Chapter 7 green cloak of six earths

Water, soil, and the green cloak of the earth made of plants make up the world that supports the life of the animals on Earth; Without it, humans would not be able to survive.Our attitude towards plants is unusually narrow.If we see that a plant has some immediate use, we plant it.If for any reason we deem the existence of a plant undesirable or unnecessary, we can immediately sentence it to death.Besides all kinds of plants which are poisonous to man or livestock, or which crowd out crops, many plants are doomed only by our narrow view that they happened to grow in the wrong place at the wrong time.There are also many plants that happen to grow alongside some of the plants that are to be removed, and are subsequently destroyed.

Ground plants are part of the web of life in which there are intimate and vital connections between plants and the earth, between some plants and other plants, and between plants and animals.Sometimes there is nothing we can do but destroy these relationships, but we should be careful to fully understand the long-term consequences of our actions in time and space.But the sudden boom in the herbicide industry, which is now booming and widely used and which requires the mass production of plant-killing chemicals, is certainly not characteristic of caution. There are many incidents that we did not expect and that caused great damage to the landscape.To give just one example, that happened in the West Sagelands, where a large project was going on to destroy the sage and convert it to pasture.The same should be true if a cause is understood from a historical point of view and in a landscape sense.For the natural landscape here is a moving picture of the interplay of the many forces that created it.It lies before us like an open book, from which we can read why the earth is the way it is, and why we should keep it whole.But now, the book is open there, but no one reads it.

Millions of years ago, this land of sage was the western plateau and the low slopes of the mountains on the plateau, a land created by the great uplift of the Rocky Mountain system.It is a place with an exceptionally harsh climate: in the long winters, when blizzards blow from the mountains, the plains are covered with deep snow; soil, dry winds strip moisture from leaves and stems. As an evolving landscape, transplanting plants on this windswept plateau was a long process of trial and error.Plant after plant failed to grow.Finally, a class of plants developed that possessed all the characteristics needed for survival.Sage, a low-growing shrub that grows on hillsides and plains, keeps water from the thieves' wind by means of its small gray leaves.This is not accidental, but the long-term result of natural selection, so the western Great Plains became the land where sage grows.

Animal life and plant life developed together, in keeping with the exigencies of the land.Just at this time, there are two animals that are as perfectly adjusted to their habitat as the sage.One is a mammal—the swift and graceful antelope; the other is a bird—the sage grouse, the plains chicken of Lewis and Clark. Sage and grouse appear to be interdependent.The natural lifespan of the birds coincides with that of the sage; and when the sage fields decline, the grouse declines accordingly.Sage provides everything for the survival of these birds on the plains.The low-growing sage at the foot of the hill shelters the nests and young birds, and the dense grass is a place for the birds to wander and rest. At any time, the sage provides the main food for the grouse.It's still a back and forth relationship.This apparent dependence is also shown by the grouse helping to loosen the soil under and around the sage, removing other weeds that grow under the sage's shelter.

Antelopes have also adapted their lives to sage.They are the most important animals on this plain, and when the first snow falls in winter, those antelopes that spend the summer in the mountains move to the lower places.There, sage provides food for the antelope to survive the winter.Where all the other plants drop their leaves, only sage remains evergreen; retaining its grey-green foliage, which twines around the bushy stalks, which are bitter, fragrant, and rich in Proteins and fats, as well as inorganic substances that animals need.Although the snow has piled up, the tops of the sage are still exposed, accessible to the antelope with its sharp, scratching hooves.Now the sage-eating grouse find the grass on bare, wind-swept overhangs, and follow the antelope to feed where they scrape away the snow.

Other life is also looking for sage.Mule deer often live off it.Sage can be said to be the guarantee of survival for those winter herbivorous livestock.The sheep graze on many winter pastures where almost only tall sage bushes grow.Sage, a plant with a higher energy value than alfalfa, is the staple feed for sheep for half the year. So the cold highlands, the purple sage stubble, the wild and swift antelope, and the grouse, it's a perfectly balanced natural system.really?I am afraid that "yes" should be replaced by "no" in those areas where people are trying to change the way nature exists, and there are many such areas and they are increasing day by day.In the name of development, the Bureau of Land Management has set out to satisfy the rapacious demands of more pastures from cattlemen.From this, they contrived to create a sage-free meadow.Thus, in a field where the natural conditions are suitable for grass to grow mixed with or under the cover of sage, plans are now being made to remove the sage in order to create a meadow of grass.It seems seldom asked whether the meadow is a stable and desired end in this area.Of course, nature's own answer is not so.In this rain-sparse region, the annual rainfall is not sufficient to support a good turf pasture; but it is more favorable to the perennial plumes under the cover of sage.

However, programs to eradicate sage have been underway for years.Some government agencies have been active in this activity; industry has also enthusiastically increased and encouraged the enterprise, which has created a broad market not only for grass seeds but for large complete machines for harvesting, tilling, and seeding.The latest added weapon is the application of chemical sprays.Millions of acres of sage fields are now sprayed each year. What are the consequences?The ultimate effect of excluding sage and sowing pastures can only be largely speculated.People with long experience of the properties of the land say that pastures probably do better among the sage and under the sage than they do by themselves once the moisture-holding sage is gone.

This plan only achieved its immediate purpose, but the result was obviously that the whole closely connected structure of life was torn apart.The antelope and grouse will go extinct along with the sage.Deer will also be persecuted; and the land will become more infertile due to the destruction of land-dependent wildlife.Even intentionally bred livestock would suffer; there would not be enough grass in the summer, and sheep would starve in the winter blizzards on plains devoid of sage, hardy shrubs, and other wild vegetation. These are the primary, obvious effects.The second-step effect has to do with nature's spray gun: spraying also destroys a great deal of vegetation beyond its target.In his recent book "My Wilderness: Eastern Kentucky," Attorney General William Douglas recounts a striking example of the ecological damage wrought by the U.S. Forest Service in Wyoming's Brunei National Forest.Yielding to the pressure of herdsmen who want more grassland, more than 10,000 acres of sage land were sprayed by the company, and the sage was killed according to the expected plan.But the same fate befell the green, vibrant willows of the weeping willow, which ran along the meandering stream and across the fields.Moose have always lived among these willow groves, and willow is to moose what sage is to antelope.Beavers have always lived there, too, and they feed on the willows.They fell the willows, creating a strong embankment across the creek.Through the labor of beavers, a small lake was created.Trout in mountain streams are seldom more than six inches long, but in such lakes they grow fat, and many reach five pounds.Waterfowl are also attracted to the lake area.Just because of the presence of the willows and the beavers that depend on them, it has become a fascinating recreational area for fishing and hunting.

But due to the "improvement" measures enacted by the forest company, the willows have also fallen to the same fate as the sage, killed by the same indiscriminate spraying.When Douglas visited the area in 1959, the year it was being sprayed, he was horrified to see the withered and dying willows, "massive, unbelievable trauma." What would happen to the moose?What about the beaver and the little world it creates?He returned a year later to see the results of the destruction of the landscape.Both moose and beaver escaped.The important sluice has disappeared for lack of the care of an ingenious architect, the lake has dried up, and not a single larger trout descends by itself, and nothing can survive in this deserted little bay, the little river. Through the bare, hot land that leaves no shade.This living world has been destroyed.

In addition to the more than four million acres of pastures sprayed each year, other types of large areas are also directly or indirectly treated with chemicals for weed control.For example, an area (fifty million acres) larger than all of New England is being placed under utility management, and much of the land is being routinely treated for "bush control."Of the estimated 75 million acres of leguminous land in the southwestern United States that requires some treatment, chemical spraying is the most aggressively pursued method.A poorly understood but large area of ​​lumber-producing land is currently being aerial sprayed in order to "clean" debris from the sprayed conifers.During the decade after 1949, the treatment of agricultural land with herbicides doubled, reaching 53 million acres in 1959.The total area of ​​private meadows, gardens and golf courses that has now been treated is bound to reach a staggering figure.

Chemical herbicides are a gorgeous new toy.They work in a startling way; to those who use them, they display dizzying power over nature, but their long-term, less visible effects are easily dismissed as a pessimism. The groundless imagination of the ideologues was ignored. The "agricultural engineer" gleefully talks about "chemical farming" in a world where plowshares are turned into sprayers.The elders of a thousand villages and towns will gladly listen to the chemical salesmen and eager contractors who will scavenge through the jungle for a paycheck that is cheaper to hawk than to mow.Perhaps, it will appear in official documents in neat rows of figures, but the real cost will not be in dollars alone, but in the many equally inevitable losses we will shortly consider.Wholesale advertising of chemicals should be regarded as expensive in terms of the infinite loss to the landscape and the various interests connected with the landscape, if the end result is calculated in dollars. For example, how reputable is this commodity, promoted by every chamber of commerce across the land, in the eyes of holidaymakers?Protests are growing as once-beautiful roadside fields have been devastated by chemical spraying that has transformed a beautiful landscape of ferns, wildflowers, native shrubs dotted with flowers, berries A brown, withered wilderness.A New England woman angrily wrote to the newspaper: "We are creating a dirty sepia dying mess along the sides of our roads." "But this state of affairs is not what tourists expect. It costs all the money to advertise the beauty here." In the summer of 1960, conservationists from many states converged on the tranquil island of Maine to witness a giveaway to the National Audubon Society by MT Binham, its moderator.The discussion that day centered on the conservation of natural scenery and The intricate web of life is composed of a series of connections from microbes to humans.But what travelers to the island talk about behind their backs is outrage at the devastation along the way. It used to be always a pleasure to walk along the roads through the evergreen forests, lined with arbutus, sweet fern, alder and huckleberry.Now there is only a dark brown barren scene.A conservationist wrote of his visit to Maine in August: "I came here angry at the destruction of Maine's wilderness. In previous years the roads had bordered wildflowers and lovely shrubs; now there are only Mile after mile of dead vegetation... as an economic consideration, can Maine afford the loss of traveler discredit for this sight?" There is a mindless vandalism going on across the country in the name of cleaning up roadside bushes.The wilderness of Maine is but one example, and it has been particularly devastated to the heartache of those of us who love the region's beauty. Botanists in Connecticut Orchards have declared that the destruction of beautiful native shrubs and wildflowers has reached the level of a "roadside wilderness crisis."Rhododendrons, laurels, lingonberries, lingonberries, viburnums, dogwoods, bayberries, ferns, low shrubs, winter berries, bitter cherries, and wild plums were dying in the fire of chemicals.The daisies, susans, queen anne's belts, goldenrods, and asters that once brought charm and beauty to the land were withered. Pesticide spraying is not only poorly planned, it is so overused.In a southern New England town, a contractor finished his job with some chemical powder left in his bucket.He released the chemical along this roadside woodland that had never been allowed to spray.As a result the town has lost the beautiful azure and gold of its autumn roadsides, where the asters and goldenrods would have shown a view well worth the journey to see.In another New England town, a contractor who lacked knowledge of the way to go violated state regulations for spraying the town by spraying roadside plants to a height of eight feet, thus exceeding the mandated maximum of four feet. , thus leaving a broad, damaged, dark brown trail.Township officials in Massachusetts purchased herbicide from an eager pesticide salesman without knowing it contained arsenic.One of the results of what happened along the roads after spraying was the death of twelve cows from arsenic poisoning. In 1957, when the town of Netherford sprayed its fields with chemical herbicides, trees in Connecticut's Green Gardens Nature Preserve were seriously injured, even large trees that were not directly sprayed.Although it was spring growing season, the leaves of the oak tree began to curl and turn dark brown, and then the new buds began to grow, and they grew very fast, making the tree look miserable.After two seasons, the larger branches of these nets were dead, the others were leafless and deformed, and all the trees retained their sad appearance.I know very well that where the road reaches, nature has adorned the roadside with alder, viburnum, fern and juniper, sometimes bright flowers according to the seasons, sometimes jewels in autumn. A string of fruitful fruits.The road doesn't have a heavy traffic load to bear, and there are few sharp turns and intersections where bushes might obstruct a driver's view.But the sprayers have taken over the road and made it a place not to be longed for, a sight to be endured for the mind of a man who worries about a barren, terrible world, and this The world is what we let our technology create.But the authorities here and there hesitate for some reason.Some accidental oversight has left some beautiful oases in the middle of the strictly scheduled spraying area--the very oases that make the destruction of the vast majority of the road all the more intolerable.In these oases, among the flaming lilies here and there, with fluttering white clover and clouds of purple peas, our spirits were lifted. Such plants are only "weeds" in the eyes of those who sell and use chemicals.In one of the proceedings of a now-regular weed control conference, I read a curious discussion of the philosophy of herbicides.That author insists that beneficial plants are killed "because they grow with bad plants."Those who complained about the harming of wildflowers along the way inspired this author, reminding him of historical anti-vivisectionists, who said that "to these anti-vivisectionists, if judged by their views, one The life of a lost dog will be more sacrosanct than the existence of children." Many of us do suspect that the author of this lofty treatise was guilty of some serious perversion, for we love the delicate, ephemeral beauty of peas, clover, and lilies, a scene now as if Scorched by the fire, the bush is russet and breaks easily, and the fern that once held its proud cathedral aloft is now drooping withered.We seem wretchedly weak to put up with such a terrible spectacle, we do not rejoice at the extermination of weeds, we do not rejoice at another such conquest of this chaotic nature by man. Justice Douglas relates that he attended a meeting of federal farmers where the protests of the residents against the sage-spraying program described earlier in this chapter were discussed.These attendees thought it was a great joke for an old lady to oppose the plan because the wildflowers would be destroyed."As the shepherd has an inalienable right to seek a meadow, or the logger to a tree," asked the suave, wise lawyer, "is it not her right to seek a calyx or a lilac?" "We We inherit the aesthetic value of the wilderness as much as we inherit the copper and gold veins of our mountains and our mountain forests." Of course, there is more to the hope of preserving our wilderness than aesthetic considerations.In the combination of nature, natural plants play an important role.Hedgerows and patchy fields along country roads provide foraging, shelter and brooding for birds and habitat for many young animals.In many eastern states alone, more than seventy types of shrubs and vines are typical roadside plant species, 65 of which are important foods for wildlife. Such plants are also habitats for wild bees and other pollinating insects.The need for these natural pollinators is felt even more now.The farmer himself, however, is quite ignorant of the value of these wild bees, and often resorts to various measures which make them no longer serve him.Some crops and many wild plants are partially or totally dependent on the help of natural pollinator insects.Hundreds of species of wild bees are involved in the pollination of crops—100 species visit the flowers of alfalfa alone.Without free pollination, most of the soil-holding and soil-enriching plants on uncultivated land would have to die out, with profound consequences for the ecology of the entire region.Many weeds, shrubs and trees in forests and rangelands rely on natural insects for reproduction; if not for these plants.Many wild animals and pasture animals don't have much to eat.Now, the destruction of hedgerows and weeds by clean farming methods and chemicals is wiping out the last refuge of these pollinators and is severing the thread that connects life to life. These insects, as we know them, are so important to our agriculture and our fields that they deserve something better from us than the random destruction of their habitat.Honey bees and wild bees rely primarily on pollen from "weeds" such as goldenrod, mustard greens and dandelions to feed their young.Before the alfalfa blooms, the wild peas provide the basic spring feed for the bees to get them through the dry season in preparation for pollination of the alfalfa flowers.In autumn, they rely on goldenrod reserves for the winter. During this season, there is no other food available.Thanks to the precise and ingenious timing powers of nature itself, the appearance of a species of wild bee happened exactly on the day the willows were in bloom.There is no shortage of people who understand these conditions, but these are not the ones who have flooded the entire landscape with chemical potions on a massive scale. Where are the people who are supposed to understand the value of native habitats for wildlife conservation?So many of them are saying that herbicides are harmless to wildlife, that herbicides are less toxic than insecticides! That said, it can be used without harm.Yet when herbicides land on forests and fields, on swamps and pastures, officials bring dramatic changes, even permanent destruction, to wildlife habitats.In the long run, it destroys the habitat and food of wildlife—perhaps worse than killing them outright.The irony of this all-out chemical assault on roadsides and signposts is twofold.Experience has clearly shown that what is attempted is not easy to achieve.Splashing herbicides does not permanently control roadside growth, and the spraying has to be repeated year after year.The irony is even greater: we insist on doing this despite the fact that there are perfectly reliable methods of selective spraying that can control plant growth for long periods of time without repeated spraying in most plants. The purpose of controlling the jungle along roads and signposts is not to remove everything from the ground except grass, but rather to remove vegetation that will eventually grow tall to avoid other vegetation. Obstructing the driver's view or interfering with the line of the road marking area.Generally speaking, this refers to the arbor.Most shrubs are too low to be dangerous, as are, of course, ferns and wildflowers. Selective spraying was invented by Dr. Frank Eggle, who was at the American Museum of Natural History the director of the Committee on the Recommendations for Landmark Area Control of the Jungle.Based on the fact that most shrubby flora are resistant to tree encroachment, selective spraying can take advantage of this inherent stability in nature.In comparison, grasslands are easily overrun by saplings.The purpose of selective spraying is not to produce grass on roadsides and signposts, but to remove tall tree vegetation by direct treatment, while preserving all other vegetation.For those plants that are very resistant, a viable catch-up treatment will suffice, after which the shrubs maintain the control and the trees do not regrow.The best and cheapest means of controlling plants are not chemicals but other plants. This approach has now been tested in a research area in the eastern United States.The results showed that once properly treated, an area becomes stable and does not require spraying for at least 20 years.This spraying is often carried out by people on foot with sprayers on their backs, and the sprayers are tightly controlled.Sometimes the compression pump and spray equipment can be mounted on the chassis of the truck, but carpet spraying is never done.Only the trees are treated directly, and those particularly tall shrubs that must be removed are also treated.In this way, the integrity of the environment is preserved.Wildlife habitat of great value is intact, as are the beautiful displays of shrubs, ferns and wildflowers. The method of arranging plants by selective spraying has been used everywhere.By and large, ingrained habits persist, while carpet spraying continues to revive, taking a heavy annual toll on taxpayers and damaging the ecological web of life.It's safe to say that carpet spraying has been revived only because the aforementioned facts were unknown.As long as taxpayers realize that the bills for spraying town roads should be sent once in a generation, not once a year, taxpayers will surely rise up and demand a change in method. Among the many advantages of selective spraying is that it minimizes the total amount of chemicals that penetrate the soil.Instead of spreading the medicine, it is concentrated on the roots of the trees.In this way, potential harm to wildlife is kept to a minimum. The most widely used herbicides are 2.4-D, 2.4.5-T and related compounds.Whether these herbicides are actually poisonous is still being debated.People who spray their lawns with 2·4-D and get wet with the spray sometimes suffer from severe neuritis and even paralysis.Although such incidents do not occur frequently, medical authorities have issued warnings against the use of these compounds.Other dangers, more subtle, may also lurk in the use of 2·4-D.Experiments have proved that these drugs disrupt the basic physiological process of intracellular respiration, and imitate X-rays to damage chromosomes.Recent work has shown that some herbicides at much lower levels of toxicity than those lethal can adversely affect bird reproduction. Leaving aside any direct toxic effects, there have been some curious indirect consequences due to the use of certain insecticides.Animals, both wild herbivores and domestic animals, have been found to be sometimes strangely attracted to a plant that has been sprayed, even though it is not their natural food.If a herbicide as toxic as arsenic had been used, this urge to kill the plants would have had costly consequences.Less toxic herbicides can also be lethal if certain plants happen to be poisonous themselves or have thorns and prickles.For example, poisonous weeds on pastures suddenly become attractive to livestock after spraying, and livestock die from satisfying this abnormal appetite.The veterinary drug literature is replete with examples of severe disease caused by pigs eating the sprayed fenugreek and sheep eating the sprayed herb.Bees are poisoned when they collect honey on sprayed mustard greens during flowering.The leaves of wild cherry are very toxic. Once its leaf clusters are sprayed with 2·4-D, wild cherry is fatal to cattle.Obviously, the wilting of the sprayed (or cut) plants makes them attractive.Another example is hogweed, which is generally avoided by domestic animals unless forced to eat it during winter and early spring when feed is scarce.However, after the grass clumps were sprayed with 2·4-D, the animals were willing to eat them. This strange phenomenon is due to the changes brought about by the chemical drugs on the metabolism of the plants themselves.There is a temporary marked increase in sugar content, which makes plants more attractive to many animals. Another curious effect of 2.4-D has significant effects on livestock, wildlife, and apparently also on humans.Experiments carried out about ten years ago showed that the nitrate content of cereals and sugar beet treated with this chemical increased sharply.The same effect may be found in sorghum, sunflower, spiderweed, legweed, hogweed, and heartbreak.There are many grasses in which the cows are unwilling to eat, but after being treated with 2.4-D, the cows eat them with relish.According to the investigation of some agricultural experts, a certain number of dead cattle are related to the sprayed weeds.The danger lies entirely in the growth of nitrates, which immediately causes serious problems due to physiological processes peculiar to ruminants.Most of these animals have particularly complex digestive systems -- their stomachs are divided into four chambers.The digestion of cellulose is carried out in a stomach compartment by the action of microorganisms (rumen bacteria).When animals eat plants with abnormally high nitrate levels, microbes in the rumen digest the salts, turning them into highly toxic nitrites.And so the fatal chain of events takes place: the nitrite acts on the hemoglobin, turning it into a chocolate-brown substance in which oxygen is imprisoned and cannot take part in the respiration process, so that oxygen cannot be transferred from the lungs to the into body tissues.Death occurs within hours due to hypoxia, a lack of oxygen.The various reports of livestock casualties grazing on certain pastures treated with 2·4-D have at last found a logical explanation.This danger is also present in wild animals that are ruminants, such as deer, antelope, sheep and goats. Although various other factors (such as: abnormally dry climate) can cause the increase of nitrate content, the consequences of the overselling and abuse of 2·4-D can no longer be ignored.This situation has caused great concern at the Agricultural Experiment Station of the University of Wisconsin, confirming the warning issued in 1957: "The plants killed by 2·4-D may contain large amounts of nitrates." As with endangering animals, This danger extends to humans, and it helps to explain the strange recent spate of "grain bank deaths."When grains, oats, or sorghum loaded with nitrates are stored, they give off poisonous carbon monoxide gas, which can be fatal to anyone who enters the grain storage.Just a few breaths of this gas can cause a diffuse chemical pneumonitis.In a series of such cases studied by the Mississippi State College of Medicine, all but one died. "We take a walk in nature, just as an elephant walks in a small house full of porcelain." So C. J. Belkin, a Dutch scientist who clearly understands all this, sums up our use of herbicides in this way."My opinion is that there is a misconception that there are too many weeds to get rid of, and we don't know whether all the grasses growing in the crops are harmful, or some of them are beneficial," Dr Belkin said. It's a rare question to ask: What is the relationship between weeds and soil?Even from our narrow self-interest point of view, perhaps the relationship is a salutary thing.As we have seen, there is an interdependent and mutually beneficial relationship between soil and the organisms that live in and on it.Presumably, weeds take something from the soil, and maybe weeds give something to the soil. A recent urban garden in the Netherlands provides a practical example.The roses are not growing well.Soil samples showed infestation with tiny nematodes.Scientists at the Dutch plant protection company did not recommend chemical sprays or soil treatments; instead they suggested planting marigolds among the roses.This calendula, which rhetoricians would doubtless consider a weed in the middle of any rose bed, secretes from its roots a secretion that kills soil nematodes.This suggestion was accepted; some beds were planted with marigolds; others were not planted for comparison.The result is obvious.With the help of calendula, the roses grew luxuriantly, but in the beds without the marigolds, the roses became sick and wilted.Calendula is now used in many places to eliminate nematodes. At this point, there may be other plants that are doing something beneficial to the soil that we don't know much about, but which we have ruthlessly eradicated in the past.One very useful role of natural flora, now often dismissed as "weeds," is as an indicator of soil condition.Of course, this useful effect is lost where chemical herbicides have been used. Those looking for an answer to the spraying problem are also focusing on something of great scientific importance—the need to preserve some natural flora.We need these flora as a standard against which we can measure changes due to our own activities.We need them as natural habitats in which pristine populations of insects and other organisms can be preserved, as described in Chapter 16.Growing resistance to insecticides is changing the genetics of insects and perhaps other organisms.One scientist has even suggested that special kinds of "zoos" should be created to preserve insects, mites, and the like until the genetic nature of these insects is altered further. Some experts have warned that the increasing use of herbicides is causing profound but elusive changes in plants.用以清除阔叶植物的化学药物2·4－D使得草类在已平息了的竞争中又繁茂起来——现在这些草类中的一些草本身已变成了“杂草”。于是，在控制杂草上又出现了新问题，并又产生了一个向另外方向转化的循环。这种奇怪的情况在最近一期关于农作物问题的杂志上被供认：“由于广泛使用2·4－D去控制阔叶杂草，野草已增长为对谷类与大豆产量的一种威胁。” 豕草——枯草热病受害者的病原——提供了一个有趣的例子，控制自然的努力有时候象澳洲土人的飞去来回一样，投出去后又飞还原地。为控制水草，沿道路两旁排出了几千加仑的化学药物。然而不幸的事实是，地毯式喷撒的结果使豕草更多了，一点也没有减少。豕草是一年生植物，它的种子生长每年需要一定的开阔土地。因此我们消除这种植物最好的办法是继续促使浓密的灌木、羊齿植物和其它多年生植物的生长。经常性的喷药消灭了这种保护性植物，并创造了开旷的、荒芜的区域——豕草迅速地长满了这个区域。此外，大气中药粉含量可能与路过的水草无关，而可能与城市地块上、以及休耕地上的豕草有关。 山查子草化学灭草剂的兴旺上市是不合理的方法却大受欢迎的一个例子。有一种比年年用化学药物除去山查子草的更廉价而效果更好的方法。这种方法就是使它与另外一种牧草竞争，而这一竞争使山查子草无法残存。山查子草只能生长在一种不茂盛的草坪上，这是山查子草的特性，而不是由于本身的疾病。通过提供一块肥沃土壤并使其他的青草很好长起来，这会创造一个环境，在此环境中山查子草长不耙来，因为它每年的发芽都需要开阔的空间。 且不谈下达基本的状况，苗圃人员听了农药生产商的意见，而郊区居民又听了苗圃人员的意见，于是郊区居民每年都在把真正惊人数量的山查子灭草剂不断喷撒在草坪上。商标名字上看不出这些农药的特征，但在它们的配制中包括着象汞、砷和氯丹这样有毒物质。随着农药的出售和应用，在草坪上留下了极大量的这类化学药物。例如：一种药品的使用者按照指数，他将在一英亩地中使用60磅氯丹产品。如果他们使用另外一些可用的产品，那么他们就将在一英亩地中用175磅的砷。我们将在第八章看到，鸟类死亡的数量正在使人苦恼。这些草坪究竟对人类毒害如何现在还不得而知。 一直对道旁和路标界植物进行选择性喷药试验的成功提供了一个希望，即用相当正确的生态方法可以实现对农场、森林和牧场的其它植物的控制规划；此种方法的目的并不是为了消灭某个特别种类的植物，而是要把植物作为一个活的群落而加以管理。 其它一些稳固的成绩说明了什么是能够做得到的。在制止那些不需要的植物方面，生态控制方法取得了一些最惊人的成就。大自然本身已遇到了一些现在正使我们感到困扰的问题，但大自然通常是以它自己的办法成功地解决了这些问题。对于一个有足够的知识去观察自然和想征服自然的人来说，他也将会经常得到成功的酬谢。 在控制不理想的植物方面的一个突出例子是在加利福尼亚州对克拉玛斯草的控制。虽然克拉玛斯草，即山羊草是一种欧洲土产，它在那儿被叫做“圣约翰草”，它跟随着人向西方迁移，第一次在美国发现是1793年，在靠近宾夕法尼亚州兰喀斯忒的地方。到1900年，这种草扩展到了加利福尼亚州的克拉玛斯河附近，于是这种草就得到了一个地方的名字。1929年，它占领了几乎十万英亩的牧地，而到了1952年、它已侵犯了约二百五十万英亩。克拉玛斯草非常不同于象鼠尾草这样的当地植物，它在这个区域中没有自己的生态位置，也没有动物和其它植物需要它。相反，它在哪里出现，哪里的牲畜吃了这种有毒的草就会变成“满身疥癣，咀里生疮，不景气”的样子。土地的价值因此而衰落下去，因为克拉玛斯草被认为是折价的。 在欧洲，克拉玛斯草，即圣约翰草，从来不会造成什么问题，因为与这种植物一道，出现了多种昆虫，这些昆虫如此大量地吃这种草，以致于这种草的生长被严格地限制了。尤其是在法国南部的两种甲虫，长得象碗豆那么大，有着金属光泽，它们使自己全部的生存十分适应于这种草的存在，它们完全靠这种草作为食料，并得以繁殖。 1944年第一批装载这些甲虫的货物运到了美国，这是一个具有历史意义的事件，因为这在北美是利用食草昆虫来控制植物的第一次尝试。到了1948年，这两种甲虫都很好地繁殖起来了，因而不需要进一步再进口了。传播它们的办法是，把甲虫从原来的繁殖地收集起来，然后再把它们以每年一百万的比例散布下去。先在很小的区域内完成了甲虫的散布的只要克拉玛斯草一枯萎，甲虫就马上继续前进，并且非常准确地自居新场地。于是，当甲虫削弱了克拉玛斯草后，那些一直被排挤的、人们所希望的牧场植物就得以复兴。 1959年完成的一个十年考察说明对克拉玛斯草的控制已使其减少到原量的百分之一，“取得了比热心者的希望还要更好的效果”。这一象征性的甲虫大量繁殖是无害的，实际上他需要维持甲虫的数量以对付将来克拉玛斯草的增长。 另外一个非常成功而且经济的控制野草的例子可能是在澳大利亚看到的。殖民者曾经有过一种将植物或动物带进一个新国家的风习。一个名叫阿休·菲利浦的船长在大约1787年将许多种类的仙人掌带进了澳大利亚，企图用它们培养可作染料的胭脂红虫。一些仙人掌从果园里面漏出来，直到1925年发现近20种仙人掌已变成野生的了。由于在这个区域里没有天然控制这些植物的因素，它们就广阔地蔓延开来，最后占了几乎六千万英亩的土地。至少这块土地的一半都非常浓密地被覆盖住了，变成无用的了。 1920年澳大利亚昆虫学家被派到北美和南美去研究这些仙人掌天然产地的昆虫天敌。经过对一些种类的昆虫进行试用后，一种阿根廷的蛾于1930年在澳大利亚产了30亿个卵。十年以后，最后一批长傅浓密的仙人掌也死掉了，原先不能居住的地区又重新可以居住和放牧了。整个过程花费的钱是每亩不到一个辨士。相对比，早年所用那些不能令人满意的化学控制办法却在每英亩地上的花费为10英磅。 这两个例子都说明了密切研究吃植物的昆虫的作用，可以达到对许多不理想的植物的非常有效的控制。虽然这些昆虫可能对所有牧畜业者是易于选择的，并且它们高度专一的摄食习性能够很容易为人类产生利益；可是牧场管理科学却一直对此种可能性根本未予考虑。