Tahoe-Central Sierra Initiative
A Partnership to Improve the Health and Resilience of Sierra Nevada Landscapes through Large-Scale Forest Restoration Planning
The Tahoe-Central Sierra Initiative
Tahoe-Central Sierra Initiative partners
The Tahoe-Central Sierra Initiative (TCSI) is a working group led by state, federal, nonprofit, and private partners formed in response to state and federal mandates that call for increasing the pace and scale of forest management and restoration, and for better protection of communities from wildfire.
Their focus is on the Lake Tahoe-Central Sierra Nevada region, a 2.4 million-acre landscape that is crucial for downstream communities, agricultural interests, recreationalists, and the environment.
This landscape sustains communities, ensures a reliable water supply for California, provides wildlife habitat, mitigates climate change through carbon sequestration, and is an important part of California’s economy.
Tahoe-Central Sierra Initiative map
At the same time, this area is at significant risk of large severe wildfire and unnatural levels of tree mortality given the overgrown, unhealthy forest conditions that exist there. TCSI aims to improve our understanding of current landscape conditions and the potential effects of management decisions on future landscape conditions in order to inform forest management into the future.
TCSI Framework
Purpose of TCSI
- Develop and demonstrate innovative planning, investment, and management tools across a 2.4-million-acre landscape.
- Accelerate large-landscape forest restoration to improve the health and resilience of the Sierra Nevada.
- Identify management strategies leading to increased protection of communities from wildfire.
Roadmap to Resilience
To provide a foundation to improve forest health and achieve resilience, TCSI established a four-part Roadmap to Resilience:
- Framework for Resilience
- Assessment of Current Landscape Conditions
- Assessment of Future Landscape Conditions
- Blueprint for Resilience
Despite significant effort and investment, forest management actions to improve the resilience of forested landscapes are not keeping pace with stressors that are mounting as a result of climate change, and in fact the gap between current conditions and target conditions may be widening, as opposed to narrowing.
A portfolio of socio-ecological conditions was developed as the primary organizing feature of the Framework for Resilience consisting of pillars, elements, and metrics. The resulting 10 pillars of resilience represent desired landscape outcomes that explicitly recognize the interdependence of ecological and social systems:
- forest resilience,
- fire dynamics,
- carbon sequestration,
- biodiversity conservation,
- wetland integrity,
- air quality,
- water security,
- fire-adapted communities,
- economic diversity,
- social and cultural well-being.
Each pillar describes landscape benefits provided by resilient socio-ecological systems, including resiliency to disturbance, the ability to sequester carbon, and the capacity to provide beneficial fire dynamics. Each pillar is described by its unique elements and metrics and are discussed further below.
The 10 Pillars of Resilience
The purpose of this initial assessment, part two of the Roadmap to Resilience, is to understand key aspects of current forest and landscape conditions, including fire and beetle/drought risk and biomass-processing capacity, across the TCSI area to establish the need and urgency for restoration based on a scientific foundation.
This assessment evaluated key features of the landscape in terms of resilience by assessing current conditions (2018–2020) across six of the ten pillars of resilience based on availability of current data:
- forest resilience
- fire dynamics
- fire-adapted communities
- biodiversity conservation
- carbon sequestration, and
- economic diversity.
Current and future conditions will be used to identify opportunities for restoration across the landscape using the Ecosystem Management Decision Support tool in the Blueprint for Resilience.
The Blueprint for Resilience (Blueprint) is a decision support tool to help managers and decision makers achieve multiple resource objectives across the Tahoe-Central Sierra Initiative landscape. It includes evaluations of 30 unique metrics from spatially explicit data, such as large tree density and probability of high severity fire, to represent current landscape conditions and future dynamics across five of the ten pillars of resilience:
- forest resilience,
- fire dynamics,
- fire-adapted communities,
- biodiversity conservation, and
- carbon sequestration.
The result is a set of strategy maps that identify opportunities for forest protection and adaptation across a 2.4-million-acre region of the central Sierra Nevada, made available through an interactive, web-based tool.
The forest restoration strategies defined in the Blueprint allow managers to tailor actions to be strategic, forward-looking, and responsive to projections of climate change impacts. The Blueprint can help managers determine where restoration treatments are likely to improve conditions over time, and conversely where they are not needed or where their impacts are less certain in the future.
Screenshot from TCSI Blueprint tool showing current departure scores for the Fire Dynamics pillar. See "The Blueprint Model" section tab (above) for further information.
Pillars of Resilience
The TCSI framework offers a shared vision for landscape-scale resilience that recognizes the interdependent nature of social and ecological values. These values are described by ten pillars that represent the desired outcomes of landscape resilience:
- forest resilience
- fire dynamics
- fire-adapted communities
- biodiversity conservation
- carbon sequestration
- economic diversity
- wetland integrity
- air quality
- water security
- social and cultural well-being.
Elements, such as forest structure or focal species, represent the primary processes and functions that together make up a pillar. Each of the pillars’ elements have one or more measurable metrics for assessing landscape conditions and verifying that actions meet resilience objectives. Metrics describe the characteristics of elements in quantitative or qualitative terms.
Users can use metrics to assess, plan for, measure, and monitor progress towards desired outcomes and greater resilience. While pillars and elements are consistent across the Sierra Nevada, the metrics that a group uses may vary from region to region based on ecological and social differences (for example forest types, economy), available data, and user preferences. Below, we further describe each of the ten pillars, including their elements and metrics.
Forest Resilience
Resilient forests provide many ecosystem services, including wildlife habitat, clean water, stable soils, recreational opportunities, biodiversity, wood products, and carbon sequestration. They also play an important role in both mitigating and adapting to climate change.
Across the landscape, management activities and natural disturbances should maintain desired forest conditions, including forest heterogeneity and wildlife habitat.
This pillar evaluates forest vegetation composition and structure to determine their alignment with desired outcome components.
Desired outcome
Vegetation composition and structure align with topography, desired disturbance dynamics, and landscape conditions, and are adapted to climate change.
Elements and their metrics
- Forest Structure, measured by tree density and basal area, structural heterogeneity, and large tree density.
- Forest Composition, measured by seral stage and compositional heterogeneity.
- Disturbance, measured by disturbance frequency and delinquency.
Fire Dynamics
Fire is an integral part of Sierra Nevada forest ecosystems, which are evolutionarily adapted to fire. Ideally, prescribed fires and managed wildfires would be allowed to burn across the landscape periodically. They would burn primarily at low to moderate severity in a mosaic pattern that covers large areas, which would provide substantial ecological benefits. Because climate change generally increases the severity of fire dynamics, managing such dynamics will continue to grow in importance.
Desired outcome
Fire burns in an ecologically beneficial and socially acceptable way that perpetuates landscape heterogeneity and rarely threatens human safety or infrastructure.
Elements and their metrics
- Fire Severity, measured by high-severity fire probability and patch size.
- Functional Fire, measured by influence of low- and moderate-severity fire and frequency of fire as a disturbance process.
Fire-adapted Communities
Due to climate change and other drivers, wildfires increasingly threaten homes and communities, especially in the wildland-urban interface. Fire adapted communities are knowledgeable and engaged. They accept fire as part of the surrounding landscape, take action to reduce their vulnerability to fire, and adapt to live safely with fire.
Desired outcome
Communities have adapted to live safely in forested landscapes and understand the significance of fire to maintaining healthy forests. They have sufficient capacity to manage desired fire and suppress unwanted fire.
Elements and their metrics
- Fire hazard, measured by high-severity fire probability in the wildland urban interface.
Biodiversity Conservation
Biodiversity plays a major role in our ecosystems and society. Native plants and animals help forests recover after a fire, control flooding and soil erosion, and cycle nutrients. Biodiversity also holds cultural value, including Native American uses, and provides recreational benefits like birdwatching. Greater species diversity promotes adaptability and helps ecosystems withstand and recover from disturbances, including those caused by a changing climate.
Desired outcome
The network of native species and ecological communities is sufficiently abundant and distributed across the landscape to support and sustain their full suite of ecological and cultural roles.
Elements and their metrics
- Focal species, measured by suitable and critical habitats for focal species, currently represented by the California spotted owl.
- Species diversity, measured by species richness.
- Community integrity, measured by richness for each of six functional groups.
Carbon Sequestration
Carbon sequestration is the process by which carbon dioxide is taken up by trees, grasses, and other plants and stored as carbon in biomass and soils. Resilient forests and wetlands can be net sinks of carbon and can play an important role in reducing greenhouse gas emissions into the atmosphere, thereby mitigating climate change. Forest products also play a role in storing carbon for decades in building materials, thereby delaying emissions.
Desired outcome
Carbon sequestration is enhanced in a stable and sustainable manner that yields multiple ecological and social benefits.
Elements and their metrics
- Carbon stability, measured by potential carbon loss.
Economic Diversity
Economic diversity increases business opportunities that provide regional economic vitality and additional benefts to rural and vulnerable populations.
Resilient forests provide ecosystem services and forest products that in turn provide a foundation for many local and regional economic activities and employment opportunities, including recreation, tourism, and natural resource management industries.
Desired outcome
Forest management and outdoor activities support a sustainable, natural-resource-based economy, particularly in rural communities.
Elements and their metrics
- Wood product industry, measured by supply and demand for sawtimber, biomass, and small-diameter trees, and by processing capacity.
- Recreation industry, measured by recreation diversity and recreational use.
- Water industry, measured by water management infrastructure.
- Economic health, measured by job market in natural resources, employment resilience, and income diversity.
Wetland Integrity
Wetlands provide critical habitat, filter and retain nutrient pollution, store carbon, enhance water quality, control erosion, and provide spaces for recreation. They are local and regional centers of biodiversity, and support species found nowhere else across western landscapes.
Functional wetland ecosystems will serve increasingly important roles in buffering impacts from extreme climate events, and upland disturbances such as flooding and erosion.
Desired outcome
Meadow and riparian ecosystems provide multiple ecosystem services and are key linkages between upland and aquatic systems in forested landscapes.
Elements and their metrics
- Structure, measured by stream channel morphology and alluvium storage capacity.
- Composition, measured by carbon content and benthic invertebrates.
- Hydrologic function, measured by surface water flow and stream channel discharge.
Air Quality
Clean air is important to human health and wellness, clean water, biodiversity, and ecosystems.
Catastrophic wildfires degrade air quality and cause respiratory illnesses that affect millions of people, especially children and people who work outdoors. Furthermore, people prefer to enjoy the outdoors when it is safe to breathe, and the skies are clear. Smoke from wildfires discourages recreation and disrupts businesses and local economies.
Land managers seek to improve forest health and resilience by using prescribed fire to reduce the risk of uncharacteristic fire and smoke.
Desired outcome
Emissions from fires are limited to primarily low- and moderate-severity fires in wildland ecosystems. Forests improve air quality by capturing pollutants.
Elements and their metrics
- Particulate matter, measured by wildfire emissions and prescribed fire emissions.
- Visibility, measured by visual quality.
- Greenhouse gases, measured by ozone.
Water Security
Resilient forested watersheds are key for regional and statewide water security. The economic value of California’s water far exceeds that of any other forest product. Water fows from forests into rivers that provide critical aquatic and wetland habitat, and that supply agricultural and drinking water for tens of millions of people.
Forests serve as natural water collection, storage, filtration, and delivery systems. These functions will become more important as climate change intensifies.
Desired outcome
Watersheds provide a reliable supply of clean water despite wide swings in annual precipitation, droughts, flooding, and wildfire.
Elements and their metrics
- Quantity, measured by ground water, water yield, and snow accumulation.
- Storage and timing, measured by stream flow volume, reservoir storage, snow water content, and snow melt.
- Quality, measured by nitrogen, phosphorus, sediment, and pollution.
Social & Cultural Well-being
A growing body of evidence indicates that greater exposure to nature is associated with better health and well-being. Sierra Nevada forests allow people to build and maintain active cultural and social connections to a place.
Resilient landscapes offer opportunities for people to connect with the natural environment through recreation experiences, culturally valued resources, and engagement in natural resource management and conservation.
Desired outcome
The landscape provides a place for people to connect with nature, to recreate, to maintain and improve their overall health, and to contribute to environmental stewardship, and is a critical component of their identity.
Elements and their metrics
- Public health, measured by smoke-induced illness and public health susceptibility.
- Public engagement, measured by natural resource knowledge.
- Recreation quality, based on costs and benefits to recreation.
- Equitable opportunity, measured by environmental justice.
The Blueprint Model
The Blueprint is a spatially-explicit model that uses a novel application of ecosystem management decision support systems to evaluate spatial data layers against target conditions that are indicative of resilient landscapes. It integrates assessments of both current conditions (2019) and future conditions (2020–2060) under climate change to reflect where management can likely make the most impact towards achieving functions on the landscape now and into the future.
The resulting model outputs spatial maps of condition scores ranging from -1 (out of target conditions) to +1 (within target conditions) for current and future conditions separately. These metric scores were then graphed into a two-dimensional space (figure below), with current conditions on the x-axis and the potential to achieve target conditions in the future on the y-axis. Within that space, four management strategies were identified: Monitor, Protect, Adapt, and Transform. To the right is the mapped representation of each management strategy from the model across the TCSI landscape using the corresponding color key in the graph below.
Management Strategy Scores derivation.
Management Strategies
Monitor and Protect areas are currently within target conditions. Monitor areas stay within target in the future and do not appear to need management, while Protect areas move outside of target conditions without management intervention. Because of their inherent stability, Monitor areas may have value as anchors in the landscape from which to expand and connect desired conditions.
Adapt and Transform areas are both currently outside of target conditions. Adapt areas move into target conditions in the future and management can speed up that transition, while Transform areas are less likely to reach and support target conditions in the future and management is less likely to result in target conditions.
Management Impact Scores
To reach the goal of improved resilience, TCSI prioritized maintaining areas that are within target conditions currently and increasing the area in target conditions where those conditions are likely to be retained in the future.
The “Management Impact Score" (Impact Score) is useful for ranking landscape units, such as watersheds or firesheds, for management investment over time. The impact score is driven by “Adapt" and "Protect” quadrant scores, as displayed in figure below. Areas with a large proportion of Adapt and/or Protect conditions receive a high impact score (closer to 1).
Management Impact Score values associated with the combination of current and potential future conditions relative to desired target conditions.
Areas with a high Impact Score have the greatest potential to contribute to transforming the landscape into climate-ready, desired target conditions as soon as possible through management. The map to the right displays Impact Scores across the TCSI landscape, showing areas where management can have the highest impact (red) or the least impact (blue).
TCSI Blueprint Map Tool
The Tahoe Central Sierra Initiative (TCSI) Blueprint is a set of strategy maps that identify opportunities for forest protection and adaptation across a 2.4-million-acre region of the central Sierra Nevada. Its aim is to improve resilience across the region to anticipated climate change and wildfire-, beetle-, and drought-caused tree mortality.
Management strategy and management impact maps were developed for each metric, element, and pillar and were further summarized in Ecosystem-level maps that combined scores across all five pillars, as shown in the Blueprint tool example to the left for Protect scores.
These interactive Blueprint maps are best used as a guide for land managers and other stakeholders to prioritize targeted forest restoration strategies. These strategies can enhance the resilience of current forest conditions where climate change is unlikely to compromise restoration investments.
The TCSI Blueprint is available at northcoastxy.com/tcsi/# .
The forest restoration strategies defined in the Blueprint will allow managers to tailor actions to be strategic, forward-looking, and responsive to projections of climate change impacts.
The Blueprint can help managers determine where restoration treatments are likely to improve conditions over time, and conversely where they are not needed or where their impacts are less certain in the future.
We hope this project can serve as a model for future landscape-scale restoration and resilience planning projects.
