4.5 Cultural Landscapes, Historic Preservation & Adaptive Reuse

Core Focus: Cultural landscapes represent physical places shaped by the continuous interplay of natural processes and human culture over time. Landscape architects practicing historic preservation must master the Secretary of the Interior's Standards for the Treatment of Historic Properties, apply National Park Service (NPS) cultural landscape typologies, author comprehensive Cultural Landscape Reports (CLRs), evaluate the seven aspects of historic integrity, balance botanical authenticity against climate change, and execute post-industrial adaptive reuse projects.

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1. Secretary of the Interior's Standards for the Treatment of Historic Properties

Administered by the National Park Service (NPS) under the statutory authority of the National Historic Preservation Act of 1966 (NHPA) and codified in 36 CFR Part 68, the Secretary of the Interior's Standards establish the ethical and technical framework for all interventions on historic properties listed on, or eligible for, the National Register of Historic Places.

The Standards define four distinct treatment approaches, arranged hierarchically according to the degree of physical intervention and the retention of existing historic fabric:

Hierarchy of Historic Property Treatments
Retains Maximum Historic Fabric ◄────────────────────────────────► Complete Re-Creation
┌─────────────────┬──────────────────┬─────────────────┬──────────────────┐
│  PRESERVATION   │  REHABILITATION  │   RESTORATION   │  RECONSTRUCTION  │
│ (Stabilization  │ (Compatible New  │ (Return to ONE  │  (Rebuilding     │
│  & Maintenance) │  Use & Adapting) │  Significance)  │   from Scratch)  │
└─────────────────┴──────────────────┴─────────────────┴──────────────────┘

1. Preservation

• Definition: The act or process of applying measures necessary to sustain the existing form, integrity, and materials of a historic property. Focuses on ongoing stabilization, maintenance, and repair of historic materials rather than extensive replacement or alterations.
• Treatment Philosophy: Respects all historical periods that have contributed to the site over time. It strictly prohibits new additions, substantial alterations, or stripping of historic layers from subsequent periods.
• Application: Selected when the property's existing fabric already conveys its historic significance, or when financial/interpretive resources mandate stabilizing the site against further decay without altering its evolution.

2. Rehabilitation

• Definition: The act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features that convey its historical, cultural, or architectural values.
• Treatment Philosophy: The most versatile and widely applied standard in modern landscape architectural practice. It acknowledges the necessity to adapt historic sites to contemporary programmatic uses, modern building codes, universal accessibility (ADA), life-safety, and sustainable infrastructure.
• Key Design Standard (Standard 9): New additions, exterior alterations, or related new construction shall not destroy historic materials, features, and spatial relationships that characterize the property. The new work must be compatible with the historic materials, size, scale, and proportion, but must be differentiated from the historic fabric so that the intervention does not create a false sense of historical development.

3. Restoration

• Definition: The act or process of accurately depicting the form, features, and character of a property as it appeared at a particular period of significance in its history by means of the removal of features from other periods in its history and the reconstruction of missing features from the restoration period.
• Treatment Philosophy: Requires the systematic, documented removal of physical elements from later historical periods and the precise recreation of missing elements from the primary period of significance based on rigorous physical, archival, or archaeological evidence. Hypothetical conjectural designs are strictly prohibited.
• Application: Chosen when a specific era of history is of paramount cultural importance (e.g., restoring an 18th-century revolutionary battlefield or a historic presidential estate to the owner's lifetime) and later additions obscure historical interpretation.

4. Reconstruction

• Definition: The act or process of depicting, by means of new construction, the form, features, and detailing of a non-surviving site, landscape, or structure for the purpose of replicating its appearance at a specific period of time and in its historic location.
• Treatment Philosophy: Involves complete re-creation based on exhaustive archaeological, pictorial, and documentary evidence. If physical evidence is insufficient, reconstruction cannot be justified.
• Application: Employed rarely, typically when a catastrophic event (fire, earthquake, war) has destroyed a nationally significant landscape and re-creating it is vital to public interpretation.

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2. National Park Service (NPS) Cultural Landscape Typologies

Codified in NPS Preservation Brief 36: Protecting Cultural Landscapes and National Register Bulletin 18, cultural landscapes are classified into four distinct operational typologies:

1. Historic Designed Landscape

A landscape that was consciously designed or laid out by a landscape architect, master gardener, architect, engineer, or horticulturist according to recognized design principles, or an amateur gardener working in a recognized style or aesthetic tradition:

• Features intentional spatial organization, conscious geometric or picturesque composition, designed circulation networks, and curated planting palettes.
• Examples: Central Park in New York (Frederick Law Olmsted & Calvert Vaux), the grounds of Biltmore Estate, Dumbarton Oaks (Beatrix Farrand), Mount Auburn Cemetery, urban parkways, botanical gardens, and designed civic plazas.

2. Historic Vernacular Landscape

A landscape that evolved organically through functional use, physical labor, and cultural traditions of the people whose activities or behaviors shaped that land:

• Physical characteristics reflect societal values, economic survival, and environmental adaptation rather than formal high-style aesthetic theories. These landscapes represent continuous evolution driven by agricultural, industrial, or domestic traditions.
• Examples: Historic Amish farming settlements in Pennsylvania, Appalachian subsistence mountain hollows, agricultural citrus groves in California, historic canal corridors, and timber mining camps.

3. Historic Site

A landscape significant primarily for its association with an important historic event, activity, or notable person:

• The physical landscape provides the tangible setting for historical occurrences.
• Examples: Gettysburg National Military Park, presidential home grounds (Mount Vernon, Monticello), historic battlefields, historic peace treaty groves, and civil rights march assembly grounds.

4. Ethnographic Landscape

A landscape containing a variety of natural and cultural resources that associated cultural groups define as heritage resources:

• Sustained through traditional community practices, spiritual beliefs, and subsistence activities of contemporary cultural groups possessing long-standing associations with the land.
• Examples: Traditional Native American sacred ancestral gathering grounds, pinyon nut harvesting landscapes in the Southwest, contemporary Native Hawaiian taro farming terraces, and coastal Gullah Geechee fishing communities in the Sea Islands.

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3. The Cultural Landscape Report (CLR) & Evaluation of Historic Integrity

The primary technical document utilized by landscape architects to plan, manage, and preserve cultural landscapes is the Cultural Landscape Report (CLR).

Anatomy of a Cultural Landscape Report (CLR)
┌────────────────────────────────────────────────────────────────────────┐
│ PART 1: SITE HISTORY, EXISTING CONDITIONS & ANALYSIS/EVALUATION         │
│ • Comprehensive narrative of historical development and past owners   │
│ • Detailed mapping and documentation of all existing site conditions   │
│ • Formal establishment of the "Period of Significance"                 │
│ • Comparative evaluation of surviving vs. lost character features      │
│ • Assessment of Historic Integrity across the Seven National Aspects   │
├────────────────────────────────────────────────────────────────────────┤
│ PART 2: TREATMENT PLAN & DESIGN GUIDELINES                             │
│ • Selection of primary treatment (Preservation / Rehabilitation / ...) │
│ • Specific technical design guidelines for grading, access, planting  │
│ • Resolution of code compliance (ADA, life-safety, sustainability)     │
├────────────────────────────────────────────────────────────────────────┤
│ PART 3: RECORD OF TREATMENT                                            │
│ • Archival post-construction documentation of all physical work done   │
└────────────────────────────────────────────────────────────────────────┘

The Seven Aspects of Historic Integrity

To be eligible for or retain listing on the National Register of Historic Places, a landscape must possess both significance (association with events, persons, design masters, or archaeological information) and historic integrity—the physical capacity of the property to convey that significance.

The National Register defines seven distinct aspects of integrity that must be evaluated:

1. Location: The physical place where the historic property was constructed or the significant event took place. Relocating a landscape or structure severely degrades location integrity.
2. Design: The combination of elements that create the form, plan, spatial organization, proportions, and aesthetic style of the property (e.g., original axial grading, terrace geometries, path layouts).
3. Setting: The physical environment and surrounding context of the property. Evaluating setting examines adjacent land uses, viewsheds, noise levels, and surrounding tree canopy.
4. Materials: The physical elements that were combined or deposited during the period of significance (e.g., original cobblestone paving, native fieldstone retaining walls, historic plant selections).
5. Workmanship: The physical evidence of the crafts, construction techniques, and labor of a particular culture or historical period (e.g., hand-tooled ashlar masonry, dry-laid stone walls).
6. Feeling: A property's expression of the aesthetic or historic sense of a particular period of time, resulting from the cumulative presence of physical features.
7. Association: The direct tangible link between an important historic event, movement, or notable individual and the physical landscape.

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4. Character-Defining Features & Viewshed Protection

Character-Defining Features

A landscape's historical identity is expressed through physical and spatial elements termed character-defining features:

• Spatial Organization: The three-dimensional arrangement of open spaces, forest masses, agricultural fields, and structural enclosures.
• Circulation Networks: Historic carriage roads, bridle trails, sunken lanes, flagstone paths, and stone gutters.
• Topographic Landforms: Man-made terraces, ha-has (sunken ditch walls that control livestock without obstructing views), earthen ramparts, and sunken parterres.
• Vegetation Patterns: Formal allées, orchard grids, copse woodlands, specimen shade trees, and Victorian carpet beds.
• Water Features: Millraces, reflecting basins, canals, ornamental fountains, and historic retention ponds.
• Site Furnishings & Objects: Historic cast-iron bollards, gas lamps, urns, sundials, statues, and perimeter boundary markers.

Viewshed Analysis & Preservation

Historic viewsheds encompass visual axes intended by the original designer or established by historic association:

• Primary Visual Axes: Formal vistas extending along monument avenues, garden corridors, or terrace sightlines.
• Borrowed Scenery (Shakkei): Integrating off-site natural elements (distant mountain peaks, ocean horizons, or church steeples) into the garden's visual frame.
• Viewshed Protection Techniques: Enacting local historic view corridor zoning overlays, setting building height limits on adjoining parcels, securing scenic conservation easements, planting screening buffers to conceal intrusive modern infrastructure, and undergrounding overhead utility wires.

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5. Historic Plant Authenticity vs. Climate Adaptation

Preserving historic planting design presents a unique challenge: plants are dynamic, mortal biological organisms. Unlike brick, stone, or iron, living trees inevitably age, senesce, succumb to emergent pests and diseases, and experience stress from shifting regional climate zones.

The Botanical Preservation Paradox

Historical purism demands replacing dead plants "in-kind" with the identical genus, species, and historical cultivar. However, strict in-kind replacement can be ecologically reckless when:

1. The historical cultivar is highly vulnerable to fatal non-native pathogens (e.g., Dutch Elm Disease, Emerald Ash Borer, Chestnut Blight).
2. The regional climate zone has warmed, shifting the USDA Plant Hardiness Zone and subjecting the historic cold-adapted species to fatal summer drought and thermal stress.
3. The historic species is now classified as an aggressive invasive species (e.g., Japanese Barberry, English Ivy, Callery Pear historically planted on 19th-century estates).

The Hierarchy of Plant Selection Interventions

Modern preservation standards resolve this tension through a structured hierarchy of intervention:

Hierarchy of Historic Plant Material Replacement
Preserve Living Specimen ◄─────────────────────────────────────► Ecological Surrogate
┌─────────────────┬──────────────────┬─────────────────┬──────────────────┐
│ 1. Arborist     │ 2. Clonal        │ 3. Disease-     │ 4. Ecological    │
│    Care &       │    Propagation   │    Resistant    │    Surrogate     │
│    Stabilization│   (Grafts/Tissue)│    Cultivar     │    Replacement   │
└─────────────────┴──────────────────┴─────────────────┴──────────────────┘

1. Arboricultural Stabilization: Maximize the lifespan of original living historic specimen trees through crown cleaning, air-spade root flare excavation, soil decompaction, organic fertilization, and structural cabling/bracing.
2. Clonal Propagation: When an irreplaceable historic specimen declines, collect scion wood, vegetative cuttings, or tissue cultures to propagate genetically identical offspring for future replanting.
3. Disease-Resistant / Resilient Cultivars: When replacing specimens lost to epidemic pathogens, specify modern disease-resistant cultivars of the same historic species that replicate the exact mature habit, branching architecture, scale, leaf texture, and seasonal foliage color:
   • Example: Replacing Dutch Elm Disease-susceptible Ulmus americana with resistant American Elm cultivars such as 'Princeton', 'Valley Forge', or 'Jefferson'.
4. Ecological Surrogate Species: If an invasive historic plant must be removed, or if climate shifts completely preclude the original species, landscape architects select an environmentally sound, non-invasive surrogate that matches the formal aesthetic role (height, massing, texture, bloom) of the original feature without causing ecological harm.

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6. Post-Industrial & Waterfront Adaptive Reuse

One of the most dynamic sectors of contemporary landscape practice is the adaptive reuse of decommissioned industrial infrastructure, transportation corridors, and working waterfronts into resilient civic spaces:

Key Principles of Post-Industrial Design

1. Embracing Industrial Archaeology: Rather than sanitizing a site by demolishing all past artifacts, adaptive reuse celebrates industrial structures—retaining gantry cranes, rail tracks, concrete silos, blast furnaces, and brick factory foundations as monumental sculptural elements and interpretive markers.
2. Soil Capping & Contaminant Isolation: Post-industrial sites frequently contain heavy metals, VOCs, and hydrocarbons. Landscape architects engineer clean soil caps, raised planter terraces, and impermeable barrier layers to permit safe public recreation without disturbing underlying hazardous strata.
3. Ruderal & Succession Plantings: Drawing inspiration from pioneer vegetation communities that spontaneously colonized the industrial ruins, designers specify tough, disturbance-tolerant native grasses and perennials that thrive in low-nutrient, droughty conditions.
4. Flood-Tolerant Waterfront Edges: Decommissioned shipping wharves and industrial bulkheads are retrofitted with stepped tidal terraces, salt marsh intertidal shelves, and permeable riprap rip-gut revetments capable of absorbing coastal flood waters without catastrophic failure.

Benchmark Adaptive Reuse Precedents

• Gas Works Park (Seattle, WA — Richard Haag): A pioneering industrial conversion of a coal gasification plant into a public park. Haag rejected total demolition and toxic soil export, pioneering on-site bioremediation (bio-tilling with oil-eating microbes) while transforming industrial cracking towers into sculptural park features.
• Landschaftspark Duisburg-Nord (Germany — Peter Latz): Transformed an abandoned 500-acre coal and steel production plant in the Ruhr Valley. Retained blast furnaces as observation towers, converted ore bunkers into climbing gardens, and used phytoremediation bioswales to manage contaminated surface runoff.
• The High Line (New York, NY — James Corner Field Operations / Piet Oudolf): Repurposed an abandoned 1.45-mile elevated freight viaduct into an aerial linear park. Integrated salvaged rail tracks into custom concrete planking and designed layered, perennial-dominated plantings inspired by the self-seeded ruderal landscape that colonized the tracks.
• Brooklyn Bridge Park (New York, NY — Michael Van Valkenburgh Associates): Reclaimed 85 acres of defunct shipping piers along the East River. Salvaged over 100,000 board-feet of warehouse yellow pine and granite blocks, engineered extensive soil berms for acoustic traffic buffering, and created dynamic tidal salt marshes along the waterfront edge.

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7. Comparison: The Four Secretary of the Interior's Treatments

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8. Real-World Case Scenario: The Industrial Ironworks Waterfront Rehabilitation

Scenario: A municipal redevelopment agency acquires a 12-acre abandoned 19th-century foundry and ironworks along a tidal river. The site includes masonry forge buildings, rusted gantry rail tracks, timber wharf pilings, and a concrete seawall. Soil testing reveals heavy metal contamination across the foundry slag fill. The agency wants to demolish all industrial remnants, export the contaminated soil to a landfill, and construct an entirely new neoclassical garden with boxwood parterres and non-native turfgrass.

Analysis & Preservation Interventions:

1. Regulatory Treatment Selection: Demolishing the foundry violates Section 106 of the NHPA and destroys a cultural landscape eligible for the National Register as a Historic Vernacular / Historic Site. The landscape architect guides the client toward Rehabilitation, allowing the property to function as a contemporary public waterfront park while preserving character-defining industrial artifacts.
2. Artifact Preservation & Design Differentiation: Under Rehabilitation Standard 9, the gantry rail tracks, forge foundations, and overhead steel trusses are preserved and integrated into the park design. New additions—such as accessible elevated boardwalks, modern steel-and-timber benches, and a shade pavilion—are designed using contemporary detailing so they are clearly differentiated from, yet compatible with, the historic ironworks.
3. Capping & Phytoremediation: Instead of costly and carbon-intensive off-site soil export, the landscape architect specifies an on-site engineered barrier cap (orange warning geotextile plus 2 feet of clean soil) across the central lawn. Along river embankments, deep-rooted Populus and Salix species are established to stabilize soils and initiate phytoremediation.
4. Planting Palette Authenticity: The client's proposed English boxwood parterres are rejected as inappropriate for an industrial working-class ironworks landscape. Instead, the planting plan features native ruderal and coastal species (Schizachyrium scoparium, Panicum virgatum, Asclepias tuberosa) that honor the site's post-industrial succession character and survive tidal estuary winds with zero permanent irrigation.