Oregon

To meet state biocriteria, Oregon uses three separate O/E indices depending on ecoregion: Marine Western Coastal Forest, Western Cordillera and Columbia Plateau, and the Northern Basin and Range. These indices were developed in 2005 and all require identification to NAMC’s standard taxonomic resolution and sampling between June 1st and mid-October. The Northern Basin and Range O/E was developed using only 9 reference sites and does not account for environmental gradients across the ecoregion. Therefore, this index is less precise than indices used in the other two ecoregions.

Index # Reference Sites # Degraded Sites Index Mean Index SD Moderate departure from reference benchmark Major departure from reference benchmark
Oregon Western Cordillera Columbia Plateau 167 NA 1.01 0.15 < 0.93 < 0.79
Oregon Marine Western Coastal Forest 38 NA 0.99 0.12 < 0.92 < 0.86
Oregon Northern Basin Range 9 NA 1 0.29 < 0.75 <= 0.5

 

Oregon with Model Boundaries of western costal forest areas in green, northern basin range areas in yellow, and western cordillera and Columbia Plateau in orange with black dots representing reference sites
Oregon macroinvertebrate reference sites for the Marine Western Coastal Forest (green), Western Cordillera and Columbia Plateau (peach), Northern Basin and Range (tan)

Marine Western Coastal Forest

Box plots of catch elevation(m) on a scale of 0 to 900 with a mean of 300, mean annual precipitation (mm) on a scale of 0 to 3000 with a mean of 1250, temperature (C) on a scale of 0 to 13 with a mean of 6 and log watershed area (km2) on a scale of 0 to 5 with a mean of 1.25
Environmental gradients of reference sites used for Marine Western Coastal Forest and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: Discriminant function analysis predicting group membership
  • Predictors of reference assemblages or metrics: 
    • Day of year
    • longitude of the point
  • # of Macroinvertebrate groups obtained by hierarchical cluster analysis: 3
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: Yes
  • Rare taxa <0.5 probability of capture included: No
  • Documentation

Western Cordillera Columbia Plateau

Box plots of catch elevation(m) on a scale of 0 to 2500 with a mean of 1000, mean annual precipitation (mm) on a scale of 0 to 4000 with a mean of 1400, temperature (C) on a scale of 0 to 16 with a mean of 6 and log watershed area (km2) on a scale of 0 to 5 with a mean of 1.5
Environmental gradients of reference sites used for Western Cordillera Columbia Plateau and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: Discriminant function analysis predicting group membership
  • Predictors of reference assemblages or metrics: 
    • Does the point fall in an eastern Oregon ecoregion
    • Square root of elevation at the point
    • Precipitation at the point based on the OR DEQ Predator layers
    • Temp at the point based on the Predator layers
  • # of Macroinvertebrate groups obtained by hierarchical cluster analysis: 5
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: Yes
  • Rare taxa <0.5 probability of capture included: No
  • Documentation

Northern Basin and Range

Box plots of catch elevation(m) on a scale of 1400 to 2500 with a mean of 1900, mean annual precipitation (mm) on a scale of 400 to 1200 with a mean of 700, temperature (C) on a scale of 2 to 7 with a mean of 6.5 and log watershed area (km2) on a scale of 0 to 4 with a mean of 1.5
Environmental gradients of reference sites used for Northern Basin and Range and used for NAMC’s model applicability test

  • Method for accounting for natural environmental gradients: None
  • Predictors of reference assemblages or metrics: 
    • None
  • # of Macroinvertebrate groups obtained by hierarchical cluster analysis: NA
  • Fixed count: 300
  • Minimum count: 200
  • Operational Taxonomic Unit (OTU) applied: Yes
  • Rare taxa <0.5 probability of capture included: No
  • Documentation