III. Floating scaffolding food chains The ocean is made up of phytoplankton, microscopic unicellular organisms that are at the same time real plants. Phytoplankton is called the grass of the sea, but this plant community can also be viewed as

V. Brown Algae Forests In the sea, algae often form almost true forests. A scuba diver diving near La Jolla - Monterey, San Juan Island, Amchitka and many other points, would understand why one can speak of a forest. In these places, even in height

Arborist - owner of the forest

habitats, environmental disturbances (eg fire), succession and climate change. The scope of research depends on what questions the researchers ask themselves.

and what organisms they study. Most surveys are large scale, using new technologies such as computerized geographic information systems that allow large areas to be studied with a reasonable degree of accuracy. The information obtained can then be used in mathematical models designed to predict changes in landscapes and processes associated with human activity.

Majority important processes and phenomena can only be fully understood at the level of landscape ecology. Although landscape ecology still lacks theoretical foundations, it will play an increasingly important role in ecological research in the future.

See also the articles "Scale in Ecology", "Habitats: Fragmentation", "Metapopulation", "Dispersal".

TEMPERATE FORESTS

The best-known type of temperate forests (at least in the Northern Hemisphere) consists mainly of deciduous trees that shed their leaves in autumn.

Deciduous forests are located in areas that are characterized by fairly large seasonal temperature fluctuations - cool to cold winters and warm summers - as well as high rainfall all year round. Outwardly, this biome, perhaps, shows the greatest variability throughout the year. In winter, most plants are in a dormant state: terrestrial, early flowering plants in winter are presented in the form of bulbs or other underground parts. This allows them to grow quickly in the spring, before the tree canopy cuts off the light.

The forest is a three-dimensional habitat that has several tiers (levels); the total surface area of ​​the leaves is several times the area on which these forests grow. In summer, a thick tree canopy prevents light from reaching the lower level. Some-

rye shade-tolerant plants of the ground layer still grow, especially in lighter parts of the forest. In autumn, trees absorb as much nutrients and minerals as possible from their leaves, which leads to a change in their color before falling off. Fallen leaves are a rich nutrient resource for the soil decomposer community*.

Forests are a dynamic system that develops in time and space. For example, the main tree species in the temperate forests of the American Northeast are temporary associations rather than highly integrated communities. Since the last ice age, each tree species has spread northward independently of the others, and, historically speaking, it was only very recently that their paths crossed to form the forests we see today. The dynamic nature of deciduous forests is also observed at the regional level; forests are not so much a "green blanket" as a "checkered blanket". Human impact on forest areas leads to the fact that in different areas the forest is at different stages of restoration.

See also the article " coniferous forests(taiga)".

* Decomposers - organisms that decompose dead organic matter (corpses, waste) and turn it into inorganic substances that are able to assimilate other organisms - producers.

LIMITING FACTORS

The concept of limiting factors has been used in agriculture for some time.

economy. Flaw nutrients, such as nitrates and phosphates can negatively affect crop yields, so nutrient additions increase yields. In arid regions, in exactly the same way, productivity is increased by water. Here, the limiting factor is understood as a resource that is not enough for the growth needs of plants.

As for populations, a factor is called a limiting factor if its change leads to a change in the average population density. For example, the availability of nesting sites may be considered a limiting factor for a bird population if the installation of nest boxes increases population numbers. In one experiment it was found that shooting pigeons* had no effect on

* A bird of the pigeon family.

population size. The limiting factor in this case was the availability of food; the shooting of birds led to the fact that the survivors had more food left, the population was also replenished by wood doves migrating from other places. In exactly the same way, populations of game birds, such as grouse, are maintained.

Over a period of time (or consecutively over the course of a year) there may be several limiting factors, and they seem to interact with each other to determine the size of the population.

It is important to distinguish between factors that regulate the size of populations and factors that determine their average density. Population size can be controlled only by factors that depend on density (i.e., those that maintain it within certain limits), while the average density of a population is determined by factors both dependent on density and not dependent on it.

The concept of limiting factors plays an important role in many areas of ecology, from the study of interspecific competition to pest control and the prediction of the impact of rising carbon dioxide levels on plant productivity.

See also the articles “Population regulation”, “Top down - bottom up”, “Density dependent factors”.

LUGA

Most grasslands in the broad sense, that is, temperate plains (steppes, prairies, pampas), are located in the interior of the continents, where it is too dry for forests and too wet for deserts. In those areas where the forest could grow, meadows are formed artificially for grazing, for this the forest is burned. Until recently, almost all natural meadows were grazed large mammals(only on the plains North America grazed up to 60 million bison).

Winters in such an area are cold to moderate, and summers are hot, resulting in a fire hazard. To the meadows temperate climate accounts for a significant part of the fertile soils, and huge areas of them have been turned by man into agricultural land.

For better understanding meadow ecology, they are divided into natural, semi-natural and artificial. Natural grasslands arose as a result of climatic changes, processes

owls occurring in the soil, wildlife activity and fires. Semi-natural grasslands (pastures) are formed and modified by human activities, but they are not deliberately planted. Plains can be an example of such meadows. Western Europe cleared from forests. If they are left alone, then after some time forests will grow there.

Where did the plants that now grow in semi-natural meadows come from? small meadow areas available in highlands or infertile soils; individual plants grow on forest edges and clearings. Some meadows

Mitchell Paul. 101 key ideas: Ecology - Per. from English. O. Perfilieva. - M.: FAIR-PRESS, 2001. - 224 p. - (101 key ideas).

known for the diversity of their flora, and now they are even protected, preventing them from turning back into a forest.

A significant part of the biomass of plants, fungi and invertebrates in temperate grasslands is underground. Here, symbiont fungi, intertwined with a huge dense mass of roots, form a mycorrhizal* network. It serves as a rich food source for innumerable invertebrates.

See also articles "Biomes", "Savannas", "Symbiosis".

* Mycorrhiza - mutually beneficial cohabitation(symbiosis) fungal mycelium with root higher plant, for example boletus with aspen.

MACROECOLOGY

In the last decade, an approach called “macroecology” has become increasingly popular in ecology. While most ecologists study in detail the peculiarities of species relationships in small areas over a short period of time, macroecologists think and act on a large scale.

The action of some ecological processes is noticeable only in comparison with others or on a wide time scale, so they cannot be studied experimentally. Here other approaches are needed. One of the possible ones is to observe large-scale processes and phenomena of nature and then look for explanations for them, this is the main essence of macroecology.

Showing that such processes actually occur is not an easy task. In order to isolate any patterns from the confusion of facts, more evidence is needed and more samples to study, so the object of study becomes more

studied species. If there are some regularities, then it is also possible to assume that the main ecological processes are of a universal nature. General patterns include the gradient of latitudinal diversity, the dependence of the number of species on the size of the territory, as well as the relationship between body size, population size, and area of ​​distribution.

The main problem is the explanation of the processes underlying the regularities. Without an experimental approach, it is not easy to identify differences in processes. In addition, many patterns seem to have not one but several causes, several mechanisms of action, so it can be difficult to determine the importance of a particular process.

The lack of experimental validation has been a major target of criticism of the macro-environmental approach. However, a broad-based approach to ecology is still needed. Many of the criticisms leveled against macroecology were once leveled against fossils as evidence for evolution. But would it be possible to understand the mechanism of evolution without studying fossils?

See also the articles "Gradient of latitudinal diversity", "Dependence of the number of species on the size of the territory", "Scale in ecology", "Generalizations in ecology", "Experimental ecology".

SCALE IN ECOLOGY

Many different ecological processes operate on a much larger (or smaller) spatial and temporal scale than we are familiar with. Space in ecology is measured by values ​​from microscopic to global, and time - from seconds to millennia.

Most environmental studies last no more than five years and cover an area of ​​no more than 10 m2. This is quite significant, since there is no reason to assume that the processes occurring within the framework of any ecological

Mitchell Paul. 101 key ideas: Ecology - Per. from English. O. Perfilieva. - M.: FAIR-PRESS, 2001. - 224 p. - (101 key ideas).

research will remain important on a larger spatial and temporal scale.

According to one definition, ecology is analogous to the reconstruction of a film "from several fragments of the same film or successive fragments of different films, which, we hope, belong to similar films" (Vince et al., 1986). The meaning of this statement is that it is impossible to fully

Tew to understand ecological processes without judging scale. This is well understood, for example, environmentalists fresh water, since it is impossible to know the ecology of rivers without taking into account the processes operating throughout the entire space of their basin. Hence the increasing number of long-term studies that provide a more adequate picture of various ecological processes.

The sizes of organisms that ecologists study range from microscopic (bacteria) to gigantic ( blue whales and sequoias); size is important environmental significance. For example, reproduction rate, population size, and metabolic rate are related to size. In order to move in the water, the movement of the tail is enough for fish, and microorganisms move in the water, as if in thick molasses. In the same way, the significance of various processes changes if they are considered on a different time scale. What seems to us to be an accidental ecological “disturbance” may be a regular process for trees that live hundreds of years.

Do not underestimate the importance that the chosen scale has on the interpretation of processes, so you need to be able to choose it correctly. This is one of the basic rules for an ecologist.

See also the articles "Landscape ecology", "Macroecology".

INTERSPECIES COMPETITION

The prevalence and role of interspecific competition has always been one of the most hotly debated issues in ecology.

Interspecific competition is defined as a relationship between two or more species that is unfavorable to all participants (see "Interspecific Relationships"). Often such a relationship is asymmetric, then one species suffers from competition more than another. There are several ways of negative relationships, ranging from indirect ones, such as competition for limited resources (exploitative competition) or the presence of a predator common to several species (indirect competition), to direct relationships, such as the use of physical or chemical means to drive out a competitor. or depriving him of the opportunity to use resources (active competition). An example of the latter is the actions of the geese. On the rocky shores

free space is highly valued, and the geese take every opportunity to push their neighbors off the rocks.

Darwin argued that interspecific competition should be stronger between closely related species, since they tend to consume similar resources. Although in recent times competition between distant species has also been discovered, Darwin's concept is still valid.

Perceptions about the role of competition have changed over the years. At first it was assumed that it was very common and important, then some ecologists highlighted the role of predation or external influences on the structure of communities. Ecologists later recognized that competition plays an important role among some groups of organisms (for example, plants), but among other groups (for example, herbivorous insects) it is not so much. herbivores

Mitchell Paul. 101 key ideas: Ecology - Per. from English. O. Perfilieva. - M.: FAIR-PRESS, 2001. - 224 p. - (101 key ideas).

In the vast territories of North America and Eurasia, mixed and broad-leaved forests are located. The zones of these green areas are in a temperate geographic zone Earth. The list of plants that these forests are rich in includes pine and spruce, maple and linden, oak and ash, hornbeam and beech.

Mixed and broad-leaved forests are the habitat of roe deer and elk and red deer, ferrets and martens, squirrels and beavers, wild boars and foxes, hares and chipmunks, as well as many mouse-like rodents. The birds that consider these massifs their home are storks and cuckoos, owls and capercaillie, hazel grouses and geese, ducks and owls. In the lakes and rivers of this forest zone, mainly cyprinids are found. Sometimes there are salmon.

Mixed and broad-leaved forests have been heavily affected by human activities. Since ancient times, people began to cut them down, replacing them with fields.

Woodlands of North America and Western Europe

The territory has its own southern border. It is located in the western part of Eurasia and in the region of the North American Great Lakes. Its coordinates are about sixty degrees northern latitude. To the south of this mark, along with coniferous species, broad-leaved species are present in the forests. At the same time, trees in different parts lights are represented by their different types.

The climate of mixed and broad-leaved forests is warmer than in the zone of distribution of conifers. The summer period in these zones is longer than in the north, but winters are quite cold and snowy. In such mixed and broad-leaved forests, broad-leaved plants with wide blades dominate.

In autumn, they shed their cover, resulting in the formation of humus. Moderate moisture contributes to the accumulation of mineral and organic substances in the upper soil layers.

The transitional strip, on the territory of which they are located, is heterogeneous. In the formation of vegetation in these massifs, local conditions, as well as types of soil rocks, play an important role.

So, for example, in the southern part of Sweden, as well as in the Baltic States, large areas are occupied by forests with a predominance of pure spruce forest. They grow on moraine loamy soils.

Somewhat to the south, coniferous species fall out of the forest stand. Forests are only becoming broad-leaved. In these zones, the temperature in January, on average, does not fall below minus ten, and in July this figure is thirteen to twenty-three degrees Celsius.

Forest vegetation of North America and Western Europe

It is difficult to draw a clear line between mixed and broad-leaved forests. Conifers can be found far in the south, up to the subtropical zone. In addition, felling of deciduous trees was carried out more intensively. This caused a predominant proportion of conifers.

The vegetation of mixed and broad-leaved forests is diverse. In the south, from the subtropics, magnolias, paulownias penetrated into their territory. In the undergrowth, next to lilacs and honeysuckle, rhododendron and bamboo can be found. Common in such areas and creepers from lemongrass, etc.

Forests of Russia

In those latitudes where the taiga stretches its southern borders, mixed and broad-leaved forests come into their possession. Their territory extends to forest-steppes. The zone in which green massifs are located, consisting of trees of mixed and broad-leaved species, is located from the western borders of Russia to the place where the Oka flows into the Volga.

The climate, which is typical for mixed and deciduous forests of Russia

Nothing protects the zone of green areas from the influence of the Atlantic Ocean, which determines the weather conditions on its territory. The climate of mixed and broad-leaved forests of Russia is moderately warm. However, it is quite soft. Climatic conditions This zone has a favorable effect on the growth of coniferous trees along with broad-leaved trees. At these latitudes, warm summers and relatively long cold winters are observed.

The atmospheric temperature of mixed and broad-leaved forests during the warm period has average value greater than ten degrees. In addition, the climate in this zone is characterized by high humidity. During the warm period, the maximum amount of precipitation also falls (ranging from 600 to 800 millimeters). These factors favorably affect the growth of broad-leaved trees.

reservoirs

On the territory of mixed and broad-leaved forests of the Russian Federation, abounding rivers originate, the path of which passes through the East European Plain. Their list includes the Dnieper, as well as the Volga, Western Dvina and etc.

Occurrence surface water in this zone is quite close to the surface layers of the earth. This fact, as well as the dissected landscape of the relief and the presence of clayey-sandy deposits favor the formation of lakes and swamps.

Vegetation

In the European region of Russia, mixed and broad-leaved forests are heterogeneous. Oak and linden, ash and elm are widespread in the western part of the zone. Moving to the east, the continentality of the climate increases. There is a shift of the southern boundary of the zone to the north, and at the same time, fir and spruce become the predominant tree species. The role of broad-leaved species is significantly reduced. In the eastern regions, linden is most often found. This tree forms the second tier in mixed forest areas. Undergrowth develops well in such areas. It is represented by plants such as hazel, euonymus, and honeysuckle. But in the low-lying grass cover, taiga plant species grow - majnik and oxalis.

The flora of mixed and broad-leaved forests changes as you move south. This is due to climate change, which is becoming warmer. In these zones, the amount of precipitation is close to the evaporation rate. These areas are dominated by deciduous forests. Coniferous tree species are becoming rarer. Main role in similar forests belongs to oak and linden.

Territories of these green forest areas rich in floodplain and upland meadows, which are located on alluvial soil layers. There are also swamps. Among them, low-lying and transitional ones predominate.

Animal world

Mixed and broad-leaved forests in former times were rich in wild animals and birds. Now the representatives of the fauna have been pushed aside by man to the least populated zones or exterminated altogether. To preserve or restore a particular species, there are specially created reserves. Typical animals living in the zone of mixed and broad-leaved forests are the black polecat, bison, elk, beaver, etc. The species of animals living in Eurasia are close in origin to those species whose habitat is the European zone. These are roe deer and deer, marten and mink, muskrat and dormouse.

Spotted deer and deer, as well as muskrat, have acclimatized in this zone. In mixed and broad-leaved forests, you can meet snake and agile lizard.

human activities

Mixed and broad-leaved forests of Russia contain huge reserves of timber. Their bowels are rich in valuable minerals, and the rivers have colossal reserves of energy. These zones have been mastered by man for a long time. This is especially true. On its territory, significant areas are set aside for cattle breeding and agriculture. In order to preserve forest complexes, national parks are being created. Reserves and nature reserves are also open.

Broad-leaved, or summer-green, forests in the temperate latitudes of the Northern Hemisphere do not form a single zone and occupy disparate territories with a weakened continentality in Europe, Asia and North America. The climate in the area of ​​forests of this type is moderately cool, precipitation is distributed relatively evenly throughout the year, and their amount varies over a fairly wide range. A break in the growing season due to winter cold is characteristic. Depending on the degree of continentality of the climate, winters can be almost frost-free (the Atlantic regions of Europe) or with persistent frosts with heavy snow cover.

The northern boundaries of the distribution of broad-leaved forests are determined by the duration of the cold period and (or) the lack of summer heat. Late spring and early summer frosts, which are especially detrimental to undergrowth, apparently play a significant role in the advancement of individual species. On the southern borders the main limiting factor is humidity, which determines the transition to the steppes. The replacement of broad-leaved forests by coniferous forests occurs very gradually; a strip of mixed coniferous-broad-deciduous forests stands out.

Vegetation. The forests are characterized by a closed upper tree layer, the lower tree layers are either very sparse or absent. Many broad-leaved species give root and stump shoots, coppice stands are shorter and more closed. There are mono-, oligo- and polydominant forests. Beech species tend to form monodominant stands. The shrub layer varies from well developed to extremely sparse.

Lianas are usually few, but in some regions (East Asia, southern part Atlantic forests of North America) they are very abundant. The herbaceous cover is formed by perennial species, different in environmentally. There is a group of mesophilic shade-loving herbs with a long growing season. Characteristic are plants that bloom in the spring, when a lot of light enters the forest canopy, and end their above-ground existence shortly after the leaves bloom on the trees. In the humid climate of the coastal regions, the herbaceous layer includes some evergreen species, the share of which decreases in the continental regions.

Broad-leaved forests have long been subjected to uprooting followed by plowing of the land, constant cutting, often accompanied by a directional change of species. Significant

areas formerly occupied by forests have been converted into agricultural land.

European broadleaf forests are floristically the poorest and structurally relatively simple. There are practically no primary forests. The main forest-formers are species of beech, oak; the role of chestnut, as well as hornbeam, ash and linden, is limited. In the eastern more continental regions and on the border with the steppe formations, only pedunculate oak forests spread.

The specificity of the forests of Asia is determined primarily by the amazing species richness of trees, shrubs and herbs, and a significant part of them belong to ancient genera. In comparison with European forests, the role of vines and epiphytic ferns is increased in them.

In North America, broad-leaved forests are distributed only in the eastern part of the continent. Striking species diversity and richness of the composition of trees, an abundance of shrubs, as well as lianas.

between forests East Asia and North America, a certain similarity is found, which is enhanced by the preservation in them of a large number of representatives of the ancient deciduous flora. The presence of two or three tiers of forest stands is associated with a large variety of tree species. Dominant stands are species of oak, maple, plane tree, elm, ash, walnut, tulip tree, etc. The forests are preserved to the greatest extent in the foothill regions of the southwestern Appalachians and in river valleys.

Broad-leaved summergreen forests are extremely limited in the Southern Hemisphere. In conditions very humid climate evergreen deciduous forests prevail, structurally and floristically weakly delimited from subtropical forests, with an even annual temperature variation.

animal population. A well-defined layered structure of broad-leaved forests, the presence of a closed tree layer up to 30 m above the ground, abundant litter, and a thick humus horizon provide a full range of layers of the animal population of this biome.

Warm humid summers and cold winters snow cover determine a clear seasonal dynamics of animal activity. For the winter, poikilothermic animals fall into a state of suspended animation. Of the homoiothermic animals (birds and mammals), some migrate to more warm regions, others fall into hibernation or winter sleep, and only a few retain year-round activity, switching to specific foods (bark and branches of trees, insects sleeping under the bark, etc.)

The litter of trees and shrubs forms a thick layer of litter. Waste management activities plant mass in broad-leaved forests, an extensive and diverse group of saprophagous animals is carried out, among which the leading role is played by earthworms Lumbricidae family. Together with saprophages, the soil layer is inhabited by consumers of the living root mass of plants. These include insect larvae, mainly beetles: hard, densely covered larvae of click beetles, called wireworms, white fat larvae of lamellar beetles, living in the soil for several years before pupation. Of these, the larva of the May beetle is the most typical.

In the lower and middle parts of the forest stand, xylophagous insects - consumers of wood - settle in the trunks and branches of trees. These are larvae of longhorn beetles, lamellar (for example, large larvae of a stag beetle). The bark is eaten by the larvae of borers. In the crowns of deciduous trees, insects are abundant that eat the green tissues of the leaves. Caterpillars of various butterflies dominate among them: moths, silkworms, leafworms, larvae (false caterpillars) of sawflies, adult forms (adults) of leaf beetles, beetles, in particular, the already mentioned May beetles. special group phytophagous insects form sap-sucking species - aphids, mealybugs, cicadas, psyllids, cicadas, bugs.

There are also many phytophages among vertebrates. Small rodents live in the ground layer. In the Eurasian forests, this is a forest bank vole, wood and yellow-throated mice, in the broad-leaved forests of North America - outwardly similar to mice, white-legged and golden hamsters.

Large ungulates are involved in the consumption of green mass of foliage, grass, and in winter branch fodder and tree bark. In Eurasia and North America, the red deer is widespread, known in different parts of the range under the name deer, red deer, wapiti (the latter refers to the American red deer). In the Western European sector, the fallow deer joins the deer, and in the Far East, the spotted deer. Unlike deer, the wild boar feeds not only on the aboveground, but also on the underground parts of plants (rhizomes, tubers, bulbs), which he digs up, loosening the litter with his nose and upper layer soil. There he finds and eats all kinds of invertebrates.

Predatory animals - zoophages inhabit all tiers of deciduous forests. Predatory millipedes live in the soil-litter - geophiles and drupes, beetles (ground beetles and rove owls), spiders and predatory mites. Leading place among carnivores

invertebrates are occupied by ants, which build ground nests, but survey all forest tiers in search of food. top Soils are explored in search of food by various moles. Numerous in European forests common mole, in the forests of East Asia - the Moger mole.

In the terrestrial layer, amphibians and reptiles are common: brown frogs, newts and salamanders, especially diverse in the forests of North America, lizards and snakes.

Insectivorous birds gather food mainly in the crowns of trees and in the litter. Thrushes, flycatchers, tits, warblers and warblers are common in the forests of Eurasia. AT american forests thrushes and tits are also common, but the ecological niche of flycatchers is occupied by tyrants, and warblers and warblers are American warblers, or treeworts.

Predatory animals are characteristic of both the terrestrial and arboreal stages. In the terrestrial - predators live, widely settling outside the broad-leaved forests: fox, wolf, Brown bear(in the past), ermine and weasel. On the Far East a black bear and a raccoon dog (now introduced into European forests) live, in North America - a baribal bear close to black. The tree layer is used by a lynx, a wild forest cat, it constantly keeps pine marten, in the Far East - kharza.

Long-term and intensive agricultural development of the regions of broad-leaved forests has led to a sharp depletion of their animal population, to the complete disappearance of many species, especially large vertebrates. Grain-eating rodents multiplied strongly on arable lands. We can judge the primary population of animals in these communities from historical data and from the remains of natural biocenoses in the territories of reserves and in remote, poorly developed areas.

Biomass reserves in broad-leaved forests of temperate latitudes are very high - 500-400 t/ha. The production of broad-leaved forests is also high - from 10 to 30 and even 50 t / ha per year, which is explained by favorable warm and wet conditions growing season. The thickness of the soil and litter layers provides food for a huge number of soil animals. It is mainly due to them that the zoomass in these forests can reach 1 t/ha or even more, which exceeds the zoomass reserves in most other land biomes.