Growing up, I was obsessed with two things: horses and nature (to be fair, I am still pretty interested in both). As luck would have it, I lived quite close to Westwind Barn and its neighbor, Byrne Preserve. I began taking riding lessons at the barn when I was about six or seven, and soon I was looking for any possible excuse to return.

For over a decade of my childhood, I spent countless hours at Westwind Barn, riding and caring for horses, teaching summer campers and other young riders, and volunteering with Westwind Riding Institute, a therapeutic equestrian program. Part of this included fetching school horses from “the big pasture,” as we referred to Byrne Preserve.

This brings me to my first experience with the concept of invasive plants. Up until this point, I wasn’t too concerned about plants growing in the “wrong” places. They were just trying to grow wherever they could survive! My plant-neutrality started to collapse when I encountered yellow starthistle.

I often had to walk to the far reaches of Byrne Preserve to catch horses, and it seemed that dense patches of spiny yellow starthistle always stood between me and my goal. The pain of walking through spiny plants was not enough to erode my beliefs; those plants were just trying to survive, after all. However, I learned their spiny unpleasantness was coupled with a few important traits. First, yellow starthistle is toxic to horses. While most equines do not enjoy eating it, some develop a taste for it and suffer mouth and stomach ulcers. In the rare case that a horse consumes huge amounts of the plant, it can suffer from a fatal neurological condition.

Second, yellow starthistle was brought to the western United States unintentionally from the Mediterranean. While it is still often considered weedy in its native range, it evolved alongside animals that can eat it safely. Here, meanwhile, yellow starthistle grows quickly, outcompeting other plants, hogging water early in summer, and causing havoc for horses and hikers alike. I was appalled that humans had so carelessly introduced a plant that not only harmed our beloved pets, but also hurt ecosystems by forming monocultures that reduced biodiverse habitat for wild species.

Yellow starthistle was not the only prickly or poisonous invasive species I encountered back then. I have similar memories of walking through spiky purple starthistle and finding horses in the teasel-filled tributary. I also spent hours with other riders removing poison hemlock, a potent toxic species made more dangerous by its palatability to horses. At this time, I was resigned to dealing with these species by avoiding them when possible and trying to ensure horses did too. I could barely imagine what it would take to even reduce their population density: thousands of hours of work, spending year after year painstakingly removing these plants?

Yellow starthistle turns out to be bad for horses and bad for local biodiversity.

After spending eight years away from the Bay Area, I returned in 2023 as a California Climate Action Corps Fellow with Grassroots Ecology. I was thrilled to be working at my old haunt, Byrne Preserve, even as I braced myself for hours spent walking through thistle and teasel. Though these plants were still present when I began my term in September 2023, they were not the first things I noticed. Instead, I saw biodiverse habitat. Where the preserve had previously been dominated by dense stands of invasive plants, especially around the seasonally dry creek, it was now a colorful patchwork of native species: buckeyes dotting the creek, currants and gooseberries full of fruits for critters to snack on, clumps of California aster and bee plant.

California bee plant and other native biodiversity in the floodplain planting area.

Some species, including our target invasives like yellow starthistle and teasel, follow consistent yearly growth cycles with predictable peak flowering times. Yellow starthistle tends to peak in observable population size around July and August, so we have spent a good deal of time this summer removing it. Even at its peak this year, I was still shocked at how little yellow starthistle there was compared to my memories of the preserve.

Before: Yellow starthistle in the floodplain planting area, June 2017.

After: Native rushes, coyote brush, and other native plants thrive in the floodplain, August 2020.

How has Grassroots Ecology created this impact on Byrne Preserve - not just in reduction of invasive species populations, but also in revegetating the tributary and floodplain with native species? As with all of our work, the scale of the transformation at Byrne could not have been possible without engaging volunteers from our communities to get their hands dirty. Since Grassroots Ecology started working at the preserve in 2014, we have worked alongside over 4,000 volunteers who have contributed 12,000 hours of their time weeding, planting, and caring for the unique ecosystems of Byrne Preserve.

I loved working with our Summer Youth Stewards to weed yellow starthistle!

Summer Naturalist Interns mow yellow starthistle.

This summer, we tackled yellow starthistle with many volunteers, including our high school Youth Stewards and Summer Naturalist Interns. Our dedicated Youth Stewards spent one morning each week for eight weeks helping care for our sites and learning about nature. They removed huge patches of spiky yellow starthistle, pulling weeds by hand to limit the amount of seeds that return to the seed bank. The Naturalist Interns honed their skills with weed whips and hand tools to clear dense patches and dispersed populations of starthistles. It is incredible to see so many dedicated high school and college students who are willing and excited to care for our ecosystems, even on hot summer days. I feel lucky to witness the next generation of land stewards in action!

Returning to Byrne Preserve after so much time away has been an incredible experience. I have come to see the preserve in a new way, as the product of so much time and energy spent by humans who want to protect other species and improve our relationship with nature. Their efforts have real, visible impacts on wildlife and native flora. We frequently spot butterflies like the variable checkerspot and Lorquin’s admiral, as well as families of deer and coyotes that call the preserve home. I am particularly fond of the birds of Byrne; according to eBird, 84 species have been observed at the preserve! I have been lucky to get an up-close look at the western bluebirds and violet-green swallows that nested in nine nest-boxes around Byrne.

Ten years of work at Byrne Preserve has brought about serious change for the better in terms of creating diverse, resilient habitat. In another ten years, who knows? Maybe I won’t see a single hole in my socks from walking through starthistles!

One of my fellow AmeriCorps members, Laura, joined me for a day of bird box monitoring in spring.

I’m excited to continue this work next year as a Restoration Specialist at McClellan Ranch Preserve in Cupertino!

By Maya Nagaraj, California Climate Action Corps Fellow

From the Field

Growing Up with Byrne: From Horse Rider to Habitat Restorer