Excursion "natural biogeocenoses". Excursion "diversity of species in native nature" Excursion diversity of species
Excursion No. 1 . Diversity of species in native nature.Seasonal changes (rhythms) in living nature.
Tour objectives:
1. introduce the concept of diversity of species as a result of natural selection.
2. introduce the concepts of “species criteria”, “population”, “variability”, “heredity”.
3. identify different relationships between individuals of the same species and different species.
4. show, using specific examples, the adaptability of organisms to endure unfavorable conditions in the autumn.
5. teach to work collectively, develop a sense of respect for nature, a sense of beauty, and the ability to see the beauty of nature.
6. develop interest in biology, the ability to observe, compare, establish cause-and-effect relationships, highlight the main thing, and draw conclusions.
Excursion plan:
Organizing time.
Conversation, frontal observation.
Group assignments.
Summarizing. Closing conversation.
Progress of the excursion.
Group assignments, the composition of the groups is determined in class, in the previous lesson. At the beginning of the excursion, I check the composition of the groups and provide instructions on behavior during the excursion. While moving, students name the types of trees of the first tier, the second tier, herbaceous plants, and types of shrubs. I draw attention to the fact that students give the correct (double) species names. I draw the students’ attention to the fact that in a small area of the forest, plants of different species grow. I formulate the main question: “What are the reasons for the diversity of species?” This is the main question of our excursion. Then I invite students to find out how species, for example of the same genus, (American maple, Tatarian maple) differ from each other. To clarify the concept of “species”, we use plants of similar species; this works well on plants such as caustic buttercup, creeping buttercup, and Kashubian. We compare the conditions of their growth and note that the peculiarities of the existence of the species constitute an ecological criterion. Next we study their appearance. We determine similar characteristics and their differences in the structure of the flower and leaves. Let's draw conclusions. I inform students that structural features constitute the morphological criterion of a species. During the conversation, we find out that these plants have different flowering periods. We see the caustic buttercup blooming. Kashubian buttercup blooms at the end of May, and creeping buttercup in July. . We conclude that plants of different species differ in terms of flowering, growth and development rates. We note that the characteristics of the response of organisms of the same species to changes in living conditions constitute the physiological criterion of the species. Conclusion: all species differ from each other in morphological, ecological, and physiological characteristics.
Let's move on. We went out into a clearing where there were a lot of caustic buttercups. Have you ever seen caustic buttercup in the forest? No. Where else have we seen this plant? We remember that when we entered the forest, we saw this plant in that clearing. Does buttercup pollen travel from one clearing to another? Silence. During the conversation, we find out that this is unlikely, because the clearings are located far from each other. This means that these plants live separately from each other. We introduce the concept"population". A group of individuals of the same species that exists for a long time in a certain territory separately from other such groups is called a population. Warty birch, Tatarian maple, pedunculate oak, growing in our forest, also represent populations of species. A population is a form of existence of a species. A population is stable if it contains individuals of different ages. Assignment: find individuals of different ages in the Tatarian maple population. Students do this with great pleasure. Next, I propose to consider 2-3 individuals of warty birch. Find similarities. There are many common signs. What is the reason for their similarity? They are closely related, because belong to the same population. The set of basic characteristics is transmitted from parents to offspring. All living organisms tend to preserve and transmit their characteristics and properties to their offspring. This property is heredity. It is this property that determines the similarity of closely related organisms. Then I propose to find differences in these individuals. Conclusion: all individuals, even in the same population, differ from each other, which means that organisms are characterized by variability. Let me explain that variability manifests itself in varying degrees of development of certain characteristics, for example, color intensity, body size, etc. Changes in these characteristics occur under the influence of environmental conditions. We draw attention to the differences in the color of the leaves of the common pine tree, which grows in open areas and in the forest. The second leaves are darker and produce more chlorophyll. Thanks to this feature, the synthesis of organic substances in plants in the forest in low light conditions occurs quite intensively. But these changes are not inherited. This is an example of non-heritable variation. Only such changes in characteristics are transmitted by inheritance, the development of which is caused by changes in the hereditary material. It is hereditary variability that causes the emergence of new characteristics, which are the material for natural selection and a prerequisite for the formation of new species. Next, we draw attention to the huge variety of living organisms that inhabit the forest. Students try to establish what relationships exist between them. Charles Darwin called the totality of all relationships the struggle for existence. As the excursion progresses, we find herbaceous plants and count the number of seeds (fruits) on them. Will all these seeds grow into adult plants? Of course not. Why? If all the seeds fall off in this place and germinate, then in the dense shoots between the seedlings there will be an intense struggle for existence - for moisture, nutrients, light. Charles Darwin called this kind of struggle intraspecific. Then we pay attention to some oppressed plants of poplar, warty birch, and Tatarian maple. Why are they like this? C. Darwin argued that complex relationships are also established between organisms of different species. This is an interspecies struggle for existence. Plants also begin to fight unfavorable environmental conditions. Many organisms die from severe frosts, fires, heavy rain, and sometimes humans are to blame. In the struggle for existence in a population of plants (animals), natural selection occurs: some individuals die, while others survive, produce viable offspring, and are characterized by high adaptability to new environmental conditions. I invite students to establish signs of adaptation of plants and animals to living conditions. The guys are working. Next, we study what adaptations plants have to endure unfavorable conditions in the autumn-winter period. I draw attention to the beauty of the autumn forest. Students then work in groups to complete assignments.
Tasks:
Types of trees
Types of shrubs
Types of herbs
Species name
Morphological characteristics
Physiological signs
Ecological signs
Tasks:
1. Make a description of the site: relief, illumination, weather conditions.
2. Identify the main types of trees, shrubs, grasses and identify their adaptability to living together. Enter the results into the table.
Types of trees
Types of shrubs
Types of herbs
Traits of adaptation to living together
3. Determine the criteria for one type of tree (shrub or grass). Enter the data into the table.
Species name
Morphological characteristics
Physiological signs
Ecological signs
4.Draw a conclusion about the reasons for the diversity of species in nature.
Tasks:
1. Make a description of the site: relief, illumination, weather conditions.
2. Identify the main types of trees, shrubs, grasses and identify their adaptability to living together. Enter the results into the table.
Types of trees
Types of shrubs
Types of herbs
Traits of adaptation to living together
3. Determine the criteria for one type of tree (shrub or grass). Enter the data into the table.
Species name
Morphological characteristics
Physiological signs
Ecological signs
4.Draw a conclusion about the reasons for the diversity of species in nature.
Tasks:
1. Make a description of the site: relief, illumination, weather conditions.
2. Identify the main types of trees, shrubs, grasses and identify their adaptability to living together. Enter the results into the table.
Types of trees
Types of shrubs
Types of herbs
Traits of adaptation to living together
3. Determine the criteria for one type of tree (shrub or grass). Enter the data into the table.
Species name
Morphological characteristics
Physiological signs
Ecological signs
4.Draw a conclusion about the reasons for the diversity of species in nature.
This excursion can be carried out while studying the topic "Evolutionary Doctrine". It significantly increases students’ interest in the educational material of the topic, facilitates its assimilation, and contributes to students’ understanding of the main provisions of evolutionary teaching.
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Excursion on the topic: “Reasons for the diversity of species in nature.”
In the course of general biology, evolutionary teaching occupies a special place. In the KIM of the Unified State Exam in Biology there are many questions on the evolutionary teachings of Charles Darwin. The teacher’s task is to structure the educational process in such a way as to ensure that students firmly assimilate this teaching. I believe that an important role in the assimilation of evolutionary knowledge is played by an excursion into nature to study the reasons for the diversity of species, during which students become acquainted with biological phenomena, establish patterns, and master the skills of obtaining knowledge through observations in nature.
I am conducting this excursion to Kumysnaya Polyana. This is the most picturesque place in our city. Together with the students we get great pleasure from communicating with nature.
Tour objectives:
1. introduce the concept of diversity of species as a result of natural selection.
2. introduce the concepts of “species criteria”, “population”, “variability”, “heredity”.
3. identify different relationships between individuals of the same species and different species.
4. show, using specific examples, the adaptability of organisms to endure unfavorable conditions in autumn and winter.
5. teach to work collectively, develop a sense of respect for nature, a sense of beauty, and the ability to see the beauty of nature.
6. develop interest in biology, the ability to observe, compare, establish cause-and-effect relationships, highlight the main thing, and draw conclusions.
Excursion plan:
- Organizing time.
- Conversation, frontal observation.
- Group assignments.
- Summarizing. Closing conversation.
Progress of the excursion.
Group assignments, the composition of the groups is determined in class, in the previous lesson. At the beginning of the excursion, I check the composition of the groups and provide instructions on behavior during the excursion. Then we go through 5-Dachnaya, past the spring to Kumysnaya Polyana. While moving, students name the types of trees of the first tier, the second tier, herbaceous plants, and types of shrubs. I draw attention to the fact that students give the correct (double) species names. I draw the students’ attention to the fact that in a small area of the forest, plants of different species grow. I formulate the main question: “What are the reasons for the diversity of species?” This is the main question of our excursion. Then I invite students to find out how species, for example of the same genus, (American maple, Tatarian maple) differ from each other. To clarify the concept of “species”, we use plants of similar species; this works well on plants such as caustic buttercup, creeping buttercup, and Kashubian. These same examples are used to discuss this topic in the textbook. We compare the conditions of their growth and note that the peculiarities of the existence of the species constitute an ecological criterion. Next we study their appearance. We determine similar characteristics and their differences in the structure of the flower and leaves. Let's draw conclusions. I inform students that structural features constitute the morphological criterion of a species. During the conversation, we find out that these plants have different flowering periods. We see the caustic buttercup blooming. Kashubian buttercup blooms at the end of May, and creeping buttercup in July. (we know this from past excursions). We conclude that asthenia of different types differs in terms of flowering, growth and development rates. We note that the characteristics of the response of organisms of the same species to changes in living conditions constitute the physiological criterion of the species. Conclusion: all species differ from each other in morphological, ecological, and physiological characteristics.
Let's move on. We went out into a clearing where there were a lot of caustic buttercups. Have you ever seen caustic buttercup in the forest? No. Where else have we seen this plant? We remember that when we entered the forest, we saw this plant in that clearing. Does buttercup pollen travel from one clearing to another? Silence. During the conversation, we find out that this is unlikely, because the clearings are located far from each other. This means that these plants live separately from each other. We introduce the concept of “population”. A group of individuals of the same species that exists for a long time in a certain territory separately from other such groups is called a population. Warty birch, Tatarian maple, pedunculate oak, growing in our forest, also represent populations of species. A population is a form of existence of a species. A population is stable if it contains individuals of different ages. Assignment: find individuals of different ages in the Tatarian maple population. Students do this with great pleasure. Next, I propose to consider 2-3 individuals of warty birch. Find similarities. There are many common signs. What is the reason for their similarity? They are closely related, because belong to the same population. The set of basic characteristics is transmitted from parents to offspring. All living organisms tend to preserve and transmit their characteristics and properties to their offspring. This property is heredity. It is this property that determines the similarity of closely related organisms. Then I propose to find differences in these individuals. Conclusion: all individuals, even in the same population, differ from each other, which means that organisms are characterized by variability. Let me explain that variability manifests itself in varying degrees of development of certain characteristics, for example, color intensity, body size, etc. Changes in these characteristics occur under the influence of environmental conditions. We draw attention to the differences in the color of the leaves of the common pine tree, which grows in open areas and in the forest. The second leaves are darker and produce more chlorophyll. Thanks to this feature, the synthesis of organic substances in plants in the forest in low light conditions occurs quite intensively. But these changes are not inherited. This is an example of non-heritable variation. Only such changes in characteristics are transmitted by inheritance, the development of which is caused by changes in the hereditary material. It is hereditary variability that causes the emergence of new characters, which are the material for natural selection and a prerequisite for the formation of new species. Next, we draw attention to the huge variety of living organisms that inhabit the forest. Students try to establish what relationships exist between them. Charles Darwin called the totality of all relationships the struggle for existence. As the excursion progresses, we find herbaceous plants and count the number of seeds (fruits) on them. Will all these seeds grow into adult plants? Of course not. Why? If all the seeds fall off in this place and germinate, then in the dense shoots between the seedlings there will be an intense struggle for existence - for moisture, nutrients, light. Charles Darwin called this kind of struggle intraspecific. Then we pay attention to some oppressed plants of poplar, warty birch, and Tatarian maple. Why are they like this? C. Darwin argued that complex relationships are also established between organisms of different species. This is an interspecies struggle for existence. Plants also begin to fight unfavorable environmental conditions. Many organisms die from severe frosts, fires, heavy rain, and sometimes humans are to blame. In the struggle for existence in a population of plants (animals), natural selection occurs: some individuals die, while others survive, produce viable offspring, and are characterized by high adaptability to new environmental conditions. I invite students to establish signs of adaptation of plants and animals to living conditions. The guys are working. Next, we study what adaptations plants have to endure unfavorable conditions in the autumn-winter period. I draw attention to the beauty of the autumn forest. Students then work in groups to complete assignments.
Tasks:
1. Draw up a site plan and characterize its topography, humidity, lighting, and type of soil.
2. Identify the main types of trees, shrubs, grasses and identify their adaptability to living together and to factors of inanimate nature. Enter the results into the table.
Types of trees. | Types of shrubs. | Types of herbs. | Traits of adaptation to living together. | Traits of adaptation to abiotic factors. |
3. determine the criteria for one type of tree (shrub or herb). Enter the data into the table.
Species name:
Morphological characteristics:
Physiological signs
Ecological signs.
4. Compare 2-3 individuals of the same plant species growing in one place. Signs of similarity, signs of difference.
5. Compare 2-3 individuals of the same plant species growing in different conditions.
6. What impact on nature did you observe in the forest? The tasks for students are the same, but each group works in its own area.
Such excursions are very educational and exciting. During the excursion we notice broken tree branches and carved inscriptions on the bark of trees. We make sure to explain what the possible consequences of these actions may be and how they affect nature. We talk about man's caring attitude towards nature.
Excursion “Species Diversity in a Community”
Equipment: notepad, pencil, ruler, camera, 4 cords 10 meters long
Istage. Awakening Enthusiasm
We conduct the first observation on the lawn in front of the school building. There are plenty of plantains, flowering dandelions and other common lawn weeds.
At this stage, you can play an outdoor game
The class is divided into two equal teams. Students come up with team names. Conditions: in the title, use the names of living organisms that are present in a given place. For example, “bugs” and “ants”. Teams line up facing each other at a distance of no more than a meter. Behind each team, at a distance of 5 meters, we draw a line indicating the HOME.
The presenter pronounces a phrase. If it is true, then the beetles catch the ants before they reach the HOME. If the phrase is not true, then the ants are catching the beetles. Who's caught? He joins the opposing team.
Examples of questions:
1.According to legend, the fern blooms on Ivan Kupala. (Yes)
2.Bamboo grows the fastest of all plants. (Yes)
3. A creeping stem climbing along the ground is called a whip. (no whip)
4.Birch has a perpendicular type of venation. (no - there is no such venation at all, there are parallel venations)
5. The lilac bush used to be called chenille. (Yes)
6. A laurel wreath has been used to reward winners since Ancient Rome. (Yes)
7.tarragon plant is a type of wormwood. (Yes)
8. Foxtail is a small animal. (no - this is a grass of the grass family)
9.Matches are made from aspen. (Yes)
10. The ancient Slavs believed that rejuvenating apples grew on oak trees. (Yes)
IIstage. Concentration of attention This stage of the excursion takes place behind the school where there is a small area with the usual selection of plants of all types. This stage is short-lived and if students are ready to perceive, then you can do without it .
Autumn has crept up on us unnoticed,
How generous nature is with colors.
All birches are worth gold,
And the rowan is red and beautiful. (L. Isaykina)
IIIstage. Gaining experience
In nature, plants do not live alone, i.e. apart or isolated from others, but live together with other plants. If a certain territory is dominated by perennial grass, then such a community is called ... MEADOW
Conversation:
1. Do you think plants that live together interact with each other?
2.But, if they interact with each other, can they influence each other? If yes, which one?
Conclusion: plants growing in the same area interact with each other and influence each other and the environment. Write the definition in your notebook.
Conversation:
1.Is it only plant populations that can interact with each other?
2.What about populations of other living organisms?
3.And can populations of different species form a community?
4.And what will be the name of the community in which different types of living organisms interact?
Staging goals:
Set the goal and objectives of our excursion based on the title of the topic “Species Diversity in a Community.”
IVstage. Inspiration, sensory experience
Take photos of the meadow plants. Make an environmental leaflet “How to behave while being in nature.” This stage can be implemented in the classroom or at home.
Vstage. Reflection. Several students read out their reports. Together with students, draw a conclusion about the influence of humans on the life of biocenoses.
Homework: Make an environmental leaflet “How to behave while being in nature.”
Literature:
2. Patrusheva L.I., Batluk N.V. “Ecological excursions” - Barnaul: AKDETS. 2003.-40s.
3. Schwab D. “Handbook for biology teachers” translation from English. K.S. Burdin and L.M. Baskin. M., "Enlightenment" -1994
Objectives of the excursion:
- Summarize knowledge about natural communities, revealing species diversity (bacteria, fungi, plants, animals) using the example of a specific biogenocenosis; their habitat, factors of inanimate and living nature, anthropogenic factors, seasonal changes in the life of living organisms; using knowledge about the laws of the evolutionary process in the natural environment, its criteria and factors using specific examples.
- Using knowledge about the patterns of the natural community, show their vulnerability from humans; making specific decisions on rational use of natural resources; fostering a sense of responsibility and involvement in environmentally unfavorable places in the natural community; formation of environmental thinking.
- For a specific biogeocenosis, reveal its main components.
- Consider and establish the structure of the biogeocenosis of the steppe area. Identify the nature of the distribution of individuals in populations, their numbers, boundaries, life forms, age spectrum, stratified distribution in the population.
- Establish living conditions in a community, the circulation of substances and the flow of energy in it.
- Find out the main forms of interaction between various components of biogeocenosis (living, bone and bio-bone).
- Show seasonal and temporary changes in biogeocenosis.
- To achieve students' understanding of the conditions that ensure the sustainability of biogeocenosis.
- Draw up a prospect for the further existence of a specific biogeocenosis.
- Using knowledge of the theory of evolution and the patterns of development of biogeocenosis, justify the need for its protection and rational use.
Preparatory stage
- In February, approve the dates and location of the excursion.
- Discuss assignments with literature and social studies teachers.
- A month before the excursion, announce to students the topic, purpose and familiarize them with the list of references to prepare for assignments and writing a report.
- Discuss the content of the excursion “Adaptation of plants and animals to living together in a natural community,” conducted in the eighth grade.
- Watching the film “Plant Communities”.
- Analysis of herbarium material on the species diversity of the steppe biogeocenosis.
- Prepare equipment: lux meter, tape measure, ruler, thermometers, compass, camera, frame with a grid, folder and digger for collecting plants, a large envelope for each link indicating the date of the excursion, topic, purpose, link number. The envelope contains a route diagram, tasks and a notebook.
- Drawing up a diagram of the excursion route and a plan for its implementation.
Conducting an excursion
At the first stop, the route, the composition of the links are clarified, the rules of behavior in nature are recalled, with the help of a list of edifiers of steppe communities, the species that will be encountered along the excursion route are specified: grasses (forming large-turf species - feather grass and small-turf species - fescue) - creeping wheatgrass, common timothy and steppe, awnless and coastal fire, wheatgrass; from the class of dicotyledons - steppe sage, Russian and Sumy cornflower, crescent alfalfa, astragalus, low sedge, gorse-leaved toadflax, ground reed grass, common wormwood (chernobyl), paniculata, bitter and Austrian wormwood, noble and common yarrow, common chicory, rough knotweed y and convolvulus, round-headed and Russian Echinops, Tartary and compass lettuce; shrubs - Russian broom and gorse.
Animals along the route may include representatives of orders such as Arthropods: Coleoptera, Lepidoptera, Orthoptera, Diptera; representatives of classes such as Chordata: Reptiles, Birds and Mammals; representatives of soil microflora: yeasts from the order protomarsupial; bacteria: butyric acid bacteria, fiber-oxidizing bacteria, azotobacteria, causative agents of ammonification of protein substances. To study microbial cenoses in the soil, the glass fouling method according to N.G. is used. Cold. Since seventh grade students were asked to work with this method on the excursion “Diversity of the kingdoms of living nature,” the listed organisms from the kingdoms “Mushrooms” and “Bacteria” can be used as links in the food chain of the steppe biogeocenosis.
Exercise 1
Identify the main types of plants. Reveal their adaptability to living together and to abiotic factors. Enter the observation results into the table.
Enter the results of observations of animals into the table.
Task 2
Find a rare plant. Determine the number of individuals per 1 m2, select young and adult individuals from them. Establish forms of struggle for existence (intraspecific, interspecific, with unfavorable environmental factors). Establish features of adaptation to living conditions (leaf shapes, waxy coating, pubescence, development of the root system, regrowth, etc.). Prospects for the existence of the species in nature.
Moving to an area of weeds bordering the meadow.
In the introductory conversation, students' attention is drawn to the fact that the plants of the wasteland contain a lot of interesting things for students of evolutionary science. During a brief acquaintance with these plants, adaptations to living conditions are revealed. For protection from being eaten by animals: thistle (has needles along the edges of the leaves); wormwood (acrid and bitter-tasting cell sap). For the distribution of fruits and seeds: large burdock (fruits are attached to animal fur with the help of hooks), tripartite string (fruits are two-pronged), field thistle (seeds with parachutes, flying away when the wind blows). To abiotic factors: unpretentiousness to the composition, soil fertility, moisture conditions; love of light.
Then the students' attention is drawn to a typical representative of weeds - the common thistle. They are asked to compare two closely related species: field thistle and common thistle. Students note the differences between them in the degree of division of the leaf blade, prickliness, and the size of the inflorescences. Then, during the conversation, it turns out that all these differences relate to the morphological criterion of the species, and a description of the criterion as a group of characteristics is given. At the same sites, an ecological criterion is considered (different habitats of plants: although both thistle and thistle are found in weedy areas, but thistle can also be found in meadows among forbs, and thistle is a typical wasteland plant).
Next, the tour stops in a meadow where three closely related species of clover are found: creeping clover, hybrid clover and meadow clover. Their differences according to morphological and ecological criteria are considered, attention is drawn to the physiological criterion (creeping clover is fading, hybrid clover and meadow clover are still in full bloom), as well as biochemical (the color of the inflorescences is different, which indicates the presence of different chemicals). Under the guidance of the teacher, the conclusion is formulated that even closely related species have many differences among themselves, each of which is an adaptation to specific living conditions; These adaptive differences are responsible for the enormous diversity of flora on earth.
Schoolchildren are divided into 4 groups (groups and consultants are determined in advance), each group receives its own task.
Exercise 1
Find populations of different plant species in the study area. Why can we call these groups of organisms populations? What is a population?
Task 2
Identify variability using the example of a population of a species. What form of variability can you attribute the highlighted differences to? What is the significance of the form of variation for the existence of the species as a whole?
Task 3
Reveal the adaptability of large plantain to trampling conditions. Due to what property are these features passed on from generation to generation? Think about the importance of producing a huge number of seeds on each plant.
Task 4
Think about how the relative nature of fitness may manifest itself. Give examples using plants from the study area.
After working on the assignments, each group makes a short presentation, and the teacher asks clarifying questions.
Next, they listen to a message prepared in advance by one of the students on the topic: the intensity of reproduction of various types of weeds, many of which, under favorable living conditions, could populate the entire surface of the globe in a few months. The conclusion is formulated that the lack of space, resources, and conditions for all emerging organisms leads to a struggle for existence. It is noted that Darwin used this concept to designate the entire set of relationships between individuals and various environmental factors. Students are invited to study these relationships using the example of a pine forest biocenosis.
During the conversation, a description of the biological characteristics of the pine is compiled (unpretentious to soils, withstands sharp temperature fluctuations, but demanding of light, etc.), its landscape-forming role in this community is noted; an analysis of the herbaceous layer is given (preliminarily studied by two students at five test sites); It is noted that the grass cover of a pine forest is not as thick and dense as a deciduous forest, and even more so a meadow forest, which can be called sparse. The reason for this phenomenon may be the small thickness of the coniferous decline. In frosty winters with little snow, needle litter does not protect most herbaceous plants and they freeze out. At the same time, as a result of the slow decomposition of needles, an acidic reaction of the environment is created in the soils of the pine forest, which is also unsuitable for many plants. Pine releases special substances into the air - phytoncides, which have the property of inhibiting the growth and development of bacteria, as well as some herbaceous plants. Students write down the main chains of relationships among organisms identified during the conversation.
Further, the teacher notes that even in such harsh living conditions, herbaceous plants live, which have special adaptations for this. One of the students talks about the tenacious creeping creature, which can withstand any frosts and winter frosts, survives this unfavorable period in a green state, has a high vegetative ability to reproduce, and forms many whiskers; about the May lily of the valley, which releases special substances into the soil that prevent other plants from spreading near it.
At the next stop, plants are demonstrated that, as a result of the struggle for existence, have gained advantages in development and distribution and are an example of the biological progress of the species, although they are reserves and were not found in our wild nature many years ago.
The first one is common pork. The following features gave the plant its predominant development in this forest: high growth activity, which results in a large space “captured” by shrubs; unpretentiousness to soils, moisture, lighting, resistance to pests; propagation by layering (long branches pressed to the soil that take root in the same year); distribution by seeds (fruits are carried by field thrushes).
Second plant - impatiens vulgare. This plant is interesting because its seeds germinate even in trampled soil and withstand its freezing; it is unpretentious to a wide variety of living conditions, it can absorb moisture from fogs over the entire surface of the body; annual, has a small root system.
The narrow adaptability of plants to harsh living conditions in the lower layer is examined using the example of wood sorrel.
The children are asked the question: which organisms - narrowly adapted to the environment or unpretentious to different conditions - will have advantages in the process of evolution under changing environmental conditions and why?
Having summarized the answers, the teacher suggests considering another form of struggle for existence - intraspecific.
A sample plot of pine forest measuring 10×10 m with trees of the same age is considered. It is noted that with the homogeneity of the bulk of the trees, there are rare dead trees, drying trees, and tall strong trees.
During the conversation, students are led to the conclusion that the reasons for this phenomenon are mutational variability and intraspecific struggle for existence.
One of the students studied the features of intraspecific struggle at 6 sites, three of which differ in different degrees of compaction of the soil, and three in different moisture conditions. After a message containing numerical indicators (the number of dead, drying, weakened and healthy trees), students come to the conclusion that the most “fierce” intraspecific struggle takes place under normal conditions, because the action of another factor that inhibits the development of trees causes a reduction in the number of pine trees per unit area. In these environmental conditions, the most adapted are individuals with the qualities of intensive growth of the stem and root system. Darwin called the “survival of the fittest” forms natural selection.
Another question: how should the pine genotype change under long-term unchanged environmental conditions? During the conversation, students are led to an understanding of the mechanism of adaptation as a result of long-term selection, the accumulation of many small hereditary changes that are useful in given conditions. Individuals survive because hereditary changes become the “property” of the entire population and quickly spread throughout it. A population isolated from others can become an independent species due to the accumulation of mutations and the strengthening of a trait.
The final stage of the excursion takes place on the edge of a pine forest, near a swampy meadow. Here, students receive cards for group independent work in order to consolidate the knowledge acquired on the excursion.
Card 1
Identify the dependence of the species composition and nature of vegetation in a given area on the degree of compaction (trampling) of the soil. Record the observation results in the table.
Using the identification card “Changes in the biogeocenosis of a pine forest with increasing load,” determine the recreational load in different areas of the biogeocenosis.
Card 2
Name the forms of struggle for existence and reveal them using the example of the biogeocenosis of a swampy meadow. Express your assumptions about how the vegetation of this meadow will develop over the next decades.
Card 3
Using an example of any adaptation of a plant or animal to its environment, show how it could arise in the process of evolutionary development. For this:
- imagine that this species previously had different features;
- tell us about the environmental conditions that contributed to the formation of this trait.
Card 4
Identify the adaptability of plants and animals, fungi and bacteria to living together in a pine forest. Fill out the table “Adaptation of organisms to life in a community.”
Indicate the meaning of tiers in space and time.
After work, the groups get together and exchange short messages. The teacher asks additional questions and clarifies the students' answers.
Based on the results of the excursion, students write a report according to the following plan:
- A variety of species of different kingdoms seen on the excursion.
- The adaptability of plants in different habitats, different communities (weeds, forest, meadow) and its relative nature.
- Forms of struggle for existence and their examples (based on excursion materials).
- Hereditary variability and natural selection are the driving forces of evolution.
- Examples of anthropogenic impact on biogeocenoses and their significance for evolutionary processes.
- Forecasts for further development of the community (using the example of one of them).