the development and use of ecological site descriptions for
TRANSCRIPT
The Development and Use of Ecological Site Descriptions for
EcosystemRestoration on Working Lands in the
United States
Wendell Gilgert Stephen BradyUSDA –NRCS
National Technical Support CentersPortland, OR/Ft. Worth, TX
“The time has come for science to busy itself with the earth
itself. The first step is to reconstruct a sample of what we
Gary KramerGary Kramer
itself. The first step is to reconstruct a sample of what we
had to start with.”
Aldo Leopold
Ecological Site Description Value to Users
1. Decision Support for Restoration and Management
2. Performance Criteria
3. Risk Analysis and Assessment
Ecological siteEcological site
A distinctive kind of land with specific physical characteristics that differs from other kinds of
A distinctive kind of land with specific physical characteristics that differs from other kinds of that differs from other kinds of land in its ability to produce a distinctive kind and amount of
vegetation.
that differs from other kinds of land in its ability to produce a distinctive kind and amount of
vegetation.
MLRA’s are:Geographically associated land resource units
Cover thousands to millions of acres
Characterized by particular
Ecological Sites Occur Within Major Land Resource Areas
Characterized by particular patterns of soils, geology, climate, water resources, and land usesFactors that influence
formation of ecological
site.
May be one continuous area or several separate nearby areas.
Ecological Site Descriptions
•Specific to each MLRA
•Four types of data in a site description•Four types of data in a site description1. Physical site characteristics
2. Plant communities
3. Site interpretations
4. Supporting information and documentation
Physical Site Characteristics
Influence an Ecological Site’s Potential as Habitat-Physiography
Elevation, slope, aspect, water tables, frequency
of flooding
-ClimateAnnual precipitation and seasonal distributionAnnual precipitation and seasonal distribution
Frost and freeze free period
-SoilDepth, texture, permeability, drainage, parent
material, pH and other aspects of soil chemistry
-Water FeaturesWetland, riparian, flow regime, etc.
Influencing Water Features :Wetland Systems: Cowardin
•Marine
•Estuarine
•Riverine
•Lacustrine
•Palustrine
Rosgen Stream Classification &
Valley TypesValley Types
Montana ExampleMontana Example
Plant Community
• Potential (historical) plant community-Average annual production (air dry weight)
-Relative composition by life-form
-Trees, shrubs, bunchgrasses, forbs, biotic crusts
-Relative composition by the primary / significant species
-Ground cover (%) and structure (ht) -Ground cover (%) and structure (ht)
-May include plant growth curves
• Variability in species composition due to variation in physical site characteristics
• How it responds to disturbance
• Provides a general model for vegetation dynamics
Site Interpretation
•Discussion about the major and/or important uses and management strategies for the site-Can and should list constraints or important issues
•Not all inclusive•Major / potential uses
-Livestock grazing-Livestock grazing
-Fish and Wildlife
Important species and habitat requirements
-Watershed
-Wood products
-Recreation
-Other products
Minerals, nuts, berries, biomass potential, etc.
Historic Climax Plant CommunityHistoric Climax Plant Community
The plant community that was best adapted to the unique combination of
factors associated with the ecological site. It was in a natural dynamic equilibrium It was in a natural dynamic equilibrium with the historic biotic, abiotic, climatic biotic, abiotic, climatic factorsfactors on its ecological site in North
America at the time of European immigration and settlement.
State And Transition Concepts (Models)
•States-Different, recognizable plant communities-Can have multiple seral stages (phases) within a state
•Transitions-Direction of community change between states-Describe conditions for changes between states
•Thresholds•Thresholds-Vegetation composition-Vegetation structure - irreversible changes in plant life forms -Functional – one or more ecological processes are altered -Fire frequency-Hydrology
•Triggers-Events or combinations of events that cause transitions
State 1
thre
shold
State 2State 1
thre
shold
State 2
Process-based State and Transition Model
Stringham, T.K., W.C. Krueger, and P.L. Shaver. 2003. State and transition modeling:an ecological process approach. Journal of Range Management 56:106-113
State 1
State 3
thre
shold
State 2
Plant community phase
Community pathway
(within states)
Irreversible transition
Reversible transition
State 1
State 3State 3
thre
shold
State 2
Plant community phase
Community pathway
(within states)
Irreversible transition
Reversible transition
ab
States
• Boxes identify distinct plant communities
Wyoming Sagebrush,
Wyoming Sagebrush
A
Sagebrush, Perennial
Grasses and Forbs
Sagebrush Without
Perennial Grasses
Cheatgrass
Brad Schultz
State A (1, 2a, 2b): State A (1, 2a, 2b): Natural variability Natural variability
within HCPCwithin HCPC
State B (3 & 4):State B (3 & 4):DeepDeep--rooted perennial rooted perennial
grass functional grass functional group lostgroup lost
State C ? (5 & 6): Warm State C ? (5 & 6): Warm season/annualseason/annual
grasses dominant grasses dominant ––medium grasses lost medium grasses lost (6)& shrubs lost (both (6)& shrubs lost (both
for 5)for 5)
Fundamental Value to Users
1. Decision Support for Restoration and Management
2. Performance Criteria
3. Risk Analysis and Assessment
West National Technology Support Center
Wendell Gilgert
Wildlife Biologist
Portland, Oregon
503-273-2426
United States Department of Agriculture
Natural Resources Conservation Service
Central National Technology Support Center
Steven Brady
Wildlife Team Leader
Ft. Worth, Texas
817-509-3285
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Natural Resources Conservation Service
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