Producers, or manufacturers, - these are autotrophs, which in the process of life synthesize organic compounds from inorganic substances, using carbon dioxide as a source of carbon. The biomass formed in the ecosystem by autotrophic organisms is called primary products. It serves as food and energy source for the rest of the organisms in the community.
The main producers are green plants, although photosynthetic and chemosynthetic bacteria also contribute to the formation of primary products of the ecosystem. Each large ecosystem or any biogeocenosis has its own specific plants that carry out photosynthesis, i.e., their producers.
Consumptions, or consumers, Are heterotrophic organisms that use biomass synthesized by producers for their own life. By eating and processing plants, consumers receive energy and form secondary products ecosystems.
Consumables are a wide variety of living organisms - from microscopic bacteria to large mammals, from protozoa to humans. From the point of view of the structure of the ecosystem and the role that different consumers play in maintaining its equilibrium state, all consumers can be subdivided into several subgroups, which we will do a little later when we analyze the nutritional relationships of ecosystems.
Reducers, or decomposers, recycle dead organic matter ( detritus) to mineral compounds, which can again be used by producers. Many organisms, such as, for example, earthworms, centipedes, termites, ants, etc., feed on plant and animal debris, and part of the wood rots and decomposes during the life of fungi and bacteria. When fungi and other decomposers die off, they themselves turn into detritus and serve as food and energy source for other decomposers.
Thus, despite the diversity of ecosystems, they all have structural similarity. Each ecosystem capable of independent existence has its own producers, different kinds consumers and reducers (fig. 76).
Ecosystem of oak groves. Consider, as an example, an oak grove, a very resilient terrestrial ecosystem (Figure 77). Dubrava is a typical layered deciduous forest in which many hundreds of plant species and several thousand species of animals, microorganisms and fungi coexist.
The upper tree layer is formed by large (up to 20 m) perennial oaks and lindens. These light-loving plants, growing quite freely, create favorable conditions for the formation of the second tree layer, represented by undersized and less light-loving pear, maple, apple trees.
Rice. 76. Required components ecosystems
Shrub vegetation is formed under the canopy of two tiers. Hazel, euonymus, viburnum, hawthorn, blackthorn, elderberry, buckthorn - this is not a complete list of plants that form the third tier up to a height of 2–4 m.
The next, herbaceous layer is made up of numerous shrubs and half-shrubs, ferns, tree shoots and various grasses. Moreover, during the year in the oak forest there is a change in the herbaceous cover. In the spring, when there is still no foliage on the trees and the soil surface is brightly lit, light-loving primroses bloom: lungwort, corydalis, anemone. In the summer they are replaced by shade-tolerant plants.
In the ground layer, the height of which is only a few centimeters from the soil surface, lichens, mosses, mushrooms, and low grasses grow.
Hundreds of plant species ( producers), using the energy of the sun, create a green biomass of the oak forest. Oak groves are very productive: within a year, on an area of 1 hectare, they create up to 10 tons of an increase in plant mass.
Dead roots and fallen leaves form a litter in which numerous reducers: earthworms, larvae of flies and butterflies, dung beetles and dead-eating beetles, woodlice and millipedes, springtails, ticks, nematodes. While feeding, these organisms not only transform detritus, but also form the soil structure. The activity of such diggers as moles, mice and some large invertebrates prevents the soil from caking. Numerous soil protozoa live in water droplets between soil particles, and fungi form a symbiosis with plant roots and participate in the decomposition of detritus.
Rice. 77. Oak forest ecosystem
Despite the fact that every year 3-4 tons of dead plants per 1 hectare of soil surface in the oak forest, almost all of this mass is destroyed as a result of the activity of decomposers. A special role in this processing belongs to earthworms, of which there are a huge number in oak forests: several hundred individuals per 1 m2.
Varied animal world the upper tiers of the oak forest. Dozens of bird species nest in the tree crowns. Magpies and jackdaws, songbird and chaffinch, great tit and blue tit make nests. Eagle owl and tawny owl hatch chicks in hollows. The Hobby and Sparrowhawk scare small songbirds. The bushes are inhabited by the robin and the blackbird, the pied flycatcher and the nuthatch. Even lower are the nests of the warbler and wren. The gray squirrel moves along all the tiers in search of food. Butterflies, bees, wasps, flies, mosquitoes, beetles - more than 1600 species of insects are closely related to the oak! Grasshoppers and beetles, spiders and haymakers, mice, shrews and hedgehogs share a place under the sun in the grass layer. The largest consumers of this ecosystem are roe deer, fallow deer and wild boars.
The stability of this and any other ecosystem is provided by a complex system of relationships between all organisms that make up its composition.
Review questions and assignments
1. What is biogeocenosis?
2. Tell us about the spatial structure of the ecosystem.
3. What are the essential components of any ecosystem?
4. In what relations are the inhabitants of biocenoses with each other? Describe these connections.
5. Describe the species composition and spatial structure of the oak forest ecosystem.
Think! Execute!
1. Name the common features of biogeocenoses of deciduous forests and freshwater reservoirs.
2. Is it possible for the existence of a biocenosis consisting only of plants? Justify your point of view.
3. Do your research on "My home as an example of an ecosystem."
4. Design an excursion route to demonstrate the species, spatial and ecological structures of a typical ecosystem in your region (group project).
Work with computer
Please refer to the electronic attachment. Study the material and complete the assignments.
Remember!
What are the essential components of any ecosystem?
Living organisms are in constant interaction with each other and with environmental factors, forming a stable self-regulating and self-sustaining ecosystem. Features of the species composition of this system are determined by historical and climatic conditions, and the relationship of organisms with each other and with the environment is based on eating behavior.
In the considered ecosystem of oak groves, deer eat herbaceous plants and leaves of shrubs, squirrels are not averse to feasting on acorns and mushrooms, a hedgehog eats an earthworm, and an owl catches mice and voles at night. Numerous insects, oak acorns, fruits of the wild apple and pear, seeds and berries are excellent food for birds. Dead organic matter falls to the ground. Bacteria develop on them, which are consumed by protozoa, which, in turn, serve as food for numerous small soil invertebrates. All types of organisms are linked to each other by a complex system food relationships.
When studying the structure of any ecosystem, it becomes obvious that its sustainability depends on diversity. food ties, existing between the different types of this community. Moreover, the greater the species diversity, the more stable the structure. Imagine a system in which the predator and prey are represented only by single species, for example, the "fox - hare". The disappearance of hares will inevitably lead to the death of predators, and the ecosystem, having lost two of its components, will begin to collapse. If the fox can use rodents, frogs, and small birds as food in a given ecosystem, then the loss of one food source will not lead to the destruction of the entire structure, and the vacated ecological niche will soon be occupied by other organisms with similar requirements for the environment.
Introduction Layer of plants in the oak forest - first layer - second layer - third layer - fourth layer - fifth layer Different periods of flowering Ephemeroid plants Pollination, seed distribution Role of fungi Animals oak forests Forest litter Causes of oak forest stability Circulation of substances in the oak forest Conclusions Assignments
Oak grove is a typical biogeocenosis. As in any other biogeocenosis, it can be divided into components: 1. Producers - creators of organic matter. These are plants. 2. Consumers - consumers of organic matter. These are animals and mushrooms. 3. Reducers - destroyers of organic matter. These are bacteria, fungi, some animals. 4. Abiotic factors - climate, soil composition, etc. On the territory of the Smolensk region, oak forests, along with pine forests and spruce forests, are classified as primary forests. Primary forests are primary forests. They arose in the post-glacial period, 12-15 thousand years ago. There are few primary forests left on the territory of the region. Typical oak forests, which could still be found 300 years ago, are now almost nonexistent. But in those places where there used to be oak forests, and now a secondary forest grows, you can see the preserved plants of oak forests. Sokolya Gora is such a place. Let's get acquainted with the biogeocenosis on Sokolya Gora. table of contents
Plants growing in the forest have different heights. This is achieved by the possibility of coexistence of light-loving, shade-loving and shade-tolerant plants. Due to the layering per unit area, a large number of species can grow. The area of the leaf surface in the oak forest is 7.5 times larger than the surface of the earth on which it grows. As a mirror image of the terrestrial tier, there is an underground tier in the soil. Trees in the first tier have the deepest roots. Consider the tiers of the oak forest. table of contents
The first tier is made up of tall trees: pedunculate oak, common ash, rough elm, small-leaved linden. Plants of the first tier are light-requiring. They are taller than the rest and therefore absorb maximum light. table of contents
Trees of the first tier English oak (summer) Small-leaved linden. Leaves bloom later than the rest of the trees - at the end of May. Demanding on the composition of the soil. Height up to 50 m. Lives up to 1000 years. Height - up to 30 m. Lives up to 400 years. Blooms in July. Good honey plant. One tree at the age of 50 yields 10 -12 kg of honey.
The second tier is made up of trees below the trees of the first tier: plane maple, mountain ash, bird cherry, wild apple. This tier also includes the understorey of the trees of the first tier. Plants of the second tier are light-loving or shade-tolerant. Rowan ordinary Bird cherry ordinary Height up to 15 m. Lives up to 100 years. The fruit is an apple. Tree or shrub up to 10 m tall. It emits a lot of phytoncides. table of contents
Third tier Shrubs belong to this tier: warty euonymus, forest honeysuckle, hazel, viburnum, brittle buckthorn, cinnamon rosehip. Plants of the third tier are shade-tolerant. Rosehip cinnamon table of contents
The fourth tier is formed by herbaceous plants: ferns, lily of the valley, kupena, raven eye, zelenchuk, spreading pine forest, hairy sedge. These plants are shade-loving. They are perennial, have underground organs that reproduce vegetatively. In the forest, there are few pollinators in insects, and few fruits with seeds are formed. Vegetative propagation also the adaptation of plants to life in the forest. table of contents
Herbs of the fourth tier Lungwort obscure Dwarf bush male Blue coppice Crow's eye Kupena officinalis European Clefthoof
Oak grove plants bloom in different terms... This can be called layering in time. Thanks to this, the best pollination of the plants is achieved. Four waves of flowering can be distinguished. table of contents
The first wave of flowering Alder In late March - early April wind-pollinated trees and shrubs bloom. There are no leaves on the trees. The pollen flies freely over long distances. Inflorescences in plants are dangling catkins. Wind-pollinated trees and shrubs include aspen, poplar, hazel, alder, birch. table of contents
The second wave of bloom The second wave of bloom includes the blooming of snowdrops. In April - early May, the entire forest is bathed in sunshine. In its rays, a multi-colored carpet of flowers of a blue copse, an anemone of an oak tree, an anemone of a buttercup, a crested bird, and a lungwort are clearly visible. These plants are pollinated by insects, which by this time have already appeared in the forest. table of contents
Plants - ephemeroids (second wave of flowering) Snowdrops are light-loving plants. Among them there are ephemeroids - perennial plants with a fast development period. In late May - early June, the aerial part of the ephemeroids dies off, and the seeds have time to ripen. Anemone oakwood Corydalis Anemone buttercup Goose onion table of contents
This is what a spring forest looks like when snowdrops are in bloom. There is a lot of light in the forest. In the leaves, the process of photosynthesis proceeds intensively. In the underground organs - rhizomes, tubers or bulbs, nutrients are stored for flowering next spring. The picture shows the oak anemone
The third wave of flowering At the end of May, most insect pollinated trees, shrubs, grasses bloom: maple, oak, bird cherry, apple, mountain ash, honeysuckle, euonymus, lily of the valley, kupena, raven eye, zelenchuk. Most plants have white flowers and a strong aroma. Bird cherry Apple tree The white color is the most noticeable in the forest twilight. Rowan lily of the valley table of contents
The fourth wave of bloom The fourth wave of bloom includes plants that bloom in summer. In June, the common willow bloom, the spreading pine forest, the forest starlet, the amazing violet. Cereals and strawberries bloom on the edges. Most plants are pollinated by insects. Small-leaved linden blooms later than all trees and shrubs - in July and is pollinated by bees. Forest starwort Common runny Linden small-leaved
Ash fruits Part of the plants of the first tier is pollinated by the wind and the fruits are spread with the help of the wind (birch, poplar, aspen, ash). Plants of the lower tiers are most often pollinated by insects, and the fruits are distributed with the help of animals: insects, birds, mammals. The fruits of these plants are juicy, bright, well visible to birds. Many of the plants have fruits with small outgrowths - tidbits for the ants, which spread them. Buckthorn fruits Lily of the valley May Mineral two-leaved
Dependence of seed distribution on tiers Tier I II Distribution Number of plants (in%) seeds by Wind 83 83 Ants III, IV Birds 50 Birds 16 Rodents 13
For a year, oak forest plants produce 10 t / ha of net growth (including the growth of roots). The forest creates its own microclimate: humidity, shade, protection from the wind. This is why many animals live here. Usually, certain species of animals are confined to the vegetation layers. Consider the typical animals of the oak forest. table of contents
Animals confined to the first tier Silkworm Black woodpecker Jay This tier is inhabited by birds: finch, songbird, blue tit, pika. There are many insects: leaf beetles, bark beetles, longhorn beetles. Nuthatch
Animals confined to the second tier Redstart Oriole Flycatcher In this tier there are many insects, mainly beetles. Squirrel woodpecker table of contents
Animals confined to the third tier of Warbler Zaryanka Slavka This tier is inhabited by many insects and mollusks. Spiders
Animals confined to the fourth tier Roe deer Elk Wolf Snake Dormouse Frog Fox In this tier there are bees, wasps, bumblebees, white hare ants, butterflies and other insects, some species of birds nesting on the ground. There are many mouse-like rodents, among them the wood and yellow-throated mouse.
Fallen leaves protect the soil from freezing and rapid evaporation of moisture. Many insects and other animals overwinter in the forest floor. Animals that form detrital food chains feed on forest litter. Bacteria, fungi, protozoa, mites, worms, insects or their larvae contribute to the decomposition of litter. Most of the animals are distributed to a depth of 50 cm. Under 1 square. m of soil inhabits up to 20,000,000 protozoa, worms nematodes number up to 50,000.
Reasons for the stability of the oak forest The oak forest is home to a huge number of species of plants, animals, fungi, microorganisms (according to estimates, more than 10,000 species without microorganisms). The species in the oak grove are linked in the food chain. Food chains are intertwined in a very complex food web. The disappearance of a species usually does not disrupt the entire system. Self-regulation is well developed in the oak forest. All the diverse population of the forest exists together, not completely destroying each other, but only limiting the number of individuals of each species. In the oak forest, the circulation of substances and the movement of energy are clearly traced. Dubrava - open system, that is, it receives energy from outside in the form of solar energy. Organic substances formed during photosynthesis pass along the food chains and give up the energy stored in them for the vital activity of organisms. Ultimately, the mineralization of substances by decomposers occurs. table of contents
The cycle of substances in the oak forest Energy of the sun Trees, shrubs, herbaceous green plants Rodents (squirrel, forest mouse) Snakes Granivorous birds (bullfinch, chaffinch, hazel grouse) Birds of prey (hawks, owls) Herbivorous insects (butterfly caterpillars, bark beetles, longhorn beetles, leaf beetles (warblers, cuckoo, flycatcher Amphibians (grass frog, toad) Ungulates (elk, roe deer, deer, wild boar) Carnivorous mammals (wolf, fox, weasel, lynx) Consumers of the remains of dead plant and animal organisms (rotting bacteria, earthworms, beetles - gravediggers, soil protozoa, fungi) (Inorganic substances (mineral salts, etc.)
conclusions Vadim Shefner You, a man, loving nature, Though sometimes you feel sorry for it. On pleasure trips Do not trample her fields. In the station bustle of the century, you hurry to appreciate it. She is your old, kind doctor, She is an ally of the soul. Do not burn it recklessly And do not exhaust it to the bottom. And remember the simple truth - We are many, but she is one. The adaptability of living organisms to living together- the result of a long evolution. Any species occupies a definite place in the biogeocenosis. The existence of other species depends on it. To preserve all species means to preserve sustainable biogeocenoses, it means to preserve the biosphere. table of contents
assignments Find answers to the questions (verbally): 1. What is the significance of the layered arrangement of plants in the oak forest? 2. What is the significance of different periods of flowering of oak forest plants? 3. How do seed distribution methods depend on the longline? 4. What role do mushrooms play in the oak forest? 5. Why are there many animals in the oak forest? 6. What is the significance of the forest floor in the life of the oak forest? Writing Assignments 1. Fill in the table. Layer Ecological group of plants Examples of animals 2. Record two food chains in the oak forest. 3. List the adaptations of plants to living together in an oak forest. 4. Why is the oak forest a sustainable biogeocenosis? 5. Write down the definitions of the terms: epiphytes, ephemeroids. table of contents
Literature 1. 2. 3. 4. 5. 6. MA Gulenkova, AA Krasnikova Summer field practice in botany. - M., Education. 1976. Kriksunov E. A., V. V. Pasechnik. Ecology 10 (11) grade. - M., Bustard. 2004. A. V. Kulev General Biology Grade 10. Lesson planning. - Saint Petersburg. Parity. 2001. General Biology. Textbook for grades 9-10. Ed. Yu. I. Polyansky. - M., Education. 1987. OV Petunin Biology lessons in the 11th grade. - Yaroslavl. Development Academy. Academy holding. 2003. Lessons in General Biology. Ed. V. M. Korsunskaya. - M., Education. 1977. Photos of Yushkova Anastasia, Perlina N.B.
Take a look at Figures 198, 200-202 with groups of organisms living together in biocenoses. What are the connections between them?
Various types of existing relationships between organisms in biocenoses contribute to the preservation of their species composition and maintenance of the optimal number of species populations that make up the biocenosis.
The structure of the biocenosis is expressed in the species composition of its population and the quantitative ratio of organisms by species (species structure), in the regular distribution of organisms of different species relative to each other in the occupied space (spatial structure), in food (trophic) and other relationships of organisms.
Species structure of biocenosis. Any biocenosis is formed by species of organisms characteristic of it with a certain number of each of them. The total number of species in one biocenosis can reach several tens of thousands. Coral reefs and tropical forests are especially rich in species of organisms (Fig. 197, 1, 2). For biocenoses that have developed in the harsh living conditions of organisms, for example, in the Arctic, a much smaller number of species is characteristic (Fig. 197, 3).
Rice. 197. Biocenoses rich and poor in species: 1 - coral reef; 2 - tropical forest; 3 - polar tundra
The number of organisms of each species in the biocenosis is different. The most abundant species, or dominant (dominant) ones, make up its “species core”. In some spruce forests, for example, in sorrel spruce forests, spruce dominates from trees, from herbaceous plants- oxalis, from birds - kinglet, robin, chaffinch, and from mammals - bank and red-gray voles (Fig. 198).
Rice. 198. Numerous species of organisms of the sorrel-spruce forest: 1 - common spruce; 2 - common oxalis; 3 - finch; 4 - red-gray vole
The number of small species in biocenoses is always greater than that of numerous. Scarce species create the species richness of biocenoses and increase the diversity of its connections. The same species serve as a reserve for replacing the dominant species when environmental conditions change. The richer the species composition of the biocenosis, the better its resistance to changing environmental conditions is ensured.
The spatial structure of the biocenosis. The distribution of organisms in terrestrial biocenoses is mainly associated with the layering, or vertical arrangement of vegetation.
Layered, or vertical, composition of biocenoses is most clearly expressed in forests, where there can be up to 5-6 layers of plants (Fig. 199). So, in deciduous forests, or oak forests, oak, linden and other tall deciduous trees with large leaves form the first (upper) tier. Less light-loving, for example, Norway maple, elm and other companion trees of oak - this is the second tier. Hazel (hazel), honeysuckle, euonymus, wild rose, viburnum, buckthorn and other shrubs - the third tier (underbrush). Perennial herbaceous plants (corydalis, anemone, goose, lungwort, lily of the valley, green zelenchuk, European hoof, raven's eye) form the fourth tier. Mosses, lichens and fungi grow in the lower (fifth) layer of deciduous forest and are rare, without forming a continuous cover.
Rice. 199. Layered distribution of plants in the biocenosis of deciduous forest - oak grove
The tier structure of the forest allows plants to use sunlight more efficiently: light-loving plants form the upper tier, and plants of other tiers have adapted to life in low-light conditions or develop and bloom in early spring before the leaves bloom on the trees (woodlands, anemone, corydalis, goose onions).
The vertical distribution of animals and other organisms is associated with the layers of biocenoses (Fig. 200). So, in the crowns of trees of the first and second tiers of the forest, various leaf-eating insects, insectivorous birds (blackbirds, orioles, cuckoos), small animals (squirrels, dormouse) live. Are here and predator birds, for example a sparrowhawk. The population of animals in the lower forest layer is especially diverse. Moose, hares, wild boars, hedgehogs, forest mice, wolves, foxes and other animals live here.
Rice. 200. Longline distribution of animals in the biocenosis of a mixed forest
Many animals, due to their mobility, live in several tiers. For example, the common squirrel builds nests and feeds its young in trees, and gathers food for itself both in trees and on bushes and on the ground. Black grouse, wood grouse, hazel grouse feed mainly in the lower layer of the forest, spend the night in trees, and breed their offspring on the ground.
The distribution of animals over the tiers in the biocenosis reduces the competition between them in nutrition, the choice of places for building nests. So, the pied flycatcher hunts insects in the crowns of trees, and the garden redstart - in the bushes and above the soil. Great spotted woodpecker and nuthatch feed on insects and their larvae, usually in the middle layer of the forest. However, they do not compete with each other: the woodpecker hunts insects, their larvae and pupae from under the bark of trees, and the nuthatch collects insects from the surface of the bark.
Tiering, like floors, is also observed in the location of the roots. The roots of the trees in the upper tiers go deepest into the soil. In each layer of the soil there are bacteria and fungi, due to which the transformation of organic residues into humus (humus) and its mineralization occur. Many insects, ticks, worms and other animals live here permanently or temporarily. The number of species and individuals of animals associated with the soil exceeds the number of terrestrial ones. The soil population is most numerous in areas where the soil is rich in organic matter and has a great influence on soil formation.
Food (trophic) structure of the biocenosis. All organisms of biocenoses are interconnected by the relationship "food - consumer" and each of them is included in one or another link of the food chain - a sequential series of organisms that feed on each other. There are two main types of food chains: grazing (grazing chains) and detrital (decomposition chains).
Plants (autotrophic organisms) and animals (heterotrophic organisms) form the basis of pasture food chains. Herbivorous animals such as locusts, leaf beetles, crossbills, waxwings, voles, hares, deer are first-order consumers; carnivores (frogs, toads, lizards, snakes, insectivorous birds, many birds of prey and animals) - consumers of the second order; and predatory animals feeding on consumers of the second order are consumers of the third order (Fig. 201).
Rice. 201. Oak grove pasture food chain
In detrital food chains (from Latin detritus - worn out, small organic particles), the food source of the first-order consumer organisms is the remains of decomposed animals, plants, fungi, together with the bacteria they contain. Detrital food chains are most common in forests (Fig. 202). Thus, a significant part of plant production (leaf litter) is not consumed directly by herbivorous animals, but dies off and undergoes decomposition and mineralization by saprotrophs (from the Greek sapros - rotten) - rotting bacteria. Earthworms, centipedes, mites, insect larvae feeding on detritus serve as food for the consumers of the next link.
Rice. 202. Detrital food chain of deciduous forest
So, the species, spatial and food (trophic) structures of the biocenosis form the basis for maintaining its integrity. The species composition of organisms is formed in accordance with the environmental conditions in which a particular natural community exists. The species that make up the biocenosis, distributed over the tiers and connected with each other by food chains, ensure the long-term existence of various natural communities on our planet.
Make up of the listed organisms and their waste products several grazing and detrital food chains: herbaceous plants, leaves of trees and shrubs, plant litter, earthworms, butterfly caterpillars, slugs, flyworms, frogs, snakes, a dead crow, tits, hawks, hedgehogs ...
The life of forest plants has its own characteristics. The trees that form the forest grow more or less closely together, influencing each other and all other forest vegetation. Plants in the forest are arranged in tiers, which can be compared to floors. The upper, first tier is represented by the main trees of the first degree of importance (spruce, pine, oak). The second tier is formed by trees of the second size (bird cherry, mountain ash, apple tree). The third tier consists of shrubs, for example, wild rose, hazel, viburnum, euonymus. The fourth tier is the herbaceous cover, and the fifth is mosses and lichens. The access of light to plants of different tiers is not the same. The crowns of the first tier trees are better illuminated. From the upper to the lower tiers, the illumination decreases, since the plants of the upper tiers retain the proportion of sunlight. Mosses and lichens occupying the fifth tier receive very little light. These are the most shade-tolerant plants in the forest.
Different forests have a different number of layers. For example, in a dark spruce forest, only two or three tiers are distinguishable. The first tier contains the main trees (spruce), the second is a small number of herbaceous plants, and the third is formed by mosses. Other woody and shrubby plants do not grow in the second tier of a spruce forest, as they cannot stand strong shading. Also, the herbaceous cover is not observed in the spruce forest.
The tiered arrangement is typical not only for the aboveground parts of plants, but also for their underground organs - the roots. Tall trees have roots that penetrate deep into the ground, while the root system of trees of the second tier is shorter and conditionally forms the second tier of roots. The roots of other plants in the forest are even shorter and are found in the upper layers of the soil. Thus, the plants in the forest absorb nutrients from different soil layers.
Trees of the first size (oak, pine, spruce) close their crowns and form a forest canopy, under which a small proportion of sunlight penetrates. Therefore, herbaceous plants of the forest, as a rule, are shade-tolerant and have wide leaf blades. Many of them cannot withstand exposure to direct sunlight and may die in open spaces. A feature of broadleaf forest grasses is their flowering in early spring, when the trees still have no foliage. With the help of wide leaves, forest plants accumulate organic matter in low light and deposit them in underground organs, for example, lungwort - in rhizomes. In the gloomy thickets of spruce, the flowers of herbaceous plants have white corollas so that they can be seen from afar by pollinating insects. For example, such flowers are in the lily of the valley, wintergreen, septench, dream, mine. But, despite these adaptations, the flowers of forest herbs often do not pollinate and do not form seeds. Therefore, the reproduction of many herbaceous plants is carried out by dividing the rhizomes, for example, in the acid plant, lily of the valley, kupena, weekly, and minenik. This explains the placement of these herbs in the forest in groups.
The forest litter covering the soil consists of fallen leaves or needles, respectively, in deciduous or coniferous forests, as well as bark and branches of trees, dead areas of grasses, mosses. Loose forest litter is moist, which is favorable for the development of mold and cap fungi. The myceliums of various fungi penetrate the litter through and through, gradually converting organic matter into humus and mineral salts to nourish the green plants of the forest.
Dubrava, as a natural community (biogeocenosis), is characterized by integrity and stability.
Dubrava is one of the most complex terrestrial biogeocenoses. Biogeocenosis- these are complexes of interrelated species (populations of different species) living in a certain territory with more or less homogeneous living conditions. The biogeocenosis of oak forests is made up of more than a hundred species of plants and several thousand species of animals. It is clear that with such a variety of species inhabiting the oak forest, it will be difficult to shake the stability of a given biogeocenosis by exterminating one or several species of plants or animals. It is difficult, because as a result of the long-term coexistence of plant and animal species from scattered species, they have become a single and perfect biogeocenosis - an oak forest, which, as already mentioned above, is capable of existing for centuries under constant external conditions.
The overwhelming majority of biogeocenosis is based on green plants, which are known to be producers of organic matter (producers). In the biogeocenosis, herbivorous and carnivorous animals are necessarily present - consumers of living organic matter (consumers) and, finally, destroyers of organic residues - mainly microorganisms that bring the decomposition of organic matter to simple mineral compounds (decomposers). Plants - main source organic matter and if they disappear, then life in the biogeocenosis will practically disappear.
The cycle of substances in biogeocenosis - necessary condition existence of life. It arose in the process of the formation of life and became more complex in the course of the evolution of living nature. On the other hand, in order for the cycle of substances to be possible in the biogeocenosis, it is necessary to have organisms in the ecosystem that create organic substances from inorganic ones and convert the energy of the sun's radiation, as well as organisms that use these organic substances and turn them back into inorganic compounds. All organisms are divided into two groups according to the way of feeding - autotrophs and heterotrophs. Autotrophs (mainly plants) use inorganic compounds for the synthesis of organic substances environment... Heterotrophs (animals, humans, fungi, bacteria) feed on ready-made organic substances that are synthesized by autotrophs. Hence, heterotrophs are dependent on autotrophs. In any biogeocenosis, all reserves of inorganic compounds would very soon be exhausted if they were not renewed in the course of the life of organisms. As a result of respiration, decomposition of animal corpses and plant debris, organic substances are converted into inorganic compounds, which return again to the natural environment and can again be used by autotrophs. Thus, in biogeocenosis, as a result of the vital activity of organisms, a flow of atoms is continuously carried out from inanimate nature to living nature and vice versa, closing into a cycle. For the circulation of substances, an inflow of energy from the outside is required. The source of energy is the Sun. The movement of matter caused by the activity of organisms occurs cyclically, it can be used repeatedly, while the flow of energy in this process is unidirectional. The energy of the sun's radiation in the biogeocenosis is converted into various forms: into the energy of chemical bonds, into mechanical and, finally, into internal energy. From all that has been said, it is clear that the circulation of substances in the biogeocenosis is a necessary condition for the existence of life and plants (autotrophs) in it the most important link.
A characteristic feature of the oak forest is the species diversity of vegetation. As mentioned above, the biogeocenosis of oak forests is made up of more than a hundred species of plants and several thousand species of animals. There is intense competition between plants for basic living conditions: space, light, water with minerals dissolved in it. As a result of long-term natural selection, oak forest plants have developed adaptations that allow different types coexist. This is clearly manifested in the layering characteristic of the oak forest. The upper tier is formed by the most light-loving tree species: oak, ash, linden. Below, there are less light-loving trees accompanying them: maple, apple, pear, etc. various shrubs: hazel, euonymus, buckthorn, viburnum, etc. Finally, a layer of herbaceous plants grows on the soil. The lower the tier, the more shade-tolerant the plants that form it. Tiering is also expressed in the location of root systems. Trees in the upper tiers have the deepest root systems and can use water and minerals from the deeper layers of the soil.
