sri-13 mei 2017-621 (Romnick - Ecological) rev layout.cdr

ECOLOGICAL SERVICES OF AGROFORESTRY LANDSCAPES
IN SELECTED WATERSHED AREAS IN THE PHILIPPINES

AND INDONESIA

ROMNICK S. BALITON , CHRISTINE WULANDARI , LEILA D. LANDICHO , ROWENA
1 2 3*

ESPERANZA D. CABAHUG , ROSELYN F. PAELMO , REYNALDO A. COMIA , ROBERTO G.
3 4 3

VISCO , PITOJO BUDIONO , SUSNI HERWANTI , RUSITA and ARNOLD KARL SA. CASTILLO
1 5 6 6 3

1
Institute of Renewable Natural Resources, College of Forestry and Natural Resources,

University of the Philippines Los Banos, College, Laguna 4031, Philippines
2
Graduate Program of Forestry, Universitas Lampung, Bandar Lampung 35141, Indonesia

3
Institute of Agroforestry, College of Forestry and Natural Resources,

University of the Philippines Los Banos, College, Laguna 4031, Philippines
4
Institute of Crop Science, College of Agriculture and Food Science,

University of the Philippines Los Banos, College, Laguna 4031, Philippines
5
Faculty of Social Science and Politic, Universitas Lampung, Bandar Lampung 35141, Indonesia

6
Forestry Department, Faculty of Agriculture, Universitas Lampung, Bandar Lampung 35141, Indonesia

Received 7 February 2016/Accepted 18 January 2017

ABSTRACT

This article argues that the practice of agroforestry provides ecological contributions to the smallholder farmers
cultivating in the watershed areas. Specifically, this farming system provides contribution to carbon sequestration
potential of the woody perennials and the biodiversity conservation of the other components of the system. This
argument is based on the research conducted in Molawin-Dampalit Sub-Watershed, Mt. Makiling Forest Reserve in
the Philippines and Way Betung Watershed in Indonesia. The research involved an interview session of 106 and 261
smallholder farmers and an assessment of 27 and 14 agroforesty plots for carbon stock assessment and biodiversity
assessment, respectively. Results indicated that the total carbon found among the crop components was 52.32 MgC/ha
in Molawin-Dampalit Sub-Watershed and 244.26 MgC/ha in Way Betung Watershed, which suggested the high
carbon sequestration potential of the woody perennials and understory crops in an agroforestry system. The farm lots
being cultivated by the smallholder farmers were found to contribute to biodiversity conservation having a moderate
biodiversity index of 2.59 and 2.53, respectively. With these findings, promotion of desired agroforestry systems in
suitable portions of the watershed areas should be intensified and heightened to contribute to ecological balance
across the landscape. Agroforestry should always be an integral part of all initiatives toward ecological restoration
with the cultivators/smallholder farmers as potential partners. The agroforestry system should consider all the
technical and socioeconomic considerations toward having diverse components and ensure food security among the
smallholder farmers throughout the year.

Keywords: Agroforestry, biodiversity index, carbon stock, Molawin-Dampalit Sub-Watershed, Way Betung
Watershed

BIOTROPIA 4 1 7 71 84 Vol. 2 No. , 201 : - DOI: 10.11598/btb.201 .2 . .7 4 1 621

* Corresponding author: ldlandicho@gmail.com

INTRODUCTION

Southeast Asia is among regions enlisted as
biologically rich and diverse. Three countries,
including Malaysia, Philippines and Indonesia, are
in fact cited as mega-diverse countries in the
region, being the homes of a number of plant and
animal species. At present, however, Southeast

Asia's biodiversity is highly threatened. Sodhi et al.
(2004) highlighted that the International Union
for the Conservation of Nature and Natural
Resources (IUCN) listed three plant and eight
animal species as already extinct in the region.
Furthermore, the authors emphasized that the
number of threatened species in Southeast Asia
including in the IUCN categories of critically
endangered (CE), endangered (EN) and
vulnerable (VU) ranges from 20 (CE) to 686 (VU)

BIOTROPIA Vol. 24 No. 1, 2017

crops, woody perennials and/or animals or
aquatic resources for the twin purpose of
production and conservation. Tolentino et al.
(2010) highlighted that the diversity of plants
used in agroforestry provides multiple benefits at
different times of the year. These diverse
combinations can help buffer its practitioners
from the risk of income loss due to price
variability, crop failure and other unanticipated
problems. Ecologically, agroforestry helps
enhance biodiversity of the environment. It is
expected that as the diversity of agroforestry
farms increases, farmers would have the
opportunity to make use of the flora-fauna
interaction to control pests and diseases, improve
microbiology and nutrient cycling. All these are
requisites for survival and improved plant growth.

This article highlights the respective
biodiversity and carbon sequestration potentials
of selected agroforestry landscapes in the
Molawin-Dampalit Sub-Watershed in the
Philippines and Way Betung Watershed in
Indonesia.

MATERIALS AND METHODS

Study Site

Way Betung Watershed has an area of 5,260
ha, 51% of which is classified as the forest park
area and the remaining 49% is classified as
agricultural areas (Fig. 1). Most of the upland
farmers are engaged in agroforestry, particularly

species for vascular plants, 6 - 91 species for fish,
0 - 23 amphibian species, 4 - 28 reptile species,
7 - 116 bird species and 5 - 147 mammal species
(Sodhi et al. 2004).

Biodiversity loss in Southeast Asia is attributed
to a number of factors, including deforestation or
clearing of the forest cover; conversion of
agricultural lands to other economic purposes;
natural calamities such as El Niño, extreme
weather events, climate change, forest fires;
continued dependence on forest resources as
livelihood of the growing population; and,
invasive species. These all boil down to the rapid
ecological, social and economic changes that the
world faces. Most often, the forest dwellers are
accused as culprits of the biodiversity loss because
of their continued dependence on the forest
resources for economic and livelihood activities.

Two of the most popular watersheds in
Southeast Asia are the Molawin-Dampalit Sub-
Watershed located inside the Mt. Makiling Forest
Reserve (MMFR) in the Philippines and the Way
Betung Watershed in Indonesia. Besides being
the habitat of different flora and fauna, both
watersheds have similar conditions such that they
are both forest reserves, and therefore, should be
free from human occupancy. While policies for
the protection, preservation and conservation of
these two watersheds are being imposed by their
respective governments, these areas continue to
be the homes of a number of upland farmers and
migrants.

Agroforestry is a land use management system
which combines the production of agricultural

Figure 1 Map of Way Betung Watershed, Lampung, Indonesia

Ecological services of agroforestry landscapes in watershed areas – Baliton et al.

Figure 2 Map of the MMFR highlighting the Molawin-Dampalit Sub-Watershed as the study site in the Philippines

combining the major fruit tree species such as
durian, mangosteen, jackfruit, integrated with
cacao, coffee, rubber and other forest trees such as
mahogany, Alstoria and other forest species.
The MMFR in the Philippines, on the other
hand, is a 4,244-ha multiple use forest reservation
area (Fig. 2). According to Sargento (1995),
MMFR is a protection forest and a watershed
reserve, specifically used for training and research
laboratory, water source for surrounding
communities, biological sanctuary and gene pool
of many plant and animal species. This reserve,
however, has become a home to a number of
farmers and migrants who are engaged in farming.
These farmers practice agroforestry, particularly
the multi-storey system which combines the
production of coconut, fruit trees and other
agricultural cash crops.

Socioeconomic Characterization

The characterization was carried out using a
p r e - t e s t e d s u r v e y q u e s t i o n n a i r e . T h i s
q u e s t i o n n a i r e c a p t u r e d s o c i o e c o n o m i c
information, views and perceptions about
agroforestry practices. A total of 106 respondents
in Molawin-Dampalit Sub-Watershed and 261
respondents in Way Betung Watershed were
selected using random sampling. Results of the
socioeconomic survey were analyzed using
descriptive statistics, such as frequency counts,
percentages and weighted scores.

Biodiversity Assessment

The assessment was conducted by measuring
the following parameters of biodiversity, i.e.
population density or the number of individual
species per unit area; frequency of species
distribution; dominance value based on
frequency, diameter or biomass; relative and
importance values based on density and
frequency; and diversity and evenness indices
based on the relative and importance values.
Importance value (IV) was computed to
determine the dominant species for each site.
The IV is the sum of the relative density,
relative frequency and relative coverage. These
values were computed using the following
formula:

Total Area Sampled

Total Number of tree individuals counted per species
Density =

100*

Relative Density
Total Number of all Species

Total Number of tree individuals counted per species
=

Species Dominance
2

(DBH)*(0.7854)=

Relative Dominance 100*
Dominance of a Species

Total Dominance of all Species
=

100*
Total Number of Plots

Number of Plots species occur
=Species Frequency

100*
Total Frequency of all Species

Frequency of a species
Relative Frequency =

Importance Value =�Relative Density + Relative Coverage +�Relative Frequency

BIOTROPIA Vol. 24 No. 1, 2017

S
H= ∑ - (Pi * ln P i)

i=1

J = ______
ln S

The measures of biodiversity were obtained
using the Shannon-Wiener Diversity Index (H)
(Magurran 2004) calculated using formula as
follows:

The Pielou's Evenness Index (J) was calculated
using formula:

where: H = Shannon-Wiener diversity index
J = Pielou's Evenness Index
P = fraction of the entire population made up of i

species i
S = total numbers of species encountered
∑ = sum from species 1 to species S

Note: The power to which the base e (e = 2.718281828.......)
must be raised to obtain a number is called the natural
logarithm (ln) of the number

The index was calculated by dividing the
number of individuals of each species found in
the sample by the total number of all species
(represented by P), multiplied by the fraction of its
natural log (P * ln P ). This procedure was 1 1
repeated for all of the different species. The sum
of all the (P * ln P ) represents the value of H. 1 1
Physical evidences of the movement of wildlife in
the agroforestry matrix were noted in terms of
frequency, duration and kind of species.

Carbon Stock Assessment

The carbon stock of different agroforestry
systems was measured using the biomass
estimation method. Tree biomass was calculated
using the allometric equation of Brown (1997)
(Equation 1). This was done by measuring the
standing aboveground biomass of the woody
perennials or live trees with Diameter at Breast
Height (DBH) of 5 cm and above. The total tree
biomass density and carbon stored in various
agroforestry systems were calculated using
Equation 2. Carbon stock of herbaceous (living
non-perennial crops) and litter found in the soil
surface was calculated to get the total
aboveground biomass of each agroforestry
system (Equation 3). Belowground biomass of
trees and other perennials was obtained using the
default value proposed by Delaney (1999) i.e. 15%
of the aboveground biomass.

Equation 1:

TAGB= - exp(2.134+2.530 ln(DBH))

where:
TAGB = total aboveground biomass in kg/tree
exp {…} = “raised to the power of ”
ln = natural log of {…}
DBH = Diameter at Breast Height in cm

Equation 2:

C stored (MgC/ha) = Tree biomass density *C content

Tree biomass density = Tree biomass (Mg)/Sample area in hectare

Equation 3:

Total fresh weight (kg) * Subsample dry weight (g)
2 ______________________________________Total Dry Weight (kg/m ) =

2
Subsample fresh weight (g) * Sample area (m )

C stored (MgC/ha) = Tree biomass density *C content

RESULTS AND DISCUSSION

Socioeconomic and Biophysical
Characteristics of the Study Sites

Way Betung Watershed and Molawin-
Dampalit Sub-Watershed are considered as
watershed and forest reserves, which are
inhabited by a number of people. Results of the
socioeconomic characterization indicated that
most of the farmers in the two study sites were
male as represented by 73% of the total number
of respondents (Table 1). This finding validated
previous research which concluded that, in
general, farming had become a male-dominated
activity (Landicho et al. 2014; Landicho, 2015).
Majority (86%) of them were married with
an average household size of 5. Majority (51%)
of the participants had family members
ranging from 4 - 6 members. Concurrent
with other research, this finding implied the
availability of family labor and that the farm
households in the upland communities were
mostly big.
Table 1 also highlights that the age of farmers
in the two study sites were entirely different. The
age range of the farmers in Molawin-Dampalit
Watershed was from 51 to 60. This data suggested
that despite their age, the farmers were able to
maintain their current far ming systems.
However, this finding also presented threat on
the sustainability of their farming system,
especially considering that not all family members

Table 1 Socioeconomic characteristics of the farmer-respondents in Molawin-Dampalit Sub-Watershed and Way Betung
Watershed

Socioeconomic characteristic

Study site Total %

Molawin-Dampalit Way Betung

Frequency % Frequency %

Sex

Male 63 59 204 78 267 73

Female 43 41 57 22 100 27

Subtotal 106 100 261 100 367 100

Civil status

Single 9 9 5 2 14 4

Married 80 75 237 90 317 86

Separated 2 2 1 1 3 1

Widow/er 14 13 18 7 32 9

No answer 1 1 0 0 1 0

Subtotal 106 100 261 100 367 100

Household size

1-3 40 38 87 33 127 35

4-6 41 39 147 56 188 51

> 6 23 22 27 10 50 14
No answer 2 1 0 0 0
Total 106 100 261 100 367 100
Average

Age
< 30 8 32 40 11
30-40 12 93 105 29
41-50 24 83 107 29
51-60 29 42 71 19
> 60 33 11 44 12
Subtotal 106 100 261 100 367 100
Average 54 43

Number of household members involved in farming
1-3 101 96 164 63 265

72
4-6 4 4 37 37 41

27
> 6 1 1 0 0 1

00.27

Subtotal 106 261 367 100

Income source
Farming 44 41 214 82 258

Off-farm 0 0 27 10 27
7

Non-farm 2 2 20 8 20
5

Farming+Off-farm 2 2 0 0 2
1

Farming+Non-Farm 52 49 0 0 52
14

Farming +Off-farm+

Non-Farm

Subtotal

106

100

261

100

367

100

Ecological services of agroforestry landscapes in watershed areas – Baliton et al.

Table 2 Biophysical characteristics of the farms being cultivated by the farmer-respondents in Molawin-Dampalit Sub-
Watershed and Way Betung Watershed

Biophysical characteristic

Study site Total %

Molawin-Dampalit Way Betung

Frequency %
Frequency %

Farm size
< one hectare 51 44 149 57 200 54
1-3 45 46 111 42 156 43
3.1-5 6 6 1 1 7 2
> 5 4 4 0 0 4 1
Total 106 100 261 100 367 100

Status of farm ownership
Owned 9 8 0 0 9 2
Tenant 19 18 17 7 36 10
Rented 1 1 0 0 1 1
In public lands 70 66 244 93 314 85
No answer 7 7 0 0 7 2
Total 106 100 261 100 367 100
Farm topography
Rolling 48 45 132 51 180 49
Steep 10 9 57 22 67 18
Flat 31 29 72 27 103 27
Flat to rolling 16 15 0 0 16 15
No answer 1 1 0 0 1 1

Total

106

100

261

100

367

100

Source of water for crop irrigation
Spring 12 11 60 23 72 19
River/Creek

Rainfed

166

640

251

Others (e.g. irrigation)

Total

108

100

261

100

369

100

BIOTROPIA Vol. 24 No. 1, 2017

were trained to develop and maintain their farms.
On the other hand, the farmers in Way Betung
were still young and most probably in their
productive age, as majority of them fell within the
age range of 31 - 40 years old. This finding
suggested that these farmers could already be
the second-line farmers. These young farmers
might have already been trained by the older
farmers, and/or farming may have just started
recently in Way Betung Watershed. Furthermore,
this data indicated that these young farmers would
have higher opportunities for improving their
farms.
There were only 1 - 3 members of the family
that were engaged in farm development activities.
In most cases, though, only the husband and the
wife concentrated in farming. It could be that
their children were still young; busy in their
schooling, or not interested in farming at all.

While farming was the major source of income of
most (70%) of the farmer-respondents, there
were also households whose members were
engaged in non-farm activities as an additional
source of income. In general, farm income was
relatively low with most of the respondents
having an estimated farm income of less than
USD 200 and USD 200 - 500 in the Philippines
and Indonesia, respectively. The low farm income
could be attributed to the biophysical conditions
of their farm as well as the scope and orientation
of their agricultural production.
In general, farm lots in the two study sites were
cultivated by smallholder farmers. This was
because majority (54%) of the far mer-
respondents in the two study sites cultivated lands
which were less than a hectare (Table 2). This
farming practice provided them with an estimated
annual income of less than USD 200 (Table 1).

Table 3 Agricultural production systems being employed by the farmer-respondents in Molawin-Dampalit Sub-
Watershed and Way Betung Watershed

Production system

Frequency Total %

Molawin-Dampalit Way Betung

Frequency % Frequency %

Cropping system
Monocropping 7 7 1 0.40 7 2
Crop rotation 3 3 0 0 3 1
Relay cropping 4 4 0 0 4 1
Multiple cropping 43 42 31 12 74 20
Agroforestry 45 43 229 87.6 274 77
Forest plantation

Total

106

100

261

100

367

100

Crop components

Vegetables

Rice

0.30

0.17

Corn

Root crops

16.7

Fruit trees

101

192

73.56

293

Herbs

0.33

Ornamentals

Forest trees

26.44

134

Total

333

100

261

100

594

100

Understandably, these farmers could not cultivate
big farm sizes primarily because they were
cultivating in the public/state lands. Thus, they
were bound with certain rules and policies in their
agricultural production. Most (85%) of the
farmer-respondents did not own the lands that
they cultivated, and therefore, agricultural
expansion was not possible.
Smallholder farmers are described as those
who cultivate less than three hectares of land area
(ESFIM ). By this definition, farmers in 2017
the two study sites are categorized as smallholder
farmers. While their production orientation was
for subsistence, the surpluses were sold in the
market for their additional household income.
Besides being smallholder far mers, the
biophysical characteristics of their farms were
characterized as marginal. The topography was
generally rolling (49%) and some with steep slopes
(18%) and, therefore, the risk of soil erosion was
high. However, the risk was being controlled with
the practice of sustainable farming system, such
as agroforestry. Crops are generally dependent on
rainfall as the main source of water/irrigation.

Thus, any drastic changes in rainfall and
temperature patterns greatly affect their
agricultural production.

Agroforestry Practices in the Two Study Sites

With the prevailing biophysical and
socioeconomic conditions, the far mer-
respondents were observed to maximize the land
use of their farms. Most of the farmer-
respondents were engaged in agroforestry (77%)
and multiple cropping (20%) across the
landscapes in the two study sites (Table 3).
The practice of agroforestry was noted in the
high-elevation areas, while multiple cropping was
highly observed in relatively lower elevation
across the two landscapes. This was because the
study sites were mostly dominated by forest and
fruit trees. Thus, opening of areas to give way for
the production of agricultural crops was not
permitted. Farmers whose farms were located
within the upper stream of the reserves/
watershed planted other woody perennials with
smaller canopy, root crops and other shade-

Ecological services of agroforestry landscapes in watershed areas – Baliton et al.

BIOTROPIA Vol. 24 No. 1, 2017

tolerant crops as understory. On the other hand,
farmers cultivating in open areas having lower
elevation had higher opportunities for raising
short-term and medium-term crop species.
Farmer-respondents in Molawin-Dampalit
Sub-Watershed planted a variety of crop
components compared with the far mer-
respondents in Way Betung Watershed who
planted only fruit trees (Table 3). Among crop
components included vegetable crops (16%), fruit
trees (30%), root crops (17%), cereals like rice and
corn (4.34%), forest trees (19%) and ornamentals
(19%).
Farmers in the Molawin-Dampalit Sub-
Watershed might have enough open spaces where
they could plant short-term crops, while farmers
in Way Betung Watershed might have shaded
spaces, which might not be suitable for cultivating
short-term agricultural crops. Furthermore,
almost 100% of the farmlands in Way Betung
Watershed were considered as public lands, which
made the farmers bound with policies and
regulations on crop cultivation (Table 2).
Farmlands in Molawin-Dampalit Sub-Watershed
were bound for forest reserve. Farmlands located
in the lowland ecosystems were still suitable for
appropriate agricultural production.

Biodiversity Assessment

Species composition in the two watersheds

A total of 35 tree species with at least 5 cm
DBH were found across the 27 sampling plots in
Molawin-Dampalit Sub-Watershed (Table 4).
These identified species consisted of 333
individuals belong to 19 tree families. The data
revealed that Fabaceae had the highest number of
species (6), followed by Moraceae (5) and
Meliaceae with three (3) species. Annonaceae,

th
Malvaceae and Sapindaceae ranked 4 having two
(2) species each, while the remaining families had
one (1) species each. In terms of the total number
of individuals, the dominant families recorded
were Meliaceae with a total of 90, followed by
Musaceae (84), Sapindaceae (50) and Fabaceae
(30). Four families namely Euphorbiacea,
Lamiaceae, Oxalidaceae and Sapotaceae ranked
the least with only one individual recorded across
the sampling areas.
In Way Betung Watershed, there were 14
families and 26 species, with 548 individuals
found (Table 5).
The highest number of species belongs to
family Fabaceae having six (6) species, followed
by Myrtaceae, Meliaceae and Arecaceae. Family

Table 4 Summary of existing tree families with corresponding number of species and individuals in Molawin-Dampalit
Sub-Watershed

Family name

Number of species

Number of

individuals

Rank

# of species

# of individual

Anacardiaceae

1 8 5 8
Annonaceae

2 7 4 9

Arecaceae

1 9 5 7
Bignoniaceae

1 2 5 12

Caricaceae

1 6 5 10
Euphorbiaceae

1 1 5 13

Fabaceae

Fagaceae

Lamiaceae

Lauraceae

Malvaceae

Meliaceae

Moraceae

Musaceae

2
Oxalidaceae

13
Rubiaceae

11
Rutaceae

11
Sapindaceae

3
Sapotaceae

Total 35 333 -- --

Table 5 Summary of existing tree families with corresponding number of species and individuals in Way Betung Watershed

Family name Number of species
Number of
individuals

Rank

# of species # of individual

Anacardiaceae 1 2 4 10
Arecaceae 3 9 2 9
Euphorbiaceae 1 161 4 1
Fabaceae 6 27 1 5
Gnetaceae 1 35 4 4
Lauraceae 1 16 4 7
Malyaceae

Malvaceae

154

Meliaceae

Myrtaceae

Rubiaceae

Rhamnaceae

Sapindaceae

Sapotaceae

Total

548

Euphorbiaceae had the highest number of
individuals (161), followed by Malvaceae and
Malyaceae.
These findings indicated a higher general
species composition in Molawin-Dampalit Sub-
Watershed compared to that in Way Betung
Watershed. However, the number of individual
species in Molawin-Dampalit Sub-Watershed was
lower compared to that in Way Betung Watershed.
This could be explained by the fact that the
Molawin-Dampalit Sub-Watershed was one of
the area severely hit by Typhoon Glenda
(International name Rammasun) in 2014. This
could explain why, at the time of the study, the
floral components were still on their regeneration
stage, mostly below 5 cm DBH.

Importance Value of identified plant species in
agroforestry landscape

Across the sampling plots of Molawin-
Dampalit Sub-Watershed, banana (Musa
sapientum) was found to be the most dominant
having the highest Importance Value (IV) of
62.07%. It was followed by rambutan (Nephelium
lappaceum) and lanzones (Lansium domesticum) with
IV of 36.47% and 32.59%, respectively. Other
species having high IV were chico (Manilkara
sapota) – 25.66%, mangga (Mangifera indica) –
21.58% and mahogany (Swietenia macrophylla) –
18.79% . Table 6 shows the summary of seven (7)
dominant plant species with the highest IV.
The dominance of banana, rambutan and
lanzones in Molawin-Dampalit Sub-Watershed

Table 6 Top seven dominant species across sampling plots in Molawin-Dampalit Sub-Watershed, Mt. Makiling Forest
Reserve, Philippines

Species name Scientific name
Importance Value (IV)

(%)

Saging Musa sapientum 62.07
Rambutan Nephelium lappaceum 36.47
Lanzones

Lansium domesticum

32.59

Chico

Manilkara sapota

25.66

Mangga

Mangifera indica

21.58

Mahogany

Swietenia macrophylla

18.79

Durian Durio zibethinus 12.00

Ecological services of agroforestry landscapes in watershed areas – Baliton et al.

BIOTROPIA Vol. 24 No. 1, 2017

indicated the farmers' preference for cultivating
these crops, primarily because of their economic
value.
Meanwhile, this research found out that the
dominant tree species in Way Betung was rubber
tree (Hevea brasiliensis) with IV of 70.36%,
followed by durian, cacao, melinjo, petai, avocado
and coffee. Based on the IV, the dominance level
of a species in a community can be known
(Indriyanto 2006). Table 7 shows the top seven
dominant species across the sampling plots in Way
Betung Watershed. Rubber tree is one of the
major high value crop that is being cultivated in
Indonesia, Malaysia and Thailand because of its
economic potential. This explains why this species
was frequently found in Way Betung Watershed.

Shannon-Wiener diversity index (H) and
Pielou's Evenness Index (J) across sampling plots
in Molawin-Dampalit Sub-Watershed was 2.59
and 0.45, respectively (Table 8).
Sampling plots in Way Betung Watershed
recorded Shannon-Wiener Diversity Index (H)
of 2.53 and Pielou's Evenness Index (J) of 0.41.
Based on the H value, diversity of the
agroforestry landscape in Molawin-Dampalit
Sub-Watershed and Way Betung Watershed was
considered to be moderate (Fernando et al. 1998)
(Table 9).
The computed Shannon-Wiener diversity
index (H) indicated that employing an
agroforestry practice/system in a landscape may
increase the diversity of the landscape compared

Table 7 Top seven dominant species across sampling plots in Way Betung Watershed, Indonesia

Species name Scientific name
Importance Value (IV)

(%)

Rubber Hevea brasiliensis 70.36

Durian Durio zibethinus 59.72
Cacao Theobroma cacao 48.07
Melinjo

Gnetum gnemon

22.54

Petai

Parkia speciose

12.46

Avocado

Persea americana

12.14

Coffee

Coffea robusta

8.87

Table 8 Shannon-Wiener Diversity Index and Pielou's Evenness Index across sampling plots in the two study sites

Main plot Molawin-Dampalit Sub-Watershed Way Betung Watershed

Circular Plot: 8.9 m Radius

H 2.59 2.53

J 0.45 0.41

Table 9 Classification scheme of Shannon-Wiener Diversity Index (Fernando et al. 1998)

Relative value
Shannon-Wiener
Diversity Index

(H)

Very high 3.50 and above
High 3.00 – 3.49
Moderate 2.50 – 2.99
Low 2.0 – 2.49
Very low

1.99 and below

to employing monoculture type of farming
system. Meanwhile, low value of computed
Pielou's Evenness index (J) indicated that the
number of individual per species in the
agroforestry landscape was not evenly distributed.
This finding was validated by Noble and
Dirzon (1997) who highlighted that agroforestry
is increasingly being identified as an integrated
land use that can directly enhance plant diversity
while reducing habitat loss and fragmentation
(Brent et al. 2006). Khanal (2011) also contends
that traditional agroforestry practices contribute
to the conservation of biodiversity in the western
hills of Nepal through in-situ conservation of tree
species on farms, reduction of pressure on
remaining forests, and the provision of suitable
habitat for a number of plants on farmland. This
contention was supported by meta-analysis on the
effects of agroforestry, biodiversity levels and
ecosystems services conducted by Torralba et al.
(2016). Torralba et al. (2016) argued that agro-
forestry can enhance biodiversity and ecosystem
service provisions related to conventional
agriculture and forestry in Europe. Furthermore,
agroforestry can help the flow of wild plants’

genes as well as increase fauna population size and
diversity in protected area corridors, if it is tried as
a buffer to connect patches of natural forests to
facilitate habitat interconnectivity on a larger scale
(Baguinon et al. 2007).

Carbon Stock Assessment
Biomass density of agroforestry landscape

A mean total of 116.26 Mg/ha was recorded in
the agroforestry landscape of Molawin-Dampalit
Sub-Watershed (Table 10).
The computed mean total biomass density in
this study site was higher than the overall mean of
agroforestry (102.80 Mg/ha) in the Philippines
(Lasco & Pulhin 2003). Another study of
Zamora (1999) on biomass density of narra
(Pterocarpus indicus) + cacao agroforestry system
in Makiling (191.6 Mg/ha) was also comparable
with the results obtained in this study.
It can be noted that sampling plots in Way
Betung Watershed were mostly forest and fruit
trees which in turn contributed much on the
biomass density with a mean total value of 542.80
Mg/ha. This was comprised mostly of 86.12%

Table 10 Biomass density (Mg/ha) of agroforestry landscape in Molawin-Dampalit Sub-Watershed and Way Betung
Watershed

Item

Biomass density (Mg/ha)

Aboveground Belowground
Mean
total

Trees and other
perennial

Herbaceous Litter
Trees and other

perennial
Molawin-Dampalit

Minimum

1.98

0.27

0.34

0.30

116.26

Maximum

401.83

2.31

7.45

60.27

Mean (µ)

97.87

(84%)

1.33

(1%)

2.38

(2%)

14.68

(13%)

Standard deviation (±)

91.76 0.73 2.07 13.76

# of Sample plots (n)

27 27 27 27

Way Betung

Minimum

168.74

1.58

1.78

25.31

542.80

Maximum

1,160.17

2.31

4.22

174.03

Mean (µ)

467.47
(86.12%)

1.81
(0.33%)

3.40
(0.63%)

70.12
(12.92%)

Standard deviation (±)

242.10

0.17

0.59

36.31

# of Sample plots (n) 14

Note: Values shown inside the parenthesis are the percentage compositions of different carbon pools

Ecological services of agroforestry landscapes in watershed areas – Baliton et al.

BIOTROPIA Vol. 24 No. 1, 2017

Item

Carbon density (MgC/ha)

Aboveground Belowground

Mean total Trees and other
perennials

Herbaceous Litter
Trees and other

perennials

Molawin-Dampalit

Minimum

0.89

0.12

0.15

0.13

52.32

Maximum

180.82

1.04

3.35

27.12

Mean (µ)

44.04
(84%)

0.60
(1%)

1.07
(2%)

6.61

(13%)
Standard deviation (±)

41.29

0.33

0.93

6.19

# of Sample plots (n)

27 27 27 27

Way Betung

Minimum

75.93

0.71

0.80

11.39

244.26

Maximum 522.08 0.96 1.90 78.31

Mean (µ)

210.36
(86.12%)

0.82
(0.33%)

1.53
(0.63%)

31.55
(12.92%)

Standard deviation (±)

108.94

0.08

0.27

16.34

# of Sample plots (n) 14

Table 11 Carbon stored in agroforestry landscape of Molawin-Dampalit Sub-Watershed and Way Betung Watershed

Note: Values shown inside the parenthesis are the percentage compositions of different carbon pools

from the trees and other perennials, while the
lowest was recorded in herbaceous and litter with
less than 1%. These results were consistent with
the previous study conducted by Wulandari (2013)
in watershed areas in Indonesia.
Biomass density of the agroforestry landscape
varied considerably in all carbon pools measured
as indicated by high values of standard deviation.
Huge variation in the biomass density could be
attributed to the differences of the components
of sampled agroforestry or farming systems.
Based on the characterization of the farms, there
were some farmers who cultivated fruit trees as
their main crop which contributed much to the
biomass density. Other farmers planted only few
fruit trees. In addition, farming practices
influenced the amount of biomass density of the
herbaceous and litter pool, such as weeding and
composting. These practices reduced the amount
of herbaceous/undergrowth biomass in the area.
Some farmers were doing these practices, while
others were not.

Carbon stock of agroforestry landscape

The aboveground tree and other perennial
crops (84%) ranked first in terms of percentage

contribution to mean total carbon density of the
area. It is followed by belowground tree and other
perennial with 13%, then litter (2%) and
herbaceous plants provided the least percentage
contribution with 1% (Table 11).
The computed mean total carbon stock (52.32
MgC/ha) was comparable to the overall mean
carbon density of secondary forests in the
Philippines (59.0 MgC/ha) as reported by Lasco
and Pulhin (2003). A study of Palma and
Carandang (2014) reported a higher mean carbon
stock (92.78 MgC/ha) of an agroforestry system
in Misamis Oriental. Results of these studies
already included soil carbon content in the
analysis, while this research only focused on the
total above and belowground biomass. Inclusion
of the soil carbon pool could significantly
increase the carbon stock due to high
concentration of carbon in the soil.
Expectedly, the computed mean total carbon
density of Way Betung Watershed was higher than
that of the Molawin-Dampalit Sub-Watershed.
Carbon density in Way Betung was 244.26
MgC/ha, which was almost four (4) times bigger
than that in Molawin-Dampalit (52.32 MgC/ha).
The huge difference could be directly attributed

to the abundance of tree in agroforestry systems
in Indonesia. Therefore, this research also
validates the argument that agroforestry is a cost-
effective strategy for climate change mitigation,
particularly the tree-based farming systems.

CONCLUSIONS

Agroforestry farms and practices contribute to
the conservation and protection of the Way
Betung Watershed and Molawin-Dampalit Sub-
Watershed. Diverse crop components in the
agroforestry farms, including their interaction,
promote biodiversity conservation in these
watershed areas, both yielding a moderate level of
diversity index. Woody perennials, herbaceous
crops and litter components of the agroforestry
farms contribute to carbon sequestration by
having carbon stock of 244.26 MgC/ha in Way

Betung Watershed and 52.32 MgC/hain Molawin-
Dampalit Sub-Watershed. These ecological
ser vices are significant contributions of
agroforestry to climate change mitigation.

IMPLICATIONS AND
RECOMMENDATIONS

Agroforestry farming practices provide
ecological contributions, particularly in carbon
sequestration and biodiversity conservation.
These contributions of agroforestry practices
a l r e a d y o f f e r p o t e n t i a l s i n a d d r e s s i n g
environmental degradation in many upland
communities in Southeast Asia.
It is necessary to promote the use of
agroforestry as a production technology of the
government and/or non-government programs
on sustainable forest management and upland
development. Such programs or policies should
put emphasis on the use of fruit tree-based
agroforestry system to avoid further opening or
clearing of forested areas in higher and mid-
elevation areas. The use of fruit tree-based
system can enhance the use of soil and water
conservation measures and other supportive
technologies to control soil erosion and
degradation particularly in high-elevation areas.
Results of carbon stock assessment of various
agroforestry systems can provide information on
national Green House Gas (GHG) inventory

which is mandated to the committed parties
including the Philippines in the United Nations
Framework Convention on Climate Change
(UNFCCC).
Future research should dwell on analyzing the
effects and contribution of each of the different
types and variants of agroforestry systems to
b i o d i ve r s i t y c o n s e r va t i o n a n d c a r b o n
sequestration. This kind of research would
generate empirical data that would guide
researchers, extension workers and policy makers
the most appropriate type of agroforestry system
that should be scaled-up among the upland
farming communities.

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