified amount of time) and time since last grazed (rest period)
- Larger disturbances are also documented, such as conditions before and after prescribed burns or wildfires.
Stephanie: Why is long-term monitoring preferable for understanding grassland ecosystems rather than short-term – what does long-term monitoring show us that short-term cannot?
Michelle: Grasslands are very dynamic – they have what’s called high interannual variation and do not stay the same from year to year. They may have cycles on larger time scales that we’re only beginning to understand. Having a long-term project like this enables us to ask important questions about short-term changes (such as in direct response to wildfire) and long-term changes that may go undetected (such as community conversion from mesic-preferring species (wet/cool adapted) to more drought resilient and/or weedy communities, or even biological invasions that may affect ecosystem function).
We can ask questions about processes that last beyond a couple years such as how the combination of the recent exceptional drought and wildfire may influence native plant diversity and abundance. Or how our land stewardship activities are influencing the persistence and possible expansion of native perennial grasses and wildflowers, which happens slowly over time.
Also, short term research and monitoring projects can be highly influenced by short term environmental conditions. For example, this year there is high soil moisture content from all the rain we received that will result in high productivity and biomass accumulation (meaning the rain made the plants grow larger). After high rainfall years and high fine fuel accumulation there is a greater risk for wildfires during the wildfire season. Through our monitoring at Pepperwood we can observe this short-term phenomenon and directly measure the community and biomass differences from this year compared to others. Based on our observations and familiarity with these processes gained from our monitoring, we can address high fuel loads by strategically modifying our conservation grazing impact (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.
Stephanie: Is there anything else that we monitor other than plants during our grassland monitoring? It seems to me that grasslands include more than just grasses…
Michelle: Yes! In fact, grassland health goes way beyond the plants! We also annually monitor our birds during breeding season to assess how our management is affecting our bird populations, including grassland dependent birds like western meadowlarks and grasshopper sparrows that nest on the ground in grasslands, or predatory birds like kestrels, white-tailed kites, and burrowing owls (which visit in winter months) that forage on rodents. Small voles and mice rely on sufficient ground cover to hide and maintain their populations that ultimately feed the predators – including birds, snakes, coyotes, bobcats, foxes, and more. If we overgraze we are putting the food web at risk. If we undergraze we are also putting the food web at risk. Maintaining variability in disturbance type, intensity, and timing inherently supports greater biodiversity. In other words, by modifying our stewardship we can support communities with variable structure and complexity across the landscape that in turn supports the diversity of species reliant on those niches.
Stephanie: What are some of the key takeaways that you’ve found in the years you’ve been engaged in this process?
Michelle: Grasslands are dynamic! They move, change, ebb, and flow. Some species come while other species go, and some stand guard for over a hundred years, like our native perennial bunchgrasses. Some species may lay dormant in the seedbank for decades waiting for the right conditions, like fire. Common species may also “wake up” during droughts or after fire or grazing – like we saw after the Tubbs Fire with bursts of lupines, poppies, creamcups, and blue-eyed grass.
Grasslands are diverse! Where else can you find over 30 plant species in 0.25 square meters?! Grasslands support over 90% of the endangered plants and animals in California. They support our important pollinators too!
Grasslands are highly threatened. They are threatened by conversion, mismanagement (including a lack of cyclical disturbances like fire and grazing, which they require to remain grasslands), and species invasion.
Native grasslands are critical for ecosystem services! Like groundwater infiltration and storage, carbon sequestration deep underground, erosion control, supporting pollinators, providing forage for wildlife after summer fires, and for providing beauty we can enjoy.
Grasslands are not well understood. If you look at vegetation maps, grasslands are typically lumped into one category: “grassland.” They are the black box of vegetation types. They are not well understood and operate at both fine- and large-scales – spatially and temporally – which are difficult to understand and characterize or categorize. Hence the importance of us doing long-term data collection so we may better understand the complexities at play. I do like a challenge, though, and appreciate that they don’t fit so nicely into our mapping categories!
Stephanie: What excites you about grasslands, what hope do they hold?
Michelle: Grasslands may look like fuzzy green hillsides or dry brown rolling slopes from a distance, but when you get up close there is a whole world to explore and discover. And they are not named properly! They should be called “wildflowerlands” in my opinion because there is so much more going on – and grasses are wildflowers too! Just not showy ones with petals.
Superblooms! Look at the immense craving we have for beauty and natural wonder at an epic scale. Superblooms are a perfect example of the dynamic and stunning displays that wake up after limiting factors are released. Meaning, in water limited places the rains will wake up the seedbank. In fire limited places (like at Pepperwood) fire is what awakens the seedbank.
As far as creating a sustainable, resilient future, grasslands are a great place for regenerative agriculture and ecosystem conservation to work together. We cover this unique relationship in our upcoming Spring issue of our Life+Landscapes Magazine. Subscribe to our print and email newsletters to learn more about amazing topics like this one!
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