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Maintaining FIA’s Credibility as The Nation’s Forest Census Dave Struble Maine Forest Service PowerPoint Presentation
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Maintaining FIA’s Credibility as The Nation’s Forest Census Dave Struble Maine Forest Service. Critical Attributes. Accurate Timely Unbiased Relevant. NRS Estimates Inventory Data for 2006. Tree-Level Volume Estimation.

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slide1
Maintaining FIA’s Credibility

as

The Nation’s Forest Census

Dave Struble

Maine Forest Service

critical attributes
Critical Attributes
  • Accurate
  • Timely
  • Unbiased
  • Relevant
tree level volume estimation
Tree-Level Volume Estimation
  • Previously (for the most part), individual tree volumes were estimated and based on field-measured diameters, merchantable lengths, and cull discounts.
  • It has found that “NOISE” in the measurements of tree lengths and assessment of cull outweighed the true “SIGNAL”; despite the fact that QA/QC checks were consistently meeting the Measurement Quality Objective (MQO) tolerances.
  • A taper model is now used to estimate needed tree lengths (merchantable, sawlog) as a function of DBH and total height (mostly field estimated)
  • Another model estimates the percent of total tree volume represented by cull, as a function of species group, D-Class, dead/alive, and tree class
component ratio method crm for biomass
Component Ratio Method (CRM) for Biomass
  • In the past, merchantable volume and biomass were estimated using separate sets of equations.
  • Now CRM harmonizes volume, biomass, and carbon estimates and is comprised of a series of steps.
  • We are still trying to fully understand and match up transitions from 1982 to 2008. Suffice to say, the deck chairs keep getting reshuffled, and several 2008 estimates do not make sense.
biomass estimation quandaries
Biomass Estimation Quandaries
  • 2008 growing stock bole biomass estimate (385 MDT) is 1.4% higher than its equivalent 1982 estimate (380 MDT).
    • Counter – The 2008 growing stock merchantable bole cubic foot estimate is 8% less than its 1982 equivalent.
  • Old version 2003 growing stock bole biomass estimate is 21% more than the new 2003 equivalent.
    • Counter – The new 2003 growing stock merchantable cubic foot estimate is 4% more than 2003 equivalent.
  • 2008 sapling biomass estimate is only 5.2% more than its 1982 equivalent.
    • Counter – The 2008 sapling stocking estimate (# of stems) is 97% more than its 1982 equivalent.