fia new growth accounting system: a state-partner perspective

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FIA New Growth Accounting System: A State-Partner PerspectiveChris EdgarTexas A&M Forest ServiceMarch 20, 2014

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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

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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?

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What FIA tools are there?FIDOEVALIDatorEVALIDator-PC

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Govern

ment

Acade

mia

Corpora

teNGO

Outside

the U

S

Indivi

duals

or un

know

n0

5,000

10,000

15,000

20,000

25,000

30,000

FIDO EVALIDator

Use

rs

Source: FIA Fiscal Year 2012 Business Report

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FIDO

OtherEVALIDator-PC

EVALIDator

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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

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2005 2006 2007 2008 2009 2010 2011 2012 20130

20,000,000

40,000,000

60,000,000

80,000,000

100,000,000

120,000,000

140,000,000

160,000,000

180,000,000

Mortality on ForestlandEast Texas

Insect Disease Fire Animal Weather Vegetation Unknown/other

Evaluation

Mill

ion

cubi

c fe

et p

er y

ear

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2006 2007 2008 2009 2010 2011 20120

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

Plot Measurement Before Rita After Rita - Before Ike After Ike

Evaluation

Num

ber o

f plo

ts

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Net growth – total Data Retrieval Tool Cubic feet per yearFIDO 693,255,597EVALIDator-PC 693,255,603EVALIDator

Accounting 693,328,343Previous 693,328,343Current 693,328,343

All live on forestland, ETX 2012

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Net growth – totalEstimates from the various retrieval tools match

pretty well

New growth accounting system implemented in EVALIDator Temporal basis selection

Accounting, previous, current

12http://apps.fs.fed.us/Evalidator/evalidator.jsp

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Summarizing by an attributeOften there is interest in summarizing total net

growth by an attribute made up of classesAttributes commonly used are based on a

characteristic of the plot, condition, or tree Plot – for example county or ecoregion Condition –for example owner or forest type Tree – for example species or diameter

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Net growth – oak/hickory groupData Retrieval Tool Cubic feet per yearFIDO 63,087,704EVALIDator-PC 63,087,704EVALIDator

Accounting 31,825,275Previous 66,450,351Current 63,091,182

All live on forestland, oak/hickory forest type group, ETX 2012

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Net growth – oak/hickory groupFIDO 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

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Net growth – oak/hickory groupEVALIDator 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

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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

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Current

Previous

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

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Previous temporal basisGrowth 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

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Current temporal basisGrowth 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

21http://apps.fs.fed.us/Evalidator/evalidator.jsp

Current

Previous

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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

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Accounting estimateAccounting 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

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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

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Net growth – oak/hickory groupData Retrieval Tool Cubic feet per year

FIDO 63,087,704

EVALIDator-PC 63,087,704

EVALIDator

Accounting 31,825,275

Previous 66,450,351

Current 63,091,182

All live on forestland, oak/hickory forest type group, ETX 2012

Nearest to the approximate value of 26.0 million

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Communicating with clientsNo difference on grand totalsDifferences arise when summarizing by attributes

Small differences if attribute changes infrequently Large differences if attribute changes frequently

Different resources are estimatedAll estimates are validUnderstand what resource is estimated and

whether that is what is sought

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Thank you. Questions?

Chris EdgarTexas A&M Forest Service200 Technology Way, Suite 1281College Station, TX 77845(979) 458-6630cedgar@tfs.tamu.edu