Click for next page ( 19


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

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 18
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 18
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 18
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 18
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

OCR for page 18
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 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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

OCR for page 18
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.