The impact of human activities on the environment. Human influence on nature

All mankind is faced with the most important task - the preservation of the diversity of all organisms living on Earth. All species (vegetation, animals) are closely related. The destruction of even one of them leads to the disappearance of other species interconnected with it.

From the very moment when a person came up with tools and became more or less intelligent, his all-round influence on the nature of the planet began. The more a person developed, the more influence he had on environment Earth. How does a person influence nature? What is positive and what is negative?

Negative points

There are both pros and cons of human influence on nature. To begin with, consider negative examples of harmful:

1. Deforestation associated with the construction of highways, etc.
2. Soil pollution occurs due to the use of fertilizers and chemicals.
3. A decrease in the number of populations due to the expansion of areas for fields with the help of deforestation (animals, losing their normal habitat, die).
4. Destruction of plants and animals due to the difficulties of their adaptation to a new life, greatly changed by man, or simply their extermination by people.
5. and waters by different people and by people themselves. For example, in the Pacific Ocean there is a "dead zone" where a huge amount of debris floats.

Examples of human influence on the nature of the ocean and mountains, on the state of fresh water

The change in nature under the influence of man is very significant. The flora and fauna of the Earth are severely affected, water resources are polluted.

Typically, light debris remains on the ocean surface. In this regard, the access of air (oxygen) and light to the inhabitants of these territories is hampered. Numerous species of living creatures are trying to look for new places for their habitat, which, unfortunately, not everyone succeeds.

The ocean currents bring in millions of tons of garbage every year. This is a real disaster.

Deforestation on the mountain slopes also has a negative impact. They become naked, which contributes to the occurrence of erosion, as a result, loosening of the soil occurs. And this leads to destructive collapses.

Pollution occurs not only in ocean waters, but also in fresh water. Thousands of cubic meters of sewage or industrial waste flows into rivers every day.
And they are contaminated with pesticides, chemical fertilizers.

The dire consequences of oil spills, mining

Just one drop of oil makes about 25 liters of water unusable. But this is not the worst thing. A rather thin film of oil covers the surface of a huge area of \u200b\u200bwater - about 20 m 2 of water. This is detrimental to all living things. All organisms under such a film are doomed to slow deathbecause it prevents oxygen from entering the water. This is also a direct influence of man on the nature of the Earth.

People extract minerals from the bowels of the Earth, formed over several million years - oil, coal, etc. Such industrial production, together with cars, emit huge amounts of carbon dioxide into the atmosphere, which leads to a catastrophic decrease in the ozone layer of the atmosphere - the protector of the Earth's surface from death-carrying ultraviolet radiation from the Sun.

Over the past 50 years, the air temperature on Earth has increased by only 0.6 degrees. But this is a lot.

This warming will lead to an increase in the temperature of the oceans, which will contribute to the melting of polar glaciers in the Arctic. Thus, the most global problem - the ecosystem of the Earth's poles is disrupted. Glaciers are the most important and voluminous sources of clean fresh water.

Benefits of people

It should be noted that people bring both certain benefits and considerable ones.

It is necessary from this point of view to note the influence of man on nature. The positive lies in the activities carried out by people to improve the ecology of the environment.

In many vast areas of the Earth in different countries protected areas, wildlife sanctuaries and parks have been organized - places where everything is preserved in its original form. This is the most reasonable influence of man on nature, positive. In such protected places, people contribute to the preservation of flora and fauna.

Thanks to their creation, many species of animals and plants have survived on Earth. Rare and already endangered species must be included in the man-made Red Book, according to which fishing and collection is prohibited.

People also create artificial water canals and irrigation systems that help maintain and increase

Planting of diverse vegetation is also carried out on a large scale.

Ways to solve emerging problems in nature

To solve problems, it is necessary and important, first of all, to have an active human influence on nature (positive).

As for biological resources (animals and plants), they should be used (mined) in such a way that individuals always remain in nature in quantities that contribute to the restoration of the previous population size.

It is also necessary to continue work on the organization of reserves and planting forests.

Carrying out all these measures to restore and improve the environment is a positive influence of man on nature. All this is necessary for the good of oneself.

After all, the well-being of human life, like all biological organisms, depends on the state of nature. Now all of humanity faces the most important problem - the creation of a favorable state and stability of the living environment.

With the emergence and improvement of man, the evolutionary processes of the biosphere have undergone a significant change. At the dawn of his appearance, man had a predominantly local impact on the environment. This was expressed, first of all, in meeting the minimum needs for food and housing. Ancient hunters, with a decrease in the number of game animals, moved to hunt to other places. Ancient farmers and pastoralists, if the soil was depleted or there was less forage, they mastered new lands. At the same time, the population of the planet was small. There was almost no industrial production. The insignificant amount of waste and pollution generated at that time as a result of human activity was not dangerous. Everything could be utilized due to the destructive function of living matter.

The growth of the planet's population, the successful development of animal husbandry, agriculture and scientific and technical progress determined the further development of mankind.

Today, more than 7 billion people live on Earth, by 2030 this number will grow to 10 billion, and by 2050 - to 12.5 billion people. Providing the world's population with food and energy resources is already an acute problem. Today, countries with constant food shortages are home to about 70% of the world's population. Non-renewable natural resources are falling catastrophically. For example, according to the forecasts of scientists, mankind will use up all reserves of metals within the next 200 years.

Human economic activity at the present stage is increasingly showing negative examples of the impact on the biosphere. These include: environmental pollution, depletion of natural resources, land desertification, soil erosion. Natural communities are also disrupted, forests are being cut down, rare species of plants and animals disappear.

Environmental pollution

Environmental pollution - the entry into the environment of new, uncharacteristic for it, solid, liquid and gaseous substances or the excess of their natural level in the environment, which has a negative impact on the biosphere.

Air pollution

Clean air is essential for the life of all living organisms. In many countries, the problem of keeping it clean is a state priority. The main cause of air pollution is the combustion of fossil fuels. Of course, he still plays a leading role in providing energy to all sectors of the economy. Today, the vegetation of the planet is no longer able to fully assimilate the products of combustion of liquid and solid fuels.

Carbon oxides (CO and CO 2) released into the atmosphere as a result of fuel combustion are the cause of the greenhouse effect. Sulfur oxides (SO 2 and SO 3), resulting from the combustion of fuels containing sulfur, interact with water vapor in the atmosphere. The end products of this reaction are solutions of sulfurous (H 2 SO 3) and sulfuric (H 2 SO 4) acids. These acids fall to the surface of the earth with precipitation, cause acidification of the soil, and lead to human diseases. Forest ecosystems, especially conifers, suffer the most from acid precipitation. They have the destruction of chlorophyll, underdevelopment of pollen grains, drying and falling of needles.

Nitrogen oxides (NO and NO 2), when exposed to ultraviolet rays, participate in the formation of free radicals in the atmosphere. Nitric oxides lead to the development of a number of pathological conditions in humans and animals. These gases, for example, irritate the respiratory tract, cause pulmonary edema, etc.

Chlorine compounds make a significant contribution to the destruction of the planet's ozone layer. For example, a single chlorine free radical can destroy up to 100,000 ozone molecules, which is the cause of ozone holes in the atmosphere.

The reasons radioactive contamination atmosphere are accidents at nuclear power plants (for example, at the Chernobyl nuclear power plant in 1986). Nuclear weapons testing and improper waste disposal also contribute to this process. nuclear power... The radioactive particles that enter the atmosphere are scattered over long distances, polluting the soil, air, and water bodies.

Transport should also be mentioned as a source of air pollution. The exhaust gases from internal combustion engines contain a wide range of contaminants. Among them are oxides of carbon and nitrogen, soot, as well as heavy metals and compounds with a carcinogenic effect.

Hydrosphere pollution

Freshwater scarcity - global ecological problem... Along with the waste and scarcity of water, the growing pollution of the hydrosphere is of concern.

The main cause of water pollution is the direct discharge of industrial waste and municipal wastewater into aquatic ecosystems. In this case, with chemicals biological pollution also enter the aquatic environment (for example, disease-causing bacteria). When heated waste water is discharged, physical (thermal) pollution of the hydrosphere occurs. Such discharges reduce the amount of oxygen in the water, increase the toxicity of impurities and often lead to death (death of aquatic organisms).

Soil pollution

Depletion of natural resources

Natural resources - the means of subsistence of people, which are not created by their labor, but are in nature. The main problem of their current state is the reduction in the amount of exhaustible and the deterioration of the quality of inexhaustible natural resources. Especially it concerns animals and plant resources... Habitat destruction, environmental pollution, overuse of natural resources, poaching significantly reduce the species diversity of plants and animals.

During the existence of mankind, about 70% of forest lands have been cut down and destroyed. This became the reason for the extinction of plant species that lived in herbaceous and shrub layers. They could not survive in direct sunlight. Due to deforestation, the fauna has also changed. Animal species that had close ties with tree layers either disappeared or migrated to other places.

It is believed that since 1600, as a result of human activities, about 250 species of animals and 1000 species of plants have completely disappeared from the face of the Earth. About 1,000 species of animals and 25,000 species of plants are currently under threat of destruction.

Animal and plant resources are capable of permanent regeneration. If the rate of their use does not exceed the rate of natural renewal, then these resources can exist for a very long time. However, the speed of their renewal is different. Animal populations can recover their numbers in a few years. Forests grow in several decades. And soils that have lost their fertility restore it very slowly - over several millennia.

A very important resource problem for the planet is the preservation of quality fresh water... As you know, the total reserves of water on the planet are inexhaustible. However, fresh water accounts for only about 3% of the entire hydrosphere. Moreover, only 1% of fresh water is suitable for direct human consumption without preliminary purification. About 1 billion people on Earth do not have constant access to fresh drinking water. Therefore, mankind must consider fresh water as an exhaustible natural resource. The problem of fresh water is aggravated every year due to the shallowing of rivers and lakes as a result of reclamation measures. The consumption of water for the needs of agriculture and industry is increasing, water bodies are polluted with industrial and household waste.

Lack of fresh water and its poor quality also affect human health. It is known that the most dangerous infectious diseases (cholera, dysentery, etc.) occur in places where access to clean water is difficult.

Desertification

Desertification - a set of processes that lead to the loss of a continuous vegetation cover by the natural community with the impossibility of its restoration without human participation. Desertification is mainly caused by anthropogenic factors. These are deforestation, irrational use of water resources for irrigation, etc. For example, excessive cutting of woody mountain vegetation causes natural disasters - mudflows, landslides, avalanches. An excessive load on pastures with an increase in the scale of livestock production can also lead to desertification. The vegetation cover eaten by animals does not have time to recover, and
the soil is subject to various types of erosion.

Soil erosion is the destruction of the fertile soil layer by wind and water.

Soil erosion occurs due to the massive inclusion of more and more lands by humans in active land use.

To the greatest extent, desertification is typical for areas with an arid climate (deserts, semi-deserts) - countries in Africa and Asia (especially China).

Today this problem is of an interethnic nature. Therefore, the UN adopted the International Convention to Combat Desertification, which was signed by almost 200 states.

The main consequences of human economic activity are environmental pollution, depletion of natural resources and land desertification. Prevention of the destructive influence of the anthropogenic factor on the biosphere is today an important common human problem, in the solution of which every inhabitant of the Earth should participate.

Currently, environmental protection has become one of the most pressing problems in the development of society.

This is due to the ever-increasing interdependence of socio-ecological and natural processes.

Humanity has reached such a level of development at the present time when the results of its activities become comparable to global natural disasters.

The growth rate of the world's population is very high.

The period for which the population doubles is rapidly decreasing: in the Neolithic it was 2500 years, in 1900 - 100 years, in 1965 - 35 years.

As for the productivity of the biosphere, it is relatively small in terms of objective indicators.

Deserts occupy a significant part of the land, and the productivity of agricultural crops lags behind the rate of population growth. To this is added the plundering of natural resources.

Forest fires (deliberate or accidental) destroy up to two million tons annually organic matter planets. A huge number of trees are used to make paper. Huge areas of rainforest, after years of agricultural use, turn into a desert.

Monocultures in many tropical countries, such as sugar cane, coffee tree, etc., drain the soil.

The improvement and increase in the number of vessels for fishing fish and marine animals has led to a decrease in the number of many marine fish species. Excessive whaling has contributed to a sharp decline in global whale stocks. The Greenland whale is almost extinct, and the blue whale is endangered. As a result of human poaching, the number of fur seals and penguins has significantly decreased.

Among the natural phenomena that play an important role in the depletion of natural resources, soil erosion and drought should be mentioned. Severe erosion destroys the soil. A person also contributes to this when he destroys the vegetation cover by improper management, burning and cutting down forest plantations, unscheduled grazing of livestock (especially sheep and goats).

Through the fault of man on the globe, more than five million square kilometers of cultural lands are currently lost.

The destruction of the vegetation cover leads to more and more severe aridity.

The systematic drainage of many wet areas also contributes to the development of aridity. Aridity also increases with the steady depletion of the groundwater horizon used in industry. So, for the production of one ton of paper, 250 cubic meters of water is required, and the production of one ton of fertilizers requires 600 cubic meters of water.

Today, in many parts of the world, there is already a very strong shortage of water, and with a decrease in precipitation, this shortage is felt even more.

Systematic drainage of marshes in the temperate zone is a serious mistake of humanity. Swamps function like a sponge - they regulate the water table - supplying it in the summer and absorbing water produced by heavy rainfall, thereby preventing flooding. In addition, swamps serve as a refuge for endangered species of plants and animals, and in terms of their profitability, swamps are equal to or even surpass the most profitable crops.

Human impact on the environment has led to the fact that many species of animals and plants have become very rare or completely disappeared.

The high rates of scientific and technological progress at the present time, on the one hand, has led mankind to the achievements that people only dreamed of in the past centuries. On the other hand, the development of astronautics, the chemical and metallurgical industries, advances in medicine, veterinary medicine, agriculture, agricultural technology and other industries have a negative impact on humanity as a whole.

Systematization and generalization of information showed that scientific and technological progress has a negative impact on flora and fauna, including people.

Almost half of all diseases among the inhabitants of our planet are caused by the harmful effects of chemical, physical, mechanical, biological environmental factors.

At the same time, the degree of influence of environmental factors on the population largely depends on the age of people, the climatic conditions in which they live, latitude, length of daylight hours, social conditions, and the level of environmental pollution.

About 60% of all cases of malformations among humans and more than 50% of deaths are associated with environmental pollution. Mortality from diseases of the circulatory system, mental disorders, respiratory diseases, malignant neoplasms, diabetes mellitus, and diseases of the cardiovascular system is increasing.

Detailed solution Paragraph § 32 on biology for students of grade 6, authors Pasechnik V.V. 2014

1. What factors influence the development of the flora?

For many hundreds of millions of years, the main influence on the plant world was exerted by natural factors: light, heat, moisture, the interaction of plants and animals. With the advent of Homo sapiens, his activities began to exert an increasing influence on the world around him.

2. What adaptations to natural conditions are developed in plants?

The adaptation of organisms to the environment is called adaptation. The ability to adapt is one of the basic properties of life in general, providing the possibility of its existence, the ability of organisms to survive and reproduce.

Adaptations are manifested at different levels - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. All adaptations of organisms to existence in various conditions have developed historically.

For example, plants in arid areas are capable of individual development adapt to atmospheric and soil drought. Characteristic features are the small size of their evaporating surface, as well as the small size of the aboveground part compared to the underground one. They also have low transpiration, high osmotic pressure, and the cytoplasm is highly elastic and viscous. Some plants in arid areas are capable of shedding leaves and even entire branches.

There are many examples, since plants develop certain adaptations for specific conditions.

3. What is the importance of plants in human life?

Cultural plants are grown by humans for food, feed in agriculture, medicines, industrial and other raw materials.

By observing the most sensitive plants to pollution, scientists can very accurately judge the pollution of the environment. Pollution-resistant plants are used for greening cities with developed industry and an abundance of cars. These plants actively absorb various harmful substances from the air and are good dust collectors.

Questions

1. What is the impact of human economic activity on the flora?

Violent human activity: plowing land, stubbing and burning forests, grazing pastures and trampling grass stands by domestic animals - has led to serious changes in nature. Man began to notice that as a result of his economic activities, dense forests thinned out, the number of species of wild animals decreased, and some disappeared altogether. Deforestation caused shallowing of rivers and a decrease in fish catches. Soils were depleted, there were more ravines, dry winds and black storms became more frequent.

Especially strong changes have taken place around cities. Extensive garbage and waste dumps grew. In many bodies of water, the water has become undrinkable. Polluted water, air, soil caused disturbances and sometimes death of natural communities.

Similar changes in nature have taken place everywhere, in many countries of the world. Over the past millennia, 2/3 of all forests have been cut down and burned on the globe, over 500 million hectares of fertile lands have turned into deserts. Many species of plants and animals have disappeared from our planet. The number of some species has decreased.

2. What is the purpose of creating reserves? What is their difference from the reserves?

In contrast to nature reserves, not the entire natural complex is protected on the territory of reserves, but only that part of it that ensures the existence of certain plants and animals.

3. How are nature protected in our country?

In our country, state and public organizations environmentalists.

Currently, in our country, laws are being passed and measures are being taken to "protect the environment from harmful effects on it."

Botanical gardens, experimental stations and other similar institutions play an important role in the protection of rare plants.

4. What is the role of plants in improving the environment?

Plants that are most sensitive to pollution can serve as indicators of the state of the environment, and resistant plants should be used for greening cities with developed industry and an abundance of cars. These plants actively absorb various harmful substances from the air and are good dust collectors.

Forests around industrial centers play an important ecological and health-improving role. Being a stable plant community with a large number of species, the forest is especially active in absorbing and processing harmful substances.

In the end, man lives off green plants - the main producers of organic matter and oxygen.

5. Why should nature conservation become the concern of all people on the planet?

The protection of nature and the rational use of its resources are important not only for one state, but for the entire globe as a whole, i.e. for every person. Only in this case can you achieve the most productive results.

Protecting, restoring and multiplying the vegetation cover of our planet, we create conditions for the life of not only contemporaries, but also future generations.

Summer assignments

1. Study the species composition of trees, shrubs and ornamental (used in landscaping) plants. Establish in what period (flowering, fruiting, etc.) each species is most decorative. What plants should be more widely used in landscaping?

Plants that are resistant to pollution should be more widely used in landscaping, especially for landscaping cities with developed industries and an abundance of cars. The most resistant to air pollution are white acacia, yellow acacia (caragana), poplar, chestnut, birch, alder, willow, hawthorn, lilac, larch, etc. These plants actively absorb various harmful substances from the air and are good dust collectors. Plants skillfully used in landscaping not only cleanse the air of harmful substances, but also make settlements cozy and beautiful.

2. Study the species composition of one of the plant communities. List the plants growing in different tiers.

The species composition of deciduous forest is diverse:

In a deciduous forest, oaks, lindens, birches, maples, elms, and other large trees form the first, upper tier;

Rowan, bird cherry, hazel (hazel), forest honeysuckle - second tier;

Euonymus, raspberry - third tier (shrubs);

Rank, hoof, raven eye, runny, several types of bells, starlet, anemone, lily of the valley, medicinal lungwort, yellow zelenchuk and many other plants - the fourth (herbs and ferns);

Fifth - lichens, mosses and mushrooms.

3. Study the structural features of plants belonging to different ecological groups. Describe 2-3 plants you studied from different ecological groups.

Plants are classified into ecological groups in relation to various environmental factors. The most important of these are moisture and light.

In relation to moisture, five ecological groups of plants are distinguished:

1) hydatophytes - aquatic herbs that are completely submerged in water, their leaves are very thin, and nutrients are absorbed by the entire surface of the body. Among them are flowering plants, which again switched to an aquatic lifestyle (for example, elodea). Taken out of the water, these plants dry out quickly and die. They have no stomata and no cuticles. There is no transpiration in such plants, and water is released through special cells. Shoots supported by water often do not have mechanical tissues, they have a well-developed aerenchyma (airway tissue);

2) hydrophytes - plants, partially submerged in water, usually live along the banks of reservoirs in damp meadows, in swamps. These include common reed. They have better developed conductive and mechanical tissues than hydatophytes. Aerenchyma is well expressed. Hydrophytes have an epidermis with stomata, the intensity of transpiration is very high, and they can grow only with constant intensive absorption of water;

3) hygrophytes - plants in humid places with high air humidity.

4) mesophytes - plants living in conditions of moderate moisture, moderate temperatures and good mineral nutrition.

5) xerophytes - plants of not sufficiently humid habitats, where there is little water in the soil, and the air is hot and dry. Among them there are grasses and woody plants. They have devices that allow you to extract water when it is scarce, limit the evaporation of water, or store it during a drought. Xerophytes are better than all other plants capable of regulating water exchange, therefore, they remain in an active state even during prolonged drought. These are plants of deserts, steppes, stiff-leaved evergreen forests and shrubs, sand dunes. Among xerophytes, a distinction is made between dry (sclerophytes - adapted to austerity of water) and juicy (succulents - have fleshy stems and / or leaves). For example, feather grass, saxaul, camel thorn - sclerophytes, aloe, fat woman, prickly pear, cereus - succulents.

Opuntia vulgaris (Opuntia vulgaris) is a powerful perennial plant, up to 4-6 m tall, from the subtropics of South America.

Opuntia are able to grow quickly and form bizarre bushes. These are large cacti with dark green stalks. Their segments (cladodia) are the size of a palm - juicy, thick, light green, oblong or obovate grow one from the other. Flattened stems are sometimes mistaken for leaves.

In areoles, on young segments, rudimentary leaves pressed to the surface grow, which then fall off. Leaves are small, juicy, subulate, bright green.

Spines develop somewhat later on mature segments. Usually they are singly located in the areoles (although sometimes there are 2-4 spines in the areola). They are large and needle-shaped.

In addition to spines and leaves in areoles with gray pubescence, there are also yellowish glochidia. Glochidia are small, fragile spines that are very sharp and tough. But most importantly, they are equipped with microscopic serrated notches and hooks along the entire length and grow in large numbers in bunches around the areoles. Glochidia easily fly off the cactus and have a protective function, since they fall off the plant at the slightest touch and dig into the skin. They can cause swelling or irritation, and most importantly, they are difficult to see and remove.

From April to September, this cactus is decorated with yellow shiny flowers. They form both at the apex and along the edges of the segments, and strike with an abundance of petals and stamens. This is a feature of prickly pears - a bright and lush daytime bloom, although sometimes the flowers can remain open for 30-48 hours, attracting a huge number of bees.

Large, wheel-shaped bisexual flowers on a short tubular peduncle develop one at a time on the areoles. The prickly pear stamens are usually short corolla. They are attached to a receptacle concave in the form of a bowl and, even with a light touch, immediately twist.

The fruits ripen from mid-July to mid-August. The ovary is covered with scales on the outside, and in the axil of scales there are bundles of spines. These beams are arranged surprisingly geometrically - in a checkerboard pattern, at the same distance from each other. The resulting green "cones" of the fruit quickly increase in size, brightly colored, ripen and become red-burgundy. The fruit of Opuntia vulgaris - a pear-shaped berry - is edible. The fruits of prickly pears are fleshy, juicy, rather large (up to 5-7.5 cm long, sometimes up to 10 cm, and weighing 70-300 g). The berries contain light seeds with an ossified shell the size of a lentil grain.

The root system of prickly pear is superficial. The main root extends downward from the hypocotyl knee (hypocotyl). It gradually branches, forming a whole system of lateral roots (at a depth of 5-6 cm from the soil surface, a root system up to 7 m in length is formed).

4. Study the features and differences in the structure of the vegetative organs of plants of the same species growing in different habitats.

For example, as a result of adaptation of a plant to low light, its appearance changes somewhat. The leaves become dark green and slightly increase in size (linear leaves lengthen and become narrower), the stem internodes begin to stretch, which at the same time loses its strength. Then their growth gradually decreases, because the production of products of photosynthesis, which goes to the rear of the plant's body, is sharply reduced. With a lack of light, many plants stop blooming.

With an excess of light, chlorophyll is partially destroyed, and the color of the leaves turns yellow-green. In strong light, plant growth slows down, they turn out to be more squat with short internodes and wide short leaves.

5. Find out the effect of planting density on plant growth and development. Sow carrot (beet, radish) seeds in two identical plots (control and experimental). After the emergence of seedlings on the experimental plot, thin them out, after 10-15 days, repeat the thinning. Watch the development of the plants. Determine which plot has the highest yield. Write your results in a journal.

On the control plot, carrots will grow large, even (provided there are no negative effects on plants). And on the second small, curve, the yield is less. So with thinning, the result will be better - the roots will be larger and smoother.

6. Remove the side shoots from several tomato plants. Comparing these plants with those from which the side shoots have not been removed, determine which of the plants produced the most yield.

Plants from which the side shoots have been removed will give a greater yield. Due to this, more nutrients will flow to the fruits, and they will be larger.

7. Select several (2-3) trees and shrubs growing near your home and observe them: note the size, crown shape, branching, bark features, the location of buds and leaves on the shoot, observe the development of shoots, flowering, etc. e. Record all data in a diary. Continue your observations in the fall.

White birch

Under favorable conditions, it reaches 25-30 m in height and up to 80 cm in diameter.

The crown is branched, but not dense. Young branches hang down, which gives the crown of a birch a very characteristic appearance (name - drooping birch).

Branching is sympodial.

The bark of young trees is brown, and from 8-10 years old it turns white. Juveniles can be confused with alder species. In adulthood, it differs well from other trees in its white bark. In older trees, the bark in the lower part of the trunk becomes deeply fractured, black.

The kidneys are sessile, pointed, sticky, covered with tiled scales. The leaf arrangement is next. Leaves from rhombic-ovate to triangular-ovate, 3.5-7 cm long, 2-5 cm wide, pointed at the top with a wide-wedge or almost truncated base, smooth, sticky at a young age, smooth on both sides; edges are double-toothed. Petioles naked 0.8-3 cm.

Young shoots are reddish-brown, covered with numerous resinous rough warts - waxy glands; in adult trees, shoots with single glands are naked. The apical and lateral buds are laid on the shoots of the current year in summer and bloom in the spring.

The flowers are regular, small, inconspicuous, unisexual, collected in serratus, hanging inflorescences at the ends of the branches. It blooms before the leaves bloom (according to some sources - simultaneously with the leaves blooming) - in May.

Fruiting continues annually. The fruits ripen by the end of summer and begin to spread. Dissipation occurs gradually throughout the fall and winter. The fruit is a small winged nut.

Rosehip

Rosehip is not a tall bush from 1.5-2.5 m in height.

An upright shrub with arched branches, covered with strong crescent thorns.

Branched shoots, green, brown, dark red, dark brownish, sometimes violet-brown, brown, black-brown, brown-red or gray with tomentose pubescence; as a rule, with straight, curved or hook-shaped spines, often with an admixture of numerous setae and hairs, with pedicle glands.

Buds are spaced, reddish, less often of a different color, glabrous or hairy, small, with three to six external renal scales.

The leaf arrangement is next. Leaflets are elliptical to rounded in shape, with a wedge-shaped, rounded or slightly cordate base, serrate at the edges.

Bush forms of rose hips have branches of two types: erect and arcuate, curved downward. They form numerous vegetative shoots of the first year, sometimes reaching 1-1.5 m in height and 10-12 mm in diameter, with soft and thin thorns of various sizes, flowering and fruiting in subsequent years. Young shoots are greenish red with fine bristles and thorns.

The flowers are pink or white-pink, with five loose petals, a corolla up to 5 cm in diameter. The rose hips bloom in May-June.

The fruit is a special form of many-roots called cynarrodium, 1-1.5 cm in diameter, crowned with sepals, when ripe red, orange, purple-red, sometimes black, usually fleshy, sometimes dryish, glabrous or covered with bristles or spines, coarse-haired inside , with numerous nuts, ripen in September-October.

8. Study the structure of flowers of insect pollinated plants. Determine what is the duration of flowering, which insects pollinate them.

Heart-shaped linden

The flowers are regular, bisexual, with a double five-part perianth, up to 1-1.5 cm in diameter, yellowish-white, odorous, collected in drooping corymbose inflorescences of 3-11 pieces, with the inflorescences there is an oblong yellowish-green stipule. There are many stamens in the flower. Blooms from early July for 10-15 days. Bees and other insects pollinate.

9. Take part in the production of visual teaching aidsusing plants from the school teaching and experimental or infield. Create herbariums and thematic collections using only cultivated, weedy or widespread plants, for example, "Leaves simple and complex", "Leaf vein", "Leaf damage by pests", "Wheat development phases", "Medicinal plants", etc.

In accordance with population density, the degree of human impact on the environment also changes. However, at the current level of development of the productive forces, the activity of human society affects the biosphere as a whole. Humanity with its social laws of development and powerful technology is quite capable of influencing the secular course of biospheric processes.

Air pollution.In the course of his activity, a person pollutes the air. Over cities and industrial areas, the concentration of gases in the atmosphere increases, which in rural areas are contained in very small quantities or are completely absent. Polluted air is harmful to health. In addition, harmful gases, combining with atmospheric moisture and falling out in the form of acid rains, degrade the quality of the soil and reduce the yield.

The main causes of air pollution are the combustion of fossil fuels and metallurgical production. If in the 19th century, the products of combustion of coal and liquid fuel entering the environment were almost completely assimilated by the vegetation of the Earth, then at present the content of harmful combustion products is steadily increasing. From stoves, furnaces, exhaust pipes of cars into the air whole line pollutants. Among them, sulfurous anhydride, a poisonous gas, readily soluble in water, stands out.

The concentration of sulfur dioxide in the atmosphere is especially high in the vicinity of copper smelters. It causes the destruction of chlorophyll, underdevelopment of pollen grains, drying out and falling of leaves of needles. Part of SO 2 is oxidized to sulfuric anhydride. Solutions of sulfurous and sulfuric acids, falling out with rains on the Earth's surface, harm living organisms and destroy buildings. The soil acquires an acidic reaction, humus (humus) is washed out of it - an organic matter containing components necessary for plant development. In addition, the amount of calcium, magnesium, potassium salts decreases in it. In acidic soils, the number of animal species living in it also decreases, the rate of decomposition of litter is slowed down. All this creates unfavorable conditions for plant growth.

Billions of tons of CO 2 are released into the atmosphere each year as a result of fuel combustion. Half of the carbon dioxide from fossil fuels is absorbed by the ocean and green plants, and half is left in the air. The CO 2 content in the atmosphere is gradually increasing and has increased by more than 10% over the past 100 years. CO 2 prevents thermal radiation into outer space, creating the so-called "greenhouse effect". Changes in the content of CO 2 in the atmosphere significantly affect the Earth's climate.

Industrial enterprises and cars cause many toxic compounds to enter the atmosphere - nitrogen oxide, carbon monoxide, lead compounds (each car emits 1 kg of lead per year), various hydrocarbons - acetylene, ethylene, methane, propane, etc. Together with water droplets they form a poisonous fog - smog, which has a harmful effect on the human body, on the vegetation of cities. Liquid and solid particles (dust) suspended in the air reduce the amount of solar radiation reaching the Earth's surface. So, in big cities, solar radiation decreases by 15%, ultraviolet radiation - by 30% (and in the winter months it can completely disappear).

Freshwater pollution.The use of water resources is rapidly increasing. This is due to the growth of the population and the improvement of the sanitary and hygienic conditions of human life, the development of industry and irrigated agriculture. The daily consumption of water for household needs in rural areas is 50 liters per person, in cities - 150 liters.

A huge amount of water is used in industry. Smelting 1 ton of steel requires 200 m 3 of water, and for the manufacture of 1 ton of synthetic fiber - from 2500 to 5000 m 3. Industry absorbs 85% of all water used in cities.

Even more water is needed for irrigation. During the year, 12-14 m 3 of water is consumed per hectare of irrigated land. In our country, more than 150 km 3 are spent annually for irrigation.

The constant increase in water consumption on the planet leads to the danger of "water hunger", which necessitates the development of measures for the rational use of water resources. In addition to the high flow rate, water shortage is caused by its growing pollution due to the discharge of industrial and especially chemical waste into rivers. Bacterial contamination and toxic chemicals (such as phenol) lead to the death of water bodies. Mole rafting along the rivers, which is often accompanied by congestion, also has harmful consequences. With a long stay of wood in water, it loses its business qualities, and substances washed out from it have a detrimental effect on fish.

Rivers and lakes also receive mineral fertilizers washed out from the soil by rains - nitrates and phosphates, which in high concentrations can dramatically change the species composition of water bodies, as well as various toxic chemicals - pesticides used in agriculture to combat insect pests. For aerobic organisms living in fresh waters, the discharge of warm waters by enterprises is also an unfavorable factor. Oxygen is poorly soluble in warm water and its deficiency can lead to death of many organisms.

Pollution of the World Ocean.The waters of the seas and oceans are subject to significant pollution. With river runoff, as well as from sea transport, disease-causing waste, oil products, salts of heavy metals, toxic organic compounds, including pesticides, enter the seas. Pollution of the seas and oceans reaches such proportions that in a number of cases caught fish and shellfish are unsuitable for human consumption.

Anthropogenic changes in the soil. The fertile soil layer takes a very long time to form. At the same time, together with the harvest, tens of millions of tons of nitrogen, potassium, phosphorus - the main components of plant nutrition - are removed from the soil annually. Humus, the main factor of soil fertility, is contained in chernozems in an amount of less than 5% of the mass of the arable layer. On poor soils, humus is even less. In the absence of replenishment of soils with nitrogen compounds, its reserve can be used up in 50-100 years. This does not happen, since cultural farming involves the introduction of organic and inorganic (mineral) fertilizers into the soil.

Nitrogen fertilizers introduced into the soil are used by plants by 40-50%. The rest is reduced by microorganisms to gaseous substances, escapes into the atmosphere or is washed out from the soil. Thus, mineral nitrogen fertilizers are quickly consumed, so they have to be applied annually. With insufficient application of organic and inorganic fertilizers, the soil is depleted and yields fall. Unfavorable changes in the soil also occur as a result of incorrect crop rotations, that is, the annual sowing of the same crops, for example, potatoes.

Anthropogenic soil changes include erosion (corrosion). Erosion is the destruction and demolition of soil cover by water currents or wind. Water erosion is widespread and most destructive. It occurs on slopes and develops with improper tillage. Together with melt and rainwater, millions of tons of soil are carried away from the fields to rivers and seas every year. If nothing prevents the erosion, shallow gullies turn into deeper ones and, finally, into ravines.

Wind erosion occurs in areas with dry, bare soil and sparse vegetation. Overgrazing in steppes and semi-deserts contributes to wind erosion and rapid destruction of the grass cover. It takes 250-300 years to restore a 1 cm thick soil layer under natural conditions. Consequently, dust storms bring irreparable loss of the fertile soil layer.

Significant areas with formed soils are withdrawn from agricultural use due to the open-pit mining of minerals that lie at a shallow depth. Open pit mining is cheap, since it eliminates the need to build expensive mines and complex communications, and is safer. Dug deep quarries and dumps of soil destroy not only the lands to be developed, but also the surrounding territories, while the hydrological regime of the area is violated, water, soil and atmosphere are polluted, and the yield of agricultural crops is reduced.

Human influence on flora and fauna. Human impact on wildlife consists of direct impact and indirect changes in the natural environment. One of the forms of direct impact on plants and animals is logging. Selective and sanitary cuttings, which regulate the composition and quality of the forest and are necessary for the removal of damaged and diseased trees, do not significantly affect the species composition of forest biocenoses. Clear felling of the stand is another matter. Finding themselves suddenly in an open habitat, plants in the lower tiers of the forest are adversely affected by direct sunlight. In shade-loving plants of herbaceous and shrub layers, chlorophyll is destroyed, growth is inhibited, and some species disappear. Light-loving plants that are resistant to high temperatures and lack of moisture settle in the site of felling. The fauna is also changing: species associated with the stand disappear or migrate to other places.

Massive visits to forests by vacationers and tourists have a tangible effect on the state of the vegetation cover. In these cases, the harmful effect consists in trampling, compaction of the soil and its pollution. The direct influence of man on the animal world consists in the extermination of species that are food or other material benefits for him. It is believed that since 1600 more than 160 species and subspecies of birds and at least 100 species of mammals have been exterminated by humans. The long list of extinct species includes a tour - a wild bull that lived throughout Europe. In the XVIII century. was exterminated, described by the Russian naturalist G.V. Steller's sea cow (Steller's cow) is an aquatic mammal belonging to the order of sirens. A little more than a hundred years ago, the wild horse Tarpan, which lived in the south of Russia, disappeared. Many animal species are on the verge of extinction or have survived only in reserves. Such is the fate of the bison, who inhabited the prairies of North America in tens of millions, and the bison, which was formerly widespread in the forests of Europe. In the Far East, sika deer have been almost completely exterminated. Intensive hunting for cetaceans has brought several species of whales to the brink of destruction: gray, bowhead, blue.

The number of animals is also influenced by human economic activities that are not related to fishing. The number of the Ussuri tiger has sharply decreased. This happened as a result of the development of territories within its range and a reduction in the food supply. In the Pacific Ocean, several tens of thousands of dolphins die every year: during the fishing period, they fall into the nets and cannot get out of them. Until recently, before special measures were taken by fishermen, the number of dolphins dying in nets reached hundreds of thousands. For marine mammals, the impact of water pollution is very negative. In such cases, the ban on trapping of animals is ineffective. For example, after the ban on catching dolphins in the Black Sea, their numbers are not restored. The reason is that many poisonous substances enter the Black Sea with river water and through the straits from the Mediterranean Sea. These substances are especially harmful to baby dolphins, whose high mortality rates prevent the growth of these cetaceans.

The disappearance of a relatively small number of animal and plant species may not seem very significant. Each species occupies a certain place in the biocenosis, in the chain, and no one can replace it. The disappearance of one or another species leads to a decrease in the stability of biocenoses. More importantly, each species has unique, inherent properties. The loss of genes that determine these properties and were selected in the course of a long evolution deprives a person of the opportunity in the future to use them for their practical purposes (for example, for selection).

Radioactive contamination of the biosphere. The problem of radioactive contamination arose in 1945 after the explosion of atomic bombs dropped on the Japanese cities of Hiroshima and Nagasaki. Nuclear weapons tests carried out before 1963 in the atmosphere caused global radioactive contamination. When atomic bombs explode, very strong ionizing radiation is generated, radioactive particles are scattered over long distances, infecting soil, water bodies, and living organisms. Many radioactive isotopes have long half-lives, remaining hazardous throughout their lifetime. All these isotopes are included in the circulation of substances, enter living organisms and have a destructive effect on cells.

Nuclear weapons tests (and even more so when these weapons are used for military purposes) have another negative side. When nuclear explosion a huge amount of fine dust is formed, which is kept in the atmosphere and absorbs a significant part of the solar radiation. Calculations of scientists different countries world show that even with a limited, local use of nuclear weapons, the resulting dust will retain most of the solar radiation. A prolonged cold snap ("nuclear winter") will come, which will inevitably lead to the death of all life on Earth.

At present, almost any territory of the planet from the Arctic to Antarctica is subject to a variety of anthropogenic influences. The consequences of the destruction of natural biocenoses and environmental pollution have become very serious. The entire biosphere is under the ever-increasing pressure of human activity, therefore environmental protection measures are becoming an urgent task.

Acid atmospheric attacks on land.One of the most acute global problems of our time and the foreseeable future is the problem of the increasing acidity of atmospheric precipitation and soil cover. Areas of acidic soils do not experience droughts, but their natural fertility is low and unstable; they are quickly depleted and yields are low. Acid rains cause not only acidification of surface waters and upper soil horizons. Acidity with downdrafts of water spreads over the entire soil profile and causes significant acidification of groundwater. Acid rain occurs as a result of human economic activity, accompanied by the emission of colossal amounts of oxides of sulfur, nitrogen, carbon. These oxides, entering the atmosphere, are transported over long distances, interact with water and turn into solutions of a mixture of sulfurous, sulfuric, nitrous, nitric and carbonic acids, which fall in the form of "acid rains" on land, interacting with plants, soils, and waters. The main sources in the atmosphere are the burning of shale, oil, coal, gas in industry, agriculture, and at home. Human economic activity has almost doubled the release of sulfur oxides, nitrogen, hydrogen sulfide and carbon monoxide into the atmosphere. Naturally, this affected an increase in the acidity of atmospheric precipitation, ground and ground waters. To solve this problem, it is necessary to increase the volume of systematic representative measurements of compounds of air pollutants in large areas.