Improving DWM Data Quality 3rd of 3 Part Training Series

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Improving DWM Data Quality3rd of 3 Part Training
Series

• Christopher Woodall
• DWM National Indicator Advisor

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Outline

• QA/QC Analysis
• What Customers Want
• Measurement Errors
• Hot and Cold Checks
• Top Six List of Errors
• Training

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QA/QC Analysis
The analysis of 2001-2004 DWM QA plots is
currently ongoing. Matching algorithms are being
developed for numerous measurement variables.
Expect results for the 2006 P3 Training
Sessions. For more information contact Chris
Woodall _at_ NCFIA and Jim Westfall _at_ NEFIA
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What Customers Want
A uniform DWM sample design applied across the
entire United States producing per acre estimates
of fuels, carbon, and wildlife habitat
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Measurement Errors

• Establishing Transects
• FWD Counts
• Slope versus Horizontal Distances
• CWD Diameters
• Correct Units for Duff, Litter, and Fuelbed
  Depths
• Microplot coverage and heights

Hot checks
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Measurement Errors

• Number 1 priority is matching data and
  determining adherence to MQOs
• Number 2 priority is determining cause for
  errorsthen correcting cause

Cold/Blind Checks
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Measurement Error Propagation
Database Processing Algorithms
Core Table
Measurement errors have varying magnitudes of
effect
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Measurement Error Simulation
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Simulation Conclusions
Measurement variables whose errors most affect
core table outputs duff depths, CWD diameters,
and slash pile densities
Measurement variables whose errors least affect
core table outputs CWD decay, classes/transect
lengths, litter depth, and FWD counts
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FIAs Top Six Least Wanted DWM Errors

1. CWD Diameters
2. CWD Lengths
3. Duff Depths
4. Litter Depths
5. Slash Pile Density
6. Missing Data

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CWD Diameters
Crews mistakenly record CWD diameters to tenth of
inchused to P2 plots
?
Only measure to nearest inch!!
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CWD Lengths

15 feet
3 inches
120 inches
Some log dimensions recorded in field are
impossible
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Duff Depth
Duff is the heaviest down woody material per unit
volume
Make sure your measurements (and units) are
correct
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Litter Depth
Much lighter than duffhowever is usually much
deeper
Dont mistakenly enter the litter depth for duff
depth
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Slash Pile Density
Only neatly stacked wood can exceed 40-60
density!
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Missing/Mismatched Data
AKA Excruciating Headaches for Analysts
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Missing/Mismatched Data
Example DWM plot sheet indicates CWD transects
on a condition class 2however, only one
condition class recorded in P2 record Example
CWD piece is decay class 2, but is missing small
and large end diameters
Might be your fault, might be data managements
fault, might be computers faultno matterdo
what you can to minimize mismatch errors
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Training
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Problem Areas
Problem Field crews disturb the CWD too much
trying to determine decay class or if segmented
Correction Although field crews must disturb
CWD pieces in order to acquire measurements, try
to keep disturbance to a minimum
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Problem Areas Contd
Problem Field crews mistakenly enter extra
digit for CWD diameter (40 instead of 4 inches)
Correction Unless PDRs catch them, be sure of
very large CWD diameters
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Problem Areas Contd
If CWD piece ends in water, treat as if
underground, measure piece to water edge
For FWD, if transect under water try to enter 0
values and indicate in plot notes
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Problem Areas Contd
Problem Crews dig through litter hunting down
pieces of FWD
Correction Crews should only tally obvious FWD
pieces, namely those on litter surface
Problem Crews arent tallying FWD pieces hung
up in slash/saplings
Correction Crews should tally all FWD pieces
from forest floor up to 6 feet above ground
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Problem Areas Contd
Problem Crews either include too much of the
litter layer or upper soil mineral horizons in
estimation of duff depth
Correction Crews should be absolutely sure of
what is duff, litter, and mineral horizons. Be
absolutely sure of duff measurements!!
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Problem Areas Contd

• Duff Depths
• Identify duff from mineral soil
• Dont include moss or litter material
• What to do with deep duff
• Anything over 1 foot ? be absolutely sure

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Problem Areas Contd
Problem Crews cant decide on the fuelbed
height measurement
Correction Crews should only take 15-seconds to
determine height of dead, down woody material,
dont over analyze, use local knowledge and
reasonable definition of fuel ladders
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Problem Areas Contd

1. Measure from top of duff to top of fuel complex
2. Fuel complex composed of dead FWD, CWD, shrubs,
   and litter
3. Gaps allowed in fuel complex where one would
   reasonably expect flame lengths to connect
4. Plum-bob not required, ocular estimate around
   sample point
5. 15-second ruleDont over analyze height of
   fuelbedUse your experience and logic

Fuelbed Depths
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Problem Areas Contd
Problem Condition class boundary runs through
microplot
Correction Use entire forested condition of
microplot to estimate coverage and heights
100 cover of litter for forested conditions
(dont include asphalt or other non forested
conditions in cover assessment)

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Problem Areas Contd
Microplot Heights

1. Train with idea of imaginary 6.8 foot radius
   cylinder
2. Make sure crews know what herbs and shrubs
   include
3. Gaps allowed in fuel complex as long as
   reasonable
4. Branches from shrubs rooted outside microplot
   allowed
5. Train about vines and canopy herbaceous plants

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Problem Areas Contd
Only include epiphytes or hanging moss up to 6
feet in height
Include vines that are within microplot
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Problem Areas Contd
Only estimate density of CWD within pile
Density should rarely exceed 40
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01
70
Slash Pile Densities
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Organizing Training Sessions

1. Part 1 Introduction to DWM
2. Part 2 Field Methods
3. Analyst Example (optional)
4. Part 3 Improving DWM Data Quality
5. Certification Test

Classroom

1. Stations (test optional)
2. Go over one subplot together as group
3. Trainees do at least one subplot on their own
   hot audit and/or compare results

Field
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Bringing it all Together

• Pick training location where many conditions
  classes and sampling scenarios exist (see word
  file)
• Use powerpoint files to sculpt training session
  so trainees have understanding of why we need
  quality DWM data, what we use it for, the theory
  behind the sampling design, field methods, and
  problem areas
• Setting up a quality station course can reduce
  questions during actual field season may
  conduct test

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Sample Design Changes
The DWM Indicator must be responsive to customer
needs and improving science/techniques
Dont assume your ideas are insignificant, you
collect the data, assume you know best and pass
ideas upwards
Submit your suggestions
cwoodall_at_fs.fed.us
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End of Part 3 of 3
http//www.ncrs.fs.fed.us/4801/national-programs/i
ndicators/dwm/