Restoring Ecosystem Resiliency

Background

The Sierra Fund has been working to address the impacts of the 19^th century Gold Rush as a seminal disturbance that resulted in long lasting environmental, cultural and health impacts to the ecosystems and communities of the Sierra Nevada. Impacts of the Gold Rush went far beyond those caused by gold mining. Not only were more than 40,000 mines left abandoned across the landscape, each with chemical and physical hazards, but nearly every tree in the region was harvested to build the towns and to timber the mines of the gold and silver strikes on the western and eastern slopes of the Sierra Nevada. The majority of rivers and creeks were dammed, and thousands of miles of ditches were dug to convey water to the hydraulic, placer and hard rock mines so that mountain could be torn apart in the quest for gold. Rocks, gravels and sands from the mines contaminated with mercury were washed down the rivers in such volume that about one-third of the San Francisco Bay was filled in, and the former estuary was drowned in mud, forcing river boat pilots to dredge channels for passage, creating the forerunner of the levee and channel system that makes up the modern Delta.

The Sierra Fund’s Vision for Restoring Ecosystem Resiliency

Resiliency is the ability to recover from disruptive change and withstand ongoing pressures. The ability to recover from change is directly proportional to the size and extent of the disturbance and the degree to which an ecosystem can tolerate disturbance. Ecosystems have developed around “natural disturbance regimes” where change is a constant and critical component of dynamic function (water levels rise and fall, temperatures change with seasonality). As a result of continuous change, the dynamics of systems select for resiliency, or ability to tolerate disturbance without collapsing into a different state that is controlled by a different set of processes.

The Sierra Fund is interested restoring the processes that maintain and maximize resiliency in the Sierra.  The disturbance regimes critical to ecosystem resiliency in the Sierra Nevada include the flow regime, sediment regime, fire regime and climate regime. The natural variability of these disturbance regimes is key to ecosystem resiliency but this variability has been fundamentally altered by the impacts of the California Gold Rush and climate change.

The Sierra Fund’s vision is a restored flow regime, a restored fire regime and a restored climate regime that leaves a thriving and vibrant ecosystem for generations to come. Key to this vision is restoring the mine scared lands, reintroducing the use of prescribed fire and sequestering carbon in the soil. The Sierra Fund’s goal is to increasing the pace and scale of mine remediation, meadow restoration and forest health projects in a way that increases interest in and access to stewardship opportunities for the communities of the Sierra.

Key to this approach is engaging the First Nations of the Sierra, on whose ancestral homelands projects are planned, so that meaningful actions that work to restore ecosystem resiliency are executed in tandem with efforts to support community resiliency.

Water Flow Regime

In the 1800s, California’s streams and rivers were engineered to deliver water to the mines and today are operated to deliver water and power during periods of peak demand. The system’s ability to meet the increased demands for water and power, as well as environmental flows, may depend on maintaining the water storage space behind impoundments we rely on, as well as restoring the “green infrastructure” of the headwaters, such as meadows, that hold water higher, longer and release it slowly over extended periods of time.

Sediment Regime

The hydraulic mine sites that were denuded of soil, result in a landscape littered with scars which deliver unprecedented amounts of sediment to streams and rivers. These scars continue to erode and release sediment contaminated with mercury, choking streams with turbid conditions and filling reservoirs. The system’s ability to handle increased sediment loads from denuded mine-scarred landscapes and from overgrazed meadows is dependent on both remediation efforts that abate erosion and on sediment removal efforts coupled with reservoir maintenance that are sophisticated enough to address mercury contamination at the same time.

Fire Regime

In the fire adapted landscape of the Sierra Nevada, fire is a natural part of the ecosystem function and resiliency of the region. Fire plays a role in seed germination and forest stand diversity. The region-wide removal of timber for the mining operations followed by an era of fire suppression resulted in today’s single-age stands, which are choked with underbrush and full of invasive species. The result is an ongoing threat of severe mega fires, the likes of which the region has not seen before, including in areas that are now populated. The system’s ability to handle fire, and to recover from severe fire, is directly proportional to continued coordination of forest thinning, invasive species removal, and fire treatment efforts.

Climate Regime

The greatest pressure the Sierra Nevada ecosystems face today is climate change. Longer droughts and warmer temperatures mean that precipitation will be dominated, by rain fall, not snow, resulting in a “flashy” system characterized by increased power for erosion and less water late in the season due to decreased snow pack. The ultimate response to climate change is to reduce emissions from catastrophic wildfire and to sequester carbon by building soil in the headwaters. Building soil carbon to create a net carbon sink will include restoring high elevation meadow wetlands and creating biochar as part of forest treatments and using it to restore soil as part of hydraulic mine remediation.