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Combined lesson:
Knowledge test: Independent work on the studied topic: "Families of plants of the monocotyledonous class." We prepare and sign the leaflets!
And their effects on plants Environmental environmental factors Study of a new topic:
The purpose of the lesson: 1. Get acquainted with the Factors of the environment. 2. Find out their influence on living organisms (plants). 3. Get to know how plants are classified into groups with respect to abiotic environmental factors.
ECOLOGY The science that studies the patterns of life of living organisms (in any of its manifestations at all levels of organization) in their natural habitat, taking into account changes introduced into the environment by human activity. And the mutual influence of the environment and organisms on each other.
Learning new material
Environmental factors are called: Conditions of organic and inorganic nature, directly or indirectly affecting the state and properties of an organism, population, natural community.
Environmental environmental factors Abiotic Biotic Anthropogenic Factors of non-living nature Factors of living nature Factors of human activity
1. Light 2. Pressure 3. Humidity 4. Radiation: a) Ultra-violet b) infrared c) radioactive d) Electro-magnetic, etc. 5. Minerals. 6. Chemical substances. 7. t *(temperature) Abiotic Factors of non-living nature Biotic Factors of living nature Anthropogenic Factors of human activity 1. Animals 2. Plants 3. Fungi 4. Bacteria 5. Viruses a) Direct b) Indirect (indirect)
In relation to light: plants are subdivided…. Light-loving Shade-loving Shade-tolerant
Heat-loving In relation to temperature: plants are ... .. Cold-resistant
Plants in Excessively Moistened Habitats Effects of Moisture on Plants: Plants in Dry Habitats Plants Living in Average (Sufficient) Moisture Conditions
Moisture-loving In relation to moisture: Drought-resistant
Animals Biotic environmental factors Fungi Bacteria
Direct impact Anthropogenic environmental factors Not direct impact
Think! List the ones you know abiotic factors environments and their meanings. What groups are plants divided into regarding: A) Light B) Moisture C) Temperature Fixing the material:
A/C $ 54-55 questions Give examples of each type of environmental factor and its effects on plants
Performed:1st year student,
groups BGOm-117,
Alekseeva Irina The environment of a plant is made up of many
various elements that affect the body.
Individual elements of the external environment are
Name environmental factors.
Environmental factors are the properties of the environment
habitats that have any impact
on the body. Habitat (ecological
niche)
-
totality
concrete
abiotic
And
biotic conditions in which
a given individual lives
or
view,
Part
nature,
surrounding living organisms and
exerting direct or
indirect impact. By the nature of the impact
distinguish:
direct acting (light,
water, mineral elements
nutrition)
indirectly acting
environmental factors (factors,
influencing
on
organism
indirectly through change
direct acting
factors
such as relief). By origin, they distinguish:
1. Abiotic factors - factors
inanimate nature:
a) climatic - light, heat, moisture,
composition and movement of air;
b) edaphic - diverse
chemical and physical properties
soil;
c) topographic (orographic) factors determined by relief.
2. Biotic factors of mutual influence of cohabiting
organisms.
3. Anthropogenic factors of influence on human plants. All living organisms are affected in one way or another.
phenomena and components of inanimate nature. That's what it is
abiotic factors affecting life
humans, plants, animals. They, in turn,
divided into edaphic, climatic,
chemical, hydrographic, pyrogenic,
orographic. Light mode, humidity, temperature, atmospheric
pressure and precipitation, solar radiation, wind can be attributed to
climatic factors.
Edaphic influence living organisms through thermal,
air and water regime of the soil, its chemical composition And
mechanical structure, groundwater level, acidity.
Chemical factors are the salt composition of water, the gas composition
atmosphere.
Pyrogenic - the effect of fire on the environment.
Living organisms are forced to adapt to the terrain
(orographic) terrain, elevation differences, as well as to
features of water (hodrographic), content in it
organic and mineral substances. Light is very important for plants. Its quantity influences appearance And
internal structure. For example, forest trees that have enough
lights grow tall, have a less spreading crown. The same,
who are in their shadow, develop worse, are more oppressed. Their
the crowns are more spreading, and the leaves are arranged horizontally. This
needed to capture as much sunlight as possible. There,
where the sun is sufficient, the leaves are arranged vertically to
avoid overheating.
Light-loving =
heliophytes
birch
Shade-loving =
sciophytes
Shade tolerant =
optional
heliophytes
fern
forest herbs,
shrubs,
majority
meadow plants
wheat
oxalis Abiotic environmental factors
epistion
monstera
leaf pubescence
(reflects rays, saves from
overheating)
Decrease (or
magnification) of the surface
leaves, which increases
(or reduce)
cooling evaporation
Different intensity
fumes and other
the number of stomata
sheet Plants that grow in hot, arid climates
for example, the desert has a powerful root system,
to be able to get water. For example, shrubs
belonging to the genus juzgun, have a 30-meter
roots going deep into the earth. But cacti have roots
deep, but widely spread below the surface
soil. They collect water from a large surface of the soil during
time of rare, short rains. collected
water
necessary
save.
That's why
some
plants - succulents
time conserve moisture in
leaves,
branches,
trunks.
Among the green inhabitants of the desert
there are those who have learned
survive even with many years
drought. Some who have
the name of the ephemera, live in total
some
days.
Their
seeds
sprout, bloom and bear fruit
as soon as it rains. At that time
the desert looks very beautiful - it
blooms.
But lichens, some club mosses and
ferns,
may
live
V
dehydrated for a long time
time until rare
rain.
Crassula
Aizovye The tundra has a very harsh climate, summer
short, you can’t call it warm, but
frosts last from 8 to 10 months. Snow
the cover is insignificant, and the wind is completely
bare plants. Flora representatives
usually have a superficial root
system, thick skin of leaves with waxy
raid. Required supply of nutrients
plants accumulate substances during the period
when the polar day lasts. Tundra
trees produce seeds that germinate
only once every 100 years during the most
favorable conditions. And here are the lichens
mosses
adapted
multiply
vegetatively. Abiotic environmental factors
Plant groups in relation to water
average
low
partly high
humidity humidity humidity
in water
in water
hydatophytes
hydrophytes
hygrophytes
mesophytes
xerophytes
water lily
marigold
cattail
dandelion
camel-thorn Abiotic environmental factors
Plant adaptations to drought
camel
thorn
kalanchoe
cactus
aloe
Powerfully developed Waxy Reduced water storage
root
cuticle on leafy
in stem or
system
leaves
records
leaves microorganisms that decompose
plant residues enrich the soil
humus and minerals.
In turn, plants influence
environment. They change composition
air: moisturize it, absorb
carbon dioxide and release oxygen.
Plants change the composition of the soil. They
absorb some substances from it and
allocate others to it. Root systems
plants fix the slopes of ravines,
hills, river valleys, protecting the soil
from destruction. Forest plantations protect
dry wind fields. Plants that evaporate
a lot of moisture, such as eucalyptus, can
be used to drain
wetlands. Anthropogenic environmental factor -
This
change
conditions
life of organisms in connection
with human activity. Actions
can be both conscious and
unconscious. However, they
lead to irreversible changes in
nature.
Anthropogenic
factors
can be divided into four main
subgroups: biological, chemical,
social and physical. All of them are in
to varying degrees affect
animals, plants, microorganisms,
contribute to the emergence of new species and
wipe the old ones off the face of the earth. Human influence on plants
Some human actions affect the environment, and
that means plants. For example, forest fires, road construction,
transport, industrial enterprises, radiation in the atmosphere. All these
factors to a greater or lesser extent inhibit the growth, development
plants.
Chemical compounds emitted into the atmosphere by the pipes of factories,
power plants, vehicle exhaust gases, residues
oil products entering the soil and water, excessively pollute
ecological environment, which negatively affects the development of plants.
Many substances act on them like poison, leading to extinction.
many types of green inhabitants. Other harmful substances
cause mutations that can only be assessed after some
time. Most often, pollution of nature, poor ecology leads to He brings out new highly productive and
disease-resistant plant varieties.
Man fights weeds and promotes
distribution of valuable plants.
But human activity can cause
harm to nature. Yes, improper irrigation
causes waterlogging and salinization of soils and
often leads to the death of plants. Because of
deforestation destroys the fertile layer
soils and even deserts can form.
There are many such examples, and
all of which indicate that the
has a huge impact on plant
the world and nature in general.
We do not live in a vacuum. We have to interact with the environment every time. We interact with the atmosphere, temperature, humidity, other people, animals. And all this cannot but affect us. When it's too hot, you can get heatstroke, if a person standing next to you has the flu, then we are also very likely to get infected. Also, life, the appearance of plants directly depend on environment. We will learn exactly how in this lesson.
Ecology is the science of the relationship of living organisms and their communities with each other and with the environment.
Environmental factor - a phenomenon or object that affects the body.
Environmental factors:
Ecological niche - a set of conditions necessary for existence a certain kind. Any living organism is able to exist only under certain values of environmental factors.
Sunlight serves as a source of energy for plants, as it is necessary for photosynthesis (see Fig. 1). Light also has a regulatory effect on plant growth, flowering, fruiting.
Rice. 1. Photosynthesis
For timothy and strawberries, light is necessary for seed germination.
Plants in relation to light:
- Light-loving (heliophytes). Able to grow only on brightly lit surfaces (feather grass, wheat, pine, Robinia).
- Shade-loving (sciophytes). They can only grow in shady places. In the bright sun, burns (crow's eye, anemone) may appear.
Shade-tolerant. They grow well in lighted places, but they can also tolerate slight shading (linden, oak, ash).
Both overheating and too low temperatures are detrimental to any plants. Too high temperatures lead to loss of moisture, burns, destruction of chlorophyll.
action high temperatures heliophytes are susceptible, in connection with this they have a number of adaptations: they can turn the leaves, shed the leaf blade, leaving only the petiole, the leaves are turned into spines (cacti). Reducing the area of the leaf blade helps heliophytes avoid excessive evaporation of water. Dense white pubescence or silver color of the leaves help the plant reflect most of the rays falling on it.
When water freezes, ice crystals form in the cells, which damage them. When the temperature drops to minus values chemical processes slow down in the cell, an imbalance occurs that can lead to death.
The appearance of plants in cold habitats: evergreen, with small hard foliage, low (do not exceed the height of the snow cover) ( dwarf birch, willow).
Many plants for dry and cold periods can fall into a dormant state when all life processes are slowed down. In woody plants, the shoots of this year become woody and the thickness of the cork layer increases. herbaceous plants lose all above-ground organs. Shrubs and trees shed their leaves. Aquatic plants sink to the bottom (duckweed), retain only bottom leaves (water lily).
Sclerophytes - plants of arid habitats (cornflower false-spotted (see Fig. 2)). They have tough leaves.
Rice. 2. Cornflower false-spotted
Succulents are plants of arid habitats that are able to store moisture in the fleshy formations of the body - stems, leaves (aloe (see Fig. 3), cacti).
Rice. 3. Aloe
Plants in relation to humidity
- Aquatic plants and plants that live in conditions of excess moisture
- Plants of dry habitats
- Habitat plants with normal moisture
The chemical composition of the soil
Plants get minerals from the soil. Most of all they need compounds of phosphorus, nitrogen, potassium. They also need compounds of boron, manganese and iron.
Animals feed on plants, so plants have protective devices: needles, thorns (acacia), hard foliage (steppe plants), poisons (nightshade plants).
Other animals enter into mutualistic relations with plants: bees, butterflies, pollinate plants. Birds spread their seeds by eating delicious berries.
Mutualism is a mutually beneficial relationship between 2 organisms.
Large plants shade smaller ones, so there is a division into tiers. Epiphytic plants (orchids) can use others as support.
Plants are involved in maintaining the constancy of the composition of the air (they release oxygen and absorb carbon dioxide).
They take part in the formation of soils (root systems absorb some substances and release others). After the plant dies, most of the substances return to the soil.
The roots of plants fix the slopes of hills, ravines, protect the soil from erosion (destruction).
Forest plantations (see Fig. 4) are used to protect fields from dry winds and fires.
Rice. 4. Forest plantations
Large woody plants, evaporating a large number of moisture. Can be used to drain wetlands (eucalyptus).
People cut down forests, drain swamps, irrigate arid lands. This destroys natural habitats and creates conditions for agricultural crops. New varieties of plants are being developed.
Deforestation can lead to the loss of fertile soil and the formation of deserts. In case of illiterate irrigation, waterlogging of the soil can occur.
In 3 identical pots with the same soil, plant 3 coleus. Grow them for a month different conditions: one in bright light and with additional illumination, the second - in normal daylight, the third - in partial shade - 3 meters from the window. Watch the growth and development of plants. Try to draw conclusions.
Schematically sketch the shape of the crowns of trees (birch, linden, pine) that have grown in different lighting conditions. Draw your own conclusions.
An extreme form of adaptation of plants to extreme environmental conditions (cold, dryness, heat) is suspended animation.
Anabiosis is a state of the body in which traces of vital activity are so small that there are no visible signs of life.
So, mosses endure winter freezing or complete drying in a state of suspended animation, from which they return to normal life after thawing or rain.
Bibliography
- Biology. Bacteria, fungi, plants. Grade 6: textbook. for general education institutions / V.V. Beekeeper. - 14th ed., stereotype. - M.: Bustard, 2011. - 304 p.: ill.
- Tikhonova E.T., Romanova N.I. Biology, 6. - M.: Russian word.
- Isaeva T.A., Romanova N.I. Biology, 6. - M.: Russian word.
- Biolicey2vrn.ucoz.ru ().
- Rae.ru().
- Travinushka.ru ().
Homework
- Biology. Bacteria, fungi, plants. Grade 6: textbook. for general education institutions / V.V. Beekeeper. - 14th ed., stereotype. - M.: Bustard, 2011. - 304 p.: ill. - With. 263, tasks and question 5, 6, 7 (.
- What are the groups of plants in relation to light. Describe them.
- What are the environmental factors? Describe them.
- * Choose 2 plants different types and assign them to ecological groups in relation to light, humidity, temperature.
lesson type - combined
Methods: partially exploratory, problem presentation, reproductive, explanatory-illustrative.
Target:
Students' awareness of the significance of all the issues discussed, the ability to build their relationship with nature and society based on respect for life, for all living things as a unique and priceless part of the biosphere;
Tasks:
Educational: to show the multiplicity of factors acting on organisms in nature, the relativity of the concept of "harmful and beneficial factors", the diversity of life on planet Earth and the options for adapting living beings to the entire range of environmental conditions.
Developing: develop communication skills, the ability to independently acquire knowledge and stimulate their cognitive activity; the ability to analyze information, highlight the main thing in the studied material.
Educational:
To cultivate a culture of behavior in nature, the qualities of a tolerant person, to instill interest and love for wildlife, to form a stable positive attitude towards every living organism on Earth, to form the ability to see beauty.
Personal: cognitive interest in ecology. Understanding the need to gain knowledge about the diversity of biotic relationships in natural communities in order to preserve natural biocenoses. The ability to choose the target and semantic settings in their actions and deeds in relation to wildlife. The need for fair evaluation of one's own work and the work of classmates
cognitive: ability to work with various sources information, convert it from one form to another, compare and analyze information, draw conclusions, prepare messages and presentations.
Regulatory: the ability to organize independently the execution of tasks, evaluate the correctness of the work, reflection of their activities.
Communicative: participate in the dialogue in the classroom; answer questions from a teacher, classmates, speak to an audience using multimedia equipment or other means of demonstration
Planned results
Subject: know - the concepts of "habitat", "ecology", "environmental factors" their influence on living organisms, "connections of living and non-living";. Be able to - define the concept of "biotic factors"; characterize biotic factors, give examples.
Personal: make judgments, search and select information; analyze connections, compare, find an answer to a problematic question
Metasubject: links with such academic disciplines like biology, chemistry, physics, geography. Plan actions with a set goal; find necessary information in the textbook and reference literature; to carry out the analysis of objects of nature; draw conclusions; formulate your own opinion.
Form of organization learning activities - individual, group
Teaching methods: visual and illustrative, explanatory and illustrative, partially exploratory, independent work with additional literature and textbook, with DER.
Receptions: analysis, synthesis, conclusion, transfer of information from one type to another, generalization.
Learning new material
Anthropogenic impact on vegetable world.
The role of plants in the Earth's biosphere is enormous due to their ability to carry out photosynthesis. Vegetation affects all components of the biosphere: the atmosphere, hydrosphere, soil, wildlife. The role of plants in human life is also great.
The entire history of mankind is the history of its impact on forests. Deforestation was carried out to make room for the construction of cities, enterprises, agricultural land, in connection with the use of wood in various industries industry ( construction material, alcohol, cellulose, etc.), in transport.
When cutting down forests, a person did not think about the possible environmental consequences. The UN documents define the rate of deforestation of tropical forests: about 11-12 million hectares per year (or 14-20 hectares / min); on a global scale, felling exceeds the growth of wood by 18 times.
Let's remember what is the role of forests in our life. The forest regulates the gas regime (composition) of the atmosphere (this is the “factory” of oxygen, the “lungs” of the Planet), protects soils from destruction, regulates river flow, creates favorable environment life for animals and humans, etc. Cutting down forests on the slopes, we cause the formation of ravines, intensive soil erosion. Nevertheless, despite the huge role of forests in life on Earth, they are intensively cut down.
Currently, about 3.8 billion hectares, or 30% of the land, are covered with forests in the world. In Russia, forests occupy 42% of the territory. In our country, the following main types of forests are distinguished:
coniferous (spruce, pine, fir, cedar, larch);
broad-leaved and mixed (main species: oak, linden, elm; in the northern regions, spruce, fir, pine are mixed with broad-leaved species);
small-leaved (birch, alder, aspen);
floodplain (poplar, willow, black alder).
Some countries of the world are very careful about their forest reserves; for example, Japan does not reduce its forests at all, it imports wood from the countries of Southeast Asia.
Red Books are created to register and take emergency measures to preserve rare and endangered species of animals and plants. This work has been going on all over the world since the 1960s. In 1988, the Red Book of the RSFSR (plants) was published, which lists 533 species and subspecies of plants, of which 440 are angiosperms, 11 are gymnosperms, 10 are ferns, 4 are lycopsids, 22 are bryophytes, 29 are lichens, 17 - mushrooms.
Desertification is a serious environmental problem today.
Deserts have existed on Earth since prehistoric times. And today, according to various estimates, natural deserts occupy 8 million km - primarily within the arid belt, covering approximately 1/3 of the land surface.
The concept of "desertification" today is considered as a synonym for the concepts of "devastation" of the land, "degradation" of land in arid areas, occurring mainly under the influence of man. It should be emphasized that the desert, especially sandy, is far from empty place, this is a zonal type of landscape, where, due to a lack of moisture, peculiar soil-vegetation cover and fauna have formed, well adapted to existence in arid (arid) conditions.
Desertification is intensifying due to the secondary salinization of the territory. It is known that in dry climates surface water are saline with easily soluble salts of sodium, calcium, magnesium, chlorine, etc. Secondary salinization is caused by the rise of highly mineralized groundwater to the surface. This rise is usually due to non-compliance with the norms of irrigation of fields, a network of channels that conduct water to the fields. "Excess" water, rising to the surface, intensively evaporating, salts the upper horizon with the salts contained in it. The concentration of salts in such a soil solution can be 100 times greater than in the water used for irrigation.
The main factor modern process desertification is, first of all, the activity of the person himself, which leads to a fall, or even complete destruction of the biological potential of the territory, imbalance of existing ecosystems. Among the anthropogenic causes, first of all, it is necessary to note overgrazing, deforestation, as well as excessive and improper exploitation of cultivated lands (monoculture, plowing of virgin lands, cultivation of slopes, etc.).
Today, another 30-40 million km are under the threat of desertification2 within over 60 countries.
In 1977, the International Conference of the United Nations in Nairobi adopted the “Plan to Combat Desertification”, which concerns primarily developing countries. However, it was not fully implemented due to various reasons, and primarily due to an acute shortage of funds.
The amount of land per inhabitant of the planet is continuously decreasing: a lot of land is being lost due to urbanization, the construction of reservoirs, the development of adverse processes - erosion (soil washout) with salinization, deflation (blowing and destruction of soils), desert growth.
It is calculated that the amount of land that will fall on one person in 2000 will be reduced by half compared to 1975
(from 0.31 to 0.15 ha).
I wonder how much land a person needs to provide for his life? By
according to the prominent soil scientist V. A. Kovda (b. 1904), such land requires about 0.5 hectares: 0.4 hectares for food production and 0.1 hectares for other needs (housing, communications, etc. .). Scientists believe that humanity for the entire historical period lost about 450 million hectares, while 6-7 million hectares of land are lost annually.
Questions and tasks
1. What is the importance of plants in nature and human life?
2. How does a person affect the plant world?
3. What is the environmental problem of desertification?
4. On the basis of reference data, give examples of species (subspecies) of plants in your region, listed in the Red Book of Russia.
Human influence on flora and fauna
The impact of humanity on the ecosystems of the planet
Resources:
S. V. Alekseev. Ecology: Tutorial for students of the 9th grade of educational institutions of various types. SMIO Press, 1997. - 320 p.
Presentation Hosting
Environmental factors and their impact on plants
As you studied botany, you learned that rainforest and tundra plants, forests and grasslands are different, even if they belong to the same species. When caring for cultivated plants, you have noticed that some crops are especially demanding on moisture, while others need bright lighting. You know that weeds are difficult to control, as they form many seeds that ripen earlier than the seeds. cultivated plants. Many weeds have long rhizomes with which they multiply rapidly. Plants are adapted to certain conditions, environmental conditions.
Let's remember what ecology and environmental factors are.
Habitat and environmental factors. All nature surrounding plant, is his habitat . It has all the conditions necessary for growth and development this plant but in different quantities and ratios. Factors (conditions) of the external environment can directly affect the plant, they are necessary for the existence of the organism, but the plant is not required. Factors such as light, moisture in the air and in the soil, temperature, the presence and concentration of salts in the soil, wind and some others affect the plant.
environmental factors any element of the environment that can have a direct or indirect effect on the body is called.
Find out how environmental factors can affect plants. An environmental factor can limit plant growth. For example, if the soil contains a small amount of mineral salts, and a crop is cultivated on it from year to year, then the salt reserves are exhausted and plant growth stops. If the environmental factor is below the critical level or, conversely, exceeds the maximum possible level, it becomes a plant growth limiter, even if other factors are present in required quantity. This environmental factor is called limiting factor . In the aquatic environment, oxygen is most often the limiting factor. For plants that love the sun (sunflower) - light. Moreover, not only the intensity of lighting is important, but also the duration.
At different stages of development, the plant reacts differently to environmental factors. It is known that the most resistant to too high or too low temperatures are the buds of higher plants, seeds, spores.
All factors together determine the conditions for the existence of plants, orliving conditions . It is clear that the living conditions in the Far North and in the steppe zone, in the forest and in the meadow are different. But habitat conditions change seasonally and even during the day. Plants, like all living organisms, have an amazing ability to respond to changes and adapt to environmental conditions.
Adaptation of plants to dry and hot habitats. In arid and hot habitats, plants must be able to extract water, store it, avoid excessive evaporation, but also not “overheat” in the sun.
Plants with powerful root systems live in semi-deserts and deserts. Some root systems are very deep, which allows them to use ground water. So in the bushesclan Juzgun roots go as deep as 30 m. In other plants (cacti) the root system is shallow, but widely overgrown, so during rare rains they quickly absorb moisture from large areas.
The third group of plants (for example, Tatar rhubarb ) does not have a highly developed root system, but they are able to absorb morning dew with their large leaves, spread over the surface of the earth.
These plants tend to have thick skins and very few stomata. They slow down the process of metabolism and as a result - growth.
Shrubs with a deep root system do not accumulate water, but retain it. To reduce evaporation, their small leaves are densely hairy. Often there are no leaves at all, and photosynthesis occurs in shoots that look like twigs or thorns.(saxaul). With a lack of water, a few stomatal gaps close.
In addition to adaptations for the absorption and conservation of water, desert plants have the ability to tolerate even long-term drought. Among them - ephemera - plants completing their life cycle from seed to seed within a few days. Their seeds germinate, and the plants bloom and bear fruit immediately after the rain falls. At this time, the desert is transformed - it blooms.
These plants survive a long period of drought in the seed stage.
Perennial bulbous or rhizomatous plants survive drought in the form of underground storage organs.
In the most amazing way, lichens survive a long drought, many lower plants, some species of club mosses and ferns, even a few flowering plants: they lose all moisture and, being completely dehydrated, are dormant until rain falls.
Plant adaptations to cold weather wet conditions a habitat.The living conditions of plants in the tundra are very harsh. First of all, it is temperature. Average monthly summer temperatures rarely exceed +10 °C. Summer is very short - about two months, but even in summer frosts can occur.
There is little precipitation in the tundra, respectively, and the snow cover is small - up to 50 cm. Therefore, they are dangerous strong winds- they can blow away the snow that protects the plants. Why is there a lot of moisture in the tundra? First, it does not evaporate as intensely as in warmer zones. Secondly, water does not go deep into the soil, as it is retained by a layer of permafrost. Therefore, there are many small lakes and swamps.
Plants in this zone are usually stunted and covered with snow in winter, which protects them from cold and wind. Root systems are superficial. On the one hand, their development is hindered by permafrost, on the other hand, high humidity soil and, as a result, a lack of oxygen in the soil. It is interesting that the structural features of the shoots resemble plants of a hot climate, only they protect not from heat, but from cold. This is a thick skin, wax coating, cork on the stem. Plants should have time to bloom and produce seeds in a short summer.
Tundra trees only once a century produce seeds that can germinate. Seeds fully ripen only when the summer is warm for the tundra for two years in a row. As a rule, tree seeds fall into conditions unsuitable for germination. Many tundra plants reproduce vegetatively, such as mosses and lichens.
Light as an environmental factor. The amount of light that a plant receives affects its appearance, and on the internal structure. Trees grown in the forest have taller trunks and a less spreading crown. If they grew under the canopy of other trees, then they are oppressed and much worse developed than their peers in the open space.
Shade and light plants can also differ in the arrangement of leaf blades in space. In the shade, the leaves are arranged horizontally to capture as much as possible. sun rays. In the light, where there is enough light - vertically to avoid overheating.
Shade-grown plants have larger leaves and longer internodes than sun-grown plants of the same or similar species.
Leaves are not the same internal structure: in the light leaves, the columnar tissue is better developed than in the shadow ones. In the stems of light plants, more powerful mechanical tissue and wood.
Interactive lesson simulator. (Complete all the tasks of the lesson)
Audio fragment "Environmental factors" (4:33)
ABOUTnature circling the body -this is his habitat. science, studythe relationship of organismswith each other and with the environment,called ecology. influence the plantyat environmental environmental factors:light, temperature, humidity, wind,soil composition, etc. All factors necessaryplants that are used for lifeliving conditions. Excess orlack of one or morelogical factors affectthe structure of the body. Plants fitsuccumb to living conditions incertain boundaries.
The environmental factoris below the critical levelor, conversely, exceeds the maxihardly possible for a plantvein, called limitingfactor .