Forest Inventory Methods
and Carbon Analysis
In Support of the United States Submission on
Land-Use, Land-Use Change, and Forestry
Lyon, France 9 September 2000
Linda S. Heath
Richard A. Birdsey
USDA Forest Service
Northeastern Research Station
Outline of Presentation
• The United States Forest Inventory
• Methods to Estimate Carbon in Forests
• Estimates for Article 3.3 of the Kyoto Protocol
– Afforestation, Deforestation, and Reforestation
• Estimates for Article 3.4 of the Kyoto Protocol
– Forest Management Activities
Inventory Sample Design
• Phase One – Remote Sensing to Stratify Forest Area
– 3,000,000 forest sample points, each equals 100 ha
• Phase Two – Ground Sampling of Forest Attributes
– 120,000 forest sample points, each equals 2200 ha
• Phase Three – Forest Health Monitoring
– 4,500 forest sample points, each equals 38,500 ha
Phase One – Remote Sensing
Source: NAPP 1:40,000 color infrared photography
Sample Points: 16 photo points located systematically
over the “effective area” of each photo.
Measurement: land cover
Note: in process of shifting to
satellite data
Phase Two – Field Sampling
Five-Year Panel
Year
Year
Year
Year
Year
Sample Intensity = 1 sample location
per 6,000 acres of land
Inventory Cycle Length = Five years or
20 percent of the sample locations
each year
One
Two
Three
Four
Five
Phase Two Sample Location Design
Old 1/5-acre plot
Condition A =
Forest Land Use
Condition B =
Nonforest Land Use
Plot measurements: age, disturbance, owner, physiography, etc.
Tree measurements: species, dimensions, damage, etc.
Phase Three – Forest Health Monitoring
• FHM and FIA sample locations are co-located
• Additional data: crown condition, soils, understory,
coarse woody debris, etc.
Forest Inventory Estimates as a Basis
for Carbon Analysis
(Trends by State and Region)
•
•
•
•
Area by land class (reconciled with NRI)
Area by forest type, owner, age class
Tree volume by species and size class
Tree biomass by species and size class
Methods to estimate carbon
I.
Calculating carbon based using
inventory data
II.
Estimating forest sector carbon
III. Uncertainty
Basic estimation of carbon stocks and
stock changes
• Carbon stock = CARBON/AREA times
AREA
• Carbon stock change =
C stock at time 2 minus C stock at time 1
Divide by length of period = carbon/year
•  Estimated values can be obtained from
measured data or from using models
How to calculate carbon stock
estimates from forest inventory data?
• Calculate biomass and convert to carbon
(carbon = 50% of dry weight biomass)
• Estimate forest floor carbon using simple
relationships
• Estimate soil carbon based on USDA State
Soil Geographic database (STATSGO),
coupled with historical land use change
knowledge and assumptions of soil dynamics
following land use change and disturbance
• Sum carbon pools
Example: Average forest C budget for one
rotation of pine on a high site in the SE
Carbon (MT/ha)
250
200
Tree
150
Understory
100
Floor & Debris
Soil
50
0
0
20
Age
40
Avg C stock change (MT/ha/yr)
Example: Average forest C stock changes on one
rotation of pine on a high site in the SE
8
6
4
2
0
-2
-4
0-4
5-9
10-14
15-19 20-24
25-29 30-34
Ageclass
35-39 40-44
Example: Two rotations of pine on a high site in SE
Forest C and disposition of C in harvested wood
400
Emissions
Energy
Landfill
Products
Tree
Understory
Floor & Debris
Soil C
Carbon (MT/ha)
350
300
250
200
150
100
50
0
0
20
40
60
80
Age
NOTE: Energy and emissions are releases of C to the atmosphere
Disposition of carbon in harvested
wood – U.S. average
100%
Percent
80%
Emissions
Energy
Landfills
Products
60%
40%
20%
0%
0
10
20
30
40
45
55
Years since harvest
Source: Heath and others, 1996; Skog and
Nicholson, 1998
65
75
Major characteristics that affect
forest C budgets
• Region (Ex: Northeast, Pacific
Northwest)
• Forest Type (Ex:Douglas-fir,
Oak/Hickory)
• Site Quality (High, Medium, Low)
• Prior Land Use (Cropland, Pasture,
Forest)
• Age or Volume
Regions of the U.S.
Overall review: illustration of
significant C stocks and changes
ATMOSPHERE
decay
Growth
decay
HARVESTED
CARBON
Recycling
Removals
processing
decay
BIOMASS
Above and Below
Harvest
residue
Litterfall,
Mortality
STANDING
DEAD
Mortality
Treefall
burning
FOREST COARSE
WOODY
FLOOR
DEBRIS
PRODUCTS
disposal
burning
Humification
LANDFILLS
burning
ENERGY
Decomposition
SOIL
Imports/
Exports
Forest sector system of models and data for C estimates and
projections of managed U.S. forests
WOODCARB
(K.Skog)
FIA tree
data
dfasfds
FIA
ecosystem
data
Harvest, Production,
Trade, End use recycling
WOODCARB
parameters
(K.Skog)
Removals
TAMM
ATLAS
(Haynes/Adams)
(J.Mills)
Sawtimber
Prices
NAPAP
Pulpwood
merch vol
removals
& area
Type/area
transitions
(P. Ince)
Products
Live
Merch
Volume
Dead
Tree
Other
live
biom.
FORCARB
(L.Heath)
Understory
Coarse Woody Debris
Forest Floor
AREA
Economic
data including
production &
consumption
Mineral Soil
(R.Alig)
Carbon Budget Pools
NRI Land
Use data
NRCS
Soils data
Assumptions for Base projection
Assumptions involve factors about U.S.
•
•
•
•
•
Forest growth
Population
Income
Economic activity
Utilization factors
What is uncertainty? – IPCC
guidelines
• Generic definition of uncertainty
• IPCC guidelines suggest that it is more
useful to express uncertainty
quantitatively and systematically in the
form of well-developed confidence
intervals.
Uncertainty - definition and method
• Uncertainty: an expression of likely
values for an estimate when the true
value is not exactly known.
• Methods: We use Monte Carlo
simulations to represent uncertainty as
probability distributions
Uncertainty represented by a probability
distribution
95 %
CONFIDENCE INTERVAL
Projected inventory of privately owned
managed forests of US
95%
interval
18
20
22
10%
50%
24
90%
Carbon inventory (Pg C)
Source: (Smith and Heath, in press)
26
Absolute and relative uncertainty
C estimates on private managed forests of the U.S.
Inventory:
Flux:
80% confidence interval
80% confidence interval
22,400 +/- 950 MMT
74 +/- 11.5 MMT
22,400 +/- 4% MMT
74 +/- 15% MMT
Source: Smith and Heath, in press; C in harvests not included in these estimates; also
based on older inventory data.
Summary of methods for Articles 3.3 and 3.4
• Followed IPCC definitions and accounting
• All C pools included where appropriate
• Estimates based on comprehensive forest
inventory data and carbon estimation models
• Used multiple strata (region, owner, forest
type,..)
• Used projection models and adjusted periodic
estimates to required reporting dates
Identification of Kyoto Lands
(FAO Definitions)
1000 ha per period
Data
Projections
18000
16000
14000
12000
10000
8000
6000
4000
2000
0
95 000 005 010 015 020 025 030 035 040
9
-1 5-2 0-2 5-2 0-2 5-2 0-2 5-2 0-2 5-2
0
9
9
0
0
1
1
2
2
3
3
19 19 20 20 20 20 20 20 20 20
Afforestation
Deforestation
Reforestation
Average C Uptake on Land by Region and
Age - Regeneration After Harvest
t C per ha per year
(Includes decay of logging debris)
6
5
4
3
2
1
0
-1
-2
-3
-4
Southeast
South Central
Northeast
North Central
Rocky Mountain
Pacific Coast
0-5 5- 10- 15- 20- 25- 30- 35- 40- 4510 15 20 25 30 35 40 45 50
Age Class
Characteristics of Several Accounting
Approaches
Reforestation includes:
Accounting
Approach:
IPCC Land
Based
Afforestation
+
Forest
Deforestation Regrowth
Yes
Decay of
Logging
Debris
FAO Activity
Based
Yes
Yes
FAO Land
Based II
Yes
Yes
Yes
FAO Land
Based I
Yes
Yes
Yes
Harvest
Emissions
Yes
Average Annual Carbon Stock Changes
by Reporting Period and Accounting
Framework
Million t C per year
300
250
200
FAO Activity Based
FAO Land Based II
FAO Land Based I
IPCC Land Based
150
100
50
0
-50
2008-2012 2013-2017 2018-2022
U.S. submission for Article 3.4
• Proposes inclusion of three broad land
management activities: Forest
Management, Cropland Management,
and Grazing Land Management
• Proposes a comprehensive land-based
accounting system
Definition of managed forests
Forest management is an activity involving the:
• Regeneration, tending, protection
• Harvest, access, and utilization
of forest resources to meet the purposes of the
forest landowner.
Comparison of managed and all forests
Where are unmanaged
forests?
350
Millions hectares
• Almost half in Alaska
• Almost 40% in
Rocky Mountain
region and California
1997 Area statistics
300
250
200
150
100
50
0
All Forests Managed
Carbon stocks and area estimates, 1990
(Table II)
• Does not include
carbon in existing
forest products.
45
40
Carbon (Billion MT)
• In 1990, managed
forests in the U.S.
covered
198,611,000
hectares and
contained 36,203 +/6% MMT of C
35
Understory
30
Floor
25
Tree
20
Soil
15
10
5
0
1990
Managed forest lands, US, 2008-2012
Avg. annual C stock change
C taken up by trees in managed
forests
381.9
C released by harvesting trees
-276.0
Net C taken up in Soil
52.4
Net C taken up in Floor
12.8
Net C taken up in Understory
0.7
Net C accrued in live biomass &
soil
171.8
C increase in logging residue
26.1
C in products in use
39.1
C in products in landfills
51.3
C stored in products & landfills
90.4
Net C removals related to
managed forests
288 +/- 15% MMT/yr
Trend of carbon sequestration on
managed forests, U.S.
C stock change (MMT/yr)
Data
Projections
400
300
200
100
0
19901991
19921996
19972001
20022007
20082012
20132017
20182022