Stewarding a Spray Zone

Stewarding a Spray Zone

A Yosemite ecological restoration crew removes and revegetates social trails in the Vernal Fall spray zone, a haven for at least six species of rare plants. Photo courtesy of NPS.

 

Moisture-loving mosses, lichens and rare specialist plants thrive in the unique "spray zone" habitat near the base of Vernal Fall. Photo: NPS.Vernal Fall, the 317-foot waterfall that helps usher the Merced River into Yosemite Valley, is a hugely popular day-hike destination — with good reason. From the trailhead near Happy Isles, a short, sometimes steep climb leads you to the base of the fall, where you can cool off in the spray and look for glints of colorful light in the cascading water.

Sounds magical, right? It is! But there’s a lot more to Vernal Fall than rainbows and refreshing mist. See the patch of bright green in the photo at right? That’s Vernal Fall’s “spray zone,” a haven for at least six species of rare water-loving plants (Davidson’s rock cress, Yosemite rock cress, California bolandra, wood saxifrage and Yosemite woolly sunflower) as well as more common flora.

 

The Yosemite woolly sunflower (Eriophyllum nubigenum, at left), one of at least six rare plant species in the Vernal Fall spray zone, is an annual herb found only in and around Yosemite National Park. Invasive velvet grass out-competes those rare plants and other native flora, such as arnica, in the lush habitat near Vernal Fall. As hikers tread on informal trails, they can inadvertently introduce non-native plant seeds into the spray zone ecosystem. Photos: Barry Breckling (left) and NPS (right).

 

Over time, hikers straying off the stone steps that zigzag up along the fall inadvertently created a series of informal “social trails” in the spray zone. That informal network fragmented the fragile fall-side habitat, encouraging erosion and even increasing the introduction of invasive plants such as velvet grass, which compete with rare native flora for nutrients, sunlight and water. Some of the social trails also led to slippery, unsafe areas close to the fast-flowing water.

 

In this bird's-eye view of the Vernal Fall spray zone, the yellow line traces the Mist Trail, while the red lines map the network of informal "social trails" that have been created over time. Visitor use data showed that on busy days, thousands of people were hiking on these informal paths. Photo: NPS.

 

Ready for some good news? In 2015, through a project supported by our donors, Yosemite’s ecological restoration crew set to work on improving conditions in the spray zone. Here’s how:

With support from volunteers and interns, the team removed acres of invasive velvet grass at Vernal Fall and neighboring Nevada Fall (pictured here) to help protect the rare flora that depend on the spray zone habitat. Photo: NPS.

A major part of the project  involved removing and revegetating some of the social trails along the edge of Vernal Fall. The team worked with colleagues from Visitor Use and Social Services to determine which paths needed to be eliminated, and which could be formalized as safe, sustainable trails. Will, a NatureBridge educator with a background in field work, spent his day off volunteering with the restoration crew to help kick off the social trail removal process by loosening compacted soil. Photo: NPS.

After decompacting the soil on the informal trails, which will encourage new plant growth, the team used plant debris, such as non-invasive grass and leaves, to mulch the freshly loosened earth. Photo: NPS.

To prevent erosion and revegetate the areas where social trails were removed, the team planted plugs, young plants with established root systems. They also used blocked off the restored areas with sticks to discourage hikers from creating new social trails and trampling the vulnerable plants. Photo: NPS.

 

New signs remind hikers to observe Vernal Fall's rare plants — and rainbows — from the safety of official trails. Photo: NPS.

Many people played a part in this Conservancy donor-supported effort to protect both plants and people in the Vernal Fall spray zone. Seven Student Conservation Association interns and numerous other volunteers (such as Will!) gained first-hand field work experience while collecting visitor use data, treating velvet grass and restoring social trails alongside Yosemite's ecological restoration experts. 

Now, it's your turn to be a spray zone steward! You can help protect the Vernal Fall spray zone (and other sensitive habitats) by staying on official trails and spreading the word about the need to "give plants a chance". The Mist Trail is often closed in the winter, but we hope you'll head up there during warmer months to see the results of the work — and in the meantime, take a look at some of the other ways you can make a difference for Yosemite's diverse habitats.

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