Production Forecast &
The National Forest
Inventory
Ben Ditchburn
NFI Programme Leader
High Level Reporting Aims
‘State of The Nations’ Forests’
•Woodland and Forest Area
•Forest Type
•Forest Habitat
•Forest Habitat Condition
•Forest Management
•Forest Use
•Carbon Sequestration
•Timber Production Forecasting
•Wood fuel potential
National and International Reporting, e.g UN
- FAO, MCPFE, LULUCF
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NFI Outputs
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Key Issues to Resolve
•How do you measure a forest?
•What are you interested in within that forest?
•What do you need to measure within that forest to monitor
those areas of interest?
•How far wrong in the answers can you afford to be?
+/- 1% ?
+/- 2% ?
+/- 5 % ?
+/- 10% ?
+/- 50 % ?
+/- 200% ?
•Establish the level of sampling required to achieve the above
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Basic Components of a NFI
MAP
The map gives us:
•Area
•Interpreted Forest Types
•Interpreted Open areas
•In the future, it will give us changes in these, by comparing successive maps.
This constitutes a near census of the whole population, which is very accurate. FC can
achieve this by making use of Remote Sensing. FC will currently use Aerial Photography, but
will also use other forms of RS, as they become utilisable.
FIELD SAMPLING
We need to know more than just area and the IFT and have to go a step further to find out
more detailed information about the forests. We achieve this through sending surveyors out
into the field to observe and measure a proportion of the forests. This will tell us things like:
•Species
•Age
•Top height
•Dbh
•Habitat, etc
The field measurements and the proportion of the samples that they represent are
then multiplied by the total forest area from the map, to give a total estimate of that
reporting requirement
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Core Elements to Manage
•Cost.
What can we afford? (What do stakeholders require,
what do we require as a business require, what must
we do legally?)
•Timing.
How quickly and often do we need answers?
•Quality.
A combination of requirements and accuracy
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Wood - A renewable resource
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Stages in Deriving a PF
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Error Budgeting
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Error Budgeting
9. +/5.7%
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Consequences on the PF of estimating fell
year incorrectly - Current Assumptions
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Consequences on the PF of estimating
fell year incorrectly - Current PS Practice
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Separating what we can predict confidently
from what we cannot in the PF
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PF 2011 Outputs
•Total Current Standing Volume, very accurate
•Conifer Volume Forecast for 10 yr. - Biological potential:
•GB - +/- 2%
•Country +/- 4%
•Region average of +/- 8%*
(*this will go up or down with area of conifer (more conifer gets better results, less
conifer results decline))
•Conifer Volume Forecast - 10 to 25 yr. - Biological potential:
•Precision as above with some decrease over time
•Stem Straightness assessments
• Feeding into assortments for SS and Pine
•Biomass
•Carbon Sequested
Beyond 2011 (2012 - 2014)
As above for Blvd, same CI as conifer in 2014, four fold decrease in precision at 2012
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NFI Methodology
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NFI Woodland definition for
Great Britain
To map all woodland (both
urban and rural,
regardless of ownership)
which is 0.5 ha or greater
in size.
Canopy – the land must have
> 20% tree canopy cover,
or potential to achieve
>20%.
Width – minimum width of
woodland is 20m
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Mapping
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Forest Map - Derived from Aerial
Photography
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Sample Squares - Random and
Systematic
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Field Sampling
• 8x8km grid
• simple random
sampling
•plus top ups
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Field Work Required
• Silvicultural Systems
• Woodland Pasture
• Deadwood - visual
• Forest Type
• Invasive Species
• Original Ground Preparation
• Recent Treatment
• Management Practice
• Boundary Features
• Cultural Features
• Micro-Habitats
•Thinning
• Recreation Features
• NVC
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• General health
• Ground Layer Vegetation
• Field Layer Vegetation
• Shrub Layer Vegetation
• Mensuration Assessments
•dbh
•height measurements
•stocking
•species
•straightness
•live / dead
• Natural Regeneration
• Veteran Trees
Sample Square - Divided Into Sections
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Vertical structure
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Canopy Structure
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Canopy Types
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Canopy Types
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Pilot data collection
• Lying Deadwood
• Stumps
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Sampling Timelines
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Bulking Up the Field Data to the Map
1. Individual
Sample
Squares
2. Captured
on Pen
Tablets
3. Brought
together on the
National Forest
Inventory
Database
(Forester based)
4. Sample Square
details multiplied
up to the NFI
map area
Forester
Pen Tablets
X
Forester
Pen Tablets
Forester
Pen Tablets
5. NFI
Information
Produced
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Volume
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Accuracy and Precision - Increased Sampling
Increases reliability of results
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Private Sector Conifer Production Forecast / Carbon
/Biomass Sampling Requirements and Target CI
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Summary Requirements to Confidence
Interval
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Setting Sample Square Numbers
•The Systematic Grid will allow for harmonisation with
European Reporting and IFM
•The number of random samples will be set through the
levels of precision required and the application of
statistical methodology
•This will also depend upon the confidence intervals and
accuracy’s acceptable at GB, Country and Region for
each requirement.
•The Number of Regions chosen will also affect this
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Reporting Structures
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Reporting Boundaries England and
Wales
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Reporting Boundaries - Scotland
50% less samples in the
mill catchment means a 4
fold reduction in precision
+/- 8% to +/- 32%
The standard number of FC
PS conifer plots of circa 150
to 200 (for 2011 (circa 300
for 2014)) in the NE region
available to run a PF, would
effectively be halved in this
scenario to 75 to 100
working for the mill
forecast. A top up of 100 (at
a cost of £12500) plots
would rectify this . Further
topping up would create
additional accuracy
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TOP UP Process
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•
•
•
Customer formulates business requirements
Customer and IFOS work through and refine requirements
IFOS evaluate what will be delivered of the requirements from
the core NFI work as is
IFOS present options with costs for meeting the extra customer
requirements:
•
•
•
•
•
•
•
•
•
Providing more focussed forecasts and reports on smaller geographic
areas (e.g a specific mill catchment)
Improving CI in a region (e.g. plus or minus 8% to plus or minus 2%)
Adding to content (e.g including timber density, rot, branching etc)
Bringing forward delivery dates (e.g 2011 to 2010, 2015 to 2103)
Additional analysis or forecast scenarios ( different products etc)
Content, timelines, delivery date and cost agreed
Contract entered into guaranteeing FCs minimum delivery of
‘match’ squares
Customer funded squares put in on ground, plus FC’s if not
already in place
Data analysis and forecasting undertaken and final report
produced
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Conclusions
•Methodology and approach is sound
•Clear Link between what is measured, spent on measurement and
confidence in outputs established
•Effective use of new technologies (AP, GIS, RS)
•Evidence base for timber, carbon and biomass accounting and
forecasting established
•Permanent sample squares will allow for increased capacity in change
detection
•Reporting boundaries allow for working with less money,shorter reporting
cycles and new political structures
•Defined target snapshot dates
•5 year cycle
•Rolling programme, not boom and bust
•Top up capacity will allow for regional, industry (mill) and country
stakeholder specific requirements to be met (e.g SWE and Y & H top ups)
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Questions & End
Questions
Contact
ben.ditchburn@forestry.gsi.gov.uk
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NFI and NIWT 1 Key Elements
Method
Map
Number of Sample
Squares (sample fraction)
Survey design
Clustered and stratified
Sample Square type
Size of sample squares
Number of or time taken to
measure a sample square
Temporary
I Hectare
1.5 a day (range 1 to 9 per
day)
Period over which taken
Reporting cycle
5 years
4 - 19 years, 19 – 27 years
for NIWT1
(1924,1938,1947,1951,19
65,1980, 1999 (not all
were full surveys))
GB, Country, Region,
County
Reporting levels
Funding for plotting
780K per annum
Error budgeting employed
to design the programme
No (flat 1% sample
employed in 1999, but
some was employed in
1980)
None
Use of private sector data
for aiding inventory
Use of private sector data
for aiding building a
management intent picture
Top up option available to
improve accuracy
Small woods Survey
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NIWT 1
Created once every 15
years from AP then left as
a snapshot in time. In the
last map some AP was up
to 17 years old, due to
lack of availability. A
second version of the map
was update to 2002.
35,000- a 1% sample, with
a second pass moving
squares
NFI
Created once and then
continually updated using
new AP and G & L data.
No AP data older than 3 to
6 years. The FE Forester
map will be used to
improve precision.
Target 20000 to 15000,
set by funding limits and
the use of working
backwards from desired
outputs
Random, with a small
element on a systematic
grid
Permanent
1Hectare
Estimated 1.5 per day (but
more data taken at each
square)
5 years
5 yearly, with one or two
interim reports for the
samples and an annual or
biennial map based, area
report
GB, Country , Region for
sample data, down to
county for the map (areas)
540 yr. one, 440k per
annum
Yes
Partial
None
Partial / significant
No
Yes
Yes
Yes
NFI and NIWT 1 Key Outputs
Outputs /data taken
Forest type
Forest area
Forest Area Change
Stand structure
Shrub layer
Deadwood
Field layer
Regeneration
Broad and priority habitat
type
Condition
No – but some measures
have been derived
Woodland edge
NVC
Recreation
Not
Not taken
Taken as part of mgt
practice
Yes
Not taken
None
Management practice
Archaeology
Mensuration, biomass and
co2 sequestration data
taken (dbh, top height,
stocking density, stem
form)
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Taken
Yes (based on old AP)
Survey areas compared
but unable to monitor real
change in woodland area
between surveys
Taken
Taken
Taken for fallen only,
standing (qualitative), not
for stumps (qualitative and
quantitative)
Yes
Yes (broad assessment,
not species specific or
quantitative)
Was not taken, but could
be calculated to a level
(about 80% could be
classified)
Soil
Timber Quality
No
No
Damage
Invasive species
Yes (abiotic and biotic)
No (maybe a bit as
shrubs)
Taken
Yes
Yes, including real change
and causes
Taken
Taken
Taken for standing,
stumps and lying
(quantitative)
Yes
Yes
Taken, most of basic data
is collected , but there is
some debate over whether
this can define beyond
80% of Priority HAP types
(re soils and NVC)
Yes , probably, based on
expert advice, but as no
definitive condition
protocol in place, this
cannot be absolutely
guaranteed
Proposed
Taken
Taken
Yes
Not taken
Two 0.01Ha
mensurational plots per
section (with an average
of 2 sections per sample
square this equates to four
0.01ha plots per sample
square)
No?
Yes, stem straightness
and timber density
Yes
Yes
Diversity of woodland structure
Tree and shrub
composition
Quality
indicator
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Biodiversity Attributes
Required NFI data - all at section level
We need % cover of all species in all sections and all layers of canopy,
Woodland Area by Priority Habitat
happy to just note presence if less than say 5% canopy cover. (Decision key
(identified at the section level)
needed using key tree species, and NVC)
NVC
Woodland loss:
Number of vertical storeys
Regeneration
potential
UKNWHAP
Groups
Woodland
Condition
Requirements
Woodland Area
Theme (in line
with Common
Standards
Monitoring)
Cover of shrub layer
Index of horizontal diversity
Young Growth
Old Growth
In native sections (defined by species mix): NVC using NWSS method Needs
adaptation for England/Wales
Ensure plots that become unwooded are revisited (unless lost to concrete). On
return to plot and no longer wooded: 1) Reason? 2) Current species cover (I.e.
ground/field layer) or road /hardcore/ concrete etc
No storyes (in canopy, shrub, regen layers) in each section
% cover of each species and total % cover in shrub layer (2-5m) all sections.
Tree and shrub species. Most important where a canopy exists.
Sections from the map only. No additional field survey
Planting year or 'established regen % cover' plus shrub layer % cover' in each
section
Planting year in each section
Volume of Deadwood
Mensuration plot: DBH dead standing trees, and DBH along transect for fallen
trees. All sections: quick deadwood method - AND method to infer volume/ha
for all sections/square to be agreed
Woodland edge
Where there is an edge to a permanent open areas, either internal or external,
1) whether it is sharp, or graded (see FC bulletin on ride management), 2)
broad woodland habitat and the 3) broad open habitat. Further discussion
required
Open areas
Broad Habitat type of open sections (those without potential to achieve canopy
20% cover)
Regeneration present where
expected
For both height classes of regen in all sections: % cover of natural regen.
Nativeness of regeneration
For both height classes of regen in all sections: % cover of each species of
natural and planted regen.
Naturalness of regen and canopy
In all sections: Naturalness of regeneration (nat/planted) and naturalness of
canopy (consider NWSS method)
Level of Browsing
In all sections: Browsing AND Bark stripping: severity/frequency of canopy,
shrub layer trees and regeneration
No of tree & shrub species per
section
Record all tree & shrub species in all sections (both native and non-native)
Canopy cover
In all sections: canopy cover.
% cover of all species in all sections (and count/presence below 5-10%
Canopy share of native/ non-native
threshold). Needs to distinguish canopy (1,2,n), shrub and ER layers and record
species
composition of each
Presence of veteran trees
In all sections: speies/DBH for each veteran Please keep pollarding y/n also..
Presence of invasive non-native
species
In all sections: % cover of each invasive species on list, (plus 'other' for specific
invasive species of concern which may arise over time).
Threats and damages
Assess Area of section affected by key threats: e.g. dumping, soil exposed,
enrichment indicators, pheasant damage, dying or defoliated trees.(See NWSS
list)
NFI Principles
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