USDA Forest Service
 
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Inventory Subplot

Subplot Footprint and Data Elements

Image showing the dimensions and acreage of the Subplots and what data is collected on each subplot.  If this image is not visible, select the link to Text Version of Subplot.

Each single subplot consists of two fixed circular plots for the smallest (1/100 acre plot) and largest (1/4 acre plot) live trees, a fixed circular plot (1/8 acre plot) for down logs and snags, and a variable radius plot for intermediate sized trees. The fixed radius subplots are used for understory vegetation sampling, and for collecting woody debris and fuel bed depth information.

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1/100 Acre Fixed Area Plot

  • Radius = 11.8 feet
  • Live and Dead Saplings (1.0 - 4.9 inches)
  • Live Seedings
  • Duff and Fuelbed Depth

1/8 Acre Fixed Area Plot

  • Radius = 41.6 feet
  • Medium Sized Dead Trees (5.0 - 19.9 inches)
  • Large Woody Debris (Down logs)
  • Root Collar Trees

1/4 Acre Fixed Area Plot

  • Radius = 58.9 feet
  • Very Large Live Trees (greater than limiting distance)
    BAF 20: Trees greater than 30.3 inches
    BAF 40: Trees greater than 42.8 inches
  • Large Dead Trees (20+ inches)
  • Understory Vegetation
  • Surface Cover Material
  • Small Woody Debris
  • Special Features

Variable Radius Plot

  • For BAF 20 Prism: Trees 5.0 - 30.3 inches
  • For BAF 20 Prism: Trees 5.0 - 42.8 inches
  • Medium Sized Live Trees Tallied and Measured
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