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OCR for page 18
~-
Will slower population
growth increase the growth
rate of per capilra income
through increasing per capita
availability of renewable
resources?
In contrast to exhaustible resources, biotic resources like forests, fisheries,
and agricultural land can be renewed by natural processes. Renewable
resources are potentially capable of providing economic services in perpetuity
so long as their regenerative capability is not damaged. Consequently, they
pose a different set of issues than those for exhaustible resources.
There are two mechanisms that can create a link between population size
or grown rates and the availability of renewable resources. One can be
termed the issue of diminishing returns. When a population is larger, a
member of the population will have, on average, fewer of the renewable
resources to use in production and consumption. Certain important resources-
oxygen, for example-are so abundant that greater numbers of people have no
material effect on the amount available per person. But others, such as arable
land, are sufficiently limited in abundance that the* diminishing availability
per person can reduce labor productivity and restrain per capita production
and consumption possibilities. Unlike the case of exhaustible resources, He
number of persons alive at a moment of time can have an enduring effect
on each person's available resources. In a steady-state world population of
10 billion, for example, each member will have less arable land per capita
than in a steady-state population of 5 billion. This difference will persist
through time and over individuals born into the two populations.
The second issue is one of resource depletion. The natural processes that
produce resource renewal do not operate automatically. They are subject to
18
OCR for page 19
RENEWABLE RESOURCES
19
human interference and disruption as well as to the vagaries of nature. This
fact becomes even more salient when effective property rights governing
access to the resource do not exist or are not enforced. Resources that
are not governed by well-defined access rules are called common-property
resources. Because no private or public sector agent controls the disposition
of the stock, users of the resource must pay only the cost of harvesting it.
Because the price is lower than it would be if the asset value of the stock
were then into account, the resource will be over-exploited, and Here will
be inadequate incentives for resource conservation.
Certainly the most important renewable resource in most developing counties
is arable land. There are, however, other important renewable resources
subject to depletion, many of them common-property resources. Access to
vast extents of forest in some of these countries is virtually unrestricted,
and deforestation due to commercial lumbering, fuelwood gathering, and
agriculture is now a major issue. Similarly, fishing is an important worldwide
source of food, but overfishing has reduced yields in many ocean areas.
Freshwater is another important renewable resource, particularly due to its
use for irrigation. Although the economic relationships in each of these cases
are complex, population size and growth play at least some role in the
demand for these resources.
DIMINISHING RETURNS TO LABOR IN AGRICULTURE
Historical Responses to Diminishing Returns
Lee relations between population and agricultural production are played
out against a backdrop of static diminishing marginal returns to labor.
Diminishing returns to labor were evident in Europe over a long stretch of
time in which productive techniques were changing very slowly. Time series
of real wage and population figures for England, France, and a composite of
countries between 1300 and 1750 leave little doubt that exogenous changes
in population, induced by epidemics, plagues, and weather changes, affected
average wages: periods of unusually small population numbers had unusually
high wages (Lee, 1980; Gould, 1972; Slicher van Bay, 1963~.
One reason these relations are not very evident in contemporary populations
is Hat many factors besides land and labor have come to play an important
role in agricultural production. The application of fertilizer, irrigation, and
a great variety of biological techniques (new seeds, new methods of crop
rotation, leguminous crops) have loosened the link between labor productivity
in agriculture and He landllabor ratio. However, these new factors are
themselves often subject to diminishing returns. There is evidence that output
gains from added fertilizer use in He United States (Crosson, 1982) and
OCR for page 20
20
POPUI~ON GROWING A1V~ ECONOMIC DEVELOPMENT
in a cross-section of developing countries (Brown, 1984) are less Han
they were when fertilizer was less intensively used. Likewise, output gains
from irrigation encounter diminishing returns from waterlogging and increased
salinity of the land (Brown, 1981; Hayami and Ruttan, 1984; Hinman, 1984).
But the existence of diminishing returns to these factors does not necessarily
pose economic barriers to their increased use. Indeed, the combination of
increasing fertilizer use and diminishing returns to it in industrial countries
is a natural response to a long-term decline in the real price of fertilizer.
Such diminishing returns also can be and have been to some extent offset
by changes in plant varieties and production methods.
A second reason that declining labor productivity in agriculture resulting
from land scarcity has not been widely observed in developing countries is
that massive additions to He stock of land under cultivation have occurred
during this century. Most of the gains in food production between 1900
and 1950 were a result of expanding the area under cultivation (Brown,
1981; Johnson, 1974~. Contrary to Ricardian assumptions, this added land
was not necessarily of inferior quality; it may simply have been located
further from existing settlements (Ghatak and Ingersent, 1984~. Since 1950,
however, most of the output gains have resulted from increased yields per
unit of cultivated area. For example, it is estimated that increased yields
contributed 62 percent of the gain in world agricultural production in the
1960s and 1970s (Mellor and Johnston, 1984~. There are still substantial
possibilities, however, for expanding the amount of land tinder cultivation
in parts of Africa and Latin America.
The net result of increases in land under cultivation, increased use of
fertilizer and irrigation, and improved ag{icllltural techniques is Hat He grow
rate of total agricultural production on a worldwide basis and for developing
countries as a whol~except for parts of Africa~as consistently exceeded
population growth rates in the past two decades (Food and Agriculture
Organization, 1981). The real prices of the major sources of calories for
people in poor nations have declined in recent decades, and the proportion of
the labor force in agriculture in developing countries win market economies
declined from 68 percent in 1965 to 58 percent in 1981 (Johnson, 1985~.
Africa represents an important exception to rising per capita agricultural
production. Per capita agricultural output in Africa fell by an average of 1
percent per year between the early 1960s and 1980 (Food and Agriculture
Organization, 1981:22~. However, Africa has a relatively high ratio of arable
land to population, which suggests Cat He decline in per capita agricultural
output reRects factors over than diminishing returns due to population
grown. These factors reflect a host of human and institutional barriers to
expanded output, including a very weak human resource base for agricultural
research, extension, and entrepreneurship; overvalued foreign exchange rates
OCR for page 21
RENEWABLE RESOURCES
21
that discourage domestic production; high taxes on both food crops and export
crops; an urban bias in development strategies and investment; and failed
experiments in agrarian socialism (Etcher, lg84; Economic Commission for
Africa, lg843. Eicher (1984) argues that many of these conditions are a legacy
of colonialism and that others have been encouraged by foreign advisers.
It seems reasonable to expect that in combination with these conditions,
faster population growth will aggravate problems of low labor productivity
in agriculture in Africa (Binswanger and Pingali, 1984~.
There are many countries that have successfully increased their agricultural
output despite the problem of diminishing returns. Perhaps the best documented
case is Japan, which in 1880 had only 5 percent as much arable land
per worker as did the United States. Yet total agricultural production in
both countries grew at an average annual rate of 1.6 percent during the
next 100 years (Hayami and Ruttan, 1985b). The Japanese solution to its
high labor/land ratio was to develop and use more labor-intensive methods
of production than countries like the United States, to rely heavily on
irrigation, and to introduce biological techniques to increase yields (Pingali
and Binswanger, 1984; Hayami and Ruttan, 1985b). The Japanese-type
solution has characterized many other areas in Asia, including Taiwan, Java,
South Korea, the central plains of Thailand, the Punjab, and the Philippines
(Pingali and Binswanger, 1984; Hayami and Ruttan, 1985b; Muscat, 1984;
Khan, 1984~.
While there are many examples of successful adaptations to high labor/land
ratios, Here are other examples where intensification of agriculture has
apparently led to reduced labor productivity, sometimes accompanied by
soil depletion, exhaustion, and even abandonment. For example, the Mayan
civilization may have expanded its population beyond He point that could be
permanently sustained given its land and technical endowments (Deevey et
al., 1979~. Much of northern Africa might have lost its agricultural potential
from a combination of climatic change and population pressure (Kirchner et
al., 1984~. More contemporary examples of such processes have been noted
in Zambia (Allen, 1965) and the inter-Andine region of Ecuador (Gourou,
1980~. Gourou (1980:73-74) also cites the Kamba in Kenya, the Sukumas in
Tanzania, and He Jabros in Sudan as groups forced to migrate to other areas
because of degraded soil produced by overgrazing. Beckford (1984) argues
in more general terms that institutional structures in developing countries
create rigidities that prevent or inhibit the kind of adaptive responses to
population pressure and market opportunities exhibited in Japan.
Perhaps He most important contemporary country demonstrating diminishing
returns to labor in agriculture is Bangladesh. According to Khan (1984), real
agricultural wages in Bangladesh in the 1970s were below what Hey had
been in the 1830s. Much of the decline occurred in He period of most rapid
OCR for page 22
22
POP Ul~lON GROWTH AND ECONOMIC DEYEl~PMENI
population growth after 1950. The decline in real wages was accompanied
by an apparent increase in landlessness from an estimated 7.3 percent of
the farm labor force in 1951 to 26.1 percent in 1977 (see Cain, 1983,
for a skeptical view on the quality of these data); a decline in average
caloric consumption per Malta; and a rise in the proportion of the population
living in poverty. Khan can find no other explanation for these disturbing
trends than the rapid increase in population combined with institutional
rigidities. Ghatak and Ingersent (1984) raise the question of whether it is
realistic to speak of possibilities for adopting new technologies in response
to population pressure in countries like Bangladesh, where labor is already
extremely intensively used. The population-push model of technical change in
agriculture initially proposed by Boserup (1965) may have Rio technological
stages left to offer a country in which agrarian density is already very
high. Surely there are many possibilities for improving agricultural output in
Bangladesh, but additional density of population does not appear necessary to
induce the* adoption. Clearly, one must examine carefully the preconditions
for intensified agriculture in a specific coundy before reaching a verdict
on the long-term effects of population growth on its labor productivity in
agriculture.
Future Prospects for Agricultural Intensification
It is important to note that many soils in tropical areas do not have the
same capacity for intensified production as soils in temperate areas. Tropical
soils are usually deficient in important minerals, such as phosphorus and
nitrogen, and because they are poor in humus they have a reduced capacity
to adsorb fertilizer. The low adsorptive capacity of many tropical clays,
in combination with heavy rainfall, results in rapid leaching of important
minerals from the soil. And since organic matter generally decomposes more
rapidly in tropical areas, manure remains active a much shorter time than
in temperate areas (Gourou, 1980~. In arid and semiarid lands, the rainfall
required to support a dense population Is lacking, although phosphorus can
be introduced to increase the soil's capacity to adsorb water (Breman and
de Wit, 19831.
Despite their natural disadvantages, some tropical lands are very intensively
farmed, and a great deal of additional intensification is possible. Certain
schemes in the Amazon have resulted in continuous farming at high yields
(Sedjo and Clawson, 19841. In some counties a variety of soil types exist,
and a rise in the population/land ratio can move cultivation away from
midslope areas, where potential productivity per unit of land is relatively
low but where less land preparation is required, to lower-lying areas where
potential land productivity is higher (Pingali and Binswanger, 1985~. Such
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RENEWABLE RESOURCES
23
a movement typically incurs an expense in the form of a reduction in
leisure hours, which are often relatively high among nomadic farmers and in
lightly fanned areas (Gourou, 1980:Chapter 7~. Because of this relationship,
many low-lying areas in sparsely populated parts of Africa are uncultivated,
although they could support intensive rice production with other inputs as
well as increased labor.
To gain a sense of agricultural production possibilities under alternative
techniques, Me U.N. Food and Agriculture Organization (FAO) and the
Informational Institute for Applied Systems Analysis (IIASA) undertook a
study of the number of people who could be supported by the agricultural
production of specific areas in the developing world. The world was divided
into tens of thousands of small regions distinguished by soil type and climate.
All potentially cultivable land was assumed to be used for food crops, except
for 0.05 hectares per person devoted to all other uses. Production potential
was evaluated under three assumed levels of input: a low level, corresponding
to traditional farming practices in developing countries (manual labor, hand
tools, and the current mixture of crops); a high level, assuming the optimal
mixture of crops for a particular area and substantial mechanization; and
an intermediate level that is roughly an average of We other two (Food
and Agncultwe Organization, 1983~. The high level of inputs, though
technologically feasible, is very often well beyond what is economically
feasible.
Under the low level of inputs, 54 counties were identified as "critical',
in 1975, having insufficient food production capacity to support their current
population. Under the high-input level, the figure was 13. The numbers of
countries grow to 64 (of which 10 are in Me Middle East-see below) and l9,
respectively, under the projected national populations of 2000. Most of the
critical counties are below average in size, although India appears on the
list in 1975 under the low-input level; with high inputs, India could support
2.5 times its expected population in 2000. Zaire has enormous agricultural
potential by this calculation, awe to support 62 times its expected 2000
population of 46 million with high inputs-enough to feed the entire population
of Africa several times over-and 6 times its expected population even under
low inputs. The 24 largest developing countries as a whole (excluding China)
are projected to be able to support a total of 21.9 billion persons under high
inputs by the year 200(), more than seven times their projected populations.
As discussed above, these figures constitute technological upper limits that
help to frame discussion, but they do not constitute realistic targets.
The economic possibilities for food production may, in fact, be far
below the technical limits, since food will be produced only if it is in the
economic interests of farmers to do so. Snnivasan (1985) reviews a number
of elaborate simulation studies that seek to incorporate economic processes
OCR for page 24
24
POP ULA~7ON GROWTH AND ECONOMIC D~YELOPMENT
in food production forecasts. These studies-notably one by the Food and
Agriculture Organization (1981), Global '>000 (Council on Environmental
Quality and U.S. Department of State, 1980), and the lIASA system of
models (Srinivasan, 1985) differ in sophistication, but they are roughly
consistent in forecasting small gains in average per capita caloric intake by
2000. The IIASA model, for instance, projects an 11 percent total gain
in per capita caloric intake in developing countries over the period 1980-
2000. The FAO and Global 7000 reports stress that large investments in
agriculture will be necessary to achieve gains of this magnitude. Moreover,
the Food and Agriculture Organization (1981) projects that 260 million to
390 million people will still be severely undernourished in 2000 despite the
gains in average intake. Srinivasan (1985) surmises that all the models may
be somewhat pessimistic because they are unable to model the constructive
responses of investment, population, technology, and institutions to changing
agricultural conditions. But he also notes that a failure of institutions to
.~ ~ ~ ~ I. '_ _ A_ ~ _ ~^ do ~F~ for
respond to population growth Could result in a Decrease in access `o thou ~y
the poor due to an increase in landlessness and Me fragmentation of already
small landholdings into even smaller parcels that cannot support even one
family.
Unlike the model of the Food and Agriculture Organization (1983), the
three economic models cited above stress the importance of international
made. A county whose agricultural production falls below its population's
needs for food is in critical shape only if it does not trade with other nations
to satisfy its needs for food. The fact that many oil-exporting Middle Eastem
countries appear on the critical list mikes clear the arbitrariness of a standard
of self-sufficiency. Indeed, many more people would be counted as living
in critical counties merely by arbi~ily dividing the world into smaller
and smaller nations. The importance of trade in the world food equation
has grown considerably with improvements in bulk transportation and in We
political climate. Imports of food rose from 1.5 to 5 percent of production
in developing counties between the mid-1950s and the mid-19 7Os (Mellor
and Johnston, 1984~. The United States increased its cereal exports from
37 nonillion tons per year in the early 1960s to 115 million tons in 1981.
Some analysts view with alarm the increasing imports of food in developing
countries and Few increased dependence on American exports (Brown, 1981~.
But some of the growth is a result of higher incomes combined wid1 the
comparative advantage of the United States in food production. Taiwan,
for example, used less than 1 percent of its cereals for animal feeding in
1961, but because of rising incomes it used 6~) percent of its cereals in this
fashion in 1981, importing a substantial faction of its "needs', (Mellor and
Johnston, 1984~. Another part of the increase in world food trade is a result
of improvements in ~anspo~tion and storage that allow nations to make
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RENEWABLE RESOURCES
25
better use of their comparative advantages in production. One would expect
greater specialization and more trade as integration of nations into a world
economy premeds. Food is unique, however, in its ability to sustain life,
and the increasing dependence of the rest of the world on Norm American
exports must be viewed in this light.
When transportation is available, agricultural areas in developing countries
already have an incentive to intensify production and to increase yields even in
the absence of population pressure. There are many examples of agricultural
production in developing countries responding to market opportunities. The
building of railroads in Africa has typically led to intensified production
techniques near railroad lines. Conversely, deteriorating transportation systems
in Zaire have prevented high prices on the border from stimulating production
in the interior (Pingali and Binswanger, 1984~. The more intensive fanning
methods commonly observed near urban areas in developing countries attest to
the importance of markets in the choice of technique (Gourou, 1980:Chapter
91.
If markets provide incentives to intensify agricultural production even in
the absence of population growth, the question is what additional role, if
any, is played by population growth. The answer is that population growth
can both create markets and increase the demand within particular markets.
Agricultural goods are relatively bulky, with a high weight and volume per
unit value. Many are also subject to rapid spoilage. Consequently, a higher
fraction of production is directed toward nearby markets than is the case
for such goods as textiles. The size of local markets for food is therefore
more important than it is for many goods, particularly when transportation
facilities are poor. Population growth can also increase incentives for and
reduce per capita costs of improvement in transportation facilities and thereby
create access to new markets~ne of We most important potential benefits
of grow-although not much is known about the ranges of density over
which this might matter (Simon, lg81~. Clearly, then, population growth in
local areas can stimulate agricultural production.
However, the fact that population growth can stimulate agricultural
production does not mean that it automatically will. No response that requires
human institutional and organizational adaptation is automatic. Northern Brazil,
Argentina, and Uruguay have been cited as areas in which policies that are
affected by biases in He distribution of political and economic resources
have prevented appropriate responses to changing conditions (de Janvry,
1984~. Indeed, He literature is rife with examples of poor organization of
agriculture, including improper techniques, poorly chosen crops, inadequate
labor input, and government interventions Hat prevent proper price signals
from being transmitted to producers (Bale and Duncan, 1983). Depending
on the circumstances, population growth can exacerbate these problems or
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26
POPUI~ION GROWTH AND ECONOMIC DEVELOPMENT
provide the stimulus needed to solve them. Whether the very large potential
for expanded world agricultural output will be realized depends fundamentally
on whether agricultural research efforts will be sufficient; whether markets
for agricultural output will be allowed to function effectively; and whether
over social institutions, credit markets, educational systems, labor markets,
and government investment priorities are supportive. As noted above, some
of these conditions are affected by population growth itself. Rosenzweig
et al. (1984) elaborate on this theme, noting how labor markets can be
expected to change as agrarian density increases and how the evolution of
property rights induced by population pressure can be expected to improve
credit markets.
The importance of agricultural research attuned to local conditions, with
appropriate extension activities, has been repeatedly emphasized. The scope
for research is great: for example, only a tiny fraction of all plant and animal
species have been domesticated to play a role in the human food system
(Revelle, 1976~. Of the 350,000 plant species identified by botanists, only
3,000 or so have been tried as sources of food or over useful materials.
The rate of return from investment in agricultural research and extension
activities has often been calculated to be extremely high. Evenson (1984a)
compiles estimates of internal rates of return to agricultural research, about
half of which pertain to developing countries; only 4 of the 62 studies show
annual rates of return below 2() percent. Many authorities have stressed the
importance of adapting research to local conditions and integrating extension
activities into that research (e.g., Eicher and Staatz, 1984~.
Because of characteristics of agriculture, governments in general have a
major role to play in agricultural research, particularly in the area of biological
techniques. Some people have argued that farmer-generated technical changes
do not appear capable of proceeding rapidly enough to keep pace with
population grown Bengali and Binswanger, 1984). Furthermore, the benefits
from research in genetics and soil science cannot all be captured by private
firms, since noting prevents technical information and most seed varieties
from spreading from farmer to fanner. These characteristics suggest Tat the
private sector will underinvest in agricultural research. In addition, much of
the benefit of a~gacultural research goes to consumers rawer than producers
because of low price elasticity of demand for agricultural products (Ruttan
and Hayami, 1984a).
Semiarid lands, because of their fertile soils, long growing seasons, and
low humidity that reduces crop diseases, are particularly promising areas
for expanded production (Hinman, 19843. The potential role of research in
expanding production also appears great in tropical Africa, where there has
been little experience with intensified farming techniques, although some
are now being introduced from Asia. Intensive rice cultivation can be done
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RENEWABLE RESOURCES
27
in low-lying areas that are often unused, and the cultivation of fruit trees
also has much potential (Binswanger and Pingali, 1984; Gourou, 1980~.
Unfortunately, tropical Africa is also where the human resources needed
for agricultural research and extension activities are least abundant (Etcher,
1984~.
Research and extension activities alone are not sufficient for mayor advances
in production. Many institutional changes involving land tenure systems, credit
markets, and markets for inputs and outputs will be required. Hayami and
Ruttan (1985b) find evidence that changes in the availability of labor relative
to land have created demands for institutional reform, pointing in particular
toward experience in Japan, the United States, and the Punjab. Others have
cited the enclosure movement and other institutional changes in Europe in
the seventeenth and eighteenth centuries as a response to population grown
(North and Thomas, 19-73~. But Hayami and Ruttan (1984:39) stress that
"growing poverty and inequality will be an almost certain result if efforts
to generate technical progress are insufficient to overcome the decreasing
return to labor due to growing population pressure on land."
One recent study in north India attempts to pull together evidence on
the effect of agricultural population density on agricultural production in
the area, including the responses that work through many of the factors
considered above: research efforts, provision of credit, electrification, roads,
irrigation, and intensity of land use (Evenson, 1984b). It concludes that
ooDulation density has a significantly positive effect on the intensity of
Negation and on the net cultivated area but that it has a negative impact
on research investment, road expenditure, electrification, and credit. The net
effect is that a 10 percent expansion in population density is associated with
a 6.7 percent increase in output. In over words, output per capita falls
3.3 percent for a 10 percent expansion in population. -line poorest groups
suffer He largest decline in real income when density increases, while rents
paid to owners of land increase sharply. These results imply that a drop in
population densiW.of 10 percent would raise He real incomes of the landless
by 6.4 percent. Before allowance for the indimct effects of density, the gain
in incomes for the landless would have been 14.7 percent. Leers (1980)
estimates for preindustrial England show similar effects: a 10 percent increase
in population size depressed real wages by 22 percent and raised rents by 19
_ , ,
.
-
-
. .
percent. Evenson's (1984b) results are tentative because population density
could be in part responding to the availability of infrastructural investments,
in which case He impact of density on output is likely to be overstated. If
~~ - population growth would
so, He loss in per capita income resulting from
be larger than indicated.
In a related cross-sectional study of agricultural production in 52 specific
locations around the world, Pingali and Binswanger (1985) find Hat increases
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28
POP Ul'7ON GROWTH AND ECONOMIC DEVELOPMENT
in the amount of labor applied per unit of land are associated with greater
intensification of agricultural production (i.e., more frequent plantings), which
is, in turn, hypothesized to be a response to population pressure. More
frequent planting-controlling other inputs such as capital investment in land
and the use of tractors and animal power-is associated with slightly lower
output per hour of labor spent on cultivation. The authors speculate that
the effect would have been larger had it been possible to control for the
amount of labor time used in land preparation, which is expected to increase
with intensification of agriculture. The analysis does not fully allow for
the farmer's role in choosing intensification or technique as a response to
population pressure. However, these results are in the same direction as
those of Evenson and Lee, suggesting that slower population growth will
increase the growth rate of labor productivity in agriculture.
DEGRADATION AND ENlIANCEMENT OF
AGRICULTURAL RESOURCES
By stimulating an intensification of agriculture through shortened fallow
time, multiple plantings, more use of fertilizer or irrigation, better weed
and pest control, and the like, population grown can change the quality
of land used in production. Some of the changes reduce land productivity.
Erosion of topsoil can accelerate when production is intensified unless proper
conservation measures are taken. Shortening the fallow time will usually reduce
soil fertility because there will be less natural growth on the land to supply
nutrients to the soil. But intensification can also improve soil productivity,
especially in swampy areas (Pingali and Binswanger, 1985~. Operations to
clear land of trees and stumps obviously represent one-time investments,
sometimes induced by population grown, that can make subsequent tillage
easier. Other investments in land improvement may also require a certain
minimum density before they become profitable. For example, Pingali and
Binswanger (1984) suggest that the failure of large-scale irrigation schemes
in su~Saharan Africa can be attributed to the sparseness of population and
a corresponding lack of demand for extending the cultivated area.
If market mechanisms are working properly, landowners or public sec-
tor managers will resist the degradation of their land, or encourage its
enhancement, so as to maximize its long-term asset value. In this matter
investments in land productivity do not differ from other forms of investment
that increase future production capacity. If more rapid population grown is
seen as extending into die future, landowners will have added incentives
to invest in their land because He future market will be larger relative to
the present one; but the supply of funds for investment may be reduced
because more rapid growth increases current consumption demands. The
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RENEWABLE RESOURCES
29
effect on the volume of investment in land conservation efforts cannot be
predicted a priori, and we know of no careful empirical studies on this
matter. Impressions of informed observers are widely disparate: Pingali
and Binswanger (1984:12) argue that "anti-erosion investments in land are
becoming increasingly common in the more recently intensified areas of
Africa"; Brown (1981:995) argues that "in the* efforts to keep up with the
doubling of world food demand since mid-centaly, many of the world's
farmers have adopted agricultural production practices that are leading to
excessive rates of soil erosion.', In a later article, Brown (1984) cites China,
Nepal, Indonesia, Venezuela, Ethiopia, Pakistan, and Andean countries as
areas where population pressure is resulting in excessive rates of soil erosion.
Smil (19843 provides a vivid account of rapid soil degradation in China
between 1950 and 1980 as a result of poor cropping practices, improper
land reclamation, careless irrigation, and deforestation. A recent review of
data on Me extent of erosion in developing countries concludes Bat the data
are sparse in quantity and uncertain in quality (Crosson, 1983~.
It should be noted that what is an excessive rate of soil erosion to one
observer may correspond to efficient use of land over time. It may seem
curious that any rate of erosion could be efficient, but in fact the aggregate
of private and social decisions that establish the market rate of interest
discount future consumption relative to present consumption. In discussions
of market solutions to issues of resource scarcity, it is useful to recognize
that markets will serve only to reflect the desires of groups that can express
the* preferences (Smith and Krutilla, 1979~. Because future generations
may not be well represented in these markets, some observers feel that
government investment decisions should adopt lower discount rates than
the private market; others suggest that people in the future are likely to
be wealthier than at present, so that such interventions would exacerbate
intertemporal income inequalities; still others argue that elected governments
cannot be relied on Rouse below-market discount rates since their incentives
are to emphasize short-term goals detennined by political expediency. The
issues related to investment in soil conservation are no different in principle
from those related to other forms of investment, although there is often
a different psychological connotation when conditions are actually getting
worse instead of not improving as fast as Key could be. Governments can
choose to impose different discount rates in different markets, and in the
United States, government policy regarding soil conservation has not, in fact,
relied exclusively on market mechanisms but has actively promoted a variety
of erosion control programs, the latest of which is "conservation tillage',
(Crosson, 1982~. But in India, the political support for soil conservation
programs may be minuscule (Brown, 1981~.
Whatever the situation for privately owned land, it is widely agreed
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30
POP U1~77ON GROWTH AND ECONOMIC DEVELOPMENT
that land as a common-property resource will usually be degraded too
rapidly relative to the rate that would be established through a market. The
reason is simply that Hose people who contemplate making investments in
conservation will not reap the full benefits of those investments and therefore
will underinvest. Optimal levels of consecration can be established if all
the users of the common-property resource can agree to make production
and investment decisions as a group; as a group, they can capture all He
benefits of conservation investments.
Mere is very little infonnation on the degree to which land is held in
common in various parts of the world or the degree to which common
lands are group administered (Crosson, 1983~. The absence of land-ownership
rights is very likely most fiequent in su~Saharan Africa, where land is
most abundant relative to labor. However, much of the land is tribally
administered. Eicher (1984:455) characterizes land tenure in Africa as a
'~communal tenure system of public ownership and private use rights of
land." Africa is a particularly vulnerable continent to land degradation, since
much of it consists of tropical soils win few nutrients except those contained
in the plants Hat grow on it (Gourou, 1980~. Much of Africa's land surface
is still farmed with shifting cultivation under the fallow system (Pingali and
Binswanger, 1984~. It is well Mown and widely observed that shortened
fallow time will reduce the amount of nutrients resumed to the soil for use
in any particular crop cycle. In mm, a shortage of nutrients will reduce
soil's water absorption capacity.
It is reasonable to expect that, as populations grow, the demand for
establishing properq rights to land will increase, as it did in Europe (Norm
and Thomas, 1973~. Hayami and Ruttan (198Sa) review the evolution of
property rights to agricultural land in Japan, Thailand, and a Philippine
village, finding that population growth was instrumental in the process,
although new production techniques and expanded possibilities for trade also
played a role. Binswanger and Pingali (1984) show that sparsely populated
areas of Africa generally have easy access to land, with the transition from
shifting to permanent cultivation associated with a parallel movement toward
privatization of agricultural land. But land tenure systems are not always
smoothly accommodating. The Economic Commission for Africa (1984) notes
that efforts to change such systems in Burundi, Comoros, and Zaire have
met with considerable resistance on the part of individual farmers and tribal
groups. By fostering the evolution of property rights that are conducive to
conservation, population grown is likely to result eventually in better land
protection as institutions adapt. In the meantime, however, it is possible
that rapid population grown will exacerbate He tendency for a too rapid
rate of land degradation on common lands.
Over factors unrelated to population grown can also produce a deterioration
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RENEWABLE RESOURCES
31
in land quality. As noted above, improved markets will provide incentives
to intensify production regardless of population density. Higher incomes in
developing countries will increase demand for agricultural products. Social
groups can be forced onto marginal and more readily degradable land by more
powerful groups without any necessary demographic propellant. Ignorance
about paper soil conservation practices can produce rapid degradation even in
the face of a strong desire to conserve. Such lack of knowledge is particularly
threatening in an "indus~'-agriculture~hat is atomistically organized. Writing
about U.S. farmers in 198=surely among the world's most knowledgeable-
Crosson (19843 argues that farmers' knowledge of relations between intensity
of production and erosion is based primarily on the* experience with Heir
own land and that extrapolations of their own expenence may be a poor
guide to predicting future effects of intensified production.
FORESTS AND FISHERIES
There is increasing evidence of loss of forest reserves, although the author
of one of the major survey efforts commissioned by the National Academy
of Sciences (Myers, 1980) appears to have Educed dramatically his estimate
of He rate of permanent conversion of tropical forests since the Academy
report (Poster, 1984~. A survey by the FAG produced rates of deforestation
of tropical forests that, if continued, would shrink the size of such forests
by 10-15 percent by 2000 (Poster, 1984~. Shifting cultivation accounts for
about 45 percent of all forest clearing and for about 70 percent in Africa.
Examples of landless persons encroaching on forests to establish shifting
or permanent cultivation have been cited in Peru, Thailand, India, and
the Philippines Hostel, 1984~. Myers (1980) concluded that an increasing
intensity of agricultural practice resulting from population pressure was He
leading cause of He conversion of tropical moist forests to other uses. A
direct link between population pressure and deforestation has been created
by government policy in Indonesia, where a'~ansmigration scheme" has
attempted to move the population from the most densely populated agricultural
areas to forested areas (Sedjo and Clawson, 1984:138~.
In developing countries, ~ree-quarters of the wood that is harvested from
forests is used for fuel (Poster, 1984~. The declining abundance of forests in
certain areas has produced a fuel shortage of major proportions. In Gambia
and Central Tanzania, firewood has become so scarce that the average
household requires 25~300 worker~ays to meet its annual fuelwood needs
(Kirchner et al., 1984~. In many Central American and West African cities,
a typical family spends one-qua~er of its budget on fuelwood and charcoal
Hostel, 1984~. Large price increases for fuelwood have recendy been noted
in He Cameroon; Bombay, Lndia; and the Ivory Coast (Poster, 1984~. The
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32
POP Ul'ION GROWTH AND ECONOMIC DEYEU)PMENT
shortage of fuelwood in some areas is limiting the possibilities for agriculture.
In Burkina Faso, there is considerable potential for soybean cultivation, but
it is report that the shortage of firewood required in food preparation has
helped prevent this potential from being realized (Kirchner et al., 19843.
While an important aspect of fuelwood deforestation is linked to population
pressure, it must be noted that low incomes are a more direct cause of the
problem. Wood is a relatively inefficient source of energy for cooking and
heating, and it is bulky and differ to transport. Slightly more expensive
substitutes such as kerosene are, in contrast, both more efficient and easier to
use, and seem to be preferred to wood when affordable (MacKellar and Vining,
19853. Should depletion significantly raise the price of fuelwood relative to
alternatives, or should incomes increase, the link between population growth
and deforestation due to the demand for fuelwood would be significantly
weakened.
Forests are important not only for their direct products but also for housing
millions of species, for preventing soil erosion, and for the* aesthetic value.
Smil (1984) reports that massive deforestation in China has accelerated
erosion and produced worsening droughts and floods. Contributing to rapid
forest depletion is We fact that forests have been essentially finely accessible
to potential users in many parts of We developing world, so that overrapid
rates of exploitation can be expected. Sedjo and Clawson (1984) argue that
the regions of the world where deforestation is not a serious problem are
precisely those where the common-properq problem has been dealt with
satisfactorily. The accessibility of forests in developing countries results from
both the difficulties of limiting access and the relatively low value of forest
resources. This low value is reflected in the continuation of slash-and-bum
agricultural practices in many areas, especially Africa (Gourou, 1980; Myers,
19801. In such areas, the value of wood is not suff~cien~dy large to make
it economically worthwhile to harvest the wood for sale, and Me lumber
value of Me resource literally goes up in smoke. In fact, the harvesting of
fuelwoods from tropical forests is said to be only a marginal factor in the
conversion of these woods to nonforest uses (Myers, 1980~. Much of Me
firewood is obtained from Savannah woodlands, scrub and brush patches,
and local woodlots.
At the opposite end of the spectrum, there are clear rules for access to
commercial forests in Me United States. Such forests occupy one-quarter of Me
U.S. land area, and another one-eighth consists of forested areas administered
by governments. As a whole, Me trend in annual wood growth per acre
in the United States has been upward since 1952 (Clawson, 1982~; that is,
forests are accumulating more wood than is being harvested annually. Puerto
Rico is another example of successful forest management. After being Do
percent deforested, much of the loss has been reversed. Such management is
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RENEWABLE RESOURCES
33
not out of the reach of many developing countries. The grown of "plantation
forests" in Latin America is fast enough that they are expected to account
for half of the region's industrial wood production by the year 2000 (Sedjo
and Clawson, 1984:152~.
Ocean fisheries are the classic illustration of problems related to common-
property resources (Dasgupta and Heal, 1979~. Because access to the stock
of fish is difficult to regulate when fisheries extend beyond a single political
jurisdiction, overfishing may reduce the fish population so much that yields
fall. In extreme cases, overfishing may even reduce the stock beneath the
level required for the population to maintain itself. If this occurs, the stock
may all but disappear, and the fishery may cease to be commercially viable.
For example, the disappearance of the Peruvian anchovy fisheries in 1972
has been attributed to overfishing (Clark, 19783.
Because most important commercial fisheries extend beyond the 200-mile
economic exploitation zone for a single nation, no jurisdiction is able to
regulate catch sizes, and catches currently exceed the levels recommended
by international fishing bodies. As a consequence, world fish yields on a per
capita basis have ceased growing, and prices have increased fairly sharply
(MacKellar and Vining, 1985~. Fish is an important food source, representing
25 percent of world animal protein consumption, and it is also an important
source of animal feed. Given the difficulties in establishing international
policies limiting catches, rapid population grown in the developing countries,
through its effect on world food demand, is likely to contribute to the
continued overexploitation of the world's fisheries.
CONCLUSIONS
Rapid population growth poses two problems for agriculture. First, if
no other conditions of production change, expansion of the agricultural
labor force probably reduces labor productivity and correspondingly lowers
agricultural wages. Second, population grown can accelerate the degradation
of renewable resources. Although many other forces are capable of producing
erosion, population grow can do so by expanding the amount of land under
cultivation and intensifying land use, especially where property rights are
ill-defined and where there is substantial ignorance about good agricultural
practices. Similarly, there is evidence that forests and fisheries are being
overexploited and that the real prices of lumber and fish have increased.
Because demand for fuelwood, forest land, and fish are all sensitive to
population, continued rapid population growth poses a risk to these resources.
The extent to which slower population growth would alleviate these
problems depends on the degree to which the problems lead to other solutions
through institutional and technological adaptation. With regard to diminishing
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34
POPU1~7ON GROWTH AND ECONOMIC DEVELOPAfENT
returns to labor, the grown of population can induce a wide variety of
changes in agricultural production techniques. Experience in several countries
suggests that such induced innovations can offset much of the initially
negative impact of population growth on labor productivity. The responses
include intensified cropping practices; introduction of additional factors of
production, such as fertilizer and irrigation; improved markets; and expanded
research efforts. It is worthwhile noting that, with the important exception
of Africa, per capita agricultural output has risen in most developing regions
dun ng the recent period of rapid population growth. Similarly, population
growth can encourage changes in property rights that boost incentives for
soil conservation. Management techniques that conserve forests and fisheries
are known, and continued price increases will strengthen incentives for using
them.
However, adaptive responses to population growth are not automatic: they
are constrained by natural conditions, such as the limited responsiveness of
many tropical soils to intensification, and conditioned by human institutions.
Among the most important of these institutions are rights governing access to
renewable resources, markets to transmit signals of scarcity, and government
policies that affect the agricultural infrastructure and research. Furthermore,
the institutional change and other adaptive responses that are necessary will
have to be unusually rapid in developing countries relative to Western
historical experience simply because population growth rates are more rapid.
Institutional adaptation may be particularly difficult in the case of forests and
fisheries because some kind of negotiated collective action is necessary to
resolve the common-property aspects of the problem. In short, if institutions
do not adapt as rapidly as needed, slower population grown can retard He
decline of labor ~uc~vity and He degradation of common resources. Of
course, the most direct policy prescription is to fibs the institutions. But fixing
existing institutions, or establishing new ones, may be difficult, especially
where there are severe and long-standing political inadequacies, as may be
the case in Africa, or where there are fundamental technical problems in
res~ichng access to a resource.
Finally, it should be noted that this chapter addresses aggregate agricultural
production, not distribution; that is the subject of Question 7. Perfectly
functioning meets are no guarantee against starvation when there are
extreme disparities of wealth.
Representative terms from entire chapter:
agricultural production
