STRATIFICATION PLOT PLACEMENT CONTROLS Strategy for Monitoring Postfire Rehabilitation Treatments

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STRATIFICATIONPLOT PLACEMENTCONTROLSStrategy
for Monitoring Post-fire Rehabilitation
Treatments

• Troy Wirth and David Pyke
• USGS Biological Resources Division
• Forest and Rangeland Ecosystem Science Center
• Corvallis, Oregon

U.S. Department of Interior U.S. Geological Survey
Supported by USGS - BLM Interagency Agreement
HAI040045
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Monitoring Approach

• Objectives
• Stratification
• Control Plots
• Random Sampling
• Data Quality
• Statistical Analysis
• Repeatable, objective field methods using
  Rangeland Monitoring Database

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Stratification

• Division of treatment areas into defined
  monitoring units with similar characteristics
• Decreases variability, increases precision
• Data collected is then inferred to be
  representative of the entire monitoring unit.
• Stratification into monitoring units helps to
  determine success at the project level - and
  eventually at a regional scale

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Stratification

• Monitoring Units may vary across the landscape
  and be separated by other monitoring units.

From Herrick et al 2005b
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Stratification Background Information

• Aerial photographs
• Soil Surveys
• Determine what mapping units cover the treatment
  area
• Can you identify the soil series within the
  mapping units?
• What ecological sites are within the mapping
  units?
• How do you determine the ecological sites?

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Stratification Background Information

• GIS Layers
• Digital Elevation Model (DEMs)
• Land management activities (grazing allotments,
  previous seedings and fires etc.)
• Fire and treatment perimeters for current project
• Soils
• Roads, streams and other geographic features that
  would be avoided

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Stratification Background Information - Resources

• Web Soil Survey http//websoilsurvey.nrcs.usda.gov
  /app/
• Soil Data Mart http//soildatamart.nrcs.usda.gov/D
  efault.aspx
• USGS Seamless Data Distribution
  http//seamless.usgs.gov/
• Official Soil Series Descriptions
  http//soils.usda.gov/technical/classification/osd
  /index.html

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Stratification Identifying Ecological Sites

• Each plot must have Ecol. Site identified
• Not all Monitoring Units are defined by one Ecol
  Site.
• An ecological site is a distinctive kind of land
  with specific characteristics that differs from
  other kinds of land in its ability to produce a
  distinctive kind and amount of vegetation
  (NRCS).
• Consist of site characteristics, plant
  communities, site interpretations, and supporting
  information
• Identify ecological sites using soil and landform
  indicators (soil surveys)

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Soil maps

• Soils are grouped into soil mapping units because
  we often cannot map soils at the scale at which
  they occur
• Soil map unit includes one or more dominant soil
  map unit components inclusions (minor map unit
  components)
• Soil map unit component soil series slope and
  surface texture modifier

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A soil map unit can be

• An ASSOCIATION of two or more soils that occur
  in a repetitive and predictable pattern (e.g. low
  ridges swales)
• A COMPLEX of two or more soils that usually do
  not occur in a predictable pattern at a mappable
  scale (e.g. coarse and fine soils in a river
  floodplain)
• A single soil series (but even these map units
  usually have inclusions too small to be
  mapped). Sometimes call a CONSOCIATION

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Using soils to identify ecological sites

• An ecological site can include more than one soil
  series, provided that the soils are similar
• A soil map unit can include more than one
  ecological site. Soil map units often include
  many different soils, with different potentials
  to support plant communities
• Even a soil series can include more than one
  ecological site. Soil surface texture often
  varies within a soil series. Soil surface texture
  is very important in distinguishing ecological
  sites.

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Stratification Identifying Ecological Sites

• Determine soil mapping unit
• Examine soil mapping unit description (220)
• Determine soil series within mapping unit.

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Stratification Identifying Ecological Sites
Ninemile and Carvix Soil Series
Dig soil pits to identify soil series and
associated ecological sites
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Stratification Identifying Ecological Sites
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Stratification Criteria

• Treatment type
• Soil type / ecological site
• Slope / aspect / elevation
• Multiple polygons/ minimum size
• Each stratification criteria doubles number of
  monitoring units (if all are monitored)
• What criteria will reduce variability the most?

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Example Stratification Treatment perimeter and
DEM
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Example StratificationTreatment perimeter with
slope reclassification
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Example Stratification Treatment perimeter with
slopes lt gt 15 slope
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Example Stratification Soil mapping units
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Example Stratification Soil mapping units within
treatment perimeter
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Example Stratification Sample Areas
121 Mcpan-Chijer complex
181 Starbuck- Mcpan-rock outcrop
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Random Sampling

• Enables statistical inference to the monitoring
  unit
• GIS or traditional map grid
• Can use several types of random sampling (simple,
  stratified, and two-stage random sampling)
• Establish rejection criteria (slopes/roads/streams
  /rocks etc..)

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Random Point GenerationHawths Tools Features

• Input layer (polygon/raster)
• Minimum distance between points
• Stratified (number of points)
• Stratified design
• Polygon unique id
• Number of points per polygon
• Density of points per polygon

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• Hawths Tools Main Screen
• 1. Generate Random points
• Use for determining random plot locations
• Generate Regular points
• Other uses including separating polygons into
  roughly equal sizes

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Example Stratification (simple)Random point
generation screen
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Controls

• Was rehabilitation necessary?
• Plots that receive no treatment
• No seed
• No soil surface disturbance (affects bare ground
  and annual exotic abundance)
• Randomly place within monitoring unit prior to
  treatment implementation
• If controls are not possible, quantitative
  standards must be specified

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Controls

• Long-term monitoring controls are highly
  valuable
• May not be able to distinguish between seeded and
  unseeded plants
• Help to determine persistence of seeding
• Helps to determine treatment effect
• Provides a measure of natural recovery

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