105

Recent Forest and Peat Fire Trends in Indonesia
The Latest Decade by MODIS Hotspot Data
Nina YULIANTI1, Hiroshi HAYASAKA1* and Aswin USUP2
1

Graduate School of Engineering, Hokkaido University
N13, W8, Kita-ku, Sapporo 060-8628, Japan
2
University of Palangka Raya, Indonesia*e-mail: hhaya@eng.hokudai.ac.jp

Abstract
The worse air pollution due to haze from fires occurred in the Southeast Asia during the strongest
1997-1998 El Niño event in the last century. The dense haze came from forest and peat fires mainly occurredin Indonesia. Recent fires in Indonesia have become an annual phenomenon nevertheless rapid deforestation
rate showed declined trend. In addition, Indonesia formally admitted very large amount of CO2 emission
mostly from fires and deforestation (about 3.01 billion tonnes after the United States). Indonesia is now
requested to reduce air pollution due to haze and carbon emissions at the same time. For an execution of
REDD+ (Reducing Emissions from Deforestation and Forest Degradation plus) in Indonesia, it is alsoessential to develop an effective firefighting strategy.
In this paper, recent hotspot data captured by NASA MODIS from 2002 to 2010 was analyzed to grasp
the recent fire trend in the whole Indonesia. As Indonesia is not so small country, various grid sizes utilizing
latitude and longitude angles from 1x1 to 0.01x0.01 degrees were used for various analysis purposes. Analysis
results using one degree grids clearly showed the highest hotspot density areas in Indonesia located in
Kalimantan and Sumatra Islands. Among them, One of the Mega Rice Project (MRP) regions (grid center:
south latitude 3o, east longitude 114o) showed extremely high hotspot density, 0.188 hotspots/km2/year. Tworegions in Riau and South Sumatra of Sumatra Island followed the MRP area and their hotspot densities were0.111 and 0.106 hotspots/km2/year, respectively. Other high hotspot density regions were mostly found in
deforested area on peat. Analysis results on seasonality of peat fire showed strong correlation with El Niño
event. Finally, the authors are now proposing an effective fire forecast method based on recent fire trend inIndonesia.
Keywords: CO2, haze, hotspot, hotspot density, MODIS, MRP, peat fire, REDD+

1. Introduction
The total land area of Indonesia is 1,910,931km2 (BPS,2010), almost 50% (~940,000km2) cover tropical forest
areas which enable carbon sequestration of about
25,500Mt (FAO, 2010; Gibbs et al., 2007) and, partiallyoverlapping, approximately 11% (~200,000km2) coverpeatland areas with a carbon storage of about 55,000Mt(Page et al., 2011; Hooijer et al., 2006). Deforestation
activities have contributed to a loss of 30% of tropicalforests in Indonesia since 1950s, including for instance,
the Mega Rice Project (MRP) which converted a large
peat swamp forest (PSF) in the southern part ofKalimantan (>10,000km2) in the mid-1990’s (FWI/GWF,
2002; Broich et al., 2011; Hansen et al., 2009). Other
deforested areas of Indonesia were created from 1985 to2009, which did not include PSF areas (Fig. 1). The
deforestation rate for Indonesia declined from the 1.75%
Global Environmental Research
16/2012: 105-116
printed in Japanfor the 1990s to 0.51% in the 2000s (FAO, 2010). However, one of the adverse effects of deforestation on theenvironment was the uncontrolled forest and peat fires
that occurred prior to the period of 2010.
The worst air pollution due to haze from fires inSoutheast Asia history, occurred during the strongest the
El Niño event of 1997-98, which was the strongest El
Niño event on record prior to 2011, The dense hazecausing this air pollution was released mainly from forestand peat fires in Indonesia (Heil et al., 2006). Page et al.
(2002) estimated that 810 - 2,570Mt carbon was emitted
during the high fire incidence in 1997. Since then, recurring fires in Indonesia have become an annual phenomenon (Langner & Siegert, 2009; Putra et al., 2008; Pageet al., 2009) although the rate of deforestation is declining. The assessment of the Carbon Dioxide Analysis
Center (CDAIC) showed the total CO2 emissions forIndonesia in 2008 was 406,029Mt, an increase of about©2012 AIRIES106

N. YULIANTI et al.

Fig. 1 Peat, forest, and deforested area distribution map for Indonesia.
(Map data derived from GWI/GFW, FAO, Wetland, and BAKORSURTANAL)

280% over the 1990s. This figures includes emissions
from fuel consumption, deforestation, and forest fires(UN Statistics, 2011). Further, Indonesia has formallyadmitted to being the source of emissions of very large
amounts of CO2, mostly from fires and deforestation.
Thus Indonesia remains as one of the top carbon emitters,
after China and US.
The government of Indonesia is preparing methodology and policies for the REDD+ (Reducing Emissions
from Deforestation and Forest Degradation plus) program, which started in 2009 (Ministry of Forestry, 2011).
Fires and emissions of CO2 are clearly a serious challenge for the future implementation of the REDD+ program in Indonesia. Under REDD+, Indonesia should beenhancing carbon storage and decreasing carbon emissions especially from annual fires. To achieve theREDD+ goals, a comprehensive study related of fires andfire characteristics which considering local fire trends in
different fire prone areas of Indonesia is necessary.
Several papers related to vegetation fires in the worldusing MODIS hotspot data have been published.
Wildland fires in the Asian region have also been analyzed by many researchers. Asian vegetation fire trends
were identified by using fire statistics of individual
countries, monthly fire occurrence of the Asian regions,and so on (Vadrevu & Justice, 2011). Spatiotemporal fireoccurrence trends in Borneo (Kalimantan) were investigated by Langner & Siegert, 2009. Putra, et al (2008;2011), also analyzed peat fire activity in the MRP area in
the Central Kalimantan. This study uses a time series of
MODIS hotspot data to intensively investigate fire incidence from national to local scales in Indonesia.
We will conduct the analysis using several sizes ofgrid cells based on geographical latitude and longitude.
However, in the preliminary analysis in this paper, aone-degree grid only was used to understand recent fire
trends in Indonesia. We discuss the fire distribution andtimes of the fires in the ten years surveyed and also theaverage monthly incidence. The final results will support

the pilot project of the initial phase of REDD+ as well as
help to develop future fire firefighting strategies toreduce CO2 emissions and to design the appropriate land
use practices in Indonesia.

2. Data and Methods
2.1 Modis daily hotspot data
The NASA MODIS daily hotspot data was used here
because there is no other suitable fire data covering thewhole of Indonesia which is available for the 2002-2011
study period. The MODIS daily hotspot data (Collection
5.1 active fire product) was extracted through FIRMS(Fire Information for Resources Management System,
http://maps.geog. umd.edu/firms/).
Hotspot data provided by the NASA MODIS
which included data for neighboring countries outside
Indonesia was deleted. Representative names were used
for groupings in each region (Fig. 2). The temporary
boundaries would be different at different levels ofanalysis depending on the cell sizes. Finer mesh grids
have more accurate boundaries or are more nearly at theactual geographical or political border.
2.2 Study region and analysis grid cells
The study used 10 years of MODIS data covering thearea from north latitude 6o to south latitude 11o and fromeast longitude 95o to 142o. A map of the area of the study,
the whole of Indonesia, with the forest and peat distribution superimposed, is shown in Fig.1.
Several cell sizes were used in this analysis, allutilizing latitudes and longitudes as the basis for the gridin the identification of locations across Indonesia. Cellsizes with side lengths from 1 to 0.01 degrees were evaluated as shown in Table 1. For simplicity, the cell side
lengths were based on latitude and longitude, and the areaof cells differs depending on latitude. Representative
lengths and areas for various cell sizes are detailed inTable 1. The actual size of various grid cells is shown onRecent Forest and Peat Fire Trends in Indonesia

107

Fig. 2 Hotspot distribution and 11 highest hotspot areas in Indonesia, 2002-2011.

the map of MRP (Mega Rice Project in Central
Kalimantan) in Fig. 3, where the five blocks of the MRP(A, B, C, D, and E) are colored differently.
By using this grid cell scheme, hotspots were tallied
depending on their latitude and longitude. In this paper,
the hotspot density unit uses “cell” instead of km2,
“hotspots/cell” was used to enable a simple comparison
with various hotspot values such as annual, monthly, andmean number of hotspots in various regions composed bymultiple cells. Conversion from hotspots/cell to a general
hotspot density unit of “hotspots/km2” can be obtained by
dividing the number of hotspots in one cell by the cellarea of around 12,300 km2. The inter-cell difference inIndonesia is small less than about 1.5% difference between cell areas at the equator and at 10o south latitude.

3. Results and Discussions
3.1 Fire distribution in Indonesia
The MODIS hotspot data provided by NASA for
2002-2011 was plotted as shown in Fig. 2. A total of631,529 hotspots were recorded in the region covered by
the study (N 6o - 11o, E 95o to 142o). About ninety percentof the hotspot cells in Fig. 2 fall fully within the bordersof the grid cells covering only areas of Indonesia, theremaining is in the cells overlapping the surrounding
countries as shown in Fig. 2. The limits of the cells extending outside Indonesia is an artifact of the one degree
sized grid cells used in the analysis here. This paper
ignores administrative boundaries to simplify the analysis and for the ease of the data treatment.
In Fig. 2, all coordinate points of MODIS hotspots areindicated with the smallest size of dots. The resulting
map shows areas of dense red color regions in Indonesia(regions with high incidences of hotspots) and these canbe simply identified on the map in Fig. 2. To show fireprone areas more clearly, several cells with the number of
hotspots are marked at the cells as shown in Fig. 2.
Eleven cells overlaid by white in Fig. 2 shows cells withfire occurrences above 1,000 hotspots/(yr cell). There are
five such cells in south Kalimantan, five in north Sumatra,and one in south Sumatra. These cells are named H-1 to
H-11 (in descending order with H-1 showing the cell withthe highest fire incidence: H-1, H-2, H-3, H-5, and H-8 in
Kalimantan (Fig. 6), H-4 in south Sumatra, and H-6, H-7,
H-9, H-10, and H-11 in north Sumatra (Fig. 9).
The cell with the most fires in south Kalimantan, H-1(also named MRP*), is located at south latitude 2.5o to
3.5o and east longitude 113.5o to 114.5o (see Fig. 3 for theexact position of this cell) had a mean 2,223 hotspots/yr
and a maximum of 5,382 hotspots in 2006. To evaluate
the fire incidence in this cell objectively the concept
hotspot density will be introduced. The 2,223 hotspots/yr
for this cell was converted to an annual mean hotspot
density of 0.182 hotspots/km2 (dividing the number offires with the area of the cell in km2) and to a daily
hotspot density of 0.497 NASA fire pixels/ (1,000km2
day) (see more detail in the NASA Earth Observations,
http://earthobservatory. nasa.gov/). This 0.497 figure is
not a very high hotspot density in the NASA scale but it
becomes 1.8 pixels/ (1,000km2 day) when consideringthat fires only occur during about 100 fire days in July,
August, and September. This high daily hotspot density
shows that the fire incidence in this particular cell insouth Kalimantan is among the most intense fire incidences of any area in the world.
There are four other cells with the cells with the very
highest fire incidence in Kalimantan. The second andthird (H-2 and H-3) are adjacent to H-1 discussed above.
The H-2 cell is to the west of H-1 and H-3 is to the northof H-1.
Six of the cells with the highest fire incidences(>1.000 fires/(yr cell)) were in Sumatra, H-4, H-6, H-7,
H-9, H-10, and H-11. The H-4 cell is at south latitude
2.5o-3.5o and east longitude 104.5o-105.5o. It had 1,387
hotspots/yr or hotspot density of 0.113 hotspots/(km2yr).
This cell is located in middle of the south Sumatra areathat includes Palembang (capital of South Sumatra

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N. YULIANTI et al.

Province, (Fig. 9). The H-6 area is at north latitude
0.5o-1.5o and east longitude 100.5o-101.5o, in the middleof north Sumatra, and is close to Pekan Baru (capital of
Riau Province, (Fig. 9). It had 1,280 hotspots/yr (hotspot
density: 0.104 hotspots/(km2yr)). The H-7, H-9, H-10,
and H-11 areas are all around the H-6 cell, as shown in
Fig. 2.
Based on the eleven H-1 to H-11 cells with the highest
fire incidences in Indonesia, the authors defined three fireprone areas “South Kalimantan 12”, “South Sumatra 10”,and “North Sumatra 10” as shown in Fig. 2. The numbers
in Fig. 2 shows the number of fires in the cells with thehighest incidence in each area. There were eight areas
with fire incidences higher than 500 hotspots/(yr cell)and these are shown as blue rectangles with dotted outlines in Fig. 2. Three were in West Kalimantan, one incentral East Kalimantan and the final four in central
Sulawesi, Sumba, and Timor (two).
Finally, you will notice the above mentioned cellswith high fire incidence (H-1 to H-12) coincide withpeatland areas in Kalimantan, Sumatra, and Papua bycomparing Fig. 1 and Fig. 2. Peat fire is one of great
environmental concern not only for Indonesia but also for
the world. Peatland fires emit larger amounts of CO2 andother air pollutants due to low temperature combustion orsmoldering (Usup et al., 2004). Two high fire areas in
Sumba and Timor are due to savanna fire (Fisher et al.,2006).
3.2 Fire occurrence trends in Indonesia
3.2.1 Annual fire occurrence
The annual fire occurrence in the six major regions ofIndonesia (see Fig. 2) during the most recent ten years(2002-2011) is shown in Fig. 4. The unit of the Y-axis
in Fig. 4 and also in all other Figs. (Figs. 5, 7, 8, 10,
and 11) related to hotspot in this paper is the number of
hotspots. The bar graph in Fig. 4 shows the number offires in the six regions, from top to bottom: Papua+,

Table 1 Summary of analysis grid cells.

Grid Cell Size
(Degree of Lati.
& Long.)1x1
0.5 x 0.5
0.1 x 0.1
0.05 x 0.05
0.01 x 0.01

Representative Length & Area
(One Degree at Equator)
Length (km)Area (km2)
111.3
12,387.7
55.7
3,096.9
11.1
123.9
5.6
31.0
1.1
1.2

TargetMaximum
Number of Grids

Whole Indonesia
Kalimantan, etc.
MRP, etc.
Village, etc.
Plantation, etc.

846
3,384
84,600338,400
8,460,000* Note that the center of cell locate at grid intersects, for example, centered on 1o N and E 101o covers the area north latitude 0.5o-1.5oand east longitude 100.5o -101.5o

Fig. 3 Five grid cell sizes on the map of MRP.

Recent Forest and Peat Fire Trends in Indonesia

Java+, Sulawesi+, Sumba+ and Timor+, Sumatra+, andKalimantan+. Thus, this paper ignores administrative
boundaries to simplify the analysis and for the ease ofdata treatment and puts “+” after each region name like
“Sumatra+” to show the expanded region defined in thispaper. The bottom section of the bars for Kalimantan
distinguishes the number of fires in a cell for the Mega
Rice Project (H-1 or MRP*). The total number of cells in
the regions were 513: 198 for Papua+, 37 for Java+,
91 for Sulawesi+, 66 for Sumba+ and Timor+, 101
for Sumatra+, and 86 including the MRP* cell for
Kalimantan+. The annual mean numbers of fires in thesix regions were averaged and the rightmost bar, to theright of the bar for 2011, shows the average annual incidence of fires in the six regions.
The rightmost bar in Fig. 4 shows that the annual
mean number of hotspots in Indonesia was about 58,000.
About 80% of these fires occurred in only two of
the regions, Kalimantan+ and Sumatra+, which were
responsible for 23,460 and 21,488 fires (40.6% and37.2%) respectively. The fire incidence for the other four
regions is: Sumba+ and Timor+ with 4,774 fires (8.3%),
Sulawesi+ 4,084 (7.1%), Java+ 2,226 (3.8%), andPapua+ 1,799 (3.1%). Fire occurrence in the MRP* cellis at the bottom of this annual mean bar in Fig. 4, and the2,223 fires in the MRP* cell were very similar to thenumber in Java+ (an area nearly 40 times larger) andlarger than that of Papua+ (area about 200 times larger).
The most fires in the six major regions occurred in
two different years, 2006 (Kalimantan+ and Sumatra+)and 2002 (Sumba+ and Timor+, Sulawesi+, Java+,
and Papua+). In 2006, there were 54,302 fires in
Kalimantan+ and 42,361 Sumatra+. These two regions
contribute 84.1% of the total fires in 2006. In 2002, thefire numbers were 9,761 for Sulawesi+, 7,146 for
Sumba+ and Timor+, 4,440 for Papua+, and 3,398 for

109

Java+ but their contribution to the total fire numbers ofIndonesia was only 27.9%. The proportion of fires
occurring in Kalimantan+ was high in both 2006 (47.2%)
and 2002 (49.7%). Active fires in 2006 and 2002
occurred under the drought conditions related to the El
Niño event. A detailed discussion about relationshipbetween fire activities and drought will be elucidated inchapter 3.3.
The number of hotspots in the ten years varied by afactor of seven between the year with the most fires,
114,977 in 2006 and the year with the fewest, 16,335
fires, in 2010. The following statistical approach provides a more objective discussion of fire occurrence. The
fire occurrences in seven out of the ten years were within±1σ(=68.26%). The remaining three years had ±1σ values of 1.01 for 2002, 1.87 for 2006, and –1.36 for 2010.
Statistically, the probability of the occurrence of a yearwith a high number of fires, such as 2006 is about 6%,
suggesting that a year with the number of fires in 2006
will occur roughly every 17 years, if the fire occurrences
are assumed to follow a normal distribution.
3.2.2 Seasonality of fires
This chapter will discuss the times that fires occur
with monthly means for the ten years period from 2002 to
2011. Figure 5 shows the average fire incidence for eachmonth in the ten years for the different regions ofIndonesia. As suggested by Fig. 5 the period of the mostfrequent fire occurrence in the whole of Indonesia are thethree months August, September, and October where thenumber of fires reached 13,890, 14,589, and 11,264
respectively, for a three month total of 39,743, representing about 70% of the average annual hotspot number(57,800).
From Fig. 5 it is possible to determine the month(s)with the highest fire incidence for the different regions in

Fig. 4 Annual fire occurrence in whole Indonesia (2002 - 2011).

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N. YULIANTI et al.

Indonesia. In Kalimantan+ fires were most frequent in
the three months August, September, and October. The
months with the most fires for Sumatra+ were Augustand September, and Sumatra+ had a noticeable numberof fires in six other months but only very few fires in
April, November, and December. The months with thehighest fire incidence for the remaining four regions arealso seen in Fig. 5, for Java+, August, September, andOctober, and for the three regions of Sulawesi+, Timor+& Sumba+, and Papua+, the highest fire incidence was
October. The next chapter will be discussed in more detail the fire trends with the focus of Kalimantan andSumatra.
3.3 Fire occurrence in Kalimantan and Sumatra
3.3.1 Fires in Kalimantan
Kalimantan was divided into the following five
regions for the detailed discussion on fire distribution, theannual changes in fire incidence, and fire period on themain island of Kalimantan (“Kalimantan+” in 3.2 covers
a wider area) using the one by one degree cells. The
regions were “South Kalimantan 12”, West- and EastKalimantan, South 5, and Central 5. The number at theend of the name indicates the number of cells in its region.
West- and East- Kalimantan has 16 and 25 cells, respectively. The boundaries of the five regions are shown withwhite and yellow broken lines in Fig. 6. The extent ofthese regions is different from the four provinces of West,
East, Central, and South Kalimantan. This occurs because the “South Kalimantan 12” cells comprise threecells from West Kalimantan (rectangles numbered with
656, 634, and 932 hotspots/(yr cell) shown in Fig. 6), one
cell from South Kalimantan (with 1,489 hotspots/yr, andone cell from East Kalimantan (with 508 hotspots/yr).
Please note the MRP region surrounded by a black dottedline in Fig. 6. The “South Kalimantan12” covers theentire MRP regions with its three cells, H-1 (MRP*), H-2,
and H-3 located as shown in Fig. 6.
The fire occurrence from 2002 to 2011 is shown with
red dots in Fig. 6. The density of the dots means that thefire distribution is not very clear but it provides a better
picture than Fig. 2. Several noticeable fire and fire freeareas can be observed in Fig. 6 and in the enlarged insert
for the area around Palangkaraya near the top of Fig. 6.
Most of fires here are human-caused, and occur along
canals, roads, and at the seacoast. Such fires form linear
patterns and are simply identified in Fig. 6. The areas
with dense hotspots suggest high human activity with
deforestation, slash and burn clearing, and plantations.
There are 16 cells with more than 500 hotspots/(yr cell)in Fig. 6 that deserve special attention. One is south of
Palangkaraya in the enlarged insert in Fig. 6. There arefire free areas even in H-1 (MRP*), the cell with thehighest fire incidence in MRP. In the left upper side of
the H-1 cell, there is a fire free area. This area corresponds to a tropical swamp forest south of Palangkaraya(the dense green area in Fig. 3).
Figure 7 shows the annual number of fires in theabove mentioned five regions of Kalimantan from 2002
to 2011. The bars by year show, from top to bottom thefire incidence in the South 5, East, West, Central andother areas, and finally in South Kalimantan 12 which
includes the H-1 cell with the highest number of fires in
the MRP area. The rightmost bar shows the average ofthe annual fire occurrences. Fig. 7 also shows the annual
total precipitation of the driest three months from July to
September measured at Palangkaraya Airport by using
the inversely drawn bars from the top line of Fig. 7 illustrate the relationship between fire activity and rainfall.
From Fig. 7, the annual average is 23,250 hotspots/yr.
The annual averages show that 61% of the fires occurredin the South Kalimantan 12 and South 5, with 57.2 %Fig. 5 Fire period in six regions in Indonesia (2002 - 2011).

Recent Forest and Peat Fire Trends in Indonesia(13,183 hotspots) and 3.9% (897) respectively. Fires inWest Kalimantan accounted for 23.1% (5,314), East
Kalimantan for 11.1% (2,567), and Central and others
had 5.6 % (1,289) annual fires on average. The average
number of fires in the MRP cell, 2,223, very nearlymatches the number in all of East Kalimantan, which
covers a far larger area (25 cells).
The largest number of fires in the different areas
occurred in 2004 in East Kalimantan (5,440 fires); andin 2006 for the other four Kalimantan areas: South
Kalimantan12 with 36,101 fires, West Kalimantan with
9,631 fires, South 5 with 2,076 fires, and Central 5 andothers with 2,652 fires. In 2006 the ratio of fires reacheda very high 66.9% in South Kalimantan12 (including the
MRP* cell).

111

The above mentioned fire activities in Kalimantan
could be partially explained by using precipitation
measured at Palangkaraya. Figure 7 clearly showed that
active fires in 2002, 2004, 2006, and 2009 occurred whentotal precipitation amount of three driest months in
Palangkaraya (Putra et al., 2011) became less thanaround 100 mm. The largest fires in 2006 mainly due toSouth Kalimantan12 could be explained by extended
drought until October. The precipitation amount for
October, 2006 was only 12.6 mm and the lowest monthly
precipitation for the last 10 years.
The time of occurrence of fires in Kalimantan will be
discussed with Fig. 8, which shows the average monthly
fire incidence in the ten years surveyed. In Fig. 8,monthly mean precipitation of the last 10 years in

Fig. 6 Hotspot distribution, 5 regions, and 5 highest hotspot areas in Kalimantan.

Fig. 7 Annual fire occurrence in Kalimantan and MRP, and dry season precipitation in Palangkaraya(Central Kalimantan).

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N. YULIANTI et al.

Palangkaraya is also shown with the inversely drawn bars
from the top line of Fig. 8. Figure 8 clearly shows thatfires are most common in three months: August,
September, and October, similar to the most intense fire
period for all of Indonesia (Fig. 5). The number of fires inthese three months reached 19,895 (7,471 in August,
7,543 in September, and 4,881 in October), 85.5% of theannual hotspot average (23,250 fires).
Throughout Kalimantan, September was the monthwith the most fires except in West Kalimantan. In South
Kalimantan 12 and South 5, the number of fires in
September reached a total of 5,320 fires or 70.5% of thetotal number of fires in this month. In West Kalimantan,
the peak was 3,184 fires in August with only 882 fires in
September. Fire numbers in the one H-1 (MRP*) cellwere larger than in all of East Kalimantan (24 cells). The
number of fires in the H-1 (MRP*) cell from August to
October were 3,617, 8,931, and 8,064. These numbers
clearly show the need to pay more attention to the verylarge number of fires in MRP* during September andOctober.
Monthly mean precipitation trends in Fig. 8 supported
active fires during the driest two months, August and
September. Fires in October can be explained by theground water level. As the average lowest ground waterlevel was observed from the bottom of September to the
top of October, peat fires continue to be active even in
October (Putra et al., 2011). South Kalimantan 12 and
MRP* remarkably showed this fire trend related to theground water level in Fig. 8.
3.3.2 Fires in Sumatra
Sumatra was divided into the following four regions
for the detailed discussion of the fire distribution, theannual changes in fire incidence, and period with themost fires on the main island of Sumatra (“Sumatra +” in

3.2 covers a wider area) using one by one degree cells
like the discussion for Kalimantan above. Sumatra wasdivided into four regions because the ten provinces in
Sumatra are too small for the analysis using one by one
degree cells. The four regions in Sumatra were “South
Sumatra 10”, “South Others”, “North Sumatra 10”, and“North Others”, with the numbers at the end of the names
showing the number of cells; the number of cells for“South Others” and “North Others” 19 and 20, respectively. The boundaries of the four regions are shown withwhite and yellow broken lines in Fig. 9; Sumatra isdivided into two by the equator, and North and South
Sumatra will be used here after. South Sumatra has theH-4 cell, which is the fourth highest number of fires inSouth Sumatra 10 and shown with the number 1,387(hotspots/yr) in Fig. 9. This cell was also named
Palembang to make the fire incidence in this cell moreeasily comparable with the “MRP*” cell in Kalimantan.
Five other “high fire incidence cells,” H-6, H-7, H-9,
H-10, and H-11 with 1,280, 1,231, 1,152, 1,080, and1,001 hotspots/(yr cell) respectively lie in North Sumatra
10, mainly in Riau Province. Among these the H-10 cell
had 4,906 hotspots in 2005 and the total for these fivecells exceeded 5,700 hotspots/(yr cell). Fires in this region may be partially related to the activities of two
companies, Asia Pulp and Paper (APP) and Asia PacificResources International Limited (APRIL), during the ten
year study period. These companies have several pulp
mills and paper plants in Riau, Jambi, and South Sumatra
Province.
The fire distribution from 2002 to 2011 are shownwith red dots in Fig. 9, but due to the density of the dots,
the fire distribution was not completely clear. Most fires
appear to occur on the low-lying peatland areas of east
Sumatra (see Figs. 1 & 9). There are also other characteristics of the fire distribution that can be observed inFig. 8 Fire period in Kalimantan and MRP, and monthly mean precipitation in Palangkaraya(Central Kalimantan).

Recent Forest and Peat Fire Trends in Indonesia

Fig. 9. Human-caused fires tend to occur along canals,
roads, and the seacoast as is also the case in Kalimantan.
There is an area of dense fires near Palembang in the H-4cell in Fig. 9 (marked with the fire incidence there, 1,387).
This H-4 cell was named “Palembang” and may be seen
to be like MRP* near Palangkaraya, Kalimantan. There
are fire free areas in Sumatra in high mountain areas andpeatland areas near the coast similar to Kalimantan.
Figure 10 shows the annual number of fires in the four
regions of Sumatra distinguished above, from 2002 to
2011, the bars for each year show, from top to bottom, thefire incidence in North others, North Sumatra 10, Southothers, and South Sumatra 10 which includes the H-4 cellwith the highest number of fires in the Palembang area.
The rightmost two bars show the average of the annual
fire occurrences and the annual largest fire occurrence in
Kalimantan in 2006.
The inversely drawn two different bars from the top
line of Fig. 10 shows the annual total precipitation of thedriest three months from June to August measured at
Jambi (South Sumatra, these are shown by a white circle
located in the northeast of “H-4” in Fig. 9). The two separated dry months in February and August observed at
Pekan Baru (Riau, North Sumatra, and shown by a whitecircle located in the south of “H-6” in Fig. 9).
From Fig. 10, the annual average was 21,200
hotspots/yr and just smaller than the 23,250 hotspots/yr
in Kalimantan. The annual averages show that 51% of thefires occurred in south Sumatra (South Sumatra 10 andSouth others) and 49% of the fires occurred in north
Sumatra (North Sumatra 10 and North others). Fires inNorth Sumatra 10 accounted for 41.5% (8,799), South
Sumatra 10 for 35.7% (7,578), South others for 15.3%(3,249), and North others for 7.5% (1,581). The number

113

of fires in the Palembang cell is 1,387 and very nearlymatches the number in North others, which covers a farlarger area (20 cells).
The two years with the most fires in Sumatra occurredin 2005 and 2006 however with very different fire distributions within the island. In 2006, the year with the mostfires, the total number of fires reached 41,895 and mostoccurred in south Sumatra, 71.5%, with 22,675 (54.1%)
fires in South Sumatra 10 and 7,269 (17.4%) fires inSouth others. In 2005, the year with the second largest
number of fires, the total number exceeded 31,500, mostoccurring in north Sumatra, 84.6%, with 23,998 (76.2%)
in North Sumatra 10 and 2,640 (8.4%) in North others.
The most right hand bar in Fig. 10 allows a directcomparison with the 2006 Kalimantan fire incidence.
Comparing the two 2006 bars, both south Kalimantan
and south Sumatra show very high fire incidences under
the drought conditions due to the El Niño event in thatyear, 2006. Looking at the two cells, H-1 (MRP*, 5,382
fires in 2006) and H-4 (Palembang, 5,361 fires in 2006)shows that the fire incidences in 2006 here were very
similar.
The above mentioned very high fire incidences in
Sumatra could be explained by using precipitation
measured at Jambi (south Sumatra) and Pekan Baru
(north Sumatra). Figure 10 clearly showed two active fire
years in 2005 and 2006. In 2005, most fires occurred in
North Sumatra 10. On the contrary, most fires occurred inSouth Sumatra 10 and South Others in 2006. The twodifferent fire trends in 2005 and 2006 may be explainedby dry season trends in north and south Sumatra.
The 2005 fires in North Sumatra 10 (north Sumatra)
were due to low precipitation in February (39mm, lowest
monthly precipitation of latest 9 years from 2002 to

Fig. 9 Hotspot distribution, 4 regions, and 5 highest hotspot areas in
Sumatra.

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N. YULIANTI et al.

2010) and other dry months. Our analysis showed that the
total number of hotspots in North Sumatra 10 in 2005
reached 20,365. The largest monthly number of hotspots
was 5,313 in February. The second and third highest
numbers were 4,694 in March and 3,183 in August. The
2006 active fires in Jambi (south Sumatra) also may be
due to lowest precipitation in the four dry months from
July to October (411mm, lowest four months precipitation of latest 9 years from 2002 to 2010).
Figure 11 shows the average monthly fire incidence
in the ten years surveyed in Sumatra. The rightmost bar
in Fig. 11 shows the September fire occurrence in
Kalimantan.
Figure 11 shows that the times of highest fire incidence in Sumatra is not as clear as was found in
Kalimantan in Fig. 8. In Sumatra the highest number offires in August is not much higher than in other months,

the contribution of fires in August is only 21% of thewhole year, which is smaller than the 32% in September(the month with most fires) in Kalimantan. In addition,
north Sumatra showed a different period with the highest
fire incidence. This difference, however is not as distinct
as the high incidence period in south Sumatra. In North
Sumatra there are two fire periods, one is in February andMarch, another is from June to August. The presence oftwo periods with many fires may explain why 2005 is theyear with the second largest number of fires (Fig. 9) andwhy August is the month with the most fires in Sumatra(Fig. 10). In south Sumatra, the most fires occurred inAugust, September, and October, similar to Kalimantan(Fig. 8). The above different fire occurrence patterns innorth and south Sumatra can be explained by differencesin the precipitation patterns in the two areas.
Two different precipitation types for north and south

Fig. 10 Annual fire occurrence in Sumatra, and dry season precipitations in Jambi(Jambi, south Sumatra) and Pekan Baru (Riau, north Sumatra).

Fig. 11 Fire period in Sumatra, and monthly mean precipitations in Jambi(Jambi, south Sumatra) and Pekan Baru (Riau, north Sumatra).

Recent Forest and Peat Fire Trends in Indonesia

Sumatra are shown using inversed Y- axis and two bar
graphs in Fig. 11. Two climate zones with two different
precipitation patterns in Sumatra are described by
Aldrian & Susanto, 2003. The monthly mean precipitation trends in Fig. 11 showed that Pekan Baru (north
Sumatra) had low precipitation during the months of
February, June, and August. Fires in north Sumatra
tended to occur mainly in these months. On the other
hand, Jambi (south Sumatra) showed only one lowest
precipitation month in June but that fires could become
active from August to October. This fire trend was similar to south Kalimantan in Fig. 8. South Sumatra andsouth Kalimantan are in the same climate zone. Fire
activities from August to October in south Sumatra in
Fig. 11 were weaker than that of south Kalimantan in
Fig. 8. This difference may be mainly due to differences
in monthly precipitation amount or about 200 mm insouth Sumatra and about 100 mm in Kalimantan.

4. Conclusions
The present fire situation, fire prone areas, andthe trends in fire incidence for all of Indonesia, forKalimantan and Sumatra were analyzed using MODIS
hotspot data from 2002 to 2011 with 1x1 degree cell. The
conclusions can be summarized into the following threeparts:Firstly, the present fire situation and fire prone areas
as follows:
1. There were eleven cells where the number of hotspots
exceeds 1,000 hotspots/(yr cell) among the approximately 500 cells covering all of Indonesia. Thesemost fire prone areas were found in three regions:south Kalimantan, and south and north Sumatra. (seeFig. 2)
2. The cell with the highest fire incidence (H-1, MRP*)
was found in the Mega Rice Project (MRP) area insouth Kalimantan. This one cell had both the
maximum and the highest mean number of hotspots
in the recent ten years, 5,382 hotspots in 2006 and2,223 hotspots/yr respectively. The maximum hotspot density was 0.438 hotspots/ (km2yr). (see Figs. 2,3, 6)
3. The three cells with the highest fire incidence (H-1,
H-2, H-3) covered most of the MRP area. (see Fig. 6)
The total number of hotspots of these three cells was
5,174 hotspots/yr.
4. The cell with the fourth highest fire incidence (H-4)
was in the Palembang area in south Sumatra. The
number of hotspots was 1,387 hotspots/yr. (see Figs.
2, 9)
5. In Sumatra, the five cells with the highest fire incidence (H-6, H-7, H-9, H-10, and H-11) were in north
Sumatra. (see Figs. 2, 9) The total number of hotspotsof the five cells was 5,744 hotspots/yr.
6. Other areas where the fire incidences exceed 500
hotspots/(yr cell) were found in Sumba, Timor, west
and east Kalimantan, and central Sulawesi. (see Figs.
2, 6)
Secondly, the trends in the annual fire incidence are as

115

follows:
7. The annual mean number of hotspots in the whole ofIndonesia was 57,800 with 78% of these fires occurring in Kalimantan (41%) and Sumatra (37%). (seeFig. 4)
8. In the year with the most fires, in 2006, the total
number of hotspots was about twice (115,000) the
annual mean (57,800). In 2006, the contribution ofKalimantan (47%) and Sumatra (37%) was 84%. (seeFig. 4)
9. For all of Kalimantan, the annual mean numberof hotspots was 23,250 for the ten years. About
61% were recorded in south Kalimantan (South
Kalimantan 12 and South 5). In 2006, the year withthe most fires, the total number of hotspots was about
2.3 times larger (about 54,000 hotspots/yr) than
the annual mean, with the contribution of south
Kalimantan 71%. (see Figs. 6, 7)
10. In Sumatra, the annual mean number of hotspots was
21,200, nearly equal for south and north, 51% vs.
49%. The year with the most recorded fires in
Sumatra was also 2006, with 41,900 hotspots (about
twice the annual mean); 72% of fires in 2006 occurred in south Sumatra. (see Figs. 9, 10)
11. For north Sumatra, the year with the most fires was2005 (second highest incidence for all of Sumatra).
In 2005, the total number of hotspots was 31,500(84.6%). (see Figs. 9, 10)
Thirdly, the trends in fire incidence by month are as
follows:
12. For all of Indonesia the three months of August,
September, and October had the highest incidences,with about 70% of fires (39,743) occurring in thesethree months. The percentages of the average annual
number of fires (57,800) in August, September, andOctober were 24% (13,890), 25% (14,589), and 19%(11,264) respectively. (see Fig. 5)
13. Kalimantan and Sumatra also had high incidences offires in August, September, and October with 87%,
80%, and 66% of total number of fires in each month,respectively. (see Fig. 5)
14. Kalimantan also had the most fires in August,
September, and October. The fire peak for central andsouth Kalimantan was September and for west
Kalimantan was August. (see Fig. 8)
15. In Sumatra, the most intense fire period by month
was not easily defined. South Sumatra had the mostfires in the three months of August, September, andOctober while north of Sumatra had two periods withhigh fire numbers, one in February and March, andthe other in June, July, and August. (see Fig. 11)

5. Acknowledgements
The authors thank Minnie Wong of the University of
Maryland, USA, for providing the MODIS hotspot data.
This research was supported by the JST-JICA SATREPS
project on “Wild Fire and Carbon Management in PeatForest in Indonesia.”

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N. YULIANTI et al.

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(Received 2 February 2012, Accepted 27 April 2012)