© 2017 SAN FRANCISCO ESTUARY INSTITUTE

LANDSCAPE

RESILIENCE FRAMEWORK

Ecosystems with the capacity to adjust and reassemble in response to significant changes is increasingly important to maintain biodiversity and ecological functions across our landscapes in the context of an uncertain future. Seven key mechanisms exist that contribute to the resilience of ecosystems. When combined, these seven principles embody the most critical considerations when planning for ecological landscape resilience.

ABOUT THE LANDSCAPE
RESILIENCE FRAMEWORK

As human populations expand and our demands on the environment increase, we must wrestle with the question of how we can create and sustain diverse, healthy ecosystems across the landscapes we inhabit. How can we design landscapes that provide meaningful and lasting benefits to both people and wildlife? How can we sustain biodiverse, healthy ecosystems, from our cities to our wildlands, with the capacity to persist and evolve over time?


These questions, always challenging, have become even more so in the face of the rapid environmental changes that are anticipated over the coming century, particularly stressors associated with climate change and development. As we plan for impacts that are likely to be unpredictable or unprecedented, it is increasingly crucial that we support ecosystems flexible enough to adjust and reassemble, maintaining biodiversity and ecological functions in response to significant changes.

Scroll down to read about the components of an ecologically resilient landscape. The resilience actions focus particularly on lowland and coastal systems at this time and were produced as part of Resilient Silicon Valley.

 

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GEOPHYSICAL CONTEXT

Underlying geology, soils, hydrology, and topography key to the feature or site's identity and persistence

  • Preserved intact or restored soils, topography, and groundwater support appropriate habitats (e.g., depressional wetlands in low areas with high groundwater levels and clay soils, serpentine soils for serpentine grasslands, coarse alluvial soils for oaks; groundwater levels sufficient to maintain persistent, stratified summer stream pools for aquatic organisms and naturally perennial stream reaches)

1. SETTING

1. SETTING

 

ECOLOGICAL CONTEXT

Ecological assemblies; dominant and rare/unique vegetative communities that distinctively characterize the landscape. Includes landscape legacies -- remnants of former populations, habitats, structures, and processes that can be preserved, built on, or learned from/used as analogs

  • Dominant native vegetative communities present at sufficient scale to persist

  • Locally rare key native vegetative communities present and currently extirpated communities restored at sufficient scale to persist (e.g., oak savanna and woodlands, serpentine grasslands, sycamore-alluvial woodland)

  • Remnant habitats and habitat elements integrated into landscape (e.g., heritage oaks and other older/larger trees, standing dead and fallen trees, alkali grasslands, remnant tidal marshes, tidal channels in salt ponds, rock outcrops and cliffs)

  • Restoration and management of areas where native ecological communities can feasibly be restored (e.g. tidal marsh, willow groves, serpentine grasslands)

  • Hybrid and novel systems support ecological functions where historical habitats are not recoverable (e.g. annual grasslands, estuarine benthos)

  • Natural ecosystem processes sufficiently intact to support self-sustaining natural habitats and communities in key areas

HISTORICAL & CULTURAL CONTEXT

How the landscape has changed over time – which ecosystem elements have persisted or disappeared, and why

  • Restoration and management based on an understanding of local history and change over time (e.g., composition and width of former t-zone habitat informs t-zone restoration, understanding of historical composition and distribution of oak woodlands guides re-oaking)

  • Restoration and management based on an understanding of potential future trajectories and opportunities as infrastructure and landscapes are redesigned

  • Restoration and management based on local knowledge of how to sustainably steward landscapes and ecosystems (e.g. TEK on fire and oak management)

CRITICAL RESOURCES

Resources required for the persistence of desired ecological functions but currently limited within the landscape

  • Variable aquatic and wetland habitats (e.g. perennial, intermittent, and ephemeral streams, depressional wetlands, willow groves, high groundwater, treatment ponds, rain gardens) to support plants and wildlife in a water limited environment.

  • Thermal and drought refuges to accommodate hotter temperatures and drier summers (e.g. shaded riparian cover, hyporheic flow, deep stream pools)

  • Baylands that receive enough sediment, via watershed management or other approaches, to support rapid marsh accretion that will offset sea level rise in a time of declining Bay sediment

  • Opportunities for wildlife support on the valley floor (where open space/wildlife habitat is limited) in unconventional areas such as landfills, golf courses, institutional lawns, airports, water treatment basins, etc.

2. PROCESS

 

SYSTEM DRIVERS

Large-scale forces such as climate change and land use

  • Floodplains, flood-prone areas, and shoreline areas below Mean Higher High Water are not developed

  • Macrotidal aspect of estuary preserved

DISTURBANCE

REGIMES

Expected but unpredictable events, such as fires, floods, and droughts, that shape habitat structure and/or create opportunities for wildlife

  • Natural and managed disturbances support habitat complexity and diversity (e.g., fire, manual clearing, and grazing in chaparral/scrub/grassland in hills;  floods in channel and adjacent riparian areas)

  • Natural disturbances are encouraged by land use and zoning that keeps development out of fire and flood prone areas.

  • Management of successional transitions that reduce habitat diversity in the absence of disturbance, especially fire (e.g., Douglas fir overtopping oak woodland and coyotebush expanding in grasslands)

  • Small-scale, intermediate disturbances (e.g., gophers) to create microsite heterogeneity

HABITAT SUSTAINING PROCESSES

Dynamic processes, such as the transport of water and sediment, that are key to maintaining habitats

  • Sufficient fine sediment delivery to baylands and floodplains via creek channels, tidal waters, and enhancement projects to sustain marsh and riparian habitats; sufficient coarse sediment delivery to creeks to sustain aquatic habitat

  • Naturalistic magnitude and timing of environmental flows delivered to creeks and across floodplains (e.g., flows that cue germination of sycamores and other native riparian species in appropriate locations, and fish migration, rearing and spawning; avoidance of hydromodification [excessive stormwater flows causing creek erosion])

  • Shallow groundwater levels where appropriate to support groundwater-dependent habitats (e.g., willow groves, freshwater wetlands, permanent stream pools, naturally perennial stream reaches)

  • Native and/or managed grazing to control excessive plant growth (due to increased anthropogenic nitrogen inputs, invasive species, etc), maintain ecological diversity and groundwater recharge in grassland/savanna

  • Reservoir operation (e.g., reservoir redesign or changes flow releases) or dam removal to support sediment transport and flood pulses, as well as reliable perennial reaches

  • Maintain high propagule pressure of desired species

3. CONNECTIVITY

 

LINKED HABITAT PATCHES

Habitat distribution supports different aspects of species life history, allows for species movement and migration, exchange of resources, and gene flow between habitat patches (functional connectivity)

  • Functional connectivity/permeability between large open space areas (especially among upland habitats and among bayland habitats) connected through corridors/stepping stones.

  • Hills to baylands connectivity through streams/riparian corridors and more permeable valley floor (e.g., via urban greening) for wildlife movement, dispersal,  and transport of sediment and other materials

  • Wetland complexes that provide a critical stopover (in an area otherwise lacking appropriate habitat) for migratory songbirds along the Pacific Flyway

  • Linked channels or floodplains at the mouths of certain streams

  • Removal of barriers to wildlife movement (e.g., road underpasses and overpasses for wildlife, removal of fencing)

  • Connectivity to habitat outside of the landscape (e.g., Pacific Flyway)

SPACE FOR SPECIES AND HABITAT RANGES TO SHIFT

Space for species and habitats to move to as their ranges shift, including accommodation space

  • Accommodation space and transition zone habitats upslope of baylands to allow for landward marsh migration as sea levels rise

  • Creek corridors and floodplains of sufficient width to accommodate current and predicted future flood events and rising sea levels (e.g. via levee setbacks, retreat or removal of development, and/or floodplain grading)

  • Open space areas and habitat patches of any size throughout the landscape that could serve as stepping stones and seed sources for colonization.

  • Hot and/or dry areas occupied by drought-tolerant native vegetation that could serve as seed sources in the future

  • Contiguous open spaces that cross gradients of varying steepness (e.g., elevation gradient for upland habitats, salinity gradient for marshes)

GRADUAL TRANSITIONS

Soft edges between habitat types that support ecotones

  • Gradual transition zones between baylands and terrestrial habitats

  • A diversity of steepness in habitat transitions that includes areas of non-abrupt transitions/continuum between grassland and woodland/forest habitats, riparian and upland habitats

  • Buffers around wetland and aquatic habitats to support ecotones (and provide accommodation space and ameliorate stressors)

EXPRESSION OF HABITATS ACROSS GRADIENTS

Expression of habitats across important physical gradients, such as salinity and temperature

  • Habitats that span key spatial and physical gradients in salinity, temperature, and elevation  (e.g., tidal marsh expressed along a salinity gradient, chaparral expressed across a temperature gradient, streams expressed as longitudinal gradient)

  • Estuarine-terrestrial transition zone that rings the South Bay

  • Upland habitats across different mountain ranges (e.g., between Santa Cruz Mountains and Diablo Range)

  • Expression of upland habitats across the valley with a gradient of distance from the Bay/coast

  • Stream habitats supported across north/south and east/west gradients that account for changes in precipitation and temperature.

LANDSCAPE COHERENCE

Habitats are organized in a way that supports desired processes and ecosystem functions, including the ability of wildlife to navigate within the landscape

  • Complete ecosystems, with key components and processes intact at the appropriate scale (e.g., connected bayland habitats, including mudflat, marsh, and T-zone, that follow important physical gradients, align with natural processes, and allow system components to interact in ways that better support wildlife)

  • Hydrology (flow timing, duration, distribution, magnitude, connectivity, etc.)  and water chemistry that maintain natural cues for fish and other aquatic and riparian organisms

 

4. DIVERSITY & COMPLEXITY

4. DIVERSITY & COMPLEXITY

RICHNESS OF LANDSCAPE FEATURES

Landscape-scale diversity in habitat types and connections between different habitat types; physical heterogeneity in topography, groundwater, soils

  • A diversity of habitats, primarily for key native species (e.g., oak savanna/woodland; redwood and mixed forest; serpentine, perennial, and annual grasslands; chaparral; alkali meadow/grassland; willow groves; perennial freshwater wetlands and ponds; seasonal wetlands; riparian forest; sycamore-alluvial woodland; salt marsh, brackish marsh, salt flats, mud flats, T-zone, and ephemeral, intermittent and perennial streams)

  • Variable, heterogeneous topography to support habitats and species of interest (e.g., intact low topography to support depressional wetlands)

  • Variable aquatic and wetland habitats (e.g. perennial, intermittent and ephemeral streams, depressional wetlands, willow groves, high groundwater, treatment ponds, rain gardens) to support plants and wildlife in a water limited environment

  • Management of successional transitions that reduce habitat diversity in the absence of disturbance, especially fire (e.g., doug-fir overtopping oak woodland and coyotebush expanding in grasslands)

WITHIN-HABITAT DIVERSITY & COMPLEXITY

Site- or habitat-scale vegetative diversity (e.g., in species, structures, or height) and physical heterogeneity (e.g., in microhabitats, microtopography, and microclimates)

  • Microclimates, microtopography, complex vegetative structure, and other heterogeneity supporting within-habitat complexity to provide wildlife refuge and promote/sustain genetic and phenotypic diversity and alternative life history strategies (e.g., stream pools, pannes, channels of varying size in marsh; complex understory creating light and temperature gradients in scrub/riparian)

  • Within-habitat diversity in vegetation age structure, vertical structure, composition and spatial configuration (e.g. oaks of varying ages, different densities in chaparral)

  • Areas that provide temperature refuges in upland habitats (e.g. because of proximity to water, shading, hillslope/aspect, coastal influence, etc.)

  • High tide refuges with sufficient space for bayland species to escape flooding conditions

  • Riverine flood refuges to provide aquatic organisms, especially fishes in urban stream channels, with shelter from extreme floods (e.g. wide floodplains, small tributaries)

  • Temporal variability in resource availability (e.g., Plants with a diversity of flowering timing to support a diverse suite in pollinators as life history timing changes; wetland areas that pond at different times of year, intermittent and ephemeral streams )

  • Native species assemblages conserved in invaded annual grasslands

DIVERSITY IN APPROACH

Maintaining response diversity and a diversity of life history strategies both within and between species to deal with variability, disturbance, stressors

  • Presence of population segments that use the landscape in different ways (e.g. rainbow trout/steelhead)

  • Species that respond to similar stressors in different ways (e.g. fire re-sprouters vs. fire-germinating seeds)

GENETIC AND PHENOTYPIC VARIABILITY

Diversity in genes and traits within species

  • Sufficiently large populations of key species to support genetic and phenotypic diversity (e.g., Bay checkerspot butterfly, steelhead and rainbow trout)
     

  • Landscape/streamscape complexity to produce areas that support different species and populations
     

  • Endemic rare and endangered species (e.g., Bay checkerspot, tiger salamander, red/foothill yellow-legged frog, burrowing owl, least bell’s vireo, tri-colored blackbird).
     

  • Diverse seed banks (and range of genotypes) to support native plant persistence

5. REDUNDANCY

 

STRUCTURE / SPATIAL

Multiple habitat patches and an abundance of key structures within habitats

  • Multiple habitat patches providing similar or overlapping functions (e.g., multiple willow grove-wetland complexes, multiple variable depth pools in creeks))

  • Multiple corridors for wildlife movement (e.g., multiple continuous riparian and non-riparian corridors)

  • Flows supporting steelhead runs on multiple streams, ideally originating from watersheds experiencing different physical gradients, to minimize risk (e.g., Diablo Range vs. Santa Cruz Mountains) 

POPULATION

Distinct or disconnected populations of a species

  • Enough distance between population segments of important species to diversify risk  (e.g., high Ridgway’s rail densities in more than one marsh patch)

  • Multiple streams support freshwater fish populations, reducing the likelihood of regional extirpation

FUNCTIONAL

Multiple species within the system supporting the same ecological function

  • Support for multiple species supporting similar key functions (e.g., pollinators, burrowing mammals in grasslands)

DISCRETENESS

Isolation or disruption between habitat elements to reduce susceptibility to stressors

  • Risk diversified by disconnection (e.g., perennial stream reaches seasonally separated by intermittent reaches)

  • Reduction in inter-basin water transfers

  • Breaks in habitat continuity to provide fire breaks and barriers to the spread of other stressors and disturbances (e.g. breaks in chaparral, not over-connecting marsh channels via ditches)

6. SCALE

 

LARGE SPACES

Areas of sufficient size to accommodate sustaining physical processes and support sufficiently large wildlife populations and support genotypic and phenotypic variability

  • Large areas of open space in the hills and baylands to support wildlife (large is defined relative to the species intended to support)

  • Floodplains and riparian corridors of sufficient width to support wildlife and accommodate flooding and geomorphic dynamism (including geomorphic responses to climate change and urbanization)

  • Large areas of tidal marsh and other bayland habitats to support wildlife

LONG TIME SCALES

Broad time horizons over which ecological functions must persist under changing and variable conditions

  • Accommodation space and transition zone habitats to anticipate landward migration of tidal marsh as sea levels rise

  • Key species and habitats established early in areas that are likely to support their persistence but not establishment under future conditions (e.g., oaks established while conditions can still support seedlings, marsh restored while sediment supplies are adequate) 

  • Availability of seed stores and seedlings for vegetation communities not currently present/abundant but likely to withstand/thrive under future conditions.

  • Land use and zoning planned with time horizon for future changes

CROSS SCALE INTERACTIONS

Important interactions that occur across multiple spatial and temporal scales

  • Short term and fine-scale actions and visions that link to long term and large-scale planning and visions (e.g., preserving remnant habitat near areas likely to be available for restoration in the future)

  • A balance of resources in the landscape to account for trade-offs that happen at different spatial and temporal scales (e.g., a landscape needs large habitat patches, but not at the expense of having no habitat redundancy; habitat diversity but not to the extent that specific critical resources cannot be maintained in adequate abundance)

7. PEOPLE

 

ECOLOGICAL ENGAGEMENT

Place-based and widespread landscape stewardship

  • Opportunities for people to interact with nature in a way that educates and inspires financial and emotional investment in ecosystems and good stewardship

  • People with a deep understanding of place that can inform stewardship strategies

  • Coordination and partnerships among planning efforts, agencies, and other stakeholders

LANDSCAPE INTEGRATION

Opportunities to support ecological functions occur across urban, suburban, agricultural and open space lands

  • Habitat integrated into urban and suburban areas for wildlife support (e.g., through green buildings, landscaping, parks, backyards, street trees, and riparian corridors). 
     

  • Habitat integrated into developed areas in a way that leverages large areas and maintains landscape permeability.
     

  • Rain gardens, retention basins and other water infrastructure that links to larger regional wildlife support and physical processes (e.g. leverage recharge in urban and suburban landscape to support groundwater-dependent habitats)
     

  • Wildlife support in agricultural areas and ranchland (e.g. food, cover, perches for birds provided in hedgerow buffers)
     

  • Landscaping of developed areas using native vegetation that provides habitat for key species

ADAPTIVE MANAGEMENT

Stewardship of the land in a coordinated, flexible, and informed manner; learning from monitoring, research, and pilot projects

  • Pilot projects, novel approaches, willingness to fail and learn from mistakes
     

  • Learning through programs that support research and monitoring needed to make informed decisions and actions
     

  • Flexible governance structure and mechanisms for coordination between stakeholders; incorporation of resilience tenets into documents such as general plans
     

  • Early detection networks and ways of rapidly responding to catastrophes or novel stressors (e.g. new invasives with high potential for harm, advance planning to improve chances of rapid and ecologically effective response to catastrophes; planning for post-fire restoration/management)
     

  • Ability to respond quickly when unforeseen opportunities arise or catastrophic events occur

STRESSOR MANAGEMENT

Management of specific stressors that must be controlled in order to maintain desired ecological functions and biological processes

  • Buffers between wildlands and developed areas
     

  • Control of excess nutrients via source control, consumption of excess production, or other means (e.g. grazing in grasslands, buffers in wetland/aquatic systems, LID)
     

  • Feral cat colonies and other nuisance species are relocated far from core wildlife habitat
     

  • Control of invasive species that threaten the persistence of desired ecological functions and desired species
     

  • Reduction in contaminants that contribute to species mortality (e.g. reduced contaminants in runoff, remediation, green building, etc)
     

  • Reduced emissions to manage nitrogen deposition or control of the resulting increase in biomass production to preserve serpentine grassland communities
     

  • Native and/or managed grazing to reduce carbon accumulation where excessive due to nitrogen, grazing, etc.