沙漠研究 19-1, 53- 56 (2009 )Journal of Arid Land Studies“Desert Technology IX ”
Refereed Paper

Woody Biomass Production by Utilizing Coppice of Eucalyptus camaldulensis
in an Arid Area in Western Australia
Nobuhide TAKAHASHI1, Yasuyuki EGASHIRA2, Shin-ichi AIKAWA3, Toshinori KOJIMA4
Abstract: In order to reduce the cost for CO2 fixation by arid-land afforestation, possibility ofutilizing coppicing of the planted trees was examined in the arid area in Western Australia.
The seven-year-old planted trees and the native trees of various sizes of Eucalyptuscamaldulensis were cut down and the growths of coppice growing from the stumps after cutting
were observed for one and a half years. The resprouting rate for both planted and native trees
reached 100% until six months after cutting. The results for the native trees indicated thebigger the tree was when it was cut, the quicker the coppice grew. The growth rate of thecoppice for the planted trees was comparable to that of the coppice for the native trees. These
results indicated that utilization of coppicing for increasing CO2 amount fixed by the plantedtrees was highly possible even in the arid areas.
Keywords: Arid region, Coppicing, Eucalyptus camaldulensis, Western Australia

1. Introduction
Woody biomass production by afforestation in arid areas is expected to be a promising countermeasureagainst the global warming and the depletion of energy resources such as fossil fuels because the arid areas
widely exist all over the world and cannot be utilized for crop production. Yamada et al. (2003)
demonstrated that afforestation with embankments for water-harvesting and soil structure modification byhardpan blasting was effective in tree growth in an arid area in Western Australia. Yamada et al. (2005)
also estimated the CO2 fixation cost (input cost/fixed carbon amount) as around 16,000 yen/t-C. The CO2
fixation cost must be reduced to make the arid-land afforestation feasible.
An effective way to reduce the CO2 fixation cost is to maximize the amount of CO2 fixed by theplanted tree. Since trees cannot fix carbon any more when they reach a mature state, utilization ofcoppicing is an effective way to increase the carbon fixed by a tree over its lifetime. And also, coppicing
is expected to be more economical than replanting, especially in arid regions where a large investment isnecessary for the initial afforestation works.
The coppicing ability is much different among species. Although Eucalyptus species generally havea high coppicing ability, the ability significantly differs even among Eucalyptus species (Sims et al., 2001).
Moreover, a coppicing ability and a growth rate of the coppice depends upon climatic conditions as well.
Many researches concentrate on coppicing of trees growing in tropical and temperate climate. However,there is little information on coppicing of trees growing in arid regions. The objective of this study is toclarify the possibility of biomass production by utilizing coppicing in arid areas, aiming to reduce the CO2fixation cost by arid-land afforestation.
2. Materials and Methods
Several afforestation trial sites were constructed by a Japanese research project in an arid area near
Leonora in Western Australia where annual rainfall is around 200 mm (Kojima et al., 2006). At thesesites, some afforestation techniques such as embankments for water-harvesting and hardpan blasting with
explosives for soil structure modification were examined for successful tree growth in the arid area. Thecoppice experiment was carried out at one of the afforestation trial sites, named as Site B. Fig. 1 shows
the layout of planting at Site B. Prior to planting, hardpan blasting with explosives was done at all theplanting points at intervals of 7 m and in three rows. The rows were along the contour lines and anembankment of 1 m high, 3 m wide and 100 m long was build along the bottom row for harvesting runoff
1Department of Fine Materials Engineering, Shinshu University, Ueda, Nagano 386-8567, Japan
Graduate School of Engineering Science, Osaka University, Toyonaka Osaka, 560-8531 Japan
3
Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
4
Faculty of Science and Technology, Seikei University, Musashino, Tokyo, 180-8633, Japan2

54

water from the upstream and enhancing water penetration
Runoffinto the blasted holes. Three tree species including
Eucalyptus camaldulensis were planted at the site in 1999.
The trees still grew well after one-month-interval
irrigation was terminated in 2004, indicating that theBank
employed afforestation techniques were effective in tree100 mgrowth. It was also found out that E. camaldulensis wasquick to grow and a species suitable to arid-landPlanted tree
Blasted holeafforestation with those techniques, especially hardpan
blasting (Shiono et al., 2007).
Therefore, E.
Fig. 1. Layout of the planting site, Site B.
camaldulensis was selected as a species to be examined inthis study.
There were sixteen trees of E. camaldulensis in the two rows on the upstream side. The coppice
experiment was started by cutting down nine trees of them in September, 2006. The trees were cut with achain saw at around 10 cm above the ground. The rest were remained uncut for continuous observation of
growth and comparison in growth rate with coppice from the stumps of the cut trees. Girths at a breast
height (GBH) of these trees ranged from 40 - 90 cm when they were cut. The average abovegroundbiomass of all the trees of E. camaldulensis in these two rows was estimated as 150 kg-DM (dry matter),and there was no significant difference (p>0.1, ANOVA) between the cut and uncut trees.
On the other hand, fifty-one native trees of various sizes of E. camaldulensis growing along a wadi
were also cut down for comparison with the planted trees. The fifty-one trees were classified into fiveclasses of every 20 cm in the range of 20 – 120 cm in GBH. Table 1 summarizes the number andaboveground biomass of the cut trees for both the planted and native ones.
Resprouting rates and growth rates were investigated. A diameter of a stem at 0.3 m from its base,D0.3 [cm], and its length, L [cm], were measured for coppicing shoots longer than 0.3 m. The followingallometric relations between size and dry mass of a shoot were obtained by the destructive sampling.

( )= 0.00866(D L )20.900(n = 10, R 2 = 0.979)(1)

20.874(n = 10, R 2 = 0.954)(2)

Wstem = 0.00803 D0.3 L
Wleaf

Wcoppice =∑ (W0 .3

stem ,i+ Wleaf ,i) (i : index for a stem)(3)

iwhere Wstem is a dry mass of a stem [kg-DM] and Wleaf is a dry mass of leaves from the stem [kg-DM].
Wcoppice [kg-DM] is a dry mass of coppice from a stump and calculated as a sum of dry masses of all theshoots growing from the stump. And also, the statistical analysis was performed by a Steel-Dwass’smultiple comparison test.
3. Results and Discussion
3.1 Resprouting rate
A resprouting rate is an important factor in coppice forestry. It depends on various conditions such as
stock density and time of harvest. The stock density at Site B was 204 trees/ha, which is considered to be
sufficiently low to avoid a mutual interference. September, early spring in Australia, was selected as thetime of harvest to avoid an increase in mortality due to both dryness and frost (CALM, 2002).
Table 1.

Number and aboveground biomass of the cut trees at the time of cutting for the planted
and native trees (GBH stands for a girth at a breast height).

Number of cut trees
Aboveground biomass[kg-DM/tree]

MeanS.D.

Native tree
Range of GBH [cm]Planted tree
(GBH:4090cm)

20-40

40-60

60-80

80-100100-12091314

1095132
48

28986
27

132
41283
59547
138

Resprouting rate [%]Figure 2 shows the resprouting rates threeand six months after cutting. The resproutingrates reached 100 % for both the planted andnative trees in all the classes six months aftercutting. From the results three month aftercutting, it seemed that the bigger the tree waswhen cutting, the earlier resprouting occurred.

a55

120
100
80
60
40
6 months
20

Stem number [stems/stump]

3 months
3.2 Comparison of coppice growth between theplanted and native trees
0SiteB 20-40 40-60 60-80 80-100 100-120
Figure 3 shows multi-stem coppice growing
from a stump of the planted tree at Site B one andPlanted
Nativehalf years after cutting. Thinning is importantFig.
2.
Resprouting
ratethreeand six months
for such multi-stem coppice and recommended foraftercutting.
a good shape of a tree. In this study, however,thinning was not performed at all because an extra cost for thinningshould be avoided in practical afforestation aiming at economical biomass
production. Several dominant stems seemed to start growing more
quickly as a consequence of self-thinning.
Figure 4 shows the number of stems growing from a stump one year
after cutting. Stems of D0.3 larger than 10 mm were counted. From theresults for the native trees, the bigger stumps seemed to produce more
resprouting stems although any combination between the classes of DBH
did not show a significant difference (p>0.05). On the other hand, thestem number for the planted trees at Site B was greater only than that forthe class of 40-60 cm for the native trees (p<0.05). Considering therange of DBH of the cut trees at Site B, the planted trees have acomparable or higher coppicing ability compared with the native ones.
Biomass of the coppice one year after cutting is shown in Fig. 5.
Fig. 3. Coppice of the planted
Kamo (1997) reported based on the one-year investigation on coppice oftree one and half years
E. camaldulensis in Thailand that the coppice from a bigger stump wasafter cutting (Site B).
quicker to grow. In this study, from the results of20
the native trees, the bigger trees seemed to have a18
greater growth rate although there was no significant
16
difference for any combination between the classes
14of DBH for the native trees (p>0.05). The reason
12for the large variations may be that the environment
10
conditions such as light and soil water were not the86same among the coppice because the native trees
4
were selected from various places around the wadi.
2On the other hand, the biomass of the coppice0for the planted trees was significantly greater only
Site B 20-40 40-60 60-80 80-100 100-120
than that of the class of 40-60 cm for the native trees(p<0.05).
The results also indicated that thePlanted
Nativecoppice growing the stumps of the planted trees had Fig. 4. Stem number one year after harvestinga growth rate comparable to that for the native trees.
(Mean±S.D.).

3.3 Comparison of growth between the coppice and the planted single trees
In order to efficiently increase CO2 fixation amount by using coppicing, cutting should be performed
when the growth rate of a planted tree declines and is exceeded by the growth rate of coppice. Figure 6
shows time variations in aboveground biomass of the planted single tree after planting and in biomass ofthe coppice after cutting at Site B. The uncut trees grew at a steady rate after cutting and their average

1210864
20SiteB

PlantedFig. 5.

20-40

40-6060-80

80-100 100-120

Aboveground biomass [kg-DM] a

Aboveground biomass [kg-DM]

56

NativeBiomass of coppice growing from astump (Mean±S.D.).

Fig. 6.

300
250

Uncut tree
Cut tree before harvesting
Coppice after harvesting

200
150
100
500
Sep- Sep- Sep- Sep- Sep- Sep- Sep- Sep- Sep- Sep99
00
01
02
03
04
05
06
07
08

Time variations in biomass of the coppice andthe planted single trees at Site B (Mean ± S.D.).

growth rate during one year after cutting was 21 kg-DM/(y·tree), which was 4.2 t-DM/(ha·y) if multipliedby the stand density of 204 trees/ha. On the other hand, the growth rate of the coppice averaged over one
and half years after cutting was estimated as 4.9 kg-DM/(y·tree). The growth rate of the coppice wasmuch lower than that of the uncut planted trees. This indicates the coppice rotation period should belonger than seven years at least. Furthermore, the initial growth rate of the planted single tree during
about one and half years after planting was 11 kg-DM/(y·tree) as the average. Generally, the growth rateof first coppice exceeds that of the original single tree (Sims et al, 2001). The growth rate of the coppice,
however, was much lower than the initial growth rate of the planted trees in this study. It was because theplanted trees were irrigated for early root development while the coppices were not irrigated at all.
Moreover, as seen in Fig. 5, the growth rate of the coppice largely varied. This large variation may becaused by the difference in root development in the soil structures formed by the hardpan blasting.
However, some coppice showed a growth rate comparable to the initial growth rate of the planted trees,indicating the coppice can have a high growth rate even without irrigation when the conditions are right.
4. Conclusion
The growth rate of the coppice for the planted trees was comparable to that of the coppice for thenative trees. The results of this study indicate that biomass production by utilizing a coppice growth ishighly possible even in an arid area if root systems fully develop in the modified soil structure. Although
longer observation of the coppice growth is necessary for more reliable conclusion, the cost for CO2
fixation by arid-land afforestation is expected to be reduced by utilizing coppicing.
Acknowledgement
This work was conducted under the supports of Mitsui & Co., Ltd. Environment Fund and the New
Energy Development Organization (NEDO).
References
Kamo K. (1997): Trials of thinning and coppice regeneration for Eucalyptus forest. Nettai Ringyo, 39: 12-24 (in Japanese)
Kojima T., Hamano H., Abe Y., Tanouchi H., Egashira Y., Saito M., Law J., Takahashi N.. Yamada K. (2006): Basic Data of Research
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16: 167–174
Shiono K., Abe Y., Tanouchi H., Utsugi H., Takahashi N., Hamano H., Kojima T., Yamada K. (2007): Growth and survival of arid land
forestation species (Acacia aneura, Eucalyptus camaldulensis and E. salubris) with hardpan blasting. J. Arid Land Studies, 17:
11-22
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Zealand. Biomass and Bioenergy, 20: 329-335
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fixation system by afforestation of arid land -Enhancement of carbon fixation by technologies of soil structure modification.
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CALM (2002): Managing blue gum (Eucalyptus globulus) coppice, TreeNote No.35 May 2002, Conservation and Land Management(CALM), Department of Agriculture and Food, Western Australia.