Xeric Vegetation in the Landscape Natural Models for Site Development

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Xeric Vegetation in the Landscape Natural Models
for Site Development
Jeff Lakey Sr. Landscape Architect RNL Design,
Denver, Colorado
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Main Message

• Natural landscape patterns provide us with useful
  physical models for site development and
  vegetation selection

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Landscape and VegetationComing to Terms

• Landscape
• Plants
• Landscap-ing (verb to make a landscape,
  including plants, not a noun)

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Landscape and VegetationComing to Terms

• Xeriscape / zeroscape (water conservation)
• Xeric-mesic-hydric community moisture gradient

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Landscape and Vegetation

• Scale space time

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Landscape and VegetationPotential Plant
Communities in the United States

• Landscape elements expressions of interacting
  environmental factors

• Terrain
• Elevation
• Soil (physical, biological, chemical)
• Precipitation
• Evaporation (wind, temperature, humidity)

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Seeing Patterns in
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Wyoming Landscapes
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Vegetation in the Landscape

• Environmental factors make landscape patterns of
  vegetative communities (habitats)

• Terrain
• Elevation
• Soil (physical, biological, chemical)
• Precipitation
• Evaporation (wind, temperature, humidity)

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Pattern Effects of Elevation
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Pattern Effects of Precipitation
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Pattern Effects of Wind
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Pattern Effects of Evapo-transpiration

• Temperature
• Wind
• Humidity

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Pattern Effects of Soil
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Expressions of Moisture Gradients
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Moisture Gradient
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Change Through TimeRepeat Photography U. of AZ
Study of Utah Juniper in Wyoming

• Bighorns Tensleep 1904

Bighorns Tensleep 1998
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Change Through TimeRepeat Photography U. of AZ
Study of Utah Juniper in Wyoming

• Bighorns Tensleep 1922

Bighorns Tensleep 1998
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Change Through TimeRepeat Photography NASA
Earth Observatory

• Black Hills July 12, 2000 July 14, 2004

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Natural Models for Xeric Vegetation

• Three prevalent models (many cities are in these)
  
• Creeks and Rivers
• Plains
• Sagebrush Steppe
• others

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Creeks and Rivers
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Grassland
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Sagebrush Steppe
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Xeric Vegetation Selection Issues

• Function
• Compatibility
• Adaptability
• Stability and Management

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Xeric Vegetation Selection Issues

• Function
• Refers to the purpose that the plant serves in
  the landscape, for example
• Shade of a tree canopy
• Filtered screen from a hedge
• Erosion control of a ground cover
• Architectural (defines space, gives character)
• Engineering (physical control)
• Environmental (ecological or human comfort
  purpose)

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Xeric Vegetation Selection Issues

• Function
• Environmental (contd)
• Energy conservation
• Deciduous trees on south of building
• Maximize winter solar heating
• Maximize summer cooling
• Shade pavement areas and streets (pavement
  reflects 40, vegetation 20 of suns energy)
• Wind breaks against prevailing direction of wind
  (NW?) NRCS has design guidelines direct winds
  over and away from building 15 to 50 m away from
  building
• Dead air space against buildings for winter
  insulation

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Xeric Vegetation Selection Issues

• Compatibility
• Refers to the relationship between the needs of
  the plant and the environmental and soil
  conditions of the site
• Xeric vegetation suited to high, dry landscapes
• Fight the site creates maintenance cost
  forever
• Soil can be amended, but can you use the
  existing? (Preserve soil and structure during
  construction)
• The needs of the users are important
• Playfields need durability, xeric vegetation
  tends to be fragile
• Need to be able to use the site for required
  activities

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Xeric Vegetation Selection Issues

• Compatibility
• Terrain
• pay attention to aspect and topographic position
  select for similarity to model
• Elevation
• note the local elevation and local vegetation
  community type (i.e. montane, grassland, sage
  shrubland, etc.) use the models
• Soil (physical, biological, chemical)
• test for compatibility with regional vegetation
  community needs of desired plants

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Xeric Vegetation Selection Issues

• Compatibility
• Precipitation
• select to minimize water use, choose to avoid
  irrigation, target water to needed locations only
• Evaporation (wind, temperature, humidity)
• select hardy plants
• Wildlife
• Suitable for local animal populations to use,
  rather than impede and diminish their habitat

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Xeric Vegetation Selection Issues

• Adaptability (and performance are some plants
  adaptable to this location from others?)
• Hardiness
• Soil pH
• Topographic position
• Aspect (facing which direction?)
• Temperature
• Moisture
• Wind

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Xeric Vegetation Selection Issues

• Stability and Management
• Will the vegetation persist, and flourish?
• Can we plant it and forget it? Are we willing to
  care for it?
• Plant life cycle leaves, seeds, twigs natural
  mulch recycle trimmings
• Plant health moisture, light, pathogens can we
  manage without chemicals by selecting and
  planting well in the first place?

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Reference MaterialFrameworks for Vegetation
Selection

• US EPA Guidance for Presidential Memorandum on
  Environmentally and Economically Beneficial
  Landscape Practices on Federal Landscaped Grounds
  1994

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Presidential Memorandum Five Guiding Principles

• Use regionally native plants for vegetation
• Design use or promote construction practices that
  minimize adverse effects on the natural habitat
• Seek to prevent pollution
• Implement water and energy efficient practices
• Create outdoor demonstration projects

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Guidelines for Site and Landscape Development
Source Green Development Integrating Ecology
and Real Estate, RMI, 1998

• Involve people broadly (owners, users, builders,
  maintainers)
• Assemble a competent design team and employ all
  members up front
• Preserve and re-establish natural landscape
  patterns

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Guidelines for Site and Landscape Development

• Reinforce natural infrastructure (i.e. soil,
  drainage, vegetation patterns)
• Conserve natural features and assets (site
  capital)
• Make a habit of restoration

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Guidelines for Site and Landscape Development

• Evaluate site and landscape organizational
  solutions in terms of their larger context
• Create model solutions based on natural processes
• Foster biodiversity
• Retrofit and repair derelict lands

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Guidelines for Site and Landscape Development

• Integrate historic preservation and ecological
  management
• Develop a monitored landscape management program
  response to goals based on self-sustaining
  landscape
• Promote an ecological aesthetic

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LEED Site Related Credits - 16 of 69 Points

• Sustainable Sites 14 Points
• Prereq 1 Construction Activity Pollution
  Prevention Required
• Credit 1 Site Selection
• Credit 2 Development Density Community
  Connectivity
• Credit 3 Brownfield Redevelopment
• Credit 4.1 Alternative Transportation, Public
  Transportation Access
• Credit 4.2 Alternative Transportation, Bicycle
  Storage Changing Rooms
• Credit 4.3 Alternative Transportation,
  Low-Emitting and Fuel-Efficient Vehicles
• Credit 4.4 Alternative Transportation, Parking
  Capacity
• Credit 5.1 Site Development, Protect of Restore
  Habitat
• Credit 5.2 Site Development, Maximize Open Space
• Credit 6.1 Stormwater Design, Quantity Control
• Credit 6.2 Stormwater Design, Quality Control
• Credit 7.1 Heat Island Effect, Non-Roof
• Credit 7.2 Heat Island Effect, Roof
• Credit 8 Light Pollution Reduction
• Water Efficiency 2 Points
• Credit 1.1 Water Efficient Landscaping, Reduce by
  50

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Questions?

• Thank you!