Generating Forest Biomass Carbon Stock Estimates for Mapping the Potential of REDD+ to Deliver Biodiversity Conservation in Vietnam

Biomass Expansion Factor for different forest types in Vietnam using 2001-2005 inventory data on wood volume .... AGB above-ground biomass BEF biomass expansion factors BGB below-ground

1 SNV REDD+

Generating Forest Biomass Carbon Stock

Estimates for Mapping the Potential of REDD+

to Deliver Biodiversity Conservation in Vietnam

Benktesh D Sharma, Vu Tan Phuong & Steven R Swan

September 2013

Acknowledgements

The forest biomass carbon stock density estimates summarised in this report were

commissioned by SNV – The Netherlands Development Organisation as part of the project

‘Exploring Mechanisms to Promote High-Biodiversity REDD+: Piloting in Vietnam’ (HB-REDD)

Initial estimates were prepared by Green Field Consulting Co Ltd., in collaboration with the

Research Centre for Forest Ecology and Environment (RCFEE), with technical assistance

from the United Nations Environment Programme – World Conservation Monitoring Centre

(UNEP-WCMC) as part of the REDD+ Policy Assessment Center (REDD-PAC) project

Both the HB-REDD and REDD-PAC projects are part of the International Climate Initiative

The German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety

supports this initiative on the basis of a decision adopted by the German Bundestag

This report documents methods and results of basic nationwide forest biomass carbon stock

estimation as a contribution to the preliminary spatial analysis of potential for REDD+ to

deliver biodiversity conservation in Vietnam (Mant et al 2013)

Thanks to Florian Werner, of Deutsche Gesellschaft für Internationale Zusammenarbeit

(GIZ), who provided comments on a draft version of the report

Disclaimer

The forest biomass carbon stock density estimates and accompanying tables presented in

this report were produced using publicly available data and reports available at the time of

analysis This report does not present any official assessment or statement on Vietnam’s

forest biomass carbon on the part of the Government of Vietnam or any other entity The

analysis reported herein was conducted as a contribution to preliminary spatial analyses of the

potential for REDD+ to deliver biodiversity conservation in Vietnam (see Mant et al 2013) The

results are for illustrative purposes only, with a view to stimulating further work on estimating

and mapping biomass carbon stock density for REDD+ planning purposes in Vietnam The

example results here are not intended to promote any particular process or approach to

REDD+ in Vietnam The outputs cannot be applied as a basis for establishing reference levels

or to meet the detailed requirements for measuring, reporting and verification of greenhouse

gas emission reductions or enhanced removals under the National REDD+ Action Programme

Authors:

B Sharma

Participatory Forest Monitoring Advisor, SNV - The Netherlands Development Organisation,

San Francisco

Vu Tan Phuong

Director, Research Centre for Forest Ecology & Environment, Vietnam Forest Science

Institute, Hanoi

S Swan

Senior REDD+ Advisor, SNV - The Netherlands Development Organisation, Hanoi

Citation:

Sharma, B.D., Vu Tan Phuong & S.R Swan (2013) Generating Forest Biomass Carbon

Stock Estimates for Mapping the Potential of REDD+ to deliver biodiversity conservation in

Vietnam SNV – The Netherlands Development Organisation, Ho Chi Minh City.

3 SNV REDD+

Table of Contents

Acknowledgements 2

Abbreviations 4

Summary 5

1 Introduction 6

1.1 Aims 6

1.2 Scope 6

1.3 Review of forest biomass carbon stock estimation in Vietnam 6

2 Methods 8

2.1 Overview 8

2.2 Data availability 8

2.2.1 Wood volume estimation 9

2.2.2 Biomass expansion factors 9

2.3 Method used for Tier 2 type forest biomass carbon estimation 9

2.3.1 Forest stratification and area estimation 11

2.3.2 Estimation of forest biomass 11

2.3.3 Estimation of forest biomass carbon stock density 12

3 Results and Discussion 13

List of tables and figures: Table 1 Mean value of wood volume (m 3 ha -1 ) by forest strata in 2001-2005 8

Table 2 Biomass Expansion Factor for different forest types in Vietnam using 2001-2005 inventory data on wood volume 9

Table 3 Forest area by forest stratum in 2005 11

Table 4 Estimated biomass carbon stock by forest types in 2005 13

Figure 1 Simple methodological framework used to estimate forest biomass carbon densities Rectangles depict process while parallelograms depict specific outputs or inputs to these processes 10

Figure 2 Tier 2-type forest biomass carbon map for Vietnam, 2001-2005 14

Figure 3 Tier 1-type forest biomass carbon map for Vietnam, c 2000 15

Figure 4 Average land cover carbon density by 1 km pixel in Vietnam, 2000 16

Page

AGB above-ground biomass

BEF biomass expansion factors

BGB below-ground biomass

FAO Food and Agriculture Organisation

FIPI Forest Planning and Inventory Institute

FRA Forest Resource Assessment

FSIV Forest Science Institute of Vietnam

GHG greenhouse gas

GPG Good Practice Guidance

IPCC Intergovernmental Panel on Climate Change

LULUCF land use, land-use change and forestry

NFIMAP National Forest Inventory, Monitoring and Assessment Programme

NRAP National REDD+ Action Programme

RCFEE Research Centre for Forest Ecology and Environment

REDD+ Reducing emissions from deforestation and forest degradation, and

the role of conservation, sustainable management of forests and enhancement of forest carbon stocks in developing countries

5 SNV REDD+

This report presents a simple approach to estimating the biomass carbon stock density for

an area based on publicly available information such as timber volumes and forest area, as

applied in a recent effort to map the potential for REDD+ to deliver biodiversity conservation

in Vietnam The procedure presented here combines remote sensing products and forest

inventory data in deriving forest biomass carbon estimates as a contribution to prioritising

areas for future REDD+ activities under the National REDD+ Action Programme (NRAP)

The approaches used in deriving these estimates can also be replicated for smaller spatial

units, such as provincial or forest management unit levels, and could be extended to include

other forest carbon pools that have not been included in this study

A summary of methods used to estimate forest biomass carbon stock density in above - and

below - ground pools is presented for Vietnam for the period 2000-2005 The results, using

‘Tier 2’ national forest cover and wood volume datasets, estimated that in 2005, Vietnam’s

c 12 million ha of forest contained about 1.2 billion tonnes of biomass carbon, distributed

across 12 broad ecological forest types, at mean a stocking density of 105 tC ha-1 varying

considerably across forest types with lowest carbon stock density in bamboo forest and

highest in evergreen broadleaved forests

The forest carbon density maps produced by the methods reported herein were used to

explore the spatial relationship with the distribution of biological diversity in Vietnam This

preliminary analysis of REDD+ potential to deliver biodiversity conservation in Vietnam is

presented in a companion report (Mant et al 2013) as an example of mapping multiple

benefits of REDD+ to aid decision makers’ planning and prioritise actions and locations as

part of the NRAP

The methods used to derive forest biomass carbon estimate from publicly available

information presented here can be used to generate forest carbon estimates for smaller

geographical units such as for provinces, districts and forest management units by using

more accurate forest inventory data, specific wood density values and more accurate

root:shoot ratios as they become available

Summary

1.1 Aims

This report has been prepared to accompany the preliminary analysis of

mapping the potential for REDD+1 to deliver biodiversity conservation in Vietnam

(Mant et al 2013) The purpose of this report is to make publicly available the

methods and data sources used in estimating forest biomass carbon maps used

in this analysis of the spatial relationship between forest biomass carbon and

biodiversity in Vietnam The forest biomass carbon estimates used the latest

information publicly available in 2011, i.e the third cycle of the National Forest

Inventory, Monitoring and Assessment Programme (NFIMAP III - 2001 to 2005)

The method of biomass carbon stock estimation reported here can be used

with updated data in the future, i.e the 2006-2010 NFIMAP IV The approach

may also be used to assess the forest biomass carbon stock density at smaller

spatial scale such as provinces or individual forest management units

1.2 Scope

The estimation of forest biomass carbon stocks for carbon stock density

mapping in this report focus only on above-ground biomass (AGB) and

below-ground biomass (BGB) of live trees The other Intergovernmental Panel on

Climate Change (IPCC)-recognised carbon pools in the forest ecosystem -

dead wood, litter and soils - are excluded However, the methods illustrated

here can accommodate other carbon pool data in future estimates Indeed,

global soil carbon datasets were initially explored by this study as a contribution

to forest carbon stock estimates for Vietnam.A global map of terrestrial soil

carbon stocks (Scharlemann et al in prep.), based on up-to-date composite

datasets summarized in the Harmonized World Soil Database, was reviewed

but not incorporated with forest biomass carbon maps for Vietnam under this

study, since the coarse resolution of the global soil data would have obscured

the detailed spatial pattern for biomass carbon distribution obtained from the

national data NFIMAP III data biomass carbon (Mant et al 2013)

1.3 Review of forest biomass carbon stock estimation in

Vietnam

There are a few existing estimations of forest biomass carbon stock in Vietnam

The Vietnam National report on Greenhouse Gases (GHG) Inventory for

1994 (MONRE 2003), and the National Communication to the United Nation

Framework on Climate Change of 2000 (MONRE 2010) estimated emissions

in land use, land-use change and forestry (LULUCF) Since 2005, the Food

and Agriculture Organisation (FAO) of the United Nations has been providing

estimates for forest biomass carbon stock in its Forest Resource Assessment

(FRA) reports The Vietnam FRA Reports from 2005 and 2010 included an

estimate of forest biomass carbon stock Both these reports utilised approaches

1 Reducing emissions from deforestation and forest degradation in developing countries; and

the role of conservation, sustainable management of forests and enhancement of forest

carbon stocks in developing countries of the United Nations Framework Convention on

Climate Change.

1

7 SNV REDD+

following IPCC Good Practice Guidance (GPG) (IPCC 2006) for estimating biomass carbon

and used the suggested default values wherever relevant

At the start of the REDD+ readiness process in Vietnam, SNV created maps of forest

biomass carbon stock density as part of an initial attempt to map the potential for REDD in

Vietnam (Holland & McNally 2009) This analysis used the Vegetation Continuous Fields

remote sensing product to create maps of forest cover and forest cover change Forest

carbon maps were derived from an IPCC Tier 1 Global Biomass Carbon Map (Ruesch and

Gibbs 2000) to identify priority areas for REDD activities This report presented a biomass

carbon stock density map for all Vietnam for the first time, using a forest cover map from

2001 and 2005 (NFIMAP III) In 2009, Danish Technical Assistance in the Development

of the National REDD Programme of Vietnam also produced estimates of forest biomass

carbon (Raae et al 2010)

With respect to estimation of spatially explicit biomass carbon stock of planted forests in

Vietnam, there are several studies on forest biomass and carbon sequestration in Vietnam

These studies have mainly been implemented by the Forest Science Institute of Vietnam

(FSIV) Detailed biomass and carbon stock data for major plantations species i.e three pine

species (Pinus massoniana; P merkusii; and P keysia); three species of acacia (Acacia

mangium; A auriculiformis; A hybrid (mangium x auriculiformis); Eucalyptus urophylla; and

Mangletia glauca are available (Vu Tan Phuong 2010; Vo Dai Hai et al 2010) A few studies

on biomass and carbon stock have also been carried out in the Central Highlands, focussing

on estimation of biomass and carbon stocks for evergreen, semi-evergreen and deciduous

forests (Bao Huy et al 2012, and Vo Dai Hai et al 2013)

Studies to date offer limited information on forest biomass and carbon stocks in Vietnam’s

natural forests Biomass and carbon estimations are mostly based on coarse resolution data

resembling Tier 12 approach of the IPCC The values applicable in the Tier 1 approach are

generally not specific to Vietnam and may not be suitable for drawing inference on forest

carbon stocks for broader forest types because the default values used have large degrees

of uncertainty The maps produced by the present study used the most recent publicly

available forest cover information, and specific allometric relationships for different forest

types in Vietnam, to come up with a Tier 23 level estimate of forest carbon stock density

2 Tier 1 - approach employs the basic methods and default emission factors provided in the IPCC Guidelines

(Workbook and Reference Manual) A Tier 1 approach uses activity data that are spatially coarse, such as

nationally or globally available estimates of deforestation rates, agricultural production statistics, and global

land cover maps (IPCC 2006).

3 Tier 2 - approach can use the same methodological approach as Tier 1, but uses emission factors and

activity data that are defined by the country for the most important land uses/activities Higher resolution

activity data are typically used in Tier 2 to correspond with country-defined coefficients for specific regions

and specialised land-use categories (IPCC 2006).

2.1 Overview

2.2 Data availability

The first national forest inventory in Vietnam was started in 1991, and since then the

() has been implemented on a five yearly cycle Therefore, a good forest database

exists for the period of 1990 – 2010 However, the national forest inventory programme

in Vietnam was not primarily designed for forest biomass carbon stock estimation;

the focus of the forest inventory was on merchantable volume of wood and available

information may not be available for non-merchantable portion of trees, thus there are

challenges in deriving biomass carbon estimates comparable to a more detailed Tier

34 approach Therefore, for forest biomass carbon density mapping in Vietnam, a Tier

2 approach was targeted to maximize the use of country specific data Development of

biomass carbon stock for different forest types can use the national forest inventory data

that include mainly wood volume of different forest types It must also be noted that due

to unavailability of data, forest biomass carbon stock assessment considered only areas

covered by trees and excluded areas covered by shrubs, bushes and grasslands

2.2.1 Wood volume estimation

In the NFIMAP, there are a large number of permanent plots used for forest

monitoring For NFIMAP III (2001-2005) the volumes of wood in merchantable

tree stems, more commonly known as growing stock volume, for each of the

forest types were estimated from 4,100 sampling plots (Raae et al 2010) The

mean values of growing stock volume for each forest type are shown in Table 1

Table 1 Mean value of wood volume (m 3 ha -1 ) by forest strata in 2001-2005

Forest type Volume (m Growing Stock 3 ha -1 )

2 Medium evergreen broadleaved forest 157

4 Regrowth evergreen broadleaved forest 70

9 Mixed broadleaved and coniferous forest 137

Source: Adapted from Raae et al 2010 *The estimate of the growing stock volume of

bamboo was not available.

4 Tier 3 – approach uses models and inventory measurement systems tailored to address national

circumstances, repeated over time, and driven by high-resolution activity data and disaggregated

at sub-national to local scales These higher order methods provide estimates of greater certainty

than lower tiers and have a closer link between biomass and soil dynamics (IPCC 2006).

2

9 SNV REDD+

2.2.2 Biomass expansion factors

Stem volume is a useful proxy of biomass traditionally used in forestry A critical

requirement for estimating biomass carbon stock based on stem volume is to

develop biomass expansion factors (BEF) for different forest types The BEF serves

as substitute for the expansion ratios to calculate non-merchantable biomass (limbs,

small trees etc.) from tree biomass contained in merchantable stem volume BEFs

for different forest types were estimated from BEF and stem biomass relationship

developed by Brown (1997) (Eq 2) except for conifers, mixed broadleaved-bamboo

forests and bamboo forests For mixed broadleaved and conifer forest, default values

provided in IPCC (2003) were used, while BEF was not estimated for bamboo forest

The BEFs used for various forest types in Vietnam are shown in Table 2

Table 2 Biomass Expansion Factor for different forest types in Vietnam

using 2001-2005 inventory data on wood volume

Forest types BEF Remarks

1 Rich evergreen broadleaved forest 2.04 Estimated using

equation 2 developed by Brown (1997)

2 Medium evergreen broadleaved forest 2.60

3 Poor evergreen broadleaved forest 3.89

4 Regrowth evergreen broadleaved forest 3.90

7 Mixed wood-Bamboo forest 2.00 IPCC 2003 values (lower limit)

8 Coniferous forest 1.20 IPCC 2003 values (lower limit)

9 Mixed broadleaved and coniferous forest 2.78 Estimated using

equation 2 developed by Brown (1997)

2.3 Method used for Tier 2 type forest biomass carbon

estimation

The method to estimate forest biomass carbon used in this report is outlined in

Figure 1 The biomass carbon stock estimation process starts with the definition

of the spatial area of interest In this national-level study, the whole of Vietnam

was used Once the spatial boundary was defined, a review of available data on

biomass carbon stock density, forest area, forest types, root to shoot ratio, wood

density and carbon fraction was conducted

Figure 1 Simple methodological framework used to estimate forest biomass carbon

densities Rectangles depict process while parallelograms depict specific outputs or

inputs to these processes