Topic 18

EDAPHIC, BIOTIC AND ANTHROPOGENIC FACTORS

• Plan:• Types of plants in relation to soil factors.• Biotic factors• Anthropogenic factors• Life forms and ecological types of plants

– Literature:

• I. Karimov. Uzbekistan is on the threshold of the XXI century. Tashkent. Uzbekistan. 1997

• I.V. Belolipov, F.H. Dzhangurazov. Geography of plants with basics of ecology, Tashkent. 1987

• Biological encyclopaedic dictionary. (Editor-in-Chief MS Gilyarov) M: Sov. Encyclopaedia, 1986

• Dictionary of botanical terms (under obs..d. Dudki IA) Kiev: Science. Dumka, 1984.

• V. Tishler: Agricultural ecology (lane With him) M. Kolos. 1971.• I.M .Kultias0v: Ecology of plants. M. ed. MSU, 1982• Ponomareva I.N: Ecology of plants with the basics of biogeocenology. M.

1978• R. Dažo: Fundamentals of Ecology (Translated from French) Progress. M.

1975• M.S. Dvorakovsky. Ecology of plants. M. Vysshaya shkola, M. 1983.• Y. Odum. Fundamentals of Ecology (translated from English) Mir Zee izd.

M. 1975• R. Ricklefts. Fundamentals of general ecology (translation from English).

. M. 1979.•• .

• The soil is the upper fertile layer of the earth's crust, which emerged from the surface layers of rocks under the influence of climatic (temperature, water, wind) and biotic (animal and plant factors)

• Terrestrial plants are inextricably linked with the soil and the underlying parent rocks and soils. Soil serves as a place of plant attachment, the source of their water supply and mineral nutrition

• Adapting in the course of evolution to various features of the soil cover, the plants developed distinctive ecological types that can survive successfully only under certain soil conditions.

• The main soil factors affecting plants are: soil moisture, its chemistry and physical properties.

• Soil moisture is of utmost importance for plant life. It is one of the main environmental factors that determine the possibility of the existence of plants.

•

To the soil moisture conditions, differenttypes of plants makedifferent demands:

some of them – inhabitantsof deserts and dry steppesare able to be satisfied

with a small amount of moisture, others are moredemanding for moisteningconditions, others exist

only on wet soils or live in water.

• Therefore, in relation to soil moisture, it is customary to distinguish the following groups of plants:

• yantak-Alhagi camelorum• Xerophytes –• dry-resistant species • living in deserts and • dry steppes (yantak, • wormwood, pistachio,• kandym, keireuk, etc.)

• Mesophytes– requiring• constant, but not • excessive moistening.• These include most of• the cultivated plants:• cotton, alfalfa, • watermelons, melons,• corn, grains, legumes, • fruit and other plants.

• Hygrophytes – plants• requiring constant• moistening, growing• on constantly wet • soils, along the banks• of rivers, lakes, along• irrigation ditches, • along the margins of rice fields (reeds (reeds),

kuga, sedge, tuberkamysh, and from cultivated rice plants

• Hydrophytes – aquatic• plants, their leaves, • stems float on the• surface, or submerged• in water (algae or• higher aquatic plants:• duckweed, nymphaea,• lotus, potamogetone,• etc.).••

• Most plants are very sensitive to the chemical composition of soils and accordingly react to the content of certain substances in it.

• Humus is an important factor of soil fertility: on soils rich in humus (chernozems), rich herbaceous vegetation develops and high yields of agricultural crops are obtained. Plants that develop well only under conditions rich in humus of soils are called eutrophic (Greek Eu -good, trophy - food), This is oak, ash, hedgehog, dandelion, nettle, burdock, etc.

• Dandelion• Taraxacum• officinalis•

• Stinging nettle, • Urtica urens• knotted (dodder)• and Cuscuta•

• The burdock felt• Arctium lappa

• Other types of plants are of little demand for soil fertility and grow quite successfully and develop on humus-poor soils, oligotrophicplants (oligotrophic plants - little, trophy -food) with a low content of nutrients. These are common pine, zhuzgun, sandy acacia, aristida, etc.

• Often there are plants in which the relationship to the degree of soil wealth is not clearly expressed, they grow well and develop both in rich and poor soils. These plants are called eurythrophic (Greek Evrys -widely, trophy - food). They include many widespread weed plants: Canadian small-petrel, finger (azhrek), buttercup field, etc.

• It is known that, by their reaction, the soils can be alkaline, neutral or acidic. Some types of plants prefer acidic soils and do not grow very well on alkaline soils.

and do not grow very well on alkaline soils.

• These include tea bush, rhododendrons, blueberries, some schvali and others.

• Species prefer alkaline soils are wormwood, yarrow, geranium and others. Some plants can exist both on acidic and alkaline soils (fescue ovine, doggrass, violet swirl, etc.).

• Alkaline soil contains a significant amount of calcium carbonate (carbonates). Therefore, there are plants that prefer soils rich in carbonates. They are called calcicophylls - limy-lovers. Calcificophilous plants -feather grass, cornflowers, wormwood, and others.

•• .

• However, there are plants that do not tolerate the content of calcium salts in the soil - calcium-phobes. For example, a tea bush, whose culture is not possible in Central Asia due to the carbonate content of soils.

• In conditions of dry and hot climate in soils, an excess of salts of sulfuric or hydrochloric acids in the form of sodium sulfate, magnesium, calcium or sodium chloride, magnesium, etc. is often created. Saline soils are widespread in the famine steppe and Karakalpakia

• On saline soils, most plants can not inhabit, but there is a special, ecological group of salt-tolerant species or halophytes.

• A plant of wet solonchaks –• salters (Salicornia europea)

• They are representatives of the Chenopodiaceae family and a number of other families. Halophilic vegetation not only indicates the presence in the soil of salts of sodium, magnesium, etc., but makes it possible to some extent to judge both the nature and the degree of salinity.

• Xerophilous species forming xerophilousvegetation testify to the dryness of the soils on which they grow. Hygrophilous vegetation indicates the presence of constant moistening of the soil. Plant species indicating the existence of certain environmental conditions are called plant indicators. The presence of certain indicator plants sometimes directly indicates the presence in the soil of copper, manganese, zinc, uranium, nickel and other elements.

•••

• Biotic factors are understood as the effect on plants of living organisms (plants, animals, insects). In soils, for example, there is a huge number of niche plants (fungi, algae, bacteria), as well as protozoa, the influence of which on the plant is very diverse. It is known that in the humus-rich soils - chernozems, the total mass of microorganisms reaches 100-150 tons per 1 ha. Many soil microorganisms are useful (mycorrhizal fungi, nitrogen-fixing bacteria).

• However, there are many fungi and bacteria parasitizing the body of higher plants and causing them huge damage. There are also higher plants parasitizing other representatives of the plant kingdom (pest and broomrape), many parasitic lianas in the tropical forests.

• The plant is a parasite • of the Cistanhi in the• sands of Kyzylkum in• the vicinity of the • Tamdy settlement.• parasitizes on specie • of the genus Artemisia, • and Callygonum

• Root parasites• of plants• Cynomorium• songaricum••

Parasit Cuscuta on steam living plant

• In addition, in nature there is a continuous competition between individual plant species. Stronger suppresses weaker ones and are winners in the struggle for light, moisture, food.

• Weeds are often more competitive and can suppress cultivated plants. Therefore, we are fighting with weeds

•

• The influence of man on the surrounding nature is very great and multifaceted. The prolonged impact of anthropogenic factors has unknowably changed the face of the vast territories of the globe. For example, as a result of the plowing of soils, steppe vegetation in the south of Russia and Ukraine was destroyed almost completely, and its place was taken by crops of agricultural crops.

• The same applies to the huge virgin massifs of Western Siberia and Kazakhstan. Many thousands of hectares of the Golodnaya, Karshi and Sherabad steppes, as a result of development and irrigation, replacing the meager xerophilic natural vegetation, came cotton crops, alfalfa, orchards and vineyards

• The land area of Uzbekistan covers an area of 44,410.3 thousand hectares.

• Of these: hayfields and pastures 20,750.4 thousand hectares. The total number of heads of cattle10141.3 thousand, sheep and goats 16187 thousand heads, horses-195192 heads. The law of the Republic defines the rate of grazing for one head of cattle with extensive technology, one hectare is required conditionally.

• There are many species of plants known to pollute only certain types of insects (yucca, figs, clover). Significant impact on the plant and various animals - shrews. For example, earthworms are an important factor in soil formation, others - through their underground passages contribute to the penetration of plant roots deep into the soil, others - gnaw roots, causing significant harm to plants.

• However, of all biotic factors, the most powerful influence on the plant cover of our planet is provided by man. Therefore, human influence on the plant world is usually allocated to an independent group of factors called anthropogenic

• Man on a large scale carries out the movement of plants he needs from one area to another. So, from America brought to Europe and Asia such famous cultures as potatoes, tobacco, sunflower, corn and many others.

• Often, with cultivated plants, weeds are also added to new places. For example, from Europe to America were plantain, mullein, thistle and others. In the rice fields of Uzbekistan, there are some weeds of tropical origin that are brought in with the rice culture.

• .

• On a large scale, deforestation is carried out on the globe and many areas in the Mediterranean countries are now almost totally devoid of forests that once covered the mountain slopes.

• To a large extent, the forests were thinned even in remote places such as Central America or the interior regions of South America.

• Thus, a powerful anthropogenic impact on the natural vegetation cover, is strengthened from year to year, which forces to pay the most serious attention to the protection of rare and endangered plants.

• According to the latest data of the International Union for Conservation of Nature, more than 20 hectares of natural habitats are destroyed on the ground every minute. Today, 25,000 species of wild plants are on the verge of extinction. All this once again shows how powerful is the impact of the anthropogenic factor on plants and their communities

• Plants inhabiting different natural conditions in the process of evolution have developed various adaptations to specific conditions of existence.

•• These adaptations of species to certain

factors of the environment led to the emergence of certain life forms of plants

• Under the concept of life form is understood by groups of plants that are similar in form to growth, the rhythm of development and ecology, or both in combination. For the first time, life forms were described by A. Humboldt (1806). Not only different species can belong to the same life form, but also representatives of different genera and families.

• They are united by their adaptability to certain environmental conditions, which entails similarity in appearance, rhythm of development and physiological characteristics. At the same time, within the same family or even gender, there may be representatives of various life forms.

• The classification of plant life forms is a lot (A. Humboldt, A. Grizebach, IG Serebryakov, A. Raunkier and others)

• They are united by their adaptability to certain environmental conditions, which entails similarity in appearance, rhythm of development and physiological characteristics. At the same time, within the same family or even gender, there may be representatives of various life forms.

• The classification of plant life forms is a lot (A. Humboldt, A. Grizebach, IG Serebryakov, A. Raunkier and others)

• Based on external signs, life forms can be the following: trees, shrubs, semi-shrubs, perennial grasses, biennial grasses, annual grasses.

• Long-term exposure to plants of a combination of environmental factors led to the appearance within the species of certain forms, adapted to existence in specific conditions

• Similar groups of species or race species, distinguished by their hereditarily fixed biological and structural features and adapted to certain soil and climatic

• conditions, are called ecotypes• Ecotypes arose under the influence of

environmental factors and can change in detail in connection with changes in the external situation.

• Ecotypes are characteristic of many plant species that live in different conditions. For example, archa Turkistan in the middle belt of the south of Uzbekistan grows in the form of a tree, and in the highlands it is represented by bushes of a creeping shape. In the hedgehogs of the national team, wild alfalfa and other herbaceous plants, two ecotypes are well pronounced: tall and powerful-chopped plaster-pasture.

• Ecotypes exist not only in wild plants. They are also known for cultural - agro-ecotypes. The latter also arose under the influence of the climate and soil characteristics of the area, as well as the characteristics of agricultural crops.

• QUESTIONS FOR SELF-CONTROL:•

• What groups of plants do you know about soil moisture?• What is the difference between xerophytes and

hygrophytes?• What are eutrophic and oligotrophic plants?• Why can not an even thea bush grow in Uzbekistan?• What are halophytes?• Can you tell us about the importance of microorganisms for

the soil?• Give examples of biotic factors?• Give examples of anthropogenic factors?•• THANK YOU FOR ATTENTION••