ISBN 978-4-905304-70-8

Reducing Emissions from Deforestation andforest Degradation and the Role of Conservation,
Sustainable Management of Forests and Enhancement

COOKBOOKANNEX

HOW TO MEASURE AND MONITOR FOREST CARBON

Research Manual Vol. 1
DRAFT Ver.
1.0
Ground-Based
Inventory
TAMOTSU SATO & KAZUKI MIYAMOTO

Research achievement of the 4th mid-term plan 1 (ForestREDD+Management
Technology-1)
Cookbook

1Preface
The basic concept of REDD-plus is to provide economic incentives such as funding andcredits to developing countries for REDD activities (reducing emissions from deforestationand forest degradation) and “plus” activities (reducing CO2 emissions and CO2 levels in theatmosphere by carbon sequestration). Thus, in order to estimate the changes in the amountof carbon stored in forests, monitoring using a scientific approach is essential.
The REDD Research and Development Center, Forestry and Forest Products ResearchInstitute, compiled “REDD-plus Cookbook” in 2012, an easy-to-understand technical manualthat provides basic knowledge and techniques required for REDD-plus, with the primary
focus on forest carbon monitoring methods. Knowledge and techniques required for REDDplus are compiled in units termed as “Recipe” in this REDD-plus Cookbook. This REDD-plus
Cookbook is intended for the policy makers working for the introduction of REDD-plus andthe practitioners and experts working on REDD-plus activities.
As REDD-plus Cookbook focuses on basic knowledge and techniques required for REDDplus, the experts working on REDD-plus activities will need further detailed informationin the field. Thus, we compiled “REDD-plus Cookbook Annex” to provide the experts withmore detailed and practical information in each “Recipe”. In this manual, specific measuringmethods are explained. In addition, this manual is intended to be used as a textbook forcapacity building. In order to have a better technological understanding on these topics, it isrecommended to read this manual in conjunction with REDD-plus Cookbook.
We hope this manual will contribute to the promotion of REDD-plus in several parts of theworld.

September, 2016
The REDD Research and Development Center
Forestry and Forest Products Research InstituteContents
1 Outline		

1

1.1 Purpose of REDD-plus Cookbook Annex

1

1.2 How to use this manual

1

1.3 Recipes covered by REDD-plus Cookbook

1

2 Methods for establishing sample plots2

2.1 Purpose of establishing sample plots

2

2.2 Design of inventory2

2.3 Design of plot4

2.4 Tools required for inventory5

2.5 Members of the team6

2.6 Plot establishment in the field

6

3 Measurement of plot

9

3.1 Tools required for inventory

9

3.2 Members of team9

3.3 Measurement of DBH

9

3.4 Measurement of tree height13

3.5 Identification of tree species

13

3.6 Measurement of leaf litter layer

13

3.7 Measurement of dead wood

14

4 Data analysis for measuring carbon stock18

4.1 Calculation of aboveground biomass

18

4.2 Calculation of belowground biomass

19

4.3 Litter layer mass

19

4.4 Calculation of dead wood mass

20

4.5 Conversion from biomass to carbon stock

22

References		23iREDD-plus COOKBOOK ANNEX

1 Outline
1.1 Purpose of REDD-plus Cookbook Annex
REDD-plus Cookbook compiled in 2012 is an easy-to-understand technical manualthat provides basic knowledge and techniques required for REDD-plus, with the primary
focus on forest carbon monitoring methods. REDD-plus Cookbook explains the estimation
method of forest carbon stocks, while this manual explains, inter alia, inventory methods
focusing on the ground-based inventory needed to develop equations for estimating carbon
stocks per unit area.
This manual is intended for experts who will actually collect data on forest carbon stocks.
We hope this manual will also be useful for students studying forestry and forest ecology,
NGOs interested in REDD-plus, and people concerned in this field.
1.2 How to use this manual
A ground-based inventory is carried out by establishing a number of plots; therefore,
accurate measurement of plots is of critical importance. In particular, when the inventory
is carried out by more than one team simultaneously, the inventory method should be
carefully checked in advance. It is advisable to know the inventory process from thismanual before planning a ground-based inventory.
In this manual, Chapter 2 explains how to establish plots for the ground-based inventory,
Chapter 3 explains the specific inventory procedure, and Chapter 4 explains the specificcalculation methods of the carbon stocks per unit area from the inventory data obtained in
the field.
Please see

TIPS

as for the points to consider in the field.

1.3 Recipes covered by REDD-plus Cookbook
Recipes covered by REDD-plus Cookbook are shown in [ ]. Please refer to REDD-plus
Cookbook.
REDD-plus Cookbook can be downloaded from the Website mentioned below.
http://redd.ffpri.affrc.go.jp/index_en.html

1Research Manual Vol. 1 Ground-Based Inventory

2 Methods for establishing sample plots
2.1 Purpose of establishing sample plots
In the 2006 IPCC guidelines, two methods of calculating changes in carbon stocks (forest
biomass) are presented: the gain-loss method and the stock change method. The gain-loss
method calculates carbon stock changes by taking the difference between increases anddecreases in emissions, whereas in the stock change method the change in carbon stocks(which reflect emissions and removals) is determined from the difference in carbon stocks
measured at different time points [Recipe-P04, P07].
The gain-loss method requires accurate data on carbon stocks lost by logging and forest
disturbances, which is often difficult to obtain. For this reason, the stock change method, inwhich the difference in carbon stocks at two different time points is presumed to equal theemissions and removals during that time interval, is more widely applicable [Recipe-P07].
At the national level, remote sensing and ground-based inventory used in combination caneffectively determine carbon stock changes.
The estimation of the amount of carbon stocks per unit area is done by two methods:
a method that directly measures the amount of carbon in the forest and a methodthat indirectly measures the amount of carbon stocks using the estimation model[Recipe-P09]. Each method has advantages and disadvantages and is applicable under
different conditions. A ground-based inventory using permanent sample plots has theadvantage that it can be used to detect land-use changes, such as conversion to farmland
and selective logging, and to monitor forest carbon stocks in a large area over time
[Recipe-P09]. For national-level measurement, however, several permanent sample plots
are needed [Recipe-P10]. In this manual, methods for establishing and measuring thesample plots, which are considered to be the most technically feasible for the groundbased inventory, are explained.
This manual focuses on four carbon pools, except for soil (above-ground biomass,
belowground biomass, leaf litter layer, and dead wood).
2.2 Design of inventory
2.2.1 Auxiliary data
To calculate forest carbon stocks per unit area, a large number of permanent sample
plots need to be established; however, when the National Forest Inventory (NFI)[Recipe-T01] has been carried out in the target country, the number of plots requiredfor high-accurate data can be determined based on NFI [Recipe-T12]. Moreover, it isnecessary to collect case studies on forest carbon stocks carried out in the target country2

REDD-plus COOKBOOK ANNEX

and to know whether allometric equations required for calculating biomass have beendeveloped [Recipe-T03]. In the absence of sufficient information, data on neighboring
countries and regions are used.
2.2.2 Establishment of sample plots
To prevent permanent sample plots from being concentrated in readily accessible
locations such as near roads or villages, permanent sample plots should be establishedusing either a simple random sampling method or a systematic sampling method[Recipe-P10, T12]. Moreover, a stratified sampling method, in which the number ofsampling sites and their locations by forest categories are decided in advance on the basisof remote sensing data, can improve sampling survey efficiency [Recipe-T12].
An effective means of stratification is to create a stratification matrix (Figure 1). Thismatrix is constructed with two axes: one axis shows forest types and other shows thestate or condition of the forest (the degree of forest degradation or the succession stage)[Recipe-T12]
Forest type

Forest type

Lowland forest

Lowland forest
Dry forest<‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Forest conditions ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ >‹------------------------------- Forest condi ons ‹-------------------------------›
MatureMatureMatureDry forest

MaturePlantaon
Plantation

MatureMatureSelective logged

Selective logged
Selective logged

Selective logged

Secondary
Secondary(mediumage)

Secondary(youngSecondaryage)

Secondary
Secondary(medium age)

Secondary
Secondary(young age)(medium age)(medium age)

Mediumage
Medium age(young age)(young age)

age
YoungYoungage

Carbon stock
Carbon	
  stock

HighHigh

Low
Low

Figure 1 Example of stratification matrix
The horizontal axis shows the condition of the forest and the vertical axis shows forest types.

2.2.3 Required number of plots
Where a forest area is divided into L strata, the total required number (n) of permanent
Figure 1
sample plots is obtained as follows:

  
3

𝑛𝑛𝑛𝑛	
   = 	
  𝑁𝑁𝑁𝑁 ∗

𝐸𝐸𝐸𝐸
𝑡𝑡𝑡𝑡

(
+
%)* 𝑁𝑁𝑁𝑁%	
   ∗ 𝑆𝑆𝑆𝑆%+(+ 	   %)* 𝑁𝑁𝑁𝑁% ∗𝑆𝑆𝑆𝑆% +

Research Manual Vol. 1 Ground-Based Inventory

where i is the stratum, L is the number of stratum, N is the maximum number of plots inthe target area (a value obtained by dividing the total target region by the sample plot area),
Ni is the maximum number of plots in each stratum (the value obtained by dividing eachstratum area by the sample plot area), Si is the standard deviation of each stratum, E is thepermissible error in the estimated amount (e.g. 10% of the biomass average value), and t is
a 5% significance level of the t-distribution. The cost for establishing plots is not taken into
consideration in the above formula.
The total cost including the cost of establishing plots is calculated using a different
formula, but there is no big difference in the necessary numerical information [Recipe-T12].
After calculating the required total number of plots using the above formula, the numberof required plots for each stratum (ni) can be determined as follows:

  𝑛𝑛𝑛𝑛 " 	   = 𝑛𝑛𝑛𝑛 	
  × 	
  

𝑁𝑁𝑁𝑁" ×𝑆𝑆𝑆𝑆"(")* 𝑁𝑁𝑁𝑁" ×𝑆𝑆𝑆𝑆"

2.3 Design of plot
2.3.1 Plot area
The larger the area of each permanent sample plot, the larger the number of trees thatmust be measured and the larger the time and expense required for the measurement. On
the other hand, if the area of each sample plot is small, measurement requires relatively
little time and expense, but the error in the carbon stock measurement result will increase[Recipe-T13]. Moreover, plot area should be chosen with reference to the national forest
inventory, if one has been carried out in the past in the country, and after researching theforest structure and other characteristics of the forest. As a rough standard, an area of
0.1–0.5 ha is often used.
2.3.2 Plot shape
In general, sample plots (either circular or rectangular shape) are often used (Fig. 2).
Each shape has advantages and disadvantages in setting up and use. For example,
the location of the plot is marked with stakes. For a circular plot, a stake is establishedat the central point, but it may be difficult to know whether individual trees near the plot
boundary are within the plot and the measurement object. On the other hand, a rectangularplot requires a stake in all four corners, but it is easy to determine whether the tree is ameasuring target due to the straight lines of the plot. Moreover, the measurement is carriedout repeatedly; therefore, a rectangular plot has the advantage that is easy to locate, eventhough four stakes need to be established at all four corners.

4

REDD-plus COOKBOOK ANNEX

For accurate determination of the forest structure in a plot, all living trees within the plot
should be measured; however, this is laborious with regard to time and effort. Time andeffort can be saved using a nested plot structure (Figure 2, Gray area)[Recipe-T13].

Figure 2 Shapes of sample plot
Left: Rectangular-shaped plot (0.16 ha), Right: Circular-shaped plot (0.1 ha)

Figure 2
2.4 Tools required for inventory
Tools required for establishing plots are shown in Table 1. The distance measurement in
the forest is carried out efficiently using measurement tools such as a laser range finder or an
ultrasonic range finder.
Table 1 Tools required for establishing plots
Tool

5

NumberRemarks

Laser range finder

1

For measuring horizontal distance

Tape measure (30 –50 m)

1-3

Clinometer

1

Azimuth compass

1-2

For establishing plots and recording the plot locationGPS

1

For recording plot location

Stakes>1

Material of stakes varies depending on plot location.

Digital camera

1

For recording forest type of plot

For measuring the slope distance using a tape measure
when a laser range finder is not available.
For recording the inclination of the plot

Research Manual Vol. 1 Ground-Based Inventory

TIPS

It should be noted that an ultrasonic range finder might be unavailable near the river or
disturbed by the buzzing of cicadas and/or sound of a brook.

2.5 Members of the teamAfter deciding the point to be measured, the compartment of plot needs be determined.
For this measurement, the staff shown in Table 2 are needed. The measurement will be
carried out more efficiently with more than one team.
Table 2 Number of staff required for establishing plots
Role

Desired number ofStaff who operate a laser
range finder

Remarksstaff
1-2

For indicating orientation and distance to establish
plots

Staff for data entry1

For recording location, inclination, orientation, etc.

Assistant staff

2–4

For establishing stakes

2.6 Plot establishment in the field
2.6.1 Information to be recorded
A sample plot is classified into two types: a permanent sample plot (PSP) (for repeatedmeasurements) and one-shot plot (for a one-time use). In both cases, the plot location
measured using GPS should be recorded. There is a large amount of information to berecorded as shown in Table 3 when establishing the plot, but some of the information
should be gathered in advance.
In addition, information about the forest where the sample plot is established should
be recorded, including disturbance history and conditions of surrounding areas. The typeof disturbance, including human-induced disturbance (logging, conversion to agriculturalland, etc.) or natural disturbance (fire, meteorological damage, etc.), should be recorded
in as much detail as possible. The degree and duration of the disturbance should also
be recorded in as much detail as possible because these factors affect the forest carbon
stocks.
2.6.2 Procedures for establishing a plot
Here, the specific procedure for establishing a plot is explained by taking a rectangularshaped plot (40 m × 40 m) as an example.

6

REDD-plus COOKBOOK ANNEXFirst, select the candidate location for establishing a plot based on the predetermined location(the distance from the forest road, etc.). After selecting the candidate location, determine thelocation to establish the plot. Then, record the position measured by GPS. Here, the location isthe center point of the plot (Figure 3a).
To create a nested plot structure in the plot, establish grid points at 10 m interval. From there,
extend the survey lines to the north and south directions by 10 m, respectively, from the center
point (a total of 20 m) (Figure 3b). After extended by 20 m, change the direction by 90 degrees
and then extend the survey line to the north and south directions by 20 m, respectively. At the
point where the survey line is extended by 20 m, establish a stake as a boundary point (Figure3c). In order to establish a grid with a grid interval of 10 m, draw a survey line on the fishbone
pattern along the central point (Figure 3d) and then make a sub-quadrat by extending thesurvey line toward the boundary point (Figure 3e). Here, the distance of grid interval is not theslope distance but the horizontal distance. Stakes established at the boundary point of thereference point and the plot serve as landmarks at the time of measurement. When establishingpermanent sample plots, it is important to select stakes made of durable materials. For example,
concrete stakes are appropriate where occasional fires occur [Recipe-T12].

Table 3 Information to be recorded at the establishment of plots
Information
Location (latitude, longitude)

Remarks
Information measured using GPS is recorded. Information of
coordinate system used should also be recorded.

Altitude

Altitude at the location.

Inclination angle

Inclination angle along the central line.

Forest type
AzimuthClassification (evergreen forest, deciduous forest,
afforestation, etc.)
Azimuth along the central line.
History of fire or selection cutting should be recorded, if any.

Disturbance history

In that case, duration of disturbance should be recorded in
as much detail as possible.

Conditions of surrounding areas

7

Recording of land use in surrounding areas

Research Manual Vol. 1 Ground-Based Inventorya） Set up a central pointb）Set up a central line

10 mc）Expand lines to corner points

10 m

10 m

10 m

10 m

10 m
10 m
10 m

Central point
Corner pointe）Expand last lines to corner pointsd）Set up lines like fish bones

Figure 3 Procedure for establishing sample plot (a square of 40 m × 40 m)

Figure 3

Stake materials

Table 4 Stake materials used for establishing plots
Plot type
Characteristics
Permanent/

Available at a relatively low cost, however, vulnerable toTemporaryfire and susceptible to degradation in direct sunlight.

Metal including aluminum

Permanent

High cost, but durable

Concrete

Permanent

PVC pipe

Wood

Durable and fire resistant, but extra labor is needed
when establishing.

Permanent/

Available at a relatively low cost. Low durability

Temporarydepending on the type of wood.

Easy-to-use tools for measuring horizontal distance are widely used today. In case such

TIPS

equipment is not available, it would be convenient to prepare a conversion table to convert
slope distance to desired horizontal distance.

8

REDD-plus COOKBOOK ANNEX

3 Measurement of plot
3.1 Tools required for inventory
Tools required for inventory survey for estimating forest carbon stocks are shown in
Table 5. Other tools may be required depending on the target area, but these tools areenough for measuring the breast height diameter (DBH) and tree height.
Table 5 Tools required for inventory
Tool
Tape measure(about 10 m)
Laser range finder

Number>1

For measuring DBH

1

For measuring tree height

A largenumberLabel

Remarks

For identifying individual tree to be measured. Material should
be vinyl, plastic, aluminum, etc.

Staple gun>1

For securing the label to the tree

Marker>1

For recording the location of measurement and for marking to
avoid double measurement.

Binoculars>1

For identifying tree species

Pole pruner

1

For collecting samples to identify tree species

Slingshot1

For collecting samples in places where a pole pruner does notreach.

3.2 Members of team
Two staff per team are needed for the inventory; one for measuring DBH and theother for recording data (Table 6, Photo 1). In general, the tree height is measured after
measuring DBH; however, if these works are carried out simultaneously by teams, time forthe inventory can be saved.
3.3 Measurement of DBH
The procedure for basic measurement is as follows:◦ Record the position of a tree selected as a measurement object (if needed),◦ Assign a unique identifying number to the tree and attach a tag,
◦ Measure the tree’s diameter at breast height,◦ Mark the measurement height on the tree,◦ Identify and record the species,◦ Measure the tree height (when required), and◦ Record other pertinent information.

9

Research Manual Vol. 1 Ground-Based Inventory

Table 6 Number of staff required for inventory
Desired number of

Role

Remarks

staff

Staff for entering data of tree
census1-2

Staff for measuring DBH

1-2

Staff for measuring tree height

1-2

Staff who can identify plant
species(1) Tools

1-2Work efficiency will be improved with staff who
have an overview of the entire project.
With more than one staff, measurement of DBH
and labeling can be done separately.
Depending on the number of tools for measuring
tree height.
Identification of plant species and data entry may
be done by the same staff.

(2) Inventory carried out by a teammade up of two staff
Photo 1 Inventory in the field

3.3.1 Recording a tree position selected as a measurement object
The sample plot explained in section 2.6.2 is divided into 16 square subplots (10 m × 10 m).
Each sample plot uses a nested plot structure. It should be noted that DBH threshold of thetrees designated as measurement objects differs depending on the subplot (see Figure 2).
In the permanent sample plot, the positions of the trees should be recorded for thesecond and subsequent measurements, and the route of measurement should also
be determined. The positions of individual trees can be recorded easily and clearly byattaching the code number in each subplot. Moreover, if the trees are numbered in a
regular pattern, for example, in a counterclockwise direction from the stake used as thestarting point, it will be easy to tell if any tree has disappeared when future measurements
are carried out [Recipe-T13]. Double measurement can be avoided by simply recording the10

REDD-plus COOKBOOK ANNEX

subplot number where the individual tree designated as the measurement object is located.
All individual trees designated as measurement objects must be assigned a unique
number, and then the number must be engraved on a tag, such as a commercial aluminumtag, and attached to the individual trees (Photo 2). When it is difficult to attach the tag to thetree, the number should be written directly on the stem using paint or the position should
be recorded using the abovementioned subplot code system.
3.3.2 Measurement of DBH
In general, tree diameter is measured at 1.3 m above the ground. When measuring
the stem using a tape measure, wrap the measuring tape firmly, not loose or sagging,around the stem. Before measuring the diameter of the individual tree, the condition at
the measurement point should be checked. If there is a swelling that would distort the true
diameter, then that place should be avoided. Similar, if a climbing liana is wrapped aroundthe tree, remove it before measuring the diameter. In such a situation, field annotations
such as “measured without climber” and “measuring position moved to avoid swelling”
should be written down immediately before they are forgotten. In some cases, stems
are thickly covered by bryophytes in the cloud forests. In that case, carefully remove thebryophytes on the position of the DBH measurement. In addition, carefully determine themeasurement position if the tree has buttress roots. The measurement should always be
made at the height from the point of 50 cm above the top of the buttress (Photo 3).

Photo 2 Marking of measurement positionand labeling11

Photo 3 Diameter measurement
above the buttressResearch Manual Vol. 1 Ground-Based Inventorya) Leaning stemsb) Multiple stems

1.3 m

1.3 m

c) Stem broken above
breast height

1.3 m

Figure 4 Example of measuring DBH for irregular stems

Individual tree stem to be measured is not necessarily straight and single. The DBH
measurement of a leaning tree should be made at 1.3 m length from the base (Fig. 4a). The
measurement
Figure 4 of DBH of multiple stems should be made at 1.3 m from the base of the tree
(Fig. 4b). If the main stem is withered or broken but not dead, the DBH of the tree shouldbe measured at 1.3 m above the ground in the same manner as the regular measurement(Fig. 4c). In addition, the measurement of DBH should be made from the upper side of
the slope, and it is better to mark the position of the measurement using paint for the next
measurement (Photo 2).
3.3.3 Tools to be used
Carefully choose the tools when measuring DBH. For example, with calipers, the DBH is
measured not once, but twice, with the second measurement being made at right angles
to the first, and then the average value is used. If a tape measure is used, the DBH might
become confused with the girth at breast height (GBH). It is important to be sure that thevalue recorded is the correct one. In addition, the same type of measurement tool should
be used for all measurements of the same type. For example, some DBH measurements
should not be made with an ordinary tape measure and others with slide calipers, or both adiameter tape and an ordinary tape measure should not be used.

When the DBH measurement is carried out by two or more teams, confirm the inventory

TIPS

methods in advance. The discrepancy in the measurement value among the inventory teams
can be reduced by checking the inventory method.

12REDD-plus COOKBOOK ANNEX

3.4 Measurement of tree height
In a tropical forest, it is often difficult
to measure tree height, because it
is difficult to observe the tops of the

4 subplots(10 m x 10 m each)trees. If measurement objects are

Subplot for trees≥ 5 cm DBH

Subplot for trees≥ 10 cm DBH

selected by a sampling procedurethat takes the size str ucture intoc onsideration, then the height of
only some individual trees needs tobe measured and the tree height of
unmeasured trees can be determinedfrom a DBH –tree height curve. As
Figure 5

shown in Fig. 5, if the measurement of
the tree height is carried out within theselected subplot, labor can be saved.
Moreover, it is important to verify

Figure 5 Example of effective measurement of tree heightusing subplots
In the red subplots, individual trees with DBH of 5 cm orlarger are measured. In the blue subplots, DBH of 10 cm
or more is measured. In other plots (yellow), tree height is
not measured.

the definition of the tree height used, because some engineers may use commercial treeheight.
3.5 Identification of tree species
After measuring the DBH and height of trees, the tree species need to be identified, as
allometiric equations for calculating carbon stocks use wood density (WD) in some cases.
Identification of tree species is difficult in the tropical forest due to the presence of a large
number of tree species. When identification of tree species is difficult, try to identify asmuch as possible, preferable to the genus level.
When unknown species are found in the field inventory, take a note of their features
as much as possible such as the leaf arrangement (alternate, opposite, compound, etc.)
and the color of the bark and sap. Collect as many sample leaves as possible for later
identification by experts.
3.6 Measurement of leaf litter layer
The leaf litter layer is composed of fallen leaves and branches, including dead wood on
the mineral soil. Dead wood greater than 10 cm in diameter is measured as explained in
the following section (see 3.7).
The measurement of leaf litter layer is made by 1) creating a certain size of frame on theforest floor, 2) collecting fallen leaves and branches in the frame, and 3) measuring the13Research Manual Vol. 1 Ground-Based Inventory

total dry weight in the laboratory. In general, a square frame (50 cm × 50 cm) is enough tocollect the required amount of samples (Photo 4).
Dry weight of all dead wood smaller than 10 cm in diameter collected in a slightly larger
frame (e.g., a square of 2 m × 2 m) is measured in the laboratory. The dead wood collectedin accordance with this procedure is too large to bring to the laboratory. Therefore, after
measuring the fresh weight in the field, create a subsample for measuring dry weight.

(1) Creation of a square (50 cm × 50 cm)(2) After collecting leaf litter in the square

Photo 4 Measurement of leaf litter layer

TIPS

It is advisable to put the samples collected in the frame in a paper bag as they can be put
directly into the drying oven.

3.7 Measurement of dead wood
Dead wood is defined here as all dead wood material measuring more than 10 cm indiameter. Dead wood consists of various forms such as stump, standing dead trees (snag),fallen logs, and branches. In this manual, plot-based method is applied to measure deadwood in the plot.
3.7.1 Definition of decomposition class
The first step for measuring the weight of dead wood (necromass) is to determine thewood volume in any form. Wood density is used for converting wood volume into weight,
but the decomposition degree greatly varies, depending on the individual dead wood. Thus,
the wood density also varies.
The decomposition classes were defined by Chao et al. (2008) as:
Class 1: Material was recently dead, with more than 75% of the wood intact and hard,and sometimes still with fine twigs attached.

14

REDD-plus COOKBOOK ANNEXClass 2: Material was damaged, the log had experienced some decay, and was also
applied to piece of wood where the bark had gone but the heartwood remainedsolid.
Class 3: Material was at least 75% soft and rotten, into which a machete blade could
easily enter and which collapsed when stepped on.
Differences between Class 2 and Class 3 are easily identified using a nail. A nail can

TIPS

easily enter the wood in Class 3, but it seldom enters the wood in Class 2.

3.7.2 Stump
To know the amount of stump in the degraded forests is important, as a large numberof stumps can be found in the degraded forests. First, measure the two directions
perpendicular to the diameter of the stump (Photo 5). Then, measure the height from thesurface of the stump to the ground. The height of the stump with irregular surface shouldbe measured in the middle of the highest and lowest surface.

(1) Directions of measurement(2) Measurement of stump

Photo 5 Measurement of stump diameter

3.7.3 Standing dead trees
Measure the DBH and height of standing dead trees. Measurement of the height ofstanding dead trees can be omitted using the DBH–tree height curve. Determining thedecomposition class is also necessary. Standing dead trees still with fine twigs attachedsoon after withering are classified as Class 1, while standing dead trees whose small twigs
have been dropped and only large branches remain on the trees are classified as Class
2. When the stem is broken, measure the height to the point where stem is broken and thediameter in the middle of the broken stem.
If the height of the broken stem is less than 4 m, measurement of the diameter can be

15Research Manual Vol. 1 Ground-Based Inventory

made at the midpoint of the stem, while the measurement is difficult for the higher broken
stem. In that case, DBH is used as an alternative value.

bottom end diameter≥ 10 cm

top end diameter≥10 cm“out” = ≤ 10 cm

Figure 6 Measuring threshold of downed dead trees

3.7.4 Fallen trees
Typical methodsFigurefor 6measuring the amount of fallen trees are the plot inventory method
and the line transect method. In this manual, measurement using a plot inventory method
is explained.
All fallen trees in the sample plot with more than 10 cm of end point diameter aremeasured. However, the extended part with less than 10 cm in diameter is ignored (graypart in Fig. 6). On the other hand, a part of fallen trees that extended outside the plot (redlines in Fig. 7) are not measured, while fallen trees within the plot are measured completely(blue lines in Fig. 7).
Based on these criteria, the length and diameter at both ends of fallen trees within
the plot should be measured (Photo 6). In addition, the decomposition class should berecorded.

(1) Measurement of diameter(2) Measurement of length

Photo 6 Measurement of fallen tree

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REDD-plus COOKBOOK ANNEX

Figure 7 Measurement standard for falling dead wood in plot
Blue indicates measuring targets and red indicates beside the targets. ● are the locations of the roots.

TIPS
Figure 7

17

It is advisable to use a caliper for measuring the diameter, as a part of the fallen tree isburied in the soil in some cases.

Research Manual Vol. 1 Ground-Based Inventory

4 Data analysis for measuring carbon stock
In this chapter, methods of measuring carbon stocks using data obtained from thesample plots are explained.
4.1 Calculation of aboveground biomass
To estimate plant carbon stock in the plot, first, calculate the above-ground biomass(AGB) using allometric equation. In this manual, the following generic equation developedby Chave et al. (2014) is used:
AGB = 0.0673 * (ρD 2H ) 0.976
where D (cm) is DBH, H (m) is total height, and ρ (g cm -3) is wood density.
Species-specific wood density is recorded in some tree species. However, speciesspecific wood density is unavailable in most tree species. In that case, default values inSouth America (0.60 g m -3) and genus average can be used to estimate AGB. For moredetail about species-specific wood density data, the following database is useful (see thefollowing database for reference):
Global Wood Density Database(http://datadryad.org/repo/handle/10255/dryad.235)
In the absence of wood density data of tree species, try to find the mean value at thegenus level and then the mean value at the family level. Still, if related data cannot befound, use the default value by continent (Table 7).
Table 7 Wood density default values in tropical regions
RegionWood denisty (g cm-3)

Tropical Asia

0.57

Tropical America

0.60

Tropical Africa

0.58

Source: Reyes et al. (1992)

For a tree that has a DBH of 20.5 cm, a total height of 16.1 m, and a wood density of 0.60
g m -3, the AGB is calculated as follows:18

REDD-plus COOKBOOK ANNEX

AGB = 0.0673 * (0.60 * (20.5)2 * 16.1) 0.976= 0.0673 * (4059.6) 0.976 = 223.8 kg
After summation of the calculated AGB using tree census data in the plot, AGB per
hectare can be calculated as follows:
AGBh = (Areah / Areaplot ) * AGBplot
where AGB h is the estimation of AGB per hectare, Area h (Mg ha−1) is the area of one
hectare, Areaplot is the area of the sample plot, and AGBplot is plot-level estimation of AGB(Mg 0.16 ha−1 in this manual).
If the AGBplot is 25 Mg, AGBh is 156.25 Mg ha−1.
AGBh = (1 / 0.16) * 25
= 6.25 * 25 = 156.25 Mg ha -1.
4.2 Calculation of belowground biomass
Similar to AGB, belowground biomass (BGB), consisting of coarse and fine roots, is also
estimated using some equations. In this manual, the following generic equation developedby Mokany et al. (2006) is used:
BGBh = 0.489 * AGBh 0.890
where BGBh is the estimation of BGB per hectare, and AGBh is the estimation of AGB per
hectare. After estimating AGBh, we can simply estimate BGBh using the abovementioned
equation.
On the other hand, some allometric equations can estimate individual belowgroundbiomass (Niiyama et al. 2010) and whole-tree biomass, including belowground parts (e.g.,
Sato et al. 2015). In this case, BGB per hectare can be calculated after summation of
calculated BGB using tree census data in the plot.
4.3 Litter layer mass
Because a sample of the litter layer is collected in a determined plot, just determine thecoefficient for converting the sampling area per hectare. Where 150 g of dry weight oflitter layer is obtained in a 50 m × 50 m square, litter layer mass per hectare value (Lth) is
calculated as follows:

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Research Manual Vol. 1 Ground-Based Inventory

Lt h = Lt s * (10000 / A s) = 150 * (10000/0.25) = 150 * 40000 = 6,000,000 g = 6,000 kg
where Lts is litter layer mass in the plot (g), and As is the sampling area (m2).
4.4 Calculation of dead wood mass
To estimate dead wood mass, we initially calculate the volume of each dead wood piece.
Then, we converted the volume to dry mass using wood densities based on decomposition
class (see section 3.7.1). Some literature values are useful to adopt estimation of deadwood mass. For example, wood densities in three decomposition classes are estimated in
Amazonian forests, Peru (Chao et al. 2008; Table 8).
Table 8 Example of wood density in each decay class
Decomposition Class

Wood density (g cm-3)

1

0.55

2

0.41

3

0.23

Source: Chao et al. (2008)

4.4.1 Stump
The volume of stump can be calculated using the Huber’s formula.

V = A * L * 100
where V is the volume (cm3), A is the sectional area at the middle (cm2), and L is theheight of the stump (m). If the cutting end is shaped like an ellipse, the sectional area iscalculated using the following equation:

A = (d1/2) * (d2/2) * π

where d1 and d2 are the two orthogonal diameters.
For example, for a stump that has 64 cm and 70 cm as the orthogonal diameters and 0.7
m height, the volume is calculated as follows:

V = A * L * 100 = (64/2) * (70/2) * π * 0.7 * 100 = 246,301 cm3
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REDD-plus COOKBOOK ANNEX

If the stump has “class 2” of decomposition class, the mass is calculated as follows:
Mass = V * WD decomposition class = 246,301 * 0.41 = 100,983 g = 100.98 kg
4.4.2 Standing dead trees
The volume of standing dead trees can also be calculated using the Huber’s formula.

V = A * L * 100
The area of breast height of standing dead trees is a substitute for the sectional area of
middle (A) in some cases. For example, for a dead tree that has a DBH of 25.6 cm and aheight of 6.5 m, the volume is calculated as follows:

V = A * L * 100 = (25.6/2)2 * π * 6.5 * 100 = 334,567 cm3

If the dead tree has “class 2” of decomposition class, the mass is calculated as follows:
Mass = V * WD decomposition class = 334,567 * 0.41 = 137,172 g = 137.17 kg
4.4.3 Fallen trees
3
),can
canbe
becalculated
calculatedusing
usingSmalian’s
Smalian’sformula
formulaasasfollows:
follows:
The volume of fallen trees, V (cm(m3),

𝑉𝑉𝑉𝑉 = 𝐿𝐿𝐿𝐿	
  

𝜋𝜋𝜋𝜋

𝐷𝐷𝐷𝐷' )𝐷𝐷𝐷𝐷 )+ 𝜋𝜋𝜋𝜋 )22
  2

where L (m) is thethe length
length ofof thethe piece
piece ofof fallen
fallen tree,
tree, and
andDDisisthe
thediameter
diameter(cm)(m) at eitherend.
For example, for a fallen log that has 20 cm and 10 cm at either end and a length of 1.8 m,
the volume is calculated as follows:

V = 100 * 1.8 ((π (20/2)2 +π (10/2)2) /2) = 180 * (314.2 + 78.5) / 2 = 35,343 cm3If the fallen log has “class 2” of decomposition class, the mass is calculated as follows:
Mass = V * WD decomposition class = 35,343 * 0.41 = 14,491 g = 14.49 kg

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Research Manual Vol. 1 Ground-Based Inventory

Here is another example. For a fallen log that has rectangular cross-sections with 20 cm
and 10 cm on sides at both ends and 1.8 m in length (like a square pole), its volume andmass (with “class 2” of decomposition class) are simply calculated as:

V = 100 * 1.8 * 20 * 10 = 36,000 cm3
Mass = V * WD decomposition class = 36,000 * 0.41 = 14,760 g = 14.76 kg
4.4.3 Calculation of dead wood mass
Similar to AGB, dead wood mass also needs to be reported as per hectare estimate. If
total the amount of dead wood is 800 kg in a 0.16 ha plot, the per hectare estimate of deadwood mass is calculated as follows:
Dead Wood Mass = 800 * (1/0.16) = 5,000 kg = 5.00 Mg ha -1
4.5 Conversion from biomass to carbon stock
We should also estimate forest carbon stock per area (i.e., Mg C ha-1) as well as plantbiomass. To estimate carbon stock of biomass and dead wood mass, “carbon fraction ofdry matter (CF)” defined by IPCC 2006 GPG will be used.
If AGBh is 125 Mg ha-1 in a sample plot, carbon stock (AGBh-c) can be calculated as follows:
AGBh-c = AGBh * CF
= 125 * 0.47 = 58.75 Mg C ha -1

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REDD-plus COOKBOOK ANNEX

References
Chao K-J, Phillips OL, Baker TR (2008) Wood density and stocks of coarse woody debris in anorthwestern Amazonian landscape. Canadian Journal of Forest Research 38: 795-805.
Chave J, Réjou-Méchain M, Búrquez A, Chidumayo E, Colgan MS, Delitti WBC, Duque A, Eid T, Fearnside
PM, Goodman RC, Henry M, Martínez-Yrízar A, Mugasha WA, Muller-Landau HC, Mencuccini
M, Nelson BW, Ngomanda A, Nogueira EM, Ortiz-Malavassi E, Pélissier R, Ploton P, Ryan CM,
Saldarriaga JG, Vieilledent G (2014) Improved allometric models to estimate the abovegroundbiomass of tropical trees. Global Change Biology 20: 3177-3190.
Mokany K, Raison RJ, Prokushkin AS (2006) Critical analysis of root : shoot ratios in terrestrial biomes.
Global Change Biology 12: 84-96.
Niiyama K, Kajimoto T, Matsuura Y, Yamashita T, Matsuo N, Yashiro Y, Ripin A, Kassim AR, Noor NS(2010) Estimation of root biomass based on excavation of individual root systems in a primary
dipterocarp forest in Pasoh Forest Reserve, Peninsular Malaysia. Journal of Tropical Ecology 26:
271-284.
Reyes G, Brown S, Chapman J, Lugo AE (1992) Wood Densities of Tropical Tree Species. UnitedStates Department of Agriculture, Forestry Survice, Southern Forest Experimental Station, New
Orleans, Louisiana.
Sato T, Saito M, Ramírez D, Pérez de Molas LF, Toriyama J, Monda Y, Kiyono Y, Herebia E, Dubie N, Duré
Vera E, Ramirez Ortega JD, Vera de Ortiz M (2015) Development of allometric equations for tree
biomass in forest ecosystems in Paraguay. JARQ 49: 281-291.

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Authors
Editors
VersionCitationTamotsu Sato (Forestry and Forest Products Research Institute)
Kazuki Miyamoto (Forestry and Forest Products Research Institute)
Tamotsu Sato & Masayoshi Takahashi
1.01enThis document may be cited as:
Sato T, Miyamoto K (2016) REDD-plus Cookbook Annex. Research
Manual Vol. 1 Ground-Based Inventory. REDD Research andDevelopment Center, Forestry and Forest Products Research InstituteJapan, 23pp.