Open Journal of Forestry
2013. Vol.3, No.1, 8-11
Published Online January 2013 in SciRes (http://www.scirp.org/journal/ojf) http://dx.doi.org/10.4236/ojf.2013.31002
The Concept of the Ergonomic Spectrum
Yozo Yama da 1, Efi Yuliati Yovi2, Dianne Staal Wästerlund3, John J. Garland4, Janusz M. Sowa5
1Graduate School of Bio-Agricult ural Sciences, Nagoya University, Nagoya, Japan
2Faculty of Forestry, Bogor Agricultural University, Bogor, Indonesia
3Department of Forest Resource Management, Swedish University of Agricultural Sciences, Umeå, Sweden
4Garland & Associates, Waldport, USA
5Department of Forest and Wood Utilization, University of Agriculture in Krakow, Krakow, Poland
Received November 14th, 2012; revised December 17th, 2012; accepted December 27th, 2012
Forestry conditions differ among regions and nations. Moreover, labor costs, forestry mechanization, and
environmental impacts are also different. These factors directly or indirectly influence the ergonomic state
of nations. The ergonomic state of a nation can be described in terms of ergonomic factors such as labor
productivity, work accidents, physiological burden, and stress. Labor productivity and work accidents can
be defined as income or condition factors, and physiological burden and stress as outcome or result fac-
tors. Thus, the value of outcome factors must be examined in relationship to income factors. On the ergo-
nomic spectrum, each factor can be conceived as a continuum from a negative to a positive ergonomic
status. All factors can be set in a line, and the present state of each nation is indicated by a profile formed
by the assembled factors. The locations of nations along the two-dimensional coordinates of the world
standard can be realized by an ergonomic spectrum. Moreover, future directions for improvement can be
obtained by reference to the three-dimensional coordinates, which include the axis of time.
Keywords: Ergonomic Spectrum; Economic Situation; Forestry Condition; Working Condition; Work
Accident
Introduction
Globally, forest engineering has been shifting from manual
to mechanized work. Consequently, ergonomic issues have
changed from physical or physiological burdens of forestry
workers to psycho-physiological stressors of machine operators.
However, many developing countries continue to rely on man-
ual work for most of their forestry operations. Manual work is a
classic ergonomic issue, and it remains significant in develop-
ing countries. Moreover, some countries, such as Japan, are
located midway between manual and mechanized forestry.
Forestry mechanization has spread in Japan except in the area
of felling operations due to the steep and complicated terrain.
This situation cannot be improved unless an innovative tech-
nique is developed to overcome the adverse natural conditions.
Manual felling operations with a chainsaw have been recog-
nized globally as one of the most dangerous jobs in forestry,
and many studies have been conducted from a safety perspec-
tive. For example, Hammond studied critical safety behaviors
of differently skilled workers using a helmet camera in the USA
(Hammond et al., 2011). Bentley noted the potential for injury
among inexperienced fellers in New Zealand and claimed that
felling safety is dependent upon an appropriate assessment of
hazards and good judgment with respect to decisions regarding
felling (Bentley et al., 2005). Felling operations in Japan have
been the most dangerous forestry work during this half century
(Oka et al., 2011), and many severe accidents have occurred
during manual felling operations in Sweden among private for-
est owners (Lindroos & Burstrom, 2010).
Wearing protective devices to reduce work accidents during
manual felling operations is one of the most effective direct
safety countermeasures. Kashima claimed that wearing protec-
tive trousers while operating a chainsaw results in a 60% de-
creases in lower body injuries (Kashima & Uemura, 2008).
However, many of the protective devices have been developed
in cool and dry climate countries and are not suitable for use in
tropical or wet temperate regions. Workers in those regions hate
to wear protective devices, even helmets and gloves, because
they are uncomfortable. Wästerlund researched heat stress in
forestry and argued for a standard research method to determine
protective clothing comfort (Wästerlund, 1998). Holland evalu-
ated the ventilation capacity of various helmets for forest har-
vesting (Holland et al., 2002).
Ergonomic issues vary in every nation, as each has different
forestry conditions. Although Feyer compared fatal occupa-
tional injuries among US, Australian, and New Zealand work-
ers (Feyer et al., 2001), very few cooperative studies have in-
volved multiple nations. Thus, it is difficult to describe the pre-
sent ergonomic state of each nation using a simple world stan-
dard.
This report offers the ergonomic spectrum as a new idea to
objectively identify current forestry ergonomic conditions in
each nation and to identify the actual and more preferred future
direction to improve each nation’s ergonomic conditions. At
first, we introduce the concept of ergonomic spectrum, and then
explain how to select indices for using the ergonomic spectrum,
and finally show two experimental examples.
Concept of Ergonomic Spectrum
Everyone wants to eliminate forestry accidents. If this occurs
thorough forestry mechanization, forestry work accidents will
decrease dramatically, including in felling operations. Unfortu-
nately, it is quite difficult to realize this scenario because of the

Y. YAMADA ET AL.
forestry conditions in each nation. Work accidents are influ-
enced significantly by forestry conditions, which are influenced
by national and regional indigenous characteristics such as geo-
graphy, topography, climate, vegetation, population, wood de-
mand, wood trade, and economic and social conditions. More-
over, labor costs, forestry mechanization, labor productivity,
and environmental impacts also differ among nations. Thus,
working conditions directly or indirectly influence the ergono-
mic state of each nation.
The ergonomic state of a nation can be estimated through
ergonomic factors such as work accidents, physiological burden,
and stress. These factors indicate the current ergonomic situa-
tion based on forestry activities in each nation, and improve-
ment in these factors would result in safer conditions, lighter
work and stress loads, and more comfortable working condi-
tions. If forestry and working conditions are defined as income
or conditions, then ergonomic factors can be defined as out-
come or results. The value of outcome factors must be exam-
ined relation to the income factors.
However, it is unrealistic to comparatively evaluate factors
that differ in substances, units, and scales. Thus, the spectrum
concept is used to allow a clear comparison among different
ergonomic situations in the world.
With respect to a spectrum, the emotional spectrum and the
recreational opportunity spectrum are well known to include
some vectors. The emotional spectrum (ES) can evaluate an
emotional state of human from the electroencephalogram, and
is composed of four element emotion vectors; anger, sadness,
joy, and relaxation. The recreation opportunity spectrum (ROS)
is an applied example. The ROS is a combination of physical,
biological, social, and managerial conditions that give recrea-
tional value to a place (Clark & Stankey, 1979).
The basic concept of the ergonomic spectrum is similar to
that of the ES and the ROS. Whereas the ROS separate s nations
into seven classes from the least to the most remote (British
Columbia Resources Inventory Committee, 1998), the ergo-
nomic spectrum is more complicated and not as easily divided
into patterns.
As shown in Figure 1, each factor is represented along a
continuum from a negative to a positive ergonomic state, with a
negative state shown in orange, and a positive one in green. All
factors are set in a line, and the present state of each nation is
indicated by a cross-section of the assembled factors. It appears
like a spectrum; thus, it is easy to recognize where a nation is
located compared to the world standard using the two-dimen-
sional coordinates. Moreover, the directions needed for impro-
vement can be shown in a three-dimensional coordinates that
include the axis of time.
Ergonom ic Spectrum
Fo r est ry C o n d itio n s
Wo r kin g C o n d itio n s
Work Accidents
P hy siological Burden
Str e ss
Influences
Econ om ical Situation
Income
Outcome
Figure 1.
Concept of the ergonomic spectrum .
Selection of Ergonomic Spectrum Indices
Indices for the ergonomic spectrum were defined as the eco-
nomic situation, forestry conditions, working conditions, and
work accidents. The first three factors are income factors, and
the last is an outcome factor. Physiological burden and stress
could not be included because these types of data are difficult
to gather from official reports. Although researchers sometimes
report these data, the studies are often case studies and usually
do not represent average burdens of all workers in a country.
Furthermore, other factors are applicable to the ergonomic
spectrum, but data on these could not be obtained for every
country; thus, they were eliminated from this study.
Economical Situation
National economic and social situations have great impact on
forestry as an industry. The economic situation of a nation can
be described by many factors such as nominal or real gross
domestic product (GDP), nominal or real gross domestic index,
the domestic population, consumer price index, and Engel’s co-
efficient. In this study, the nominal GDP per person, as an in-
dex of the national economic situation, and Engel’s Coeffi-
cient, as an index of rich and poor, were selected for use in the
ergonomic spectrum.
Forestry Conditions
Forestry conditions are characterized by climate zone, aver-
age slope gradient, forest coverage rate, artificial forest rate,
planted species, wood demand, wood self-support ratio, forest
road density, and forestry mechanization rate. Data on some of
these factors are difficult to obtain because no description is
available in official reports. In this study, the forest coverage
rate, as an index of potential wood resources, and the self-sup-
port ratio of timber, as an index of logging activities, were se-
lected.
Working Conditions
Working conditions can have a crucial impact on work acci-
dents, physiological burden, stress, and decision making during
forestry work. Working conditions include wage, number of
forestry workers, the age index, management area, and labor
productivity. In this study, the average wage, average manage-
ment area, and average productivity were selected as represent-
tative factors. The average management area per person was
calculated by dividing the forest area by the number of forestry
workers. Although the actual number of workers cannot be
compared against figures for other countries, management area
can be estimated by the number of workers. The average pro-
ductivity per year per person, which is calculated by dividing
felling volume by the number of forestry workers, also indi-
cates the degree of mechanization.
Work Accidents
Work accidents are external factors or objective variables
explained by the economic situation, forestry circumstances,
and working conditions. In this study, the work accident rate
and the fatal accident rate were selected as factors. These are
expressed as the rate of workers injured or killed per 1 million
felled trees. An effort must be made to decrease these objective
factors through every possible means. Unfortunately, Indonesia

Y. YAMADA ET AL.
has not surveyed the number of workers injured and killed in
their forestry operations.
Experimental Examples
Data of nine factors for the ergonomic spectrum were ob-
tained from official reports from five countries, Sweden, USA,
Poland, Indonesia, and Japan, to compare the ergonomic situa-
tions among them. Moreover, data were gathered at five differ-
ent times in Japan, namely 1970, 1980, 1990, 2000, and 2010,
to observe changes in the ergonomic situation.
Comparison of Ergonomic Spectra among the
Five Nation s
Figure 2 shows a comparison of the ergonomic situations
among the five countries. The right-hand side of the graph is
the desirable situation. Sweden’s profile shows values mostly
well to the right side, with little variation, whereas values for
the other countries range from values toward the left-hand side
to values approaching the right-hand side. The five countries
show quite different profiles. The USA maintains a positive
status in terms of economic situation, number of work accidents,
and management area but earns low or moderate scores for
forest coverage rate, the self-support ratio, wages, and produc-
tivity. Poland maintains low or medium status for the economic
situation, forestry conditions, and working conditions but scores
high for work accidents. Indonesia maintains low scores for
their economic situation and working conditions but gets the
highest marks for self-support ratio. Japan fluctuates wildly
among factors. Japan gets high marks for nominal GDP, forest
coverage rate, and wages. However, the high wages are due to
appreciation of the yen against the US dollar. In contrast, Japan
gets low scores for the self-support ratio, management area, and
productivity, which are significant problems in the Japanese
forestry industry. Moreover, the work and fatal accident rates
are worse than those in the other countries.
The forest coverage rate is fixed in each country, and the
nominal GDP and Engel’s coefficient cannot be improved by
the forestry sector. The self-support ratio and wage could be
changed if forestry realizes a revitalization. Management area
and productivity can be improved by multi-functional mecha-
nization, but it is not easy to promote multi-functional ma-
chines in Japan and Indonesia. Without high mechanization, the
accident rates can be reduced only by wearing protective de-
0%10% 20% 30% 40% 50% 60% 70% 80% 90%100%
Fatal Accident Rate
Work Accident Rate
Productivity
Management Area
Wage
Self-Support Ratio
Forest Coverage Rate
Engel's Coeffcient
Nominal GDP
JAPAN INDONESIA POLAND
USA SWEDEN
Figure 2.
Comparison of the ergonomic spectra among the five nations.
vices and safety training for forestry workers.
Changes in the Japanese Ergonomic Spectrum
Figure 3 shows the changes in the Japanese ergonomic spec-
trum over four decades. In 1970, values for all factors except
forest coverage rate were low. In 1980, nominal GDP, Engel’s
coefficient, and wage increased gradually. Notably, the fatal
accident rate decreased largely, but the work accident rate was
the worst. In 1990, the former three factors continued to in-
crease gradually, and the work accident rate improved dramati-
cally. Since 2000, the former three factors have continued to
increase, and the work accident rate has improved slightly. The
fatal accident rate has not changed since 1980.
Although wages increased dramatically due to the high yen,
the actual wage was not so high and has actually decreased
since 2000. The nominal GDP and Engel’s coefficient have
increased steadily, and productivity and management area have
increased slightly. Improving those factors in Japan will not
occur smoothly because of the difficulties of multi-functional
mechanization.
The work accident rate improved largely from 1980 to 1990.
However, improvement has slowed in the past two decades.
Moreover, the fatal accident rate has become slightly worse
since 2000. Manual felling remains common in Japanese for-
estry. The reduction in work injuries and fatal accidents is the
most significant and urgent issue. In the future, Japan should
struggle to improve work conditions, fatal accident rates, pro-
ductivity, and the self-support ratio.
Conclusion
We can appreciate the ergonomic situation of Japan in rela-
tion the world using the ergonomic spectrum. Moreover, we
can identify the direction for improvement in our forestry er-
gonomic situation based on the changes in the ergonomic situa-
tion through the past several decades. In other words, we can
understand easily where we are now and which directions we
should improve.
However, the following problems must be solved for the er-
gonomic spectrum to become a useful tool. The first problem is
factor selection. Which factors should we choose for the ergo-
nomic spectrum? We must discuss whether the factors are suf-
ficient to show the actual ergonomic situation. Moreover, we
must examine whether a factor can be corrected even if it is
0%10% 20% 30% 40% 50% 60% 70% 80% 90%100%
Fatal Accident Rate
Work Accident Rate
Productivity
Management Area
Wage
Self-Support Ratio
Forest Coverage Rate
Engel's Coeffcient
Nominal GDP
2010 2000 1990
1980 1970
Figure 3.
Changes in the Japanese ergonomic spectrum.
10

Y. YAMADA ET AL.
issues in ergonomics, they cannot be accomplished without the
help of management, local officials, owners, planners, supervi-
sors, and leaders. In this sense, improvements can be defined as
external and passive from the point of view of workers and
operators.
Control
Sensibilities
Consciousness
Management
Planners & Managers
Classical Cognitive
Physical Psycho- p hysiologic al
Physiological Stress
Manual Man-Machine
Workers Oper ato rs
Er gonomi c S pect r um
Passive
External
Active
Internal
We must think of extending future ergonomics to forest
management control spheres (Figure 4). Control ergonomics,
which is based on the ergonomic spectrum, aims to enhance the
sensibilities and consciousness of management and fosters in-
ternal change in each manager in working not only with staff
but also with workers and operators. It is also concerned with
classical ergonomics and cognitive ergonomics and considers
management philosophy, design, decision making, social re-
sponsibility, evaluation, improvement, and education and train-
ing for workers and operators. In this sense, control ergonomics
can be defined as active ergonomics.
Figure 4.
Ergonomic strategy based on the ergonomic sp ec trum.
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world. Surely, no one wants accidents in the work place. How-
ever, in each nation, some factors can be improved and others
are indigenous to the country and cannot be improved. For
example, Japan cannot reach the same ergonomic situation as
Sweden because its climate and terrain are different. Thus, we
must find another goal that is suitable and can be accomplished.
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The ergonomic spectrum is intended mainly for forestry
workers and operators to improve their working conditions.
Although improvements are traditionally basic and essential