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FIA New Growth Accounting System: A State-Partner Perspective

FIA New Growth Accounting System: A State-Partner Perspective. Chris Edgar Texas A&M Forest Service March 20, 2014. What is the issue?. In September 2011 FIA cautioned users not to use data retrieval tools for net growth and removals by diameter class

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FIA New Growth Accounting System: A State-Partner Perspective

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  1. FIA New Growth Accounting System: A State-Partner Perspective Chris Edgar Texas A&M Forest Service March 20, 2014

  2. What is the issue? • In September 2011 FIA cautioned users not to use data retrieval tools for net growth and removals by diameter class • At this meeting last year it was announced that FIA had implemented a new growth accounting system and that it applied to all attributes that can change between inventories

  3. What questions are addressed in this talk? • What GRM options are available to users? • How do the options differ among data retrieval tools? • What are some considerations for analysis using the new system?

  4. What FIA tools are there? • FIDO • EVALIDator • EVALIDator-PC

  5. Source: FIA Fiscal Year 2012 Business Report

  6. FIDO EVALIDator EVALIDator-PC Other

  7. Hurricane Rita 24 Sep 2005 771,000 acres of Texas timber damaged or affected Hurricane Ike 13 Sep 2008 473,000 acres of Texas timber damaged or affected

  8. Net growth – total All live on forestland, ETX 2012

  9. Net growth – total • Estimates from the various retrieval tools match pretty well • New growth accounting system implemented in EVALIDator • Temporal basis selection • Accounting, previous, current

  10. http://apps.fs.fed.us/Evalidator/evalidator.jsp

  11. Summarizing by an attribute • Often there is interest in summarizing total net growth by an attribute made up of classes • Attributes commonly used are based on a characteristic of the plot, condition, or tree • Plot – for example county or ecoregion • Condition –for example owneror forest type • Tree – for example species or diameter

  12. Net growth – oak/hickory group All live on forestland, oak/hickory forest type group, ETX 2012

  13. Net growth – oak/hickory group • FIDO and EVALIDator-PC estimates match • New growth system has not been implemented in these tools • Estimate summarized based on the attribute’s current inventory value • EVALIDator-PC has some limited options for summarizing on previous inventory value • Diameter class and stand-size class

  14. Net growth – oak/hickory group • EVALIDator estimates vary depending on the temporal basis selected • An expected outcome because the attribute, forest type group, can change between first measurement and second measurement

  15. How much change occurred? • In considering summarizing by an attribute it can be helpful to know whether the attribute changes and how much • For condition-level attributes, run an area change retrieval in EVALIDator • Row = Attribute – previous temporal basis • Column = Attribute – current temporal basis

  16. http://apps.fs.fed.us/Evalidator/evalidator.jsp Current Previous

  17. Previous temporal basis • Growth on conditions typed oak/hickory at the previous inventory (time 1) • ~ 3.0 million acres total • 71 percent oak/hickory group at time 2 • 23 percent another forest type group at time 2 • 6 percent classified “other” at time 2 (nonforest) • Net growth of 66.5 million cubic feet per year

  18. Current temporal basis • Growth on conditions typed oak/hickory at the current inventory (time 2) • ~ 2.8 million acres total • 76 percent oak/hickory group at time 1 • 19 percent another forest type group at time 1 • 5 percent classified “other” at time 1 (nonforest) • Net growth of 63.0 million cubic feet per year

  19. http://apps.fs.fed.us/Evalidator/evalidator.jsp Current Previous

  20. Temporal basis considerations • Interested in what happened to oak/hickory forests • This suggests previous temporal basis • Interested in what the outlook is for oak/hickory forests • This suggests current temporal basis • Both estimates are valid

  21. Accounting estimate • Accounting estimate provides the best overall match to net growth calculated from inventory and removals Annual net change = Annual net growth – Annual removals Rearrange to get Annual net growth = Annual net change + Annual removals

  22. An approximate value • Inventory in oak/hickory • 2007 evaluation = 3,237.6 million cu ft • 2012 evaluation = 2,983.8 million cu ft • Annual net change = -50.8 million cu ft • Removals in oak/hickory (previous) • Annual removals = 76.8 million cu ft • Annual net growth = 26.0 million cu ft

  23. Net growth – oak/hickory group Nearest to the approximate value of 26.0 million All live on forestland, oak/hickory forest type group, ETX 2012

  24. Communicating with clients • No difference on grand totals • Differences arise when summarizing by attributes • Small differences if attribute changes infrequently • Large differences if attribute changes frequently • Different resources are estimated • All estimates are valid • Understand what resource is estimated and whether that is what is sought

  25. Thank you. Questions? Chris Edgar Texas A&M Forest Service 200 Technology Way, Suite 1281 College Station, TX 77845 (979) 458-6630 cedgar@tfs.tamu.edu

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