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Chapter 22: Modern agriculture and world food: why plant science?

"Within a few weeks, Draba, shown in Figure 22-1, the smallest flower that blooms, asks, and gets, but scant allowances of warmth and comfort; it subsists on the leaving of unwanted time and space. Reference books give it two or three lines, but never a plate or portrait. Sand too poor, sun too weak for bigger, better blooms are good enough for Draba to produce flowers and seeds to survive. After all, it is no spring flower, but only a postscript to hope." (A Sand Country Almanac, with other essays on conservation for Round River by Aldo Leopold. Oxford University Press.)

To the person lacking a background in plant sciences, Draba is indeed as Aldo Leopold describes--small, plain, unimportant, and unnoticed. Again, however, Leopold makes these comments tongue-in-cheek, for he knows that Draba's place in the botanical world is as important as larger, more visible, and more "useful" plants. That realization sets apart the plant educated from the average citizen. When more of the world's people view themselves as natural members of the biotic community instead of users of it, then the future balance and stability of the community is secure, as is the future of each of its individual's components. In a sense, then, humans are not more important than the lowly Draba; nor are we any less important. Now, it is possible to view the importance of the botanical world to the human world--they are one.


After completing this chapter, you should be able to:

* Discuss how all plants contribute to the natural world

* Present a basic knowledge of how plants function

* Explain how sociopolitical considerations are world wide in scope

* Describe how modern agriculture has changed

* Identify which conservation movements have been successful in this global economy

* Describe how to help educate people concerning the significance of environmental problems

Key Terms

deficit irrigation

genetic engineering

integrated pest management (IPM)

The Mechanization and World Food Supply Industrialization and the age of mechanization led to quantum leaps in the concentration of peoples; cities evolved rapidly along with new concepts in the production of material goods, communication, and transportation. This shift toward urbanization strained the existing food supplies and encouraged those in agriculture to find more efficient and productive means of supply for the cities. This challenge was met with varying degrees of success, but eventually the size of towns and cities increased.

Large cities developed in parts of the Old World thousands of years ago, and the Mayan civilizations in Central and South America was highly structured in 5000 BC. Beans and squash were being cultivated in the New World 9,000 years ago, and rice was cultivated in Thailand 12,000 years ago. By the time of the Industrial Revolution, agriculture was common throughout the world and established the basis for permanent settlement and civilization. Food plants first domesticated--wheat, barley, rice, corn, and potatoes--remain today as staple crops. Only tomatoes and coffee among major food crops have been domesticated in the past 2,000 years! Although there are as many as half a million species of plants in the world, only a few have been developed as major food crops. Farmers, traditionally reluctant to try new crops, have made up in quantity what they lacked in variety. Although surpluses were never large, farmers were able to produce more food than required. Today in industrialized nations all the food is produced by about 5% of the population.

Food Commodities

Modern human diets depend heavily on the many forms of plant life. The grass seeds have given rise to cultivated cereals, most domestic animals are fed from cultivated crops (except for range animals), and fish continue to feed on aquatic plants of fresh water and the sea. See Table 22-1 for a list of the major world food plants.


At least 90% of all human caloric intake is provided by commercially grown plants. Although meat continues to provide a large portion of the diet in countries that can afford it, the tendency is toward a greater consumption of plant products. Since energy losses increase in ascending trophic levels, it is possible to prevent these losses by eating "lower" on the chain, that is, closer to the producer organisms. In developing countries, plant consumption has always been great. In industrialized nations, however, the tendency toward meat consumption has long been associated with a higher standard of living. World food pressures now dictate even to the most developed nations that such eating patterns are no longer acceptable. Americans are rapidly learning that only a portion of what a cow, pig, or chicken consumes is converted into milk, meat, or eggs. A major portion of the feed consumed sustains metabolic function; bone, skin, and other body organs are unimportant to humans. It is necessary to consider, however, that animals do convert a great deal of nonedible and nonharvestable plant material into important productivity.

At the present time, three-grain crops--wheat, rice, and corn--provide about 80% of the total human calorie consumption (along with potatoes, yam, and cassava). Although rich in carbohydrates, these crops are not particularly high in protein or fat. Diets must be supplemented with other foods to achieve some degree of nutritional balance. Vitamins and minerals are usually supplied through vegetables. Even though poor in protein, these six crops do provide considerable protein simply because they are consumed in large quantities. In addition, beans are an excellent source of protein, and peanut, soybean, and sunflower contains both protein and fat.

Sugarcane and sugar beets were, until recently, chiefly a localized food source, but they have become major world crops as a result of better transportation. The growth of sugar beets has continued to replace sugarcane as the major source of sugar for North America.

A few other grain crops are important food sources. Barley, millet, sorghum, oat, and rye are consumed throughout the world. The world food consumption, however, is based on production of only a few species of the myriad possibilities available in the botanical world. It certainly is true that humans have tried and rejected many potential food plants because they were unpalatable, non-nutritious, or toxic. Others were too difficult to cultivate, harvest, transport, or store. On the other hand, human beings are exceedingly conservative when it comes to trying new foods. Most of us reject new foods because we do not like their look, smell, or feel.

Nutritional value is seldom a consideration. Religious and social customs often prohibit certain foods. There are hundreds of nutritious food choices available to the human populations that have not been adopted. "Experimental" new foods or new methods of preparations appear almost every day, but most discoveries fail to obtain general acceptance.

Specialty crops, such as strawberries (see Figure 22-2a), onions, and even mushrooms (see Figure 22-2b), are a recent phenomenon and contribute little to the total human diet; likewise, spices add to the palatability of foods but contribute little to human nutrition.



A major portion of the world's population can be divided into those who eat rice and those who eat wheat. Rice is grown in the warmer parts of the world, generally in regions in which predictable monsoons sweep the countryside. In a year without a monsoon, severe famine can affect localized regions, although modern methods of food transportation, distribution, and storage have alleviated much of this problem. In Asia, rice comprises 75% to 85% of the entire diet. Rice has become a major agriculture crop in the Sacramento Valley of California and along the Gulf Coast in Texas and Louisiana. Rice has never become a major part of the American diet, and most rice production is for export. Through genetic engineering, more beta-carotene (vitamin A) has been incorporated into some rice. This will help developing countries feed their people more nutritious rice.

Wheat, shown in Figure 22-3, is the dominant cereal crop in most of the temperate or cooler regions of the world, and its production extended into the subtropics and higher altitudes of the tropics. Before the development of modern plant breeding, wheat had little cold tolerance and was confined to the warmer regions of the globe. Scientists using genetic engineering have also transformed wheat. They have bred cold tolerance into the crop, and now it is grown in the most extreme latitude.


Wheat and rye are considered the bread grains because most of their production goes into flour. Although rye was a major crop a century ago in the United States, today almost all production is centered in Europe and the former Soviet Union. Regional food patterns change over time, and crop production must mirror these changes or fail economically.


The typical bread wheats are hexaploid (six sets of chromosomes in somatic cells), whereas the macaronis and noodle wheats of Europe and Asia are tetraploid (four sets of chromosomes). Wheat is grown both as a winter annual (planted in the fall) and as a spring annual (planted in the spring). The genetics of the cultivated varieties are different--the winter wheat containing genes for a great deal more cold tolerance. In recent years, livestock grazing on winter wheat has become a major source of income, sometimes exceeding the value of the grain crop. Winter wheat is an excellent source of green forage during the winter, and the grazing forces the plants to tiller (give off more stems) and produce more heads of grain.

In regions that are too warm and dry for the cool season cereals, sorghum and millet are major food crops. Sorghum is particularly important in northern China, India, tropical Africa, and the southern United States. Sorghum flour and millet flour are not considered good for baking, although they are eaten in many countries and yield a fermentation substrate for making beer. Sorghum is currently used as a feed for domestic livestock. The protein content of sorghum is higher than in most cereals, and because it can survive low rainfall, high temperatures, and alkaline soils, its popularity is increasing dramatically worldwide.

Corn, shown in Figure 22-4, was the food staple of the Incas, Mayans, and Aztecs, and today it remains a very important dietary component in the Americas. Other countries are beginning to accept corn as a food crop--slowly. It is well adapted to warm summers. Corn requires more water than many parts of the world can offer, and it is grown in those regions only with supplemental irrigation.

Other grain crops contribute to total world consumption, although rice, wheat, and corn are certainly the most significant. Barley was formerly used extensively as a bread grain, but now about half the entire world production goes into the making of beer. Oats and buckwheat enjoy regional consumption but contribute little to total world caloric intake.

A synthetic grain crop has been introduced during the past years. Plant breeders have hybridized wheat (Triticum) and rye (Secale) to form Triticale, which has better characteristics of both parents, including higher protein content than bread wheat and excellent baking properties. Triticale has been widely accepted in the regions of the former Soviet Union, but its success in the United States has been limited. The difference in quality and taste of Triticale bread does not seem to justify the development cost still attached to Triticale production.

Historical Perspective

The food situation on earth is now and always has been precarious. Approximately three-fourths of the world's population knows poverty and hunger; in contrast, about 10% live in relative affluence. The other 25% live somewhere in between, never quite sure whether the supplies of food, shelter, and fuel will be adequate. The uncertainties are the same as they were for the first Homo sapiens, and the population is larger. Modern humans still depend largely on the agricultural success. Insect and disease control is a major problem, and we have surprisingly little appreciation of how organisms interact in nature.

Throughout recorded history, agriculture productivity has increased, but concomitant rises in population have always placed food supply at a dangerously close intersection with demand. Hunger is an ever present and prominent human condition. The stress of famine can induce strange behavior, such as hoarding; stealing; selling children; eating clay, diseased rodents, and bones; murder; suicide; and even cannibalism. Early accounts of the Roman famine of 436 BC and the Indian famine of 1291 AD report that thousands of people drown themselves in rivers. Cannibalism is reported to have occurred in at least 15 famines in England, Scotland, Ireland, Italy, Egypt, and China. As recently as 1921, Russian cemeteries had to be guarded to ensure that hungry thieves did not steal recently buried bodies. Famines were often localized and involved only a few thousand people, but the great Indian famine of 1769 to 1770 cost the lives of approximately 10 million in 1869, 5 million from 1878, and 1 million in 1900. In China, between 9 and 13 million people died in the famine years of 1877 to 1879. In Asia and on the Indian subcontinent, famine has been most often seen because of the unpredictable monsoon rains.

The Irish potato famine of 1846 to 1847 caused the death of 1.5 million people and prompted a massive emigration to the United States. Before the potato famine, Ireland's population was 8 million; the current population is slightly more than 4 million, primarily a result of the long-term effects of the famine.

Through modern transportation and communication efforts, we can anticipate famine and deliver food, supplies, and education materials to relieve its effects. On the other hand, massive aid is not always possible in other than localized situations. War activities often inhibit the flow of food to areas that need it most. Since World War II, for example, supply problems caused the starvation of 2 to 4 million people in the Bengal region of India. From 1969 to 1970, civil war in eastern Nigeria led to several thousand deaths by starvation. There are always droughts, wars, and famine in many developing countries, causing several thousands of deaths by starvation. In spite of a worldwide campaign to send massive food and monetary aid to those regions, there was little relief from the situation until the rains came, and by that time the ecological destruction was excessive.

Various industrialized nations have attempted to buffer the effects of malnutrition and starvation. The United States contributes surplus food for approximately 100 million people per year. Beginning with the enactment of Public Law 480 in 1954, the United States began selling food to poor countries for payment in local currencies rather than in dollars and gold.

During the early 1960s, American grain surplus reached high levels, which were depleted after Public Law 480 came into existence. Land that had been idle was called back into production, and from 1966 to 1967, 20% of the entire U.S. wheat crop was required to reduce famine in India. From the 1980s to the present, American farmers have been asked to reduce production because of temporary surpluses.

One of the social complications of a giveaway food program is the false confidence instilled in the recipients concerning their future. Unless food is given out only in the case of temporary disaster, countries (and individuals) tend to become reliant on the contribution and finally believe that the supply is inexhaustible. Many leaders believe that such false confidence merely results in further population increases and delays the day when food will not be available. Keeping humans alive at a subsistence level so that they may produce yet more offspring raises serious moral concerns about the future of such populations.

All these examples serve to point out the precarious position of world food supplies. Some sources contend that the biosphere has the ability to produce all the food needed for the foreseeable future. Others contended that the level of human population has already surpassed the ability of the world to provide food. The truth lies somewhere in between. New sources of inexpensive energy could improve food production greatly, but such energy sources seem many years away. While we wait, the world's population continues to double at an alarming rate.

Early Agriculture

There is no question that agriculture has progressed steadily ever since the glimmer of domestication first touched the hunters and gathers. Some periods of history have seen rapid progress; others have been slow. The tillage of the rice paddies in Asia, for example, has been highly developed for thousands of years. Control of erosion by terracing has always been a standard practice. In some parts of the world, including Central America and Mexico, elaborate irrigation schemes ensured that water reached the crops at the right time.

In spite of these early advances, it was not until the Industrial Revolution that machinery became available for large-scale agriculture, which relieved a large portion from drudgeries of hand labor (see Figure 22-5). The continued growth of mechanization has increased productivity in almost all crops. Some crops are still labor-intensive, and mechanization has only partially alleviated the need for hand labor.



The New Agriculture

At the turn of the twentieth century, plant breeders and other agriculture and biological scientists began to accomplish impressive gains in crop yields. Productivity has accelerated during the past century, and some yield increases have been truly remarkable. The "North American Breadbasket" was made possible through research and technology.

Basic Research

The elucidation of metabolic processes, including photosynthesis, respiration, and protein synthesis, is only one area of discovery that has led to increased productivity (see Figure 22-6).

An understanding of water and soils has improved conservation practices and irrigation methodology, and genetic research has led to a process of genotype selection to match specific crops with specific environments. Tremendous advances have been made in growth regulation with plant hormones (see the corn and soybean examples in Figure 22-7), and the understanding of how diseases are transmitted has increased yields. Investigation of viruses and their transmission by insects has also been significant.


Applied Research

Once basic concepts have been elucidated, the processes must be put to the test under field conditions. Not all hypotheses born in a research laboratory survive the rigors of field testing. Some genotype-screening programs may look excellent in laboratory/greenhouse studies, but in the field they sometimes fail because of susceptibility to insects or diseases, low humidity, wind, soil chemistry, weed competition, and other factors (see Figure 22-8). Only those gene sources that help the plant withstand the rigors of field competition have a chance of making a contribution to world agriculture.


Once innovative ideas have proven workable, the task of transferring the information to farmers is monumental. Many good ideas of the past have been filed away in a research paper and have never been put to use. For example, the practice of not tilling the fields has proven to be very beneficial because the natural microorganisms of the soil can reestablish when the crop is grown under no-till practices. Even with modern communication and impressive sales campaigns through the media, selling farmers on a new concept, new crop, or even a new variety of the same crop may be difficult. Tradition plays a major role in farming practices and procedures in all societies. Change comes slowly unless technology transfer concepts are applied judiciously.

Perhaps the most impressive example of technology transfer in American agriculture is the land-grant university system, together with the state agricultural experiment stations and their accompanying agriculture extension service. This highly organized sector of the agricultural community managed to "sell" American farmers on innovative technology early in the twentieth century, using the demonstration plots to show that new methods and crops were superior to old ones. Farmers are impressed by success across the fence. Regional experiment stations have brought experimental farms close to every American farmer through the use of open houses, field days, and cooperative research. They have been instrumental in communicating new farming practices. With the continued demise of the family farms in the twenty-first century, farmers need to look very closely to diversifying into other crops and to the new high-technology production and equipment to survive.

At the present time, the Internet can make every corner of the world accessible. New varieties of crops are quickly recognized throughout the country. Fertilizers, seed, pesticide, and irrigation equipment manufacturers spend a large portion of their advertising budget on Web pages and Internet-related activities.

Some times, farmers are eager to accept new ideas, but financial reserves and capital investment inhibit the progress of new technology. Lending institutions are often reluctant to take chances on new innovative ideas, and the wheels of progress may move very slowly indeed. Capital investment is particularly critical in the developing countries, where lack of funds to buy seed or fertilizer may stand between private interests and a high level of productivity.

Perishability is a major factor in food production and delivery. Perhaps some of the reasons for large-scale successes of grain products are their slow perishability and ease of storage and transport. The industry is far better equipped for long-distance transport of a truckload of wheat than for a truckload of lettuce or strawberries.

Basic research has been instrumental in developing techniques to improve the processing and shipping of plant products. Consider, for example, the problem of maintaining fresh corn or pea quality.

Harvesting affects sugar content, and the best produce is obtained if harvesting can be accomplished within a matter of hours after the highest sugar content is reached. The crop must be processed immediately because respiration rates are so high that even minor biochemical changes can affect flavor, texture, and overall quality.

Perhaps the most progressive storage techniques concern apples. Advances in postharvest physiology have been so dramatic that a controlled atmosphere prolongs the storage life of apples up to an entire year with little deterioration of quality. Scientists have spent many years of efforts in plant biochemistry, physiology, genetics, and plant biotechnology. The consequences of such storage and transportation techniques are a more stable market price and therefore a better pricing structure for both growers and consumer.

The Farmer's Bargaining Power

Whether a farmer can afford to maximize yields depends to a large extent on the price of a product. Although food prices have escalated dramatically throughout the world, most of that profit has been realized not by the farmer, but by the processor, packager, distributor, and transporter. Farmers traditionally have been so poorly organized as a political group that they fail to exert a major influence in the political arena or at the marketplace. They usually take the going offer, although modern storage facilities for some farm products allow the farmer to withhold from the market until a better price is offered. Producers of perishable products do not have this luxury, except through frozen or dehydrated foods, and for them the energy costs of withholding from the market are high.

The Limits of Production

The question is often asked whether farmers can continue indefinitely to produce as much food as the world requires. Throughout recorded history this has seldom been possible. Recall that the laws of thermodynamics state that less energy comes out of a system than is put into it, that is no system is perfectly efficient. The conversion of light energy into chemical energy is relatively inefficient.

The total sunlight available at any point on the earth is readily determined. Green plants capture only about 1% of the light energy on an annual basis, and much of the energy falls on land or water without green plants. Even if plants are properly spaced to maximize light trapping, the efficiency of conservation is low. Most of the energy is reradiated or lost to the system as heat. Thus, strictly from a thermodynamic point of view, the light energy available determines the upper limits of productivity. Seldom, however, in commercial agriculture is light the limiting factor in production. On a worldwide basis, the limiting factors are unquestionably water and nutrition. Most of the world's so-called arable land is now in cultivation. The only land left is in the humid tropics, the desert, or mountainous regions too steep to cultivate safely. Although a great deal of land is available in the arid and semiarid parts of the world (somewhere between 25% to 33% of the entire land surface), water is the limiting factor in development, and much of the North American breadbasket land is irrigated. In some cases, irrigation comes from surface water and the other underground water must be pumped to the surface and then transported to the site of application. These pumps are usually located at the individual farms, and pumping may be done at very shallow depths, which requires very little energy, to hundreds of meters, which requires a great amount of energy. Many crops grown in arid regions require 2 to 5 acre-feet of water per year (1 acre-foot of water = 1 acre foot deep, or approximately 325,000 gallons). In some regions, this accounts for 90% of the entire water consumption, with all domestic and industrial uses requiring only 10%. Therefore, irrigated agriculture comes under careful scrutiny in matters of water conservation.

You will recall from Chapter 9 that transpiration accounts for about 99% of a plant's demand, and there are very few realistic suggestions for reducing that water loss. Anything applied to the plant to reduce water loss either seals off the stomata or causes them to close, and if the stomata are closed, no CO2 can enter, and photosynthesis is greatly reduced. The correct approach appears to be to grow more water-efficient plants, those which produce more biomass while using less water. Sorghum, for example, is far more water efficient than corn if water is limited. If water is not limited, then corn is more efficient.

The Future of Irrigation

The arid and semiarid parts of the western United States typify similar regions of the world. In some states, irrigation has been developed to a higher degree of sophistication with tremendous capital investment, as shown in Figure 22-9. In some states, irrigation water is transported hundreds of miles, as from the Feather River in northern California to the dry southern California desert. A similar scheme has been proposed to transport water from the Arkansas River to the farmlands of western Texas and eastern New Mexico. This particular idea never got started.

Quality is always a concern in the transport of water because irrigation water always contains some salts. In some cases, more than a ton of salt per acre-foot is solubilized in the water. As the water is stored and absorbed by the plant roots, the salt is left behind in the soil or the plant or in some cases leached beyond the root zone. Salt accumulated over a period of years is a major pollutant, and great efforts are made to drain the soil and leach the salts. The Imperial Valley in California is lined with a massive drainage system. This region produces a great percentage of the nation's winter vegetables.

In the central part of the United States, massive underground aquifers hold water stored there for millions of years that is being pumped to the surface for irrigation of the Great Plains. The Ogallala Aquifer stretches from South Dakota to Texas and has allowed the high plains of Texas to contribute significantly to the nation's supply of food and cotton. Unfortunately, this aquifer is not being recharged, and the "fossil water" is being used up. Some areas have already had wells go dry and others are becoming depleted. Depending on the locale, southern parts of the aquifer will no longer be a source of irrigation in the future.


The suggestion has been made that interbasin transfer of water be accomplished from regions with a surplus of surface water. Many proposals have been made for importing water from Canada, the Missouri River, the Arkansas River, and even from the mouth of the Mississippi River at New Orleans. While technically feasible, the costs of construction and maintenance of such a system are astronomical. The energy costs of pumping alone would be more than the states could afford. Even if such a system were to be approved by voters (it has been voted down once), legal ramifications would probably disallow construction.

The Constitution of the United States relegates the water rights to the individual states, and it seems unlikely that one state would ever be willing to sell its water to another. The projected cost of water delivered to the farmer is absolutely prohibitive for the irrigation of crops.

The future of irrigated agriculture, then, seems dimmed by accurate cost-benefit analysis. In those regions where water delivery is inexpensive, readily available, and dependable, irrigated agriculture is likely to persist. A recently introduced concept, deficit irrigation, implies that irrigation is to be used only in emergency situations to save a crop or get over a period of particularly bad weather conditions. Although yields would not be maximized, decreased energy costs of production would offset the loss of yield, and the farmer would make just as much revenue.

In regions that have been irrigated but no longer have the water to do so, the future of agriculture will depend almost entirely on rainfall and the judicious selection of crops. A return to dryland agriculture is forecast for much of the Great Plains, where rainfall is sufficient to support drought-resistant grain crops and cotton. In many cases, revenue to the farmer is just as great as with irrigated agriculture, although the regional and individual farm productivity is decreased. Regions that are forced to switch from high-intensity, dryland agriculture, as shown in Figure 22-10, simply will not be able to provide as large a segment of the world's food supply.

Most of the world's air and semiarid regions fall into desert or grassland biomes. If land has been broken out from a grassland biome, it is likely to support the original or similar vegetation.


If one decides to return the land back to its climax vegetation, reestablishment may be difficult. Under conditions of wind, high temperatures, and unpredictable rainfall, establishment of vegetation under dryland conditions is a difficult assignment. Even so, where dryland agriculture is marginal at best, farmers often consider returning to grassland for livestock or wildlife grazing. If a small amount of irrigation water is still available, the judicious use of that water for grassland establishment may be strongly considered.

The return of native vegetation is even more difficult in the deserts. The competition for water is so great the plants are far apart, and large root systems are essential for survival. When farmers or ranchers remove those plants, it is difficult to achieve reestablishment. Not only is water accumulation a problem, but nutrient cycling in the desert is particularly precarious. Individual plants are often referred to as islands of fertility; the nutrient supply cycle within the plant and in the soil directly under the plant. The desert soil between plants may be sterile, but nutrients abound in the plant. However, once that plant is removed, the nutrients are swept away by the wind or leached out of the root zone by thunderstorms. Once that nutrition has been lost, it is impossible to put it back again. The desert is indeed a delicate resource.


In 1797, Thomas Malthus published An Essay on the Principle of Population in which he put forth the hypothesis that biological species including Homo sapiens, always have the ability to produce more offspring than can be accommodated. Natural systems keep population levels in check, primarily by limiting food supply. No one is likely to be upset when a test tube of bacteria runs out of a nutrient source, or when a plague of grasshoppers runs out of forage plants, but the Malthusian concept strikes home vividly where there is a lack of human food. We have seen that famine and starvation are effective in controlling the size of the human population. The climatic problems involved in food production are compounded by social problems. The message from Malthus, and we have no reason to believe that his hypothesis is not correct, is that if the human species fails to control their own population size, natural forces will intervene and do it for us.

At the beginning of agriculture some 12,000 to 18,000 years ago, the human population was less than 5 million. At the time of Christ, the world had 250 million inhabitants, and that number had grown to 500 million by 1650. In 1850, it had doubled again to 1 billion; and by 1930 it had doubled again in just 80 short years. By 1979, it had doubled again, this time in only 46 years, and at the present rate, doubling will take approximately 40 years. Many factors kept early population levels under control, but the astounding leaps in doubling time are cause for alarm.

Countries that can least afford the population increases (the developing countries) are the ones with the most rapid rises. In Latin America, Africa, and Asia, the annual number of births far exceeds the number of deaths, and the rate of increase is more rapid than 3% per year in some regions. Throughout human history, the birth rate has fluctuated considerably, but changes in the death rate usually have the greatest effect on population growth.

In the developed countries, unlike the underdeveloped countries, population growth is declining because of technological advancements and literacy rather than religious factors. Japan and China have greatly influenced the rate of population through governmental decree and massive birth control campaigns. The availability and understanding of birth control devices and social acceptance of family planning are major factors in control. It appears that a stable food supply and lack of social upheaval are also important in reducing the desire for more children. Anticipation of insecurity in old age is often cited as a reason for large families.

As long as the earth had adequate supplies or was able to bring that land into production to keep up with the population, increases were a relatively simple matter. However, essentially all of the world's arable land is now in cultivation (except for the humid tropics). The problem confronting a move into the arid lands has already been discussed. The only other area with possibilities for expansion is in the humid tropics. The problems there are probably even greater than in desert agriculture. Soil fertility, pest management, storage, and transportation are all major obstacles to agriculture development. In spite of these problems, the tropical rain forests are rapidly being developed, often without rational decision making.

Agriculture is forced to attempt to increase yields on land already in production. In addition to all the problems associated with excessive resource usage and deterioration of the ecosystem, it would appear that the portion of the biosphere capable of supporting agriculture is already being taxed to the limit. What will the future hold?

The Future of Agriculture

Agriculture is realizing that to achieve ecological balance we should abandon the idea of modifying the environment to fit the crop. Instead, we should select or transform crops to fit specific environments, and recent advancements in molecular biology have led to the use of genetic engineering, the process of combining portions of the genome of another. Thus, desirable characteristics of totally unrelated organisms have been incorporated into another organism to impart some beneficial effect. For example, corn has been transformed with bacillus thuringiensis (a natural parasite of caterpillars). So the corn earworm that devastated corn crops can now be grown without the loss of ears due to the earworm. This is only one of many such transformations; of all the crops grown now, approximately 75% have been transformed for some better traits. Another transformation has produced Roundup-ready soybeans. This allows the farmer to spray for weeds in the field and not kill the soybean plant growing there. This technology is developing so fast that it is hard to keep up. This is the future of agriculture as well as relief for world hunger.

There are hundreds of potential foods and forage plants available but never selected for agriculture production. Introducing a new crop is exceedingly difficult in today's world. Basic research, applied research, and technology transfer must be undertaken before there is any hope of breaking into commercialization. The infrastructure that surrounds each crop is unique to that particular species. Rice, for example, must have specialized planting, cultivating, and harvesting equipment; people familiar with equipment particular to that crop handle the processing, storage, and transportation. Even the marketing and acceptance are unique to certain parts of the world. If the world's rice production should suddenly double, marketing and acceptance would be a major problem throughout the western cultures.

New crops are sometimes suspect because they upset the traditional patterns of production and consumption. On the other hand, economic pressures have caused the world's agricultural producers to take a closer look at innovation, including the new transformed crops. Although new crops are not a panacea for the world's food supply and population ills, they could be highly effective in alleviating hunger and famine in a world caught in its own ecological net.

No single factor will save Homo sapiens. We must use our best creative efforts to increase productivity within the ecosystem that surrounds us, while using the same ingenuity to keep our worldwide population at a safe and manageable level. Malthusian theory has worked through recorded history; there is a new race against time-to see whether humans are clever enough to save themselves from extinction.

Gardening: Number One Leisure Activity

Although few people become professional plant scientists, the simple awareness of plants and of their importance makes us all plant scientists in one sense. In addition to a realization of the applied worth of plants to human society, a basic knowledge of plant structure, function, reproduction, distribution, ecology, and cultivation allows us to better appreciate the total role of plants on earth. A plant's role should not be measured exclusively in terms of direct human utility, but in terms of energy flow, oxygen production, erosion control, and overall natural ecological balance (see Figure 22-11).


Learning about the plant kingdom, therefore, is not purely an academic exercise, but rather it contributes to the present and future survival of our planet and the continuation of all the organisms on it, including humans.

The Basic Importance of Plants

The importance of plants to the existence of all other organisms on earth can be summarized by reviewing two aspects of photosynthesis, (1) energy conversion and (2) oxygen production. Plants form the base of the food chain because they combine atmospheric carbon dioxide and water with sunlight energy to produce food energy in the form of carbohydrates. Without green plants, therefore, the animals of the world would have no source of food other than some single-celled aquatic organisms. The availability of plant tissue as a food source has resulted in the development of extensive and involved plant-animal and animal-animal interactions, as well as the evolution of complex forms of land-dwelling organisms.

As a by-product of this energy conversion process, oxygen is released into the atmosphere. With few anaerobic exceptions, all organisms on earth require oxygen to carry on respiration, the process of producing from carbohydrates a form of energy capable of doing biological work. Additionally, the availability of oxygen ultimately resulted in sufficient ozone accumulations to allow life on land to be screened from damaging ultraviolet radiation.

These two functions of plants, combined with their soil stabilization functions, their utility as nesting habitats, nutrient cycling, essential amino acid production, and many other interactions with other organisms, elucidate their central position in the balance of nature. Even lay plant scientists must acknowledge the magnitude of the importance of plants in nature.

Recreation and Aesthetics

Aldo Leopold began the foreword to A Sand Country Almanac by stating "There are some who can live without wild things, and some who cannot." More and more people are realizing the worth of wilderness areas and the relaxing beauty of nature. To be able to walk a quiet trail through the woods, to sit on a rock by a river, to notice the Silphium, the Draba, the first robin of spring, these are not to be taken for granted but to actively and consciously be preserved. It is in such settings that the brightness of the stars and the contrasting darkness of the voids between them stimulate poetry. It is not without reason that we refer to "escaping" from the big city to pursue recreational activities in the forest, on the mountains, at the seashore--in natural (see Figure 22-12) areas. Even within urban areas, parks can provide a measure of this feeling. Bringing plants into homes and offices is yet another example of the realization that natural surroundings relax and soothe.

Possibly it is instinctive or genetically controlled that humans want to spend time in natural settings. Possibly it is because many of us exist primarily in the concrete, plastic, and steel world we have built, and natural areas offer a change. Whatever the reason, millions visit the national parks and wilderness areas annually. Too many of these visitors contribute to the decline of such areas by their thoughtless and destructive acts of littering and vandalism. Fortunately, there are many more that follow a good land ethic by leaving these sites as they found them. We are loving our nature to death.


When we enter these areas, we should do so as members of the natural environment, not as controllers or conquerors. This attitude comes from knowing and understanding what altering natural interactions can mean to the ecological balance. Lay plant scientists have such knowledge. They are the stewards of the land.

An often unsuspected bonus of study is a more highly developed aesthetic application. If beauty is in the eye of the beholder, then the better-trained eye has a greater potential for seeing beauty. It is understandable why trained naturalists are often the most emotionally involved in the areas they study. True love can develop on those trails through the woods or on the rock by the river.

Social and Political Considerations

The importance of plants to each individual should be clear. As sources for food, shelter, recreation, and industry, plants obviously serve a purpose for each of us. To all organisms on earth, plants are the most essential. As the basis of the food chain, as a producer of oxygen, and as components in the natural ecosystem balance, plants occupy an irreplaceable position. We should not isolate our new found knowledge, however. The study of plants should improve our ability to function as a component of the biological world. We should now be wiser taxpayers and more thoughtful voters and citizens. Plants are as important in our daily activities as we humans are to each other.

It should always hold true that knowledge--in any discipline--results in an improved awareness of issues, problems, possible solutions, and personal responsibility for participation. Posing questions is a natural extension of the educational experience. Your knowledge of plants should be as much a part of your base of information for living as your actions are an impact on the botanical world around you. Directly and indirectly, both as an individual and as part of a collective society, you can have a positive influence on the world around you and thus on your niche within that world. Even though we question many policies and decisions about ecological issues, land management, increasing population, and the like, there is a large portion of our world that is still beautiful, productive, clean, balanced, and with enormous potential.

Your actions will serve both to solve problems and to ensure the continuation of the many "good" aspects of our world.

World Food Supplies and Political Involvement

One of the consequences of a world of "haves" and "have-nots" is a great deal of resentment toward those people with a relatively high standard of living, sometimes manifested in anger, terrorism, and war. Humans demonstrate responsibility to the individual and family above all else. National pride, religious fervor, and charity pale when a family breadwinner is faced with starvation for his or her family. Psychologists tell us that the bottom line to self-preservation is that the individual will do almost anything to ensure that the family is fed. Too often in history, zealous leaders have taken advantage of this human instinct to rally forces to battle making shallow promises of protection and freedom from hunger.

In the past, ignorance for many people really was bliss. Modern worldwide instant communication has allowed those in the underdeveloped countries to see and hear about a better life. Their demands are now being heard in the political arena, and local governments are under increasing pressure to provide a fair share of the world's wealth. It has been said that a child born today in India will consume only about one-fortieth as much of the world as will a child born at the same time in the United States. Although that figure may be true for the present, the demand for a better life will no doubt increase as the Indian child's share during his or her lifetime.

One point is clear in the overall picture of global food supplies: The world is overly dependent on North America for its food resources. This is not to say that other countries have totally failed in food production. In recent years, many underdeveloped countries have made major advances in achieving self-sufficiency, at least in certain crops.

Several reasons explain this growing dependence on North America. Increasing population pressures, particularly in the developing countries, have hastened the deterioration of food systems. The increased pressure on traditional farming systems to produce more and more has led to ecological degradation; once fallow land (land cropped only once every 2 or 3 years so that moisture and nutrients can be stored) is now being called into constant production, depleting nutrients at a more rapid rate and often leading to severe erosion. In some parts of the world, newly rich nations, particularly the oil-producing countries, are demanding a greater share of the world's food. The gap between the haves and many of the have-nots continues to widen.

These factors have resulted in North America having significant influence over world food supplies. The United States and Canada are in a position to dictate to the importing nations the terms on which food will be distributed. Serious moral and ethical questions arise from this political power: Does North America have the right to use food as a political force? Can food resources be used to dictate population control, religious expression, and personal philosophy? Should food ever be used as a weapon to beat a recalcitrant country into submission?

There may not be any right or wrong answers to these questions, but they deserve informed thought. There may come a day when such questions will have to be answered. In addition, other questions arise in highly productive agricultural nations.

The person without food has but one problem. The
person with food has many problems. Today in the United States,
about 98% of the people do not have to worry about food, and they
have time to create worry about many other real or imagined issues.

Without food, an individual's thoughts focus on food, as Ernest
Shackleton found out during the survival of his crew on the failed
voyage of the Endurance. One of his crew, Frank Worsley, had this
to say: "It is scandalous--all we seem to live for and think of now
is food. I have never in my life taken half such a keen interest in
food as I do now--and we are all alike ... We are ready to eat
anything, especially cooked blubber which none of us would tackle
before." (Shackleton, South: The Story of Sacketon's Last
Expedition; 1931). Next to air and water, food is essential. Food
is part of the foundation of Maslow's hierarchy.

For most of human history, civilization struggled to produce
sufficient food for survival. For varying reasons, some civilization
still struggle for sufficient food for survival. Thanks to
technological advances in crops, livestock, storage, management, and
preservation, a few people are able to provide sufficient food for
the masses in many developed countries.

People rush to blame various issues in countries where people need
food. Some blame the population; some blame the economy; some blame
politics; and some blame the environment. Providing food to those
who don't have it is a complex problem. As the Bishop of
Constantinople, John Chrysostom said in 407: "Feeding the hungry is
greater work than raising the dead."(

If people worldwide are to be fed, our nation and other nations need
to make use of the best of technology, genetics, and management
available to humankind.

Integrated Pest Management

One of the consequences of high-technology agriculture has been the tremendous money and energy put into an extended use of pesticides. The demands placed on North American agriculture have forced farmers to apply large amounts of insecticides, fungicides, and herbicides so that the monoculture could flourish without competition. Breakdowns in the ecosystems were attributed to an overload from various chemicals; some pesticides were incorporated into fatty tissue of organisms in various complex food webs, affecting reproduction and causing other negative effects. This type of pesticide was eventually banned in the United States. Strict controls and extensive testing have also eliminated many other pesticides from the market.

Renewed research efforts by scientists have led to a philosophical plan called integrated pest management (IPM), which attempts to recognize crop production as an integral part of the ecological system. Relying on ecological principles, this approach seeks to minimize the use of pesticides, while relying on natural systems to assist in production objectives. Included in this system is biological control, or the use of one organism to control another. Although spectacular successes with biological control methods have been demonstrated, often a desirable insect, such as the ladybug shown in Figure 22-13, can be introduced in large numbers to control another insect. Sometimes insects can be used to control a noxious weed; effective control of the prickly pear cactus with an insect that feeds on the pads has led to reclamation of rangelands in Australia and elsewhere. Biological controls can fail to work in certain situations because predators of the introduced species often keep populations too low to be effective. Another precaution concerns the possible introduction of a pest problem even worse than the one being controlled.


Biologists have known for a long time that some plants produce natural insecticide that discourages herbivores. Chrysanthemum and marigolds contain natural pyrethrums that are extremely effective insecticides. Synthetic pyrethrums have been manufactured and are being used widely as a safer product than insecticides used heretofore.

Another technological advance is the use of Bacillus thuringiensis, a natural parasite as shown in Figure 22-14, to get rid of Lepidoptera and other chewing insects. It was first used as an insecticide dust to repel cabbage loopers. Next, large chemical companies started to transform plants through genetic engineering to incorporate this parasite into the DNA of plants that were bothered by Lepidoptera insects. Now, 85% to 95% of all the corn grown is from transformed seeds. This technology has also transformed soybeans with a gene that makes it resistant to herbicide (Roundup) so the weeds can be controlled without harming the crop.



The pioneers who settled the United States saw before them an apparently endless vista of forests, grasslands, clear rivers, lakes, seashores--and opportunity. The natural resources seemed boundless and biological diversity vast. The far-reaching extent of the resources probably precluded any consideration they might have had for conservation. Today, however, faced with shortages of fresh water, fossil fuels, clean air, safe food, and recreational sites, we wonder how they could have destroyed so much while settling America. A great deal is written about the need for conservation measures, but there is not enough actually done. Although state and federal agencies have set aside some wilderness areas and nature preserves, much of the public still has a "parks are for the people" attitude. Too many still cannot comprehend the expenditure of public tax dollars to establish tracts of land from which the public is barred. The pioneer spirit lives on: land is to be utilized, cleared, and made "productive" and habitable."

The conservation movement began slowly in the 1940s and 1950s with relatively few champions, who were often regarded as extremists, doomsayers, and against progress. During the 1960s and 1970s, laws were passed regulating air, water, and noise pollution; tracts of land were designated as preserves; and the public was slowly educated about the need for these measures. It was not until the late 1970s and 1980s, however, that this awareness has been used to understand the conservation movement and gain the support of a large segment of the public. With continued increases in public involvement, tax dollars, and legal controls, in the twenty-first century, we should see gains and not ultimately result in a situation unique since hunting and gathering bands wandered the land: Humans in balance and in harmony with the land is part of nature, not apart from it.

Endangered Species

Nothing more vividly symbolizes the impact of humans on the natural ecosystem balance than the number of plant and animal species that have become, or are in danger of becoming, extinct, even considering that the process of natural selection has produced millions of extinctions over the ages.

The habitat destruction shown in Figure 22-15 that has taken place is fairly recent. Between 1800 and 1850, only four plant species were known to have become extinct. Between 1851 and 1900, however, 41 species were lost to extinction and another 45 between 1901 and 1950. Today, there are estimated to be some 25,000 species of plants in the continental United States; 1,200 of these are categorized as threatened, and approximately 1,000 species are in immediate danger of extinction.


No single habitat type has been altered more significantly than the tropical rainforest. The United States Environment Program estimates that over two-thirds of the world's rain forests have already been destroyed, and as many as 1,000 animals and 25,000 plant species are threatened with extinction. The tropics have an unusual delicate ecological balance. The specialized relationships of simple food webs result in a chain reaction. The removal of a link in the food chain is not an isolated event in such habitats; it can affect the survival of several other species as well.

The unfortunate response of some is "So what? There are plenty of other plant and animal species even if all the endangered ones do become extinct. Of what importance is a snow leopard or silver sword? They do not provide humans with food, medicine, or building supplies." Understanding the answer to this kind of question requires an appreciation of ecological balance. The loss of any given species may not be directly significant to human needs, but that loss may affect the status of some other species in the chain that is important.

Another part of the answer concerns potential. So little is known about most species that humans do not know that one of the lost species might include a potential crop plant, wonder drug source, or fuel reserve. Any unnecessary loss from the natural genetic pool stunts potential. In a world with massive shortages, this ought to be viewed as unacceptable. The propagation and preservation of rare and endangered pliant species in botanical gardens and arboreta is important so that their biology can be studied, and they can then be reintroduced into appropriate protected habitats where available.

Finally, even if there is no applied use for a species, and even if it could be proven that its loss would not have an impact on other plants or animals, the loss of any aspect of the world's variety is reason enough to protect these species. It would be a great loss to future generations to know of certain plants and animals only from pictures. Some species are currently known primarily from zoos and botanical gardens because they are already so scarce in the wild. The wholesale reduction in total habitat size for many species has already resulted in small recluse populations, sometimes protected by government decree, sometimes not.

The critical component in whether zoo protection, wilderness areas, legislation, and any other measures will significantly slow the rate of extinction resulting from human activity destroying available natural habitats is whether people realize the consequences of their actions. If not, then there will be little progress. In underdeveloped and overpopulated countries, the education of the layperson to these problems is especially difficult. The instinct for self-preservation is an immediate response to need; the significance of today's actions on the next generations is far too abstract to have much impact. The degree and the continuation of protection, therefore, are in the hands of the educated public. It is up to those of us who understand and care to speak out to rationally support conservation measures.

Environmental Quality

The most significant issue in human ecology during the past century is overpopulation. The degradation of our environment, as shown in Figure 22-16a and 22-16b, is a direct function of ever-increasing world population size. Resource shortages, pollution, and urban crowding all result from overpopulation.



Until humans realize that the laws of natural balance do not apply only to all other species, but also to Homo sapiens, a rational solution to these problems is unlikely. Other solutions are possible but not desirable. Mass starvation, epidemics, or war would effectively reduce the world's human population.

On the other hand, total dependence on continued technological advancement and vastly improved crop strains is not a realistic approach either. The quality of our environment will ultimately be determined by how many demands are made on it, and those reduced demands can happen only when there is a reduced human population.

Fortunately, natural systems have amazing resiliency and buffering capacity. Even ecosystems that seem for all practical purposes to be "dead" have the ability to recover if given enough time for cleaning and restoration. Lake Erie, for example, had become so polluted with industrial wastes during the 1960s that almost all life in that once magnificent lake had died. Once the cleanup began, under strict controls, Lake Erie started to recapture its ecological balance and has been restored to its magnificence.

In an industrial society, the cost of environmental quality is great. Every convenience and time-saving gimmick has its price tag, and we have sometimes cut corners for which we pay dearly at a later time. The "throw-away" attitude has made some material goods obsolete and created mountains of garbage for which there are no landfills. The intentions were valid in the beginning: Paper plates meant less dishwashing (less labor, less water, less detergent, and fewer sanitation problems) and a boon to the fast-food industry. Plastic containers were convenient: readily disposable, lightweight, and required less labor and lower shipping costs, a benefit to the transportation industry. Attention was not paid to the enormous tasks of waste, disposal, and recycling. Degradation of plastic is slow or sometimes impossible, and burning leads to toxic fumes and unsightly air pollution.

Economic and Environmental Trade-Offs

A true democracy maximizes freedom of expression, thoughts, ideals, and the pursuit of personal goals. Citizens as a group decide what restrictions will and will not apply to the society. Modern technology has led industrialized, democratic nations into a trap: On the one hand, freedom of expression dictates to "do your own thing"; to some this includes polluting the environment in its many forms (littering, gases in the air, noise, pesticides). On the other hand, concerned citizens strive to impose restrictions on society as a whole to ensure a more acceptable quality of life. Voters and taxpayers find themselves lining up on one side of an issue at one time and having to reverse themselves at another time. The determining factor is often economics. How much will it cost me and society to achieve these so-called improvements in the quality of life? Unfortunately, one person's quality of life is another person's pollution.

This freedom of expression in the developed countries has led to an environmental degradation unparalleled in history. Cleaning up the environment was simply considered too expensive for most of the paying customers. Factories spewed contaminants in the air and poured toxic wastes into rivers and streams, and increasing pressures for food forced modern agriculture to use more and more pesticides so the weeds, insects, and diseases could be kept under control. There has been environmental awareness legislation passed that has helped a great deal in improving the quality of air, water, and soil resources. Much remains to be done, and changes in political philosophy have caused a roller-coaster effect for many years and many years to come. Ultimately, however, individual responsibility must bring about the changes considered desirable by a majority of the society. Individuals must make these decisions as informed citizens, concerned taxpayers, and most importantly members of the natural community, not exclusively as exploiters of its resources. The future of the botanical world is in human hands, and the future of human society rests in the continuation of that world (see Figure 22-17a and 22-17b).




1. Industrialization led to a rapid increase in population concentration, along with production of material goods, communication, and transportation. Crops were domesticated between 12,000 and 18,000 years ago in many parts of the world, apparently in response to food pressures created by villages and towns.

The first domesticated food crops--wheat, barley, rice, corn, and potatoes--are still worldwide. Of major food crops, and there are only a few of them, only tomato and coffee have been domesticated in the past 2,000 years. Even though variety is lacking in total number of species, farmers have been very successful in total productivity.

2. Although surpluses were never large, farmers were able to produce more food, than required. Today in industrialized nations all the food is produced by about 5% of the population.

3. At the present time, wheat, rice, and corn provide about 80% of the human caloric intake. Most people receive enough carbohydrates, but protein and fat consumption is severely limited in developing countries.

4. Currently about two-thirds of the world's population suffer from poverty and hunger, 10% live in a relative affluence, and the other 25% live somewhere in between, never being sure of adequate food and shelter. Throughout recorded history, agricultural productivity has increased, but rise in population has always placed food supply at a dangerously low intersection with demand.

5. In years past, U.S. food production has enjoyed major surpluses, which have suppressed prices. Sometimes those surpluses are used for export and foreign aid, but political complications and the recipient's inability to pay for food has caused the producer nations to reduce production.

6. The exceptional productivity of the North American breadbasket reflects progress in basic and applied research, technology transfer, and the ingenuity of farmers. The land-grant college system and the agriculture cooperative extension system have been successful in providing information for farmers; similar plans have met with varying degrees of success in the developing countries.

7. The Green Revolution has brought high-yielding varieties of wheat and rice to a hungry world. These varieties are selected for maximum production under conditions of plentiful water and nutrition; some critics feel that the energy price for that productivity is too high.

8. Lack of bargaining power has forced farmers to settle for less than satisfactory profits, even though food prices continue to rise. Most of those increases are demanded by the infrastructure that harvests, packages, transports, and markets the products.

9. Lack of sufficient arable land has caused concern about agriculture ability to continue to feed a world that doubles in population every 40 years. Although desert land is available, the cost of water transport limits the potential for irrigation with current energy sources. The ecological and environmental problems associated with agriculture in the humid tropics are equally insurmountable.

10. The achievements in high technology, including transformed plants, help to increase the productivity to help feed the world population.

11. New crops never before considered for agriculture might adapt to climates where traditional crops will not grow. Even though these crops developed by genetic engineering have a great potential, the human factor is likewise important in the acceptance process.

12. No single solution will save Homo sapiens. Our best creative efforts must be used to ensure survival within the constraints of the biosphere.

13. All plants, no matter how large or small, are important in the total balance and functioning of the biological world. Obviously critical in photosynthesis, energy conversions, and oxygen production, plants form the base of the food chain.

14. Any person with a basic knowledge of plant structure and function is a lay plant person who can better appreciate the biological, ecological, aesthetic, and applied roles of plants.

15. Knowledge should help form a base of people who act more responsibly toward their natural environment and participate, more wisely, in the decision-making processes that affect their world. Many sociopolitical considerations are worldwide in scope, and yet rational evaluation of resource use can be a decision that affects each individual.

16. Modern agriculture now involves food surpluses in some countries and shortages in others and pest control with dangerous chemicals or biological agents such as IPM and genetic engineering.

17. Conservation movements have resulted in endangered species legislation in the United States and even some international efforts to legally protect the environment in the development of industrial products. The basic problem, however, is too large a world human population for the available resources.

18. Continued and increased efforts, especially by those members of the human population educated in the causes and significance of environmental problems, can result in a return to a biological world in balance and with all its members (including humans) existing as part of the world community, not apart from it.

Something to Think About

1. What organism is responsible for the basic food chain?

2. Why should the knowledge gained from this book help people understand about natural environmental issues?

3. Integrate this knowledge into the workings of global environmental conservation.

4. What makes our modern agriculture so good?

5. How do the conservation movements help us exist in balance with the world community?

Suggested Readings

Gore, A. 2006. An inconvenient truth. Emmaus, PA: Rodale.

Lombory, B. 2001. The skeptical environmentalist: Measuring the real state of the world. Cambridge, MA: Cambridge University Press.

Lombory, B. 2004. Global crises, global solutions. Cambridge, MA: Cambridge University Press.

Suzuki, D. 2001. Eco-fun: Great projects, experiments, and games for a greener earth. New Delhi: Sterling Publishers.

Suzuki, D. 2001. You are the earth: Know the planet so you can make it better. New Delhi: Sterling Publishers.


Internet sites represent a vast resource of information. The URLs for Web sites can change. Using one of the search engines on the Internet, such as Google, Yahoo!,, and MSN Live Search, find more information by searching for these words or phrases: sociopolitical conservation, world food supplies, Integrated Pest Management, synthetic pyrethrins, and remote sensing.
Table 22-1
Major World Food Plants

Type                 Plant

Grains               Wheat, rice, corn, sorghum, millet,
                     barley, oats, and rye

Tuber and root       Potato, sweet potato, yam, and cassava

Sugar crops          Sugarcane and sugar beets

Protein seeds        Beans, peas, soybeans, and lentils

Oil seeds            Olive, soybean, peanut, coconut,
                     rape, sunflower, and corn

Fruit and berries    Citrus, mango, banana, and apple

Vegetables           Cabbage, squash, and onion
(fruits eaten as
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Title Annotation:PART 5: Plants and Society
Publication:Fundamentals of Plant Science
Date:Jan 1, 2009
Previous Article:Chapter 21: Plants of medicine, culture, and industry.
Next Article:Appendix.

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