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that in the Indonesian part of Borneo was 2.9 per cent per
year. These values are a little higher than those found in
most previous studies. A possible reason is an increased
frequency of fires caused by droughts related to El Niño,
which occurred in 2006. The forest fire frequency in the
Indonesian part of Borneo was much higher than in the
Malaysian part, which might have increased the rate of
forest loss in the Indonesian part.
Next, we estimated the total AGB in Borneo. To do so, we
calculated the average GLAS-estimated AGB for each prov-
ince and for each forest type, multiplied them by the area
of each category (forest type and province) and summed
them up. As a result, AGB in Borneo totalled 10.3 billion
tons. This value corresponds to 2.1 per cent of the total
AGB on the Earth, according to the Food and Agriculture
Organization of the United Nations Global Forest Resources
Assessment 2010. Borneo occupies only 0.5 per cent of the
global land area, so we can understand that the Bornean
forest stock has a high biomass.
GLAS observed only discrete points along the track,
therefore it could not make a complete observation of large
areas. However, GLAS data can be used as reference data for
developing a wall-to-wall forest biomass map using optical
satellite imagery. We combined GLAS data with Moderate
Resolution Imaging Spectroradiometer (MODIS) imagery,
which is an optical imagery sensor making high-frequency
observations. High-biomass forests were found to be distrib-
uted along the backbone of the Bornean mountains. Such a
map can make it possible to understand the detailed distri-
bution of forest resources.
In this way, satellite laser altimetry can provide enormous
amounts of data for the efficient and accurate estimation of
canopy height and forest biomass without in-situ measure-
ments. It will be able to bring about a revolution in global
forest inventory. Since ICESat ceased operation in 2009,
there has been no satellite laser altimetry system capable of
observing land surfaces. However, ICESat-2 is scheduled to be
launched in 2017, and there are plans to mount laser altim-
etry systems for forest observation on the International Space
Station. These next-generation satellite laser altimetry systems
will play an important role in global forest resources monitor-
ing in the future.
Histograms of aboveground biomass for each province in Borneo
Aboveground biomass (t/ha)
Average = 208 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300 400 500
Brunei Darussalam
Aboveground biomass (t/ha)
Average = 233 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300 400 500
Kalimantan Utara
Aboveground biomass (t/ha)
Average = 195 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300 400 500
Aboveground biomass (t/ha)
Average = 166 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300 400 500
400 500
400 500
400 500
Kalimantan Timur
Kali
Aboveground biomass (t/ha)
Average = 184 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300
Kalimantan Tengah
Aboveground biomass (t/ha)
Average = 182 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300
Kalimantan Barat
Aboveground biomass (t/ha)
Average = 179 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300
Sarawak
400 500
Aboveground biomass (t/ha)
Average = 183 t/ha
Relative frequency
0
0%
1%
2%
3%
4%
5%
6%
100 200 300
Sabah
Source: CGER
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