Title: Urbanization, agro-ecological zones and food production sustainability
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Title: Urbanization, agro-ecological zones and food production sustainability
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Language: English
Creator: Simpson, James R.
Copyright Date: 1993
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Ur banization, Ag ro- Ecolog ica I

Zones and Food Production


Jrames R. Simpson
Food and Resource Economics Department, University of Florida, Box 110240, Gainesville,
Florida, USA 32611-0240

Human population in the world is projected to grow from about 5.2
billion in 1990 to around 8.0-8.5 billion 35 years hence in 2025. About
44% of the world's population lived in an urban setting in 1990 com-
pared with 34% in 1960. By 2025 the proportion will have grown tO
60%. These demographic shifts have had, and will continue to have,
major implications for the way in which food is produced and in the
sustainability of cropping systems and protection of ecological
resources. Particular attention is required to the type of agro-ecologi-
col zone and the influence of urbanization.

James R. simpson, Professor of
Agricultural Economics, has spent much of
his career living and working in Latin
America, Africa and Asia. He is author of
over 300 articles and five books on interna-
tional topics. His next book, to be published
in February, 1994 by CAB International, is
Livestock and Agriculture in China:
Projections to 2025.

Outlooke on Agriculture Vol. 22. No, 4, 233-239

Human population projections vary
depending on the source, the time at
which they were made and assump-
tions of various demographic factors.
Most of those presented here are from
the publication 11nited Nations World
Population Prospects (United Nations,
1991). The important aspect is not the
absolute numbers, but rather the trends
and implications. Particularly signifi-
cant is the influence of many rural pop-
ulations declining not only as a propor-
tion of the total population, but in some
cases in absolute terms.
Evaluation of the impact urbaniza-

tion will have on the world's ability to
feed itself is carried out in this article by
separate treatment of three areas of the
world. Each of these provides a very
different perspective from the view-
point of a major geographical entity.
The first discussion revolves around the
agro-ecological zones into which the
developing countries (LDCs) fall. In
fact, virtually all of this article focuses
on the LDCs, as they are the main
source of concern about population
growth and food production.
The second focus is on Central
America, a region with very rapid pop-

ulation growth and one very much the
target of concern about preservation of
natural resources. The third perspective
is Asia, and China in particular. The
final section contains conclusions about
the influence of urbanization, ethical
considerations and implications for
national and international agency poli-
cy making.

Worldwide population growth
The world's human population was
about 5 billion in the late 1980s, having
grown from about 3.1 billion in the

Table 1 Human population by continents, 1961-1988 and projections to 2025.

Three year averages
Continent 61-63 86-88 2025

Sub-Saharan Africa 220 450 1280
WANA 144 288 656
Asia 1545 2630 4315
C and S America 227 417 754
Total 2136 3785 7005
World 3135 5026 8466

Proportion of world (%)
Sub-Saharan Africa 7 9 15
WANA 5 6 8
Asia 49 52 51
C and S America 7 8 9
Total Four CAEZ 68 75 83

Proportion of four continents (%)
Sub-Saharan Africa 10 12 18
WANA 7 8 9
Asia 72 69 62
C and S America 11 11 11
Total Four CAEZ 100 100 100


Of the United Nations (FAO) (1982)
divides the developing world (with the
minor exception of the very cold areas)
into seven Agro-Ecological Zones
(AEZ). These seven zones, which are
included in the four continental zones
shown in Table 1, currently account for
about 75% of the world's population.
They are projected to include 79% of the
world's total population in the year
2000, 81% in 2010 and 83% in 2025. Sub-
Saharan Africa's population is projected
to grow from 450 million currently to
1.3 billion by 2025 (Table 1 and Figure
1). Western Asia and Northern Africa
(WANA) will grow from 288 million
people to 656 million. Asia is projected
to increase from 2.6 billion to 4.3 billion
people. Central and South America will
grow from 417 to 754 million.
The warm seasonally dry tropics
which comprise one of the seven zones
(the seven are listed in Table 2 with
urbanization rates) have the greatest
population of all seven agro-ecological
zones, 27% of the world's total, with an
increase to 30% projected by 2025.
Population in all seven AEZs grew by
77% from the early 1960s to the late
1980s, and is expected to grow by
another 85% over the next three and a
half decades to 2025.
The warm humid tropics and the
warm seasonally dry tropics with sum-
mer rainfall each currently comprise
about 17% of the seven AEZs' popula-

tion. The former will have 19% of the
total in 2025, while the latter will have
16%. The three tropical AEZs (1-3) now
have 49% of the AEZs' population; they
will account for 56% of the total in 2025.
In contrast, the warm subtropics (AEZs
4 and 5), both of which are only found
in Asia and Central and South America,
now have 31% of the AEZs' total, and
will be reduced to 27% of the total in
2025. The remaining two AEZs (6 and
7), both of which are cool subtropics,
will remain at about 19% of the total.
About 52% of the world's population
is found in the zone designated as
Continental Agroecological Zone
(CAEZ) Asia (caution must be exercised
with the four CAEZs as the country
groupings are different from those in
United Nations publications such as
FAO's Production Yearbook). Asia will
account for about the same proportion,
51% in 2025. The major change that
takes place is Sub-Saharan Africa
becoming 15% of the world population
as opposed to 9% at present. The four
CAEZs shift from having 75% of the
world population to accounting for 83%
(Table 1).
Asia constitutes 69% of the human
population when only the four CAEZs
are considered (Table 1 and Figure 1).
Sub-Saharan Africa, which presently
accounts for 12% of all four CAEZs, will
rise dramatically to 18% in 2025. Both
WANA and Central and South America
will remain at about 8 and 11% of the
CAEZs, respectively.
A global picture of population by
ecological zones is important because it
provides an indication of the major
areas in which there will be demand for
food. Furthermore, and apparently not
well recognized, the inter continental
relation of these zones provides possi-
bilities for collaborative research. As
migration takes place to urban areas,
and as agricultural technology and
mechanization increasingly become dif-
fused, expanded collaboration among
researchers and extension related per-
sonnel will be increasingly meaningful.

Urbanization by agro-ecological zones
and continents

Increases in population are one impor-
tant aspect for designing development
strategies for livestock industries in
developing countries. Equally impor-
tant are increases in the proportion of

SbSh~hk OWANA Ma OcSlr CWaM

63 toff uman population by CAEZ'

early 1960s. It will reach about 6.3 bil-
lion in the year 2000, which represents a
doubling in about a 40 year span
(Figure 1). Population will continue to
escalate reaching nearly 8.5 billion in
2025. Some demographic shifts will take
place between regions. For example,
Sub-Saharan Africa will grow from
about 7% of the world's population in
the early 1960s to about 15% by 2025.
Asia will remain at about half of the
world's population (Table 1).
Human population by agro-ecological
zones and continents

The Food and Agriculture Organization

Table 2 Urban and rural population by agro-ecological zones, 1961-1988 and projections to

Three-year averages
zone and
continent 61--63 86-88 2025


from 35% to 69%.
The warm/cool humid subtropics
(AEZ 5) and the cool subtropics with
summer rainfall (AEZ 6) are projected
to have the lowest rates of urbanization
in 2025, about 48% (Figure 3). The cool
tropics with winter rainfall (AEZ 7) will
have the largest urbanization (74%).
The warm seasonally dry tropics (AEZ
1), which has the largest population of
all AEZs (17% in the late 1980s, growing
to 19% in the year 2025), will witness
urban population growing from 320
million people to about 1.2 billion peo-
ple (Table 2).
Urban population in the seven AEZs
(the same as the total of the four
CAEZs) is projected to grow from 1.3
billion people in the late 1980s to 4.0 bil-
lion in 2025 (Table 2). This is a 307%
increase. It is rather startling that the
rural population in the four CAEZs is
only expected to grow from 2.5 billion
at present to 3.0 billion in 2025. This
represents just a 20% increase.
The warm seasonally dry tropics
(AEZ. 1) are expected to see their urban
population increase by 259% while their
rural population only grows by 30%
(Figure 4). The warm humid tropics are
projected to witness their urban popula-
tion increase by 244% and rural popula-
tion by 32%. The warm humid subtrop-
ics and cool subtropics with summer
rainfall will have essentially no rural
Urban population is projected to
increase by 434% in Sub-Saharan Africa
from the late 1980s to 2025, while rural
population increases by 79% (Figure 5).
Urban population will increase by 218%
in both WANA and Asia, but rural pop-
ulation will grow by only 31 and 11%
for the two regions, respectively. Rural
population in Central and South
America is not expected to grow.
The urbanization data are of utmost
importance because they mean that
crop farmers and livestock producers
will have to be increasingly efficient in
Order to feed not only their own fami-
lies, but also a growing number of other
people. One implication is that, in many
sub-regions of the developing world,
limited development funds will increas-
ingly have to be directed towards mar-
ket orientated producers. Another
implication is that a huge increase will
take place in the demand for grain.
Taken together, population growth and
urbanization data underscore the



1 Warm se snall dy tropics

3 Cool tropics
4 Warm seasonally dry subtropics
with summer rainfall
5 Warm cool/humid subtropics
6 Cool subtropics with summer rainfall
7 Cool subtropics with winter rainfall
Total AEZ

Sub-Saharan Africa








C and S America


1 Warm seasonally dry tropics
2 Warm humid tropics
3 Cool tropics
4 Warm seasonally dry subtropics
with summer rainfall
5 Warm cool/humid subtropics
6 Cool subtropics with summer rainfall
7 Cool subtropics with winter rainfall
Total AEZ

Sub-Saharan Africa



C and S America


people living in urban areas. The data
are absolutely astounding. Sub-Saharan
Africa is currently about 29% urbanized
compared with 12% mn the early 1960s
(Figure 2). It is projected that by 2025
nearly six out of every ten people will
reside in urban areas. Central and
South America's population will be 85%
urbanized as opposed to 72% in the late
1980s and 49% in the early 1960s. In
contrast, Western Europe was about
80% urbanized in the late 1980s. The
four continental agro-ecological zones

as a whole were 22% urbanized in the
early 1960s and 33% in the late 1980s.
The average will be 57% in 2025.
Urbanization, which will have a
major impact on the relative importance
of agricultural and livestock systems'
will vary considerably by country. For
example, while Burkina Faso in the
warm seasonally dry tropics of West
Africa is expected to increase only from
9% urban in the late 1980s to 27% in
2025 Mauritania and Benin, both in the
same AEZ, are expected to increase

Table 3 Relation between per capital income and urbanization at the world level.

Urban population
Per capital as a percentage
income of total population
Country or type of economy (US$) (%)

Low income, average 320 35
Chuna 330 50
India 340 27
Other 280 25

Middle income, average 1930 58
Lower-middle income 1380 56

Upper-middle income 3240 62
High-income 17080 78

Source: World Bank, World Development Indicators, 1990.


pressure that will be placed on the
world's resources.

Urbanization and income

Agricultural and livestock production
and marketing make a major contribu-
tion to the economies of nearly all coun-
tries of the world. The contribution is
especially large in developing countries
since a relatively high proportion of
their human population resides in rural
areas. For instance, as the 1990s began
agriculture accounted for 59% of gross
domestic product (GD)P) in Burundi
and 61% in Tanzania, countries which
had 7 and 32% urbanization, respective-
ly. Agriculture accounted for 12% of

gross domestic product in Algeria
which had 45% urbanization. A conclu-
sion is that agriculture does make an
important contribution to GDP. But the
proportion of GDP is an indicator more
of general economic development level
than of real value to an economy.
There is a strong relation between
urbanization and income per capital at
the world level even though there are
great differences between countries.
Data for 1988 at the world level show
that in low income countries, with an
average of $320 per capital, 35% of the
population was in urban areas (Table
3). The middle income countries had an
average per capital income of $1,930, but
were 58% urban. Per capital income is
associated with the level of urbaniza-
tion up to 60% or so. Above this level,
per capital income escalates rapidly with
only a small change in urbanization.
Although it is difficult to make a case
that economic development is caused
by urbanization, analysis of world data
clearly demonstrates a very strong rela-
tionship between urbanization and per
capital income. The reason is that when
a country is heavily orientated towards
agriculture, and particularly towards
subsistence agriculture, there is a rela-
tively weak interplay with the market
economy. As urbanization takes place
greater industrialization leads to more
manufacturing, which has a higher
multiplier effect than agriculture, espe-
cially if this is subsistence orientated.
That multiplier effect is crucial for eco-
nomic development.
Clearly, wide debate can be generat-
ed on the optimal speed of urbaniza-
tion. However, the message is clear: if a

Slumzs near Nairobi, Kenzya.
(Photography by Joe Connors, Johns Hopkins
Uni.l;, <- -. Population Com~munication

country's goal is economic develop-
ment, migration from agriculture is to
be encouraged. It should be pointed out
that urbanization need not mean
growth of me alo olises. Rather, it can
mean, as happened in China, creation of
industry in rural areas and expansion of
smaller towns and cities.
It may be concluded that, while
heavy urbanization is not necessarily
associated with per capital income gains
over the short term, particularly where
there are heavy migration and high
population growth rates, the data show
that urbanization is a necessary condi-
tion to reach relatively high levels of
per capital income in the longer term.
Thus, while urban poverty in LDCs
resulting from the urbanization process
is very visible and places heavy eco-
nomic strains on urban areas to accom-
modate the extremely high rates of
growth, society ultimately can be better
off economically than with a low level
of urbanization.

Central America and urbanization
The destruction of Central America's
forest habitat is viewed with alarm at
the world level. Great frustration exists
concerning how this precious resource
can be preserved (Belk et al., 1990).
Interactions between sustainable animal
agriculture and natural resource man-
agement are a critical systems problem
at the world level (Committee on
Agricultural Sustainability for

ozz p

Figure 2 Percent urbanization by CAEZ,
1961--63, 1986-88 and 2025.

- . . , ,

[ ] ==
I ..

projection is for 77% in 2000 and 85% in
Central America's human population
was 20 million in the mid 1970s. It
jumped to 27 million in the late 1980s
and is forecast to be 38 million in 2000.
The medium variant projection for 2025
by the United Nations is an astounding
63 million. Urbanization was 40% in the
mid 1970s and 47% in the late 1980s,
and will grow to 54, 60 and 68% in 2000,
2010 and 2025, respectively. Rural pop-
ulation increased from 12 million in the
mid 1970s to 14 million in the late
1980s. However, it will grow only
slightly, to 18 million in 2000, and will
then remain at about 19 million in 2010
and 2025. In other words, very little
population growth will take place in
rural Central America from now on.
Productivity and efficiency in agricul-
tural and livestock systems are critical
concepts in the evaluation of how
Central America's natural resources can
be conserved. Regardless of whether it
has been articulated or passive, devel-
opment aid focused on small producers,
with equity as a primary rationale, has
been a region-wide policy. There was
good reason for it until the past decade
because of Central America's moderate
population density, lower level of eco-
nomic development and high propor-
tion of rural population. However,
given the large increases projected in
urban populations, the very low growth
forecast in rural populations, demand
for attention to ecological factors, and
an implicit demand for increased pro-
ductivity, the time has come to reassess
equity priorities.
From the viewpoint of agricultural
sustainability and natural resource con-
servation, emphasis could best be
placed on evaluation of the extent to
which various agricultural and live-
stock systems can effectively increase
productivity, and public sector
cost/benefit ratios of the development
requirements (Simpson and Conrad,
1994). If, for example, one agricultural
system will produce a certain product
with a much greater productivity and
fewer public and private resources than
an alternative one, but requires much
less labour and significantly fewer
owner/operators, the tradeoffs should
be considered in a policy framework. In
effect, while small producers will con-
tinue to be part of the Central American
livestock production complex, the prob-

lem is to determine the speed at which
some of these~noncommercial, nonmar-
ket orientated producers shift to other
Another reason that productivity in
Central America's animal agriculture
has not increased rapidly is that prod-
uct prices are relatively low and input
prices relatively high (Simpson, 1988).
Extensive production practices are the
inevitable result, as are low levels of
technical inputs associated with low
productivity. Product prices have been
low because many governments have
controlled them as part of a cheap food
policy. In addition, relatively low con-
sumer incomes and demand for higher
quality and more processed products
have prevented price increases that
would be associated with increased
Extensive production practices imply
massive land clearing--the antithesis of
sustainable agricultural goals today.
Then, why not intensify production? In
fact, why not use production intensifi-
cation as one means to reverse ecologi-
cally abused conditions? Furthermore,
why not encourage human migration
from sensitive areas? These and associ-
ated questions demonstrate that equity
rather than economic or physical ratio-
nale may be the primary variable.

Asia and urbanization

Increases in population are a significant
factor in the design of development
strategies for the improvement of the
Asian agricultural and livestock indus-
try (Simpson, 1993). The degree of
urbanization, which has a major impact
on the relative importance of produc-
tion systems, varies considerably by
country. For example, Malaysia has
experienced a 17% growth in its urban
population since the early 1960s and is
expected to be nearly 67% urbanized by
2025. Indonesia's urban proportion will
grow from 30% today to 55% in 2025.
Thailand will jump from 23% at present
to 49% in 2025. The Peoples Republic of
China, where the distinction between
rural and urban is blurred owing to
rapid development of rural industry,
will also witness increasing urbaniza-
tion, climbing from 21% to 44% in 2025
according to official United Nations
projections (1991). China's urbanization
rate would probably be much closer to

1 2 3 4s 6 7

Figure 3 Percent urbanization by Agro-
ecological zones, 1986-88 & 2025

Developing Countries, 1989). The inter-
actions are especially critical in light of
the challenge for Central American
countries to design and implement
alternatives that will enhance sustain-
able agricultural productivity while
encouraging rehabilitation of degraded
The definition of urbanization varies
among countries and regions. However,
projections by United Nations' demog-
raphers indicate that in Central and
South America (including the
Caribbean and Mexico) urbanization
grew from 49% in the early 1960s to
61% in the mid 1970s and 72% in the
late 1980s (United Nations, 1991). The

go- []m.


5 1

Figure 4 LUrban & rural population change by
AEZ, 1986-88 to 2025.


cally improved standards of living for
rural as well as urban dwellers, then
promotion of commercially orientated
agricultural and livestock operations
should be encouraged. That means sup-
port for a policy that encourages urban-
ization, especially with a reduction of
marginal and subsistence level produc-
ers. The concept of assisting very small
producers is a laudable one, but size as
well as other constraints prevents sub-
stantial income improvements, thus
leaving these producers as an ever
alienated part of society.
There should be recognition that soci-
ety (i.e. policy makers) now needs to set
sustainability parameters on water pol-
lution, forest conservation, production,
etc. rather than simply relying on mar-
ket forces and belated public opinion.
Ths could be accomplished by an inter-
action with agricultural specialists and
economists to determine feasible targets
and appropriate legislation. It must be
recognized that producers are profit
makers who operate within rules set by
society. Development of regulations
that stimulate productivity yet provide
guides to what society wants in terms
of economic growth- and an ecological
vision--is part of the development
process. The developing world is at a
critical juncture in which these policies
and legislation should be articulated.
The policy maker's role is a critical
factor for, with equitable prices and rea-
sonable profits, i.e. a producer orientat-
ed policy, there will be an adoption of
technology that will lead to increased
efficiency per 'natural resources unit'.
Again the equity question is crucial, for
in animal agriculture much of the tech-

Urban poverty, Indonesia.
(Photograph by Joe Connors, Johns Hopkins
University, Population Communication

ter century the attention of the interna-
tional community has been focused on
small producers, based on the assump-
tion that the rural sector would contin-
ue to predominate. There seems to have
been an attitude that migration to urban
areas was somehow 'bad', and also that
every effort should be made to promote
animal power over mechanization. But,
as shown in this article, urbanization
will take place. For instance, the rural
population of Southeast Asia will
increase by only 17% between the late
1980s and 2025. The total rural popula-
tion in China in 2025 will be at the same
level as in the late 1980s. In Central and
South America the total rural popula-
tion will be the same as today. The only
area where the rural population will
grow to any extent is Sub-Saharan
Africa, where it will increase by 79%. At
the world level there will be only 16%
more people in rural areas than today.
A dialogue is needed on the question
of who should produce and why. If the
goal is economic development and radi-

Sub-SahAfr WANA Asia C&LS.Amer World

Figure5i Urban & rural population changes by
CAEZ, 1986-898 to 2025.

60 or 70% in 2025 if adjustments were to
be made for rural families engaged in
part-time farming and rural industry.
The total population of Southeast
Asia will increase from about 585 mil-
lion people at the end of the 1980s to
nearly one billion in 2025. That is a 71%
increase over the three and a half
decade period. During this interval,
urban population will increase by 232%.
In contrast--and this is crucial for agri-
cultural industry planning--rural pop-
ulations will grow by only 17%, from
436 million in the late 1980s to 510 mil-
lion in 2025. Furthermore, Southeast
Asia's total rural population will actual-
ly decline after 2010. China's rural pop-
ulation will grow only slightly between
the late 1980s and 2000, and will decline
after then-


The implications of rapid urbanization
in developing countries are numerous.
Clearly, crop and livestock producers
will have to be increasingly productive.
The demand for commodities will
change and more mechanization is
expected. The shift from extractive sys-
tems to more intensive ones will
expand the demand for grain, especial-
ly for milk production from higher pro-
ducing dairy cattle, and for poultry and
pig production. One implication is that
limited development funds will increas-
ingly have to be directed towards mar-
ket orientated producers.
It is fair to say that for the past quar-

Table 3 Relation between per capital income and urbanization at the world level.

Urban population
as a percentage
of total population

Per capital

Country or type of economy

Low income, average

Middle income, average
Lower-middle income

Upper-middle income


Source: World Bank, World Development Indicators, 1990.

nology and management practices are
of such complexity that smaller produc-
ers cannot apply effective management
realistically. Without accelerated gains
mn farm productivity, rising demands
due to both population increase and
income growth will translate directly
into environmental stress. A continuous
flow of technology and associated
intensification is critical to environmen-
tal sustainability.
The analyses presented in this paper
indi ate tda whert pro eicted urbaniza-

development focus is called for, with
emphasis placed on ways to increase
productivity. This strategy is quite dif-
ferent from those aimed at retaining
people in rural areas and attempting to
provide employment for them regard-
less of the impact on productivity.


Belk, K. E., Huerta-Leidenz, N. O. and
Cross, H-. R. (1990) Factors Involved in
the Deforestation of Tropical Forests.
Department of Animal Science, Texas
A &M University, USA.
Committee on Agricultural
Sustainability for Developing
Countries (1989) The Transition to
Sustainable Agriculture: A Two Year
Review ofAID's Agricultural and Rural
D velopment Progr ms and an Agenda

December 1989.
FAO Production Yearbook, various
FAO (1982) Potential Population
Supporting Capacities of Lands in the
Developing World. Technical Report of
the Project INT/75/P13, Rome.

Simpson, J. R. (1988) The Economics of
Livestock Systems in Developing
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Simpson, J. R. (1993) Livestock Inventory
and Feedstuff~s Reqluirements in
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Department International Working
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Agriculture in Relation to Natural
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@ C-A-B International. 1993

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