Healing a Mountain Meadow

Rolls of custom-grown sod provide dense plant and root cover before the first floods.

Halstead Meadow, a 20-acre wetland located about 5 miles north of the Lodgepole area in Sequoia National Park, transformed from a badly eroded wetland to a restored wetland, thanks to a successful restoration project between 2007 and 2013.

The meadow had developed severe erosion gullies, lowered water tables, dried wetland soils, and wetland plant dieback due to 19^th century grazing and 20^th century road building. The road built across the meadow, with water concentrated in a single set of culverts, was completed in 1934. Efforts in the 1950s through 1970s to restore the meadow using check dams and willow planting were unsuccessful.

 

A New Vision for Restoration

In 2005, park staff began a new restoration effort with a different vision: convert the channelized system back to a sheet-flow system (water flowing across meadow surface) by:

• Filling in the gully
• Replacing the road embankment with a bridge to allow maximum dispersal of water across the wetland
• Restoring natural topography (land forms), hydrology (water flow), and vegetation.

National Park Service staff, led by Restoration Ecologist Athena Demetry, cooperated with Colorado State University scientists David Cooper and Evan Wolf to study reference meadows (less disturbed meadows), design a pilot restoration project to test new methods, carry out the pilot, and monitor results.

 

Meadow Restoration Goals and Approach

1. Restore landforms: Recreate a meadow surface that is nearly level, and perpendicular to the direction of water flow, and slopes gently downward from the upper to lower meadow.
2. Restore hydrologic processes: re-establish a saturated sheet-flow system where water flows broadly over the meadow surface and the water table is near the soil surface most of the summer.
3. Restore wetland vegetation: Reestablish rapidly spreading populations of three native wetland plant species.
4. Restore wetland functions: The hydrologic and vegetation goals create conditions that allow organic matter accumulation in soils, an indicator that wetland soil functions have been restored.

 

Phase 1: Upper Halstead Meadow Pilot Restoration (2007-2009)

 

Left image: heavy equipment fills in large gully with local fill (Sept 2007); middle image: small wetland plants growing with erosion control blanket and logs providing soil protection (June 2008); right: plants are established and wetland has sheet flow of water (September 2009)

The Upper Halstead Meadow pilot restoration project began in September 2007. Contractors filled the gully with 8,000 cubic yards of local fill using heavy equipment, placed erosion control blanket and logs to slow and spread water, and planted 53,000 native wetland plants in Spring 2008. The project team successfully restored sheet flow of water, and higher water tables (within 6 inches of the ground surface) through the summer. Native wetland plants were growing and spreading, and formerly dry (de-watered) areas were converting to a plant community more similar to heathier reference site meadows. But then, there was...

 

A channel forming where rain from an October 13, 2009 storm floods the area and plants that were growing there washed away.

A Curve Ball from Nature

On October 13, 2009, the site received 8-10 inches of rain in 24 hours. This big storm created a new gully, and 600 of the 8,000 cubic yards of soil and other material that had been added to fill the gully eroded away. The team quickly repaired the gully in November 2009, planted 12,000 wetland plants in the repair area, and learned from the experience that they did not adequately plan for high-flow events. A key element to the approach used in restoring Halstead Meadow was that a thick native wetland sod would develop to hold the fill in place during the deep, high velocity flows of a flood event. The dense, aboveground stems of native wetland vegetation would also slow and spread the water during a flood event. Until that dense sod established, which can take 5 to 10 years after planting, the restoration project was vulnerable to new gully formation during storm events or high spring runoff.

 

Ecological Restoration: A Learning Process

Aspects of ecological restoration are like an experiment. Specialists and those with local knowledge plan and carry out approaches they think will work. But things will go wrong, and success requires learning from what goes wrong, and trying again. It can be discouragning when a big rain event washes away some of your work. In the first years when new plants are still growing, the meadow is vulnerable to floods. So, it's necessary to figure out how best to stabiliize the site in those early years.

Here are examples of a few lessons learned during the pilot:

Dealing with Soil Compaction
Overcompaction of soil used for erosion gully fill slowed plant growth. The solution was to rip the surface soil with heavy machinery to loosen it. Incorporating 30 percent wood chips by volume to the top 18 inches of soil also helped keep the soil looser. Native meadow soils were used for the top two feet. This solution was implemented successfully in 2012.

 

Left image: overcompaction of soil used as gully fill slowed plant growth (2007); middle image: heavy equipment loosens soil surface (2012); right image: rapid plant growth in looser soils (2013),

 

Higher quality, larger plants (one plant per tube) improve  survival and growth after planting at Halstead Meadow.

Need faster-growing, more productive plant establishment to slow water flows.

Several different approaches helped establish more dense plant cover and sod that could better slow water and minimize erosion during storms:

• Salvage native wetland sod from gully bottoms to place at the most vulnerable locations to prevent erosion.
• Plant higher quality plants – Instead of using more plants, use better quality, larger plants.
• Use custom-grown wetland sod to provide dense plant and root cover before the first floods (but beware of non-native species).

 

Left: Water flows through small wetland plants, illustrating the need for faster-growing, higher productivity plant establishment to slow water flows (2008); middle: excavator places salvaged wetland sod on areas vulnerable to erosion (2012); and right: salvaged vegetation produced mature plant and root cover in first season (2013).

 

Coconut-fiber wattles (bundles of fiber) that are placed in wetland to slow down the flow of water and reduce erosion.

Evan Wolf, Colorado State University

Phase 2: Bridge Construction and Lower Meadow Restoration (2011-2012)

Construction of a bridge to create a sustainable road crossing and maximize the spread of water flows began in 2011. Lower meadow restoration began in July 2012. The restoration team filled the gully with 16,000 cubic yards of fill and employed new methods to withstand flood flows prior to plant establishment. These included the approaches described above, that reduced soil compaction and utilized larger plants and well-developed wetland sod from the gully or acquired commercially. Other strategies included:

• Used a heavier and longer lasting fiber matting to reduce soil erosion
• Avoided placing surface logs that facilitated erosion, and instead placed subsurface logs to reduce slope in steeper areas
• Placed 700 coconut fiber "wattles" (or bulky bundles of fiber) in short segments and in diagonal angles to make the water follow a winding path and decrease the slope

With the bridge completion in September, 2012, sheet flow of water was established between the upper and lower meadow for the first time in 80 years. A total of 87,800 plants and 0.5 acre of wetland sod were installed in fall 2012 and spring 2013. Very low precipitation during the winter of 2012-2013 helped to minimize erosion damage during the first storm season for this project.

 

Halstead Meadow Restoration, Sequoia National Park

Left image
Halstead Meadow with large erosion gully created by road construction bisecting the meadow. Water was channelized under the road through culverts, 2003.
Credit: NPS

Right image
Halstead Meadow with erosion gully restored to a healthy wetland, and a bridge that connects the upper and lower meadow, allowing restoration of natural flow patterns of water, 2015.
Credit: NPS

 

The Biggest Lesson Learned

Severe gullies can be restored to pre-disturbance wetland conditions if prepared to learn from mistakes and to persist.

 

Park Restoration Ecologist Athena Demetry and Colorado State University Wetlands Ecologist David Cooper looking over a restored Halstead Meadow.

Photo courtesy of Evan Wolf, Wetland Ecologist, Colorado State University

 

Wetland importance and restoration

• 

  Log Meadow Restoration

  Restoring Log Meadow: Testing methods for restoring wilderness wetlands.

• 

  Why are wetlands important?

  Learn more about why meadows and wetlands matter.

• 

  Ecological Restoration

  Learn about how wildlife, meadows, high-elevation lakes, and giant sequoias have benefitted from restoration projects.