Dynamics of number of populations

Even in the seventeenth century. noticed that the populations growing exponentially according to the law, and at the end of the eighteenth century. Thomas Malthus proposed his famous theory about population growth exponentially.

Thus, the exponential population growth - this increase in the number of individuals in its unchanging conditions.

The impact of environmental factors on the rate of population growth can bring to a stable population size, or reduce it, ie exponential growth slows or stops completely and J-shaped curve of exponential growth as it stops and flattens, becoming the so-called S-shaped curve.

In nature, what happens: the exponential growth observed a fairly short time, after which it stabilized constraints and further development of the population follows the logistic model, which describes an S-shaped or logistic population growth. K value is also called the capacity of the environment in respect of individuals of a given population. We are talking about the biological carrying capacity - the ability of natural power or natural- human environment to ensure normal functioning (breathing, feeding, reproduction, recreation, etc.) a specific number of organisms and their communities without significant violations of the environment.

Численность населения в общей сложности особей неограниченного взгляд, присутствующих в той или иной территории.

Численность населения - важная экологическая характеристика населения. Особей в популяции число имеет огромный эволюционный значение. Но общее количество лиц в популяции, и эффективное число - репродуктивное число - та часть населения, которая формирует генофонд следующего поколения (генетически эффективные размеры) важно не.

Для человека, эффективное число равно 45, для домовой мыши - 10, для москитной аёдес и плодовых мушек - 500, для моллюска цепея неморалис - 230, для мокрица (по суше рака) - 19 лиц.

Колебания численности

Среднее число большинства крупных популяций меняется из года в год немного, потому что:

каждый год одинаковое количество лиц погибает примерно;

организмы размножаются более интенсивно1 в меньшей плотностью населения и менее интенсивно на большую плотность;

различные факторы окружающей среды противодействовать высокий репродуктивный потенциал населения. Изменение условий жизни является основными причинами колебаний численности популяций: изменение действия абиотических факторов окружающей среды, изменение межвидовых отношений (врагов, паразитов), изменение количества и качества корма. Изменение численности населения развивается за счет таких явлений: рождаемость, смертность, установки (иммиграционные) и выселение (эмиграция).

Динамика численности населения__

Даже в семнадцатом веке. заметил, что население растет в геометрической прогрессии в соответствии с законом, и в конце восемнадцатого века. Томас Мальтус предложил свою знаменитую теорию о росте населения в геометрической прогрессии.

Таким образом, экспоненциальный рост населения - это увеличение количества лиц и организаций в своих неизменных условиях.

Влияние экологических факторов на темпы роста населения может привести к стабильной численности населения, или уменьшить его, то есть экспоненциальный рост замедляется или прекращается полностью и J-образная кривая экспоненциального роста, поскольку это останавливается и объединяет, став так называемым S -образная кривая.

В природе, то, что происходит: экспоненциальный рост наблюдается1 довольно короткое время, после чего стабилизировалась ограничений и дальнейшее развитие населения следует логистическую модель, которая описывает в S-образную или логистическую рост населения. Величина К называется также способность окружающей среды в отношении особей данной популяции. Мы говорим о биологической грузоподъемности - способность природного власти или природно-человеческой среды для обеспечения нормального функционирования (дыхание, питание, размножение, отдых и т.д.) определенное количество организмов и их сообществ без существенных нарушений окружающей среды.

/23/ Demographic structures, their importance for the control of stability of human populations

Structure of populations.

The knowledge of structure of population allows the researcher to draw conclusions on her wellbeing or trouble. For example, if in population are absent generative (that is capable to give posterity) individuals and thus many old-age (senile) individuals, it is possible to make the adverse forecast. At such population can not be the future.

Age structure of population. This type of structure is connected with a ratio of individuals of various age in population. The individual of one age can unite in cohorts, that is age groups.

The age structure of populations of plants is described very in detail. In it allocate (according to T.A.Robotnova) the following age (age groups of organisms):

• the latent period - a condition of a seed;

• the pregenerativny period (includes conditions of a sprout, a juvenile plant, an immaturny plant and a virginilny plant);

• the generative period (it is usually subdivided into three subperiods - young, mature and old generative individuals);

• the post-generative period (includes conditions of a subsenile plant, a senile plant and a dying off phase).

Sexual structure of population. The sexual structure, that is ratio of floors, has a direct bearing on reproduction of population and its stability.

It is accepted to allocate primary, secondary and tertiary ratio of floors in population. Primary ratio of floors is defined by genetic mechanisms - uniformity of a divergence of sexual chromosomes. For example, at the person of a XY chromosome define male development, and XX - female. In this case primary ratio of floors 1:1, that is ravnoveroyatno.

The secondary ratio of floors is a ratio of floors at the time of the birth (among newborns). It can differ significantly from primary for a number of reasons: selectivity of ova to the spermatozoa bearing X-or a Y-chromosome, unequal ability of such spermatozoa to fertilization, various external factors.

The tertiary ratio of floors is a ratio of floors among adult animals.

Структура популяций.

Знание структуры населения позволяет исследователю сделать выводы о ее благополучии или неприятности. Например, если в популяции отсутствуют генеративные (то, что способно дать потомство) лиц и, таким образом, много по старости (старческие) лиц, можно сделать негативного прогноза. При таком населения не может быть будущего.

Возрастная структура населения. Этот тип структуры связан с соотношением особей разного возраста в популяции. Индивидуальный одного возраста1 могут объединяться в когорт, то есть возрастные группы.

Возрастная структура популяций растений описана очень подробно. В ней выделяют (по TARobotnova) следующий возраст (возрастные группы организмов):

• латентный период - состояние семени;

• pregenerativny период (включает условия росток, несовершеннолетних завода, в immaturny завода и virginilny завода);

• порождающая период (как правило, подразделяются на три подпериоды - молодые, зрелые и старые генеративные лиц);

• пост-генеративных период (включает условия в субсенильные завода, старческого основных умирающего от фазы).

Половая структура населения. Половой структура, то есть соотношение полов, имеет прямое отношение к воспроизводству населения и его стабильности.

Принято выделять первичную, вторичную и третичную соотношение количества этажей в популяции. Первичная отношение полов определяется генетическими механизмами - равномерность расхождения половых хромосом. Например, у человека хромосомы XY определить мужской развития и XX - женщины. В этом случае1 первичной соотношении полов 1:01, то есть ravnoveroyatno.

Вторичный отношение полов представляет собой отношение этажей на момент рождения (среди новорожденных). Это может значительно отличаться от основной для ряда причин: селективность яиц в сперматозоиды подшипника Х-или Y-хромосомы, неравное способности такого сперматозоидов к оплодотворению, различных внешних факторов.

Третичный соотношение полов представляет собой отношение полов среди взрослых животных.

/24/ Static properties of the population: density, structure, degree of isolation

Density — number of individuals per unit area or volume. At increase in number population density, as a rule, increases; it remains former only in case of its moving and area expansion.

The spatial structure of population is characterized by features of placement of individuals in the occupied territory. It is defined by properties of a habitat and biological features of a look. Along with casual and uniform distribution in the nature group distribution most often meets. Group of animals, making joint efforts, it can easier be protected from predators, look for and get a forage. Life in families, herds, colonies, harems leads also to group distribution of individuals. The spatial structure can change in time; it depends on a season of year, on the number of population, age and sexual structure etc.

The sexual structure reflects a certain ratio of man's and female individuals in population. The genetic mechanism of definition of a floor provides posterity splitting on a floor in the ratio 1: 1.

Change of sexual structure of population is reflected in its role in an ecosystem as males and females of many types differ from each other on nature of a food, a life rhythm, behavior, etc. So, females of some species of mosquitoes, pincers and midges are blood-sicking while males eat juice of plants or nectar. Prevalence of a share of females over males provides more intensive growth of population.

The age structure reflects a ratio of various age groups in the populations, depending on life expectancy, time of approach of a sexual maturity, number of descendants in a dung, quantities of posterities during the season, etc. If any age group is reduced or increases, it affects the total number of population..

Extent of geographical isolation. Isolation can be absolute. For example, the populations of polar foxes living on the Commander Islands and on Kamchatka, don't exchange individuals as are divided by the nonfreezing passage. However isolation depends not only on a spatial arrangement of geographical barriers, but also on the radius of individual activity - distance on which individuals during reproduction are capable to move. If the radius of individual activity is insignificant in comparison with the sizes of population and distance between the next populations, degree, or pressure, isolation will be big. For example, the populations of land mollusks removed from each other on 200-400 m, will exist separately as their individual mobility is limited. And polar foxes can migrate on ices of the Arctic on hundreds kilometers, and as a result isolation of polar foxes of Wrangel Island from populations of polar foxes of Chukotka is very insignificant. If the radius of individual activity allows individuals of the next populations to overcome distance between them (extent of isolation insignificant), these populations will gain the general properties because of full movement of a genetic material soon. So, ducks of one look occupy an area equal nearly to all Europe, and are freely crossed among themselves. Assume that all of them treat one population or very few populations.

Плотность - число особей на единицу площади или объема. При увеличении плотности число населения, как правило, увеличивается, что остается прежним только в случае его перемещения и области расширения.

Пространственная структура населения характеризуется особенностями размещения лиц на оккупированной территории. Она определяется свойствами среды обитания и биологические особенности 2взгляда. Наряду с случайных и равномерного распределения в распределении природа группы наиболее часто встречается. Группа животных, делая совместные усилия, легче могут быть защищены от хищников, искать и получить корм. Жизнь в семьях, стада, колонии, гаремах приводит также к распределению группы лиц. Пространственная структура может изменяться во времени и зависит от сезона года, от количества населения, возраста и сексуальной структуры и т.д.

Половой структура отражает определенное соотношение мужских и женских особей в популяции.Генетический механизм определения пола обеспечивает потомство расщепление на полу в соотношении 1: 1.

Изменение половой структуры населения находит свое отражение в его роли в экосистеме, как самцы и самки многих видов отличаются друг от друга по характеру пищевого продукта, ритма жизни, поведения и т.д. Так, самки некоторых видов комаров, клещей и мошки кровососущих то время как мужчины едят сок растений или нектаром. Распространенность доли женщин старше мужчин обеспечивает1 более интенсивный рост населения.

Возрастная структура отражает соотношение различных возрастных групп в популяциях, в зависимости от продолжительности жизни, время наступления половой зрелости, число потомков в помете, количество потомства в течение сезона, и т.д. Если любой возрастной группы снижается или увеличивается, это влияет на общее количество населения..

Протяженность географической изоляции. Изоляция может быть абсолютным. Например, население песцов, живущих на Командорских островах и на Камчатке, не обмениваются лиц как делятся на незамерзающей прохода. Однако изоляция зависит не только от пространственного расположения географических барьеров, но и от радиуса индивидуальной активности - расстояние, на котором индивидуумы во время воспроизведения способны перемещаться. Если радиус индивидуальной активности, является незначительным по сравнению с размерами населения и расстояния между соседними населения, степени или давления, изоляции будет большим. Например, популяции наземных1 моллюсков удаленных друг от друга на 200-400 м, будет существовать отдельно, как их индивидуальные подвижность ограничена. И песцы могут мигрировать на льдах Арктики на сотни километров, и, какизоляция результат песцов о-ва Врангеля из популяций песцов Чукотки очень незначительна. Если радиус индивидуальной активности позволяет людям из следующих групп населения, чтобы преодолеть расстояние между ними (степени изоляции незначительной), эти группы населения в скором времени получить общие свойства из-за полного движения генетического материала. Так, утки одного взгляда занимают площадь, равную почти на всю Европу, и свободно пересек между собой. Предположим, что все из них лечения одного население или очень мало населения.

/25/ Ecosystems, their classification, their properties__

The biocenosis and its biotope make two indissoluble elements, operating at each other and forming more or less steady system called by an ecosystem (Tensli, 1935). Differently, the ecosystem consists of two components. One of them – organic, is a biocenosis occupying it, another inorganic, i.e. a biotope giving a haven to this biocenosis.

From the point of view of a land relief, and also with climatic, botanical and zoological, soil, hydrological and geochemical, the ecosystem is to a certain extent uniform. Intensity of an exchange of substance and energy between components of an ecosystem makes one of its distinctive signs. In the thermodynamic relation the ecosystem belongs to open systems, rather stable in time. The elements arriving in an ecosystem, solar energy, mineral substances of the soil and atmosphere gases, water are; the leaving elements leaving an ecosystem, heat, oxygen, carbon dioxide and other gases, humus and the biogene substances transferred by water, etc. are.

The majority of ecosystems developed during long evolution and grows out of the adaptation of types to environment. Ecosystems possess self-control and are capable to resist, at least in known limits, to changes of surrounding conditions and sharp fluctuations of density of populations.

The lake can be an ideal example of an ecosystem. This accurately limited community, which various components are unseparably connected with each other and are objects of numerous interactions.

2. Classification and types of ecosystems. The term "ecosystem" is applicable to interaction of biocenoses and biotopes of the various size. Thus distinguish:

• the microecosystems similar to a trunk of the lost tree;

• mesoecosystems, for example wood or pond;

• macroecosystems, such, as ocean;

• megaecosystems, the biosphere uniting all existing ecosystems.

Ecosystems are classified and by other signs. For example, allocate natural and artificial ecosystems. Classification by biomes is widely used. This term designates the large regional ecosystem, being characterized any main type of vegetation or other characteristic of a landscape. Razlichayutnazemnye biomes (tundra, boreal coniferous forests, listopadny wood of a moderate zone, steppe, savanna, desert, evergreen tropical rain forest), fresh-water ecosystems (standing, fluid, boggy), marine ecosystems (pelagic, coastal).

Transition from one ecosystem to another can be more or less sharp. However in all cases there is a transitional zone which can seize the territory from several meters (a coastal zone of the lake) to tens kilometers (a transitional zone between the woods and steppes). Transitional zone call ecotone. The marshy spaces which are settling down between a pond and land formations surrounding it concern to him, for example; the thickets of a bush separating the wood from a field. The fauna of ecotones and in the specific relation, and chislenno is richer than the next biocenoses as there is a mixture of types. In it manifestation of so-called regional effect consists.

The ecosystem is the system consisting of living beings and the environment of their dwelling united in uniform функцион. the whole.

Main properties:

1) ability to carry out circulation of substances

2) to resist to external influences

3) to make biological production

Биоценоз и его биотоп сделать два неразрывную элементы, работающие друг на друга и образуя более или менее устойчивый систему под названием по экосистеме (Tensli, 1935). Иными словами, экосистема состоит из двух компонентов. Один из них - органические, является биоценоз занимая его, другой неорганический, т.е. биотоп давая убежище, чтобы этого биоценоза.

С точки зрения рельефа земли, а также с климатическими, ботанические и зоологические, почвы, гидрологические и геохимические, экосистема является1 в определенной степени однородности. Интенсивность обмена веществом и энергией между компонентами экосистемы делает один из своих отличительных знаков. В термодинамического соотношения экосистема принадлежит к открытым системам, а стабильные во времени. Элементы, прибывающие в экосистеме, солнечной энергии, минеральных веществ из почвы и атмосферных газов, воды являются; уходящая элементы, выходящие экосистемного, тепло, кислород, углекислый газ и другие газы, перегной и биогенные вещества, переданные1 воды и т.д. являются.

Большинство экосистем разработана в длительной эволюции и вырастает из адаптации видов к окружающей среде. Экосистемы обладают самообладание и способны сопротивляться, по крайней мере, в известных пределах, на изменения окружающих условий и резких колебаний плотности населения.

Озеро может быть идеальным примером экосистемы. Это точно ограничен сообщество, которое различные компоненты нераздельно связаны друг с другом и являются объектами многочисленных взаимодействий1.

2. Классификация и типы экосистем. Термин «экосистема» применимо к взаимодействию биоценозов и биотопов различного размера. Таким образом различают:

• в microecosystems похожие на багажнике утраченного дерева;

• mesoecosystems, например дерева или пруд;

• macroecosystems, такие, как океан;

• megaecosystems, биосфера, объединяющая все существующие экосистемы

Экосистемы классифицируются и по другим признакам. Например, выделить естественные и искусственные экосистемы. Классификация по биомов широко используется1. Этот термин обозначает крупный региональный экосистемы, характеризуется любой основной тип растительности или другой характеристике ландшафта. Razlichayutnazemnye биомы (тундра, бореальные хвойные леса, listopadny древесина умеренной зоны, степи, саванны, пустыни, вечнозеленые тропические леса), пресноводные экосистемы (стоя, жидкости, заболоченная), морские экосистемы (пелагических, прибрежные районы).

Переход от одной экосистемы в другую может быть более или менее острые. Однако во всех случаях есть переходная зона1, которая может захватить территорию от нескольких метров (прибрежная зона озера) до десятков километров (переходной зоне между лесами и степями). Переходная зона вызов экотон. Болотистые пространства, располагающиеся между прудом и земельных образований, окружающих его озабоченность ему, например; зарослях кустарника, разделяющей древесину от поля. Животный мир экотонов и в конкретном отношении, и chislenno богаче ближайшие биоценозов как есть смесь разных типов. В нем проявление так называемого регионального1 эффекта состоит.Экосистема является система, состоящая из живых существ и среды их обитания, объединенных в единую функцион. вся.

Основные свойства:1) способность выполнять циркуляцию веществ2) противостоять внешним воздействиям3) сделать биологическую продукцию

/26/ Ecosystems, biogeocoenosis, biocenosis

Ecosystem - a system consisting of living beings and their habitats united in a single Funktsional. whole.

Biogeocenosis — the system including community of live organisms and closely related set of abiotic factors of the environment within one territory, connected among themselves circulation of substances and an energy stream. Represents steady self-regulating ecological system in which organic components are inseparably linked with inorganic. Examples: pine wood, mountain valley. The doctrine about a biogeocenosis is developed by Vladimir Sukachyov in 1940. In foreign literature — малоупотребимо. Earlier it was also widely used in the German scientific literature.

Therefore biogeocenoses usually are considered as a special case of an ecosystem. Different authors in term definition a biogeocenosis list concrete biotic and abiotic components of a biogeocenosis while definition of an ecosystem has more the general character

Biocenosis — historically developed set of plants, animals, the microorganisms occupying a site of a land or a reservoir (biotope). Not the last role in formation of a biocenosis is played by the competition and natural selection. The main unit of a biocenosis — a konsortion as any organisms are to some extent connected with autotrophs and form difficult system консортов a various order, and it is a network is konsorty the increasing order and can indirectly depend on the increasing number of determinants of konsortion.

Biocenosis division on фитоценоз and зооценоз is also possible. Fitotsenoz — is set of vegetable populations of one community which form determinants of konsortion. Zootsenoz — is set of populations of animals which are консортами a various order and serve as the mechanism of redistribution of substance and energy in an ecosystem (see functioning of ecosystems).

The biotope and biocenosis together form a biogeocenosis/ecosystem.

Экосистема - это система, состоящая из живых существ и среды их обитания, объединенных в одном Функцион. Весь.

Биогеоценоз - система, включающая сообщества живых организмов и тесно связаны набором абиотических факторов окружающей среды в пределах одной территории, связанных между собой круговорот веществ и поток энергии. Представляет устойчивый саморегулируемую экологическую1 систему, в которой органические компоненты неразрывно связаны с неорганическими. Примеры: сосновый лес, горная долина. Учение о биогеоценоза разработан Владимир Сукачев в 1940 году. В зарубежной литературе - малоупотребимо. Ранее было также широко используются в немецкой научной литературе.

Поэтому биогеоценозы обычно рассматриваются как частный случай экосистемы. Различные авторы в срок определения список биогеоценоз бетон биотических и абиотических компонентов из биогеоценоза в то время как определение экосистемы имеет более общий характер

Биоценозы - исторически сложившаяся совокупность растений, животных, микроорганизмов, населяющих участок суши или водоема (биотоп). Не последнюю роль в формировании биоценоза играет конкуренции и естественного отбора. Основной единицей биоценоза - konsortion также любые организмов в некоторой степени связано с автотрофами и образуют сложную систему консортов различных заказов, и это сеть konsorty порядке возрастания и может косвенно зависеть от большего числа факторов, определяющих konsortion.

Биоценозы разделение на фитоценоз и зооценоз также возможно. Fitotsenoz - это набор растительных популяций одного сообщества, которые образуют детерминанты konsortion. Zootsenoz - устанавливается популяций животных, которые консортами различные порядок и служат в качестве механизма перераспределения вещества и энергии в экосистеме (см. функционирование экосистем).

Биотоп и биоценоз вместе образуют биогеоценоз / экосистему.

 

27. The flow of energy, and are perceived molecules of living cells is converted into chemical energy. During photosynthesis, plants use the radiant energy of sunlight to convert substances with low energy content (CO2 and H2O) into more complex organic compounds, where the solar energy is stored in the form of chemical bonds.

Formed in the process of photosynthesis organic matter can serve as a source of energy for the plant itself or move during eating and subsequent uptake from one organism to another: from plants to herbivores, they are - to a carnivorous, etc. Release of organic compounds contained in energy occurs during respiration or fermentation. Destruction used or dead biomass residues carry a variety of organisms belonging to the number of saprophytes (heterotrophic bacteria, fungi, plants and animals, some). They decompose biomass residues for inorganic constituents (salinity) to promote the participation in the biological cycle of chemical elements and compounds that provide regular cycles and production of organic matter. However, the energy contained in food does not commit cycle, and gradually transformed into thermal energy. Ultimately, all absorbed by organisms in the form of chemical bonds solar energy returns to space as heat radiation, so the biosphere needs the influx of energy from outside.

Unlike substances that circulate continuously on different ecosystem units and can always re- enter the cycle, energy can be used only once.

Cycling of matter in nature - it is relatively repetitive (cyclic) related chemical, physical and biological processes of transformation and movement of substances in nature.

The driving forces are the cycle flows of solar energy (and the cosmos as a whole) and the activities of living matter. Because of these forces are moving, concentration and redistribution of huge masses of chemical elements involved green plants through photosynthesis into organic matter of living beings.

Cycling of matter in the ecosystem of the planet maintained a constant influx of new energy portions. However, there is no circulation of energy. Energy - according to the law of conservation, does not disappear, but is transformed during the life of organisms and converted into thermal form dissipates in the environment. At the same time the chemical elements migrating from food from one organism to another, can go in the abiotic environment and re- engage in the autotrophic cycle of life, ie repeatedly move in the cycle.

Biological cycling of matter and flow of energy in the biosphere resemble rotating mill wheel in the fast flowing stream of water.

In the biological cycle of substances biosphere identify several treatment cycles of chemical elements, ie circulation paths substances from the external environment and the organisms in the external environment again. In cycles trace the movement of vital - nutrients - elements such as C, O, H, N, P. Nutrients in different ways alternately move from living matter into inorganic matter, and from it shall revert to the living substance, and thus constantly included in the organisms participating in their life.

All biochemical cycles of the biosphere are not closed. Moreover, each new cycle is not an exact repetition of the previous one, since nature does not remain unchanged. Substances and solar energy are involved in the cycle, but at the same energy as heat goes, scattered in space, and often organic matter out of the cycle in the environment, accumulate in the form of deposits. Therefore, in some Biogeocenoses and the entire biosphere cycles are not closed, and the biosphere itself is open biosystem

LAW Lindeman, 10% rule, the principle Lindemann thermodynamic interpretation of the circulation flow of energy through trophic levels in the ecosystem. Law discovered by Lindemann (1942), according to which the only part (10 %) of the energy received on a certain level trofichichesky biocenosis transmitted organisms at higher levels trofichicheskih. For example, the amount of energy that comes to tertiary carnivores (trophic level V), is about 10-4 of the energy absorbed by producers. This explains the limited number (5 - 6) units (levels) in the food chain under consideration regardless of biocenosis.

 

28. Food chain - closed linear sequence in which every living creature feeds (someone or something) and he is the food for the next body.

The movement of nutrients:

carried out by producers (convert inorganic substances into organic) to Consumers I order (herbivore), then - to the order of the consumer II - predators (carnivores) and final - to decomposers (they, in turn, converting organic matter inorganics is recycled substances in the environment medium), and inorganic substances are returned to producers. Closed system!

living organisms in nature interact with each other is more complex and visually such interaction is more like a network. Such a network is called a food chain.

The movement of energy in ecosystems occurs through two related types of food webs:

grazing and detrital.

In grazing food network live plants eaten by phytophagous and phytophagous themselves are food for predators and parasites.

In detrital food web wastes and dead organisms decompose detritus and destructors to simple inorganic compounds, which are used by plants again

LAW Lindeman, 10% rule, the principle Lindemann thermodynamic interpretation of the circulation flow of energy through trophic levels in the ecosystem. Law discovered by Lindemann (1942), according to which the only part (10 %) of the energy received on a certain level trofichichesky biocenosis transmitted organisms at higher levels trofichicheskih. For example, the amount of energy that comes to tertiary carnivores (trophic level V), is about 10-4 of the energy absorbed by producers. This explains the limited number (5 - 6) units (levels) in the food chain under consideration regardless of biocenosis.

Rule of ecological duplication

The disappeared or destroyed look within one level of an ecological pyramid replaces another, similar. The small look replaces large, below organized – more highly organized, more genetically labile and mutable – less genetically changeable.

 

29. Any organism in the nature doesn't exist out of ecosystems. Also it is shown first of all available a huge number of interrelations of this organism with other organisms and with abiotic factors. These communications – the main condition of life of organisms and their communities. Through these communications mechanisms of circulation of biogene substances, mechanisms of transmission of energy, mechanisms of stability of ecosystems are realized. These communications are so perfected by a course of evolutionary process that violation at least one of them can cause a chain of irreversible consequences up to death of an ecosystem. The person surely has to remember it, interfering with the nature the production activity.

The interrelation between organisms can divide on interspecific and intraspecific. These interrelations are usually classified by "interests" on the basis of which organisms build the relations:

1) food (trophic) communications - form trophic structure of an ecosystem which we already considered earlier; besides the relations when one organisms serve as food to another, here it is possible to carry the relations between plants and insects pollinators of the flowers, the competitive relations because of similar food, etc.; it is the most widespread type of communications;

2) topichesky communications (from the Greek word of top wasps - a place) - are based on features of a habitat, for example, the relations between trees and the birds nesting on them living on them by insects, the relations between organisms and their parasites, etc.;

3) forichesky communications (from the Latin word форас - outside) - the relations on distribution of seeds, fruits, etc.;

4) fabrichesky communications (from the Latin word of a product - production) - use of plants, down, wool for construction of nests, shelters, etc.

Information communications. All living beings are capable to communicate with similar for coordination of the actions and responses to manifestation of factors of the environment. Thus, first, signals used by them are, as a rule, simple and concrete: the danger warning, the message about food, the address to the sexual partner or posterity, etc. Secondly, the distance of their action is limited: from direct physical contact to hundred meters or several kilometers. Thirdly, informative signals are fixed extremely seldom and in the elementary form ("there was I" – through odorous tags). Accumulation of such information, its direct transfer and direct use by the second and subsequent generations are impossible.

 

30.Ecological pyramids. Food networks in each biogeocenosis have well expressed structure. It is characterized by quantity, the size and lump of organisms — a biomass — at each level of a power-supply circuit. For pasturable food chains the increase in density of populations, speeds of reproduction and efficiency of their biomass is characteristic. Decrease in a biomass upon transition from one food level on another is caused by that not all food assimilates konsument. So, for example, at a caterpillar feeding on leaves, in intestines a half of plant material is soaked up only, the rest is allocated in the form of excrement. Besides, the most part of the nutrients which are soaked up by intestines, is spent for breath and only 10 — 15% finally are used on creation of new cages and caterpillar fabrics. For this reason production of organisms of each subsequent trophic level always is less (on the average by 10 times) than production previous, i.e. the mass of each subsequent link in a power-supply circuit progressively decreases. This regularity received the name governed an ecological pyramid.

Distinguish three ways of drawing up ecological pyramids:

1. The pyramid of chislennost reflects a numerical ratio of individuals of different trophic levels of an ecosystem. If organisms within one or different trophic levels strongly differ among themselves by the sizes, the pyramid of chislennost gives the distorted ideas of istinnykhsootnosheniye of trophic levels. For example, in plankton community the number of producers in tens and hundreds times more the number of konsument, and in the wood of one hundred thousands konsumen-tov can feed on bodies of one tree — a producer.

2. The pyramid of a biomass shows quantity of live substance, or a biomass, at each trophic level. In the majority of land ecosystems a biomass of producers, i.e. total mass of plants the greatest, and the biomass of organisms of each subsequent trophic level is less than previous. However in some communities the biomass of konsument of the I order happens more biomass of producers. For example, at oceans where the main producers are monocelled algas with a high speed of reproduction, their annual production in tens and even hundreds times can exceed a biomass stock. At the same time, all production formed by algas so quickly is involved in power-supply circuits that accumulation of a biomass of algas isn't enough, but owing to high rates of reproduction their small stock is sufficient for maintenance of speed of a reconstruction of organic substance. In this regard at the ocean the pyramid of a biomass has the return ratio, i.e. "is overturned". At the highest trophic levels the tendency to biomass accumulation as longevity of predators of a bike, the speed of a turn of their generation, on the contrary, is small prevails, and in their body the considerable part of the substance arriving on power-supply circuits is late.

3. The pyramid of energy reflects the size of a stream of energy in a power-supply circuit. The form of this pyramid isn't influenced by the sizes of individuals, and it will always have a triangular form with the wide basis below as it is dictated by the second law of thermodynamics. Therefore the pyramid of energy gives the most complete and exact idea of the functional organization of community, of all exchange processes in an ecosystem. If pyramids of numbers and a biomass reflect an ecosystem statics (quantity and a biomass of organisms at present), an energy pyramid — dynamics of passing of weight of food through power-supply circuits. Thus, the basis in pyramids of numbers and a biomass can be more or less, than the subsequent trophic levels (depending on a ratio of producers and konsument in various ecosystems). The pyramid of energy is always narrowed up. It is caused by that the energy spent for breath, isn't transferred to the following trophic level and leaves an ecosystem. Therefore each subsequent level always will be less previous. In land ecosystems reduction of quantity of available energy is usually accompanied by decrease in number and a biomass of individuals at each trophic level. Owing to such big losses of energy on creation of new fabrics and breath of organisms of a power-supply circuit can't be long; usually they consist of 3 — 5 links (trophic levels).

 

31. The productivity of ecosystems

The rate of formation of organic matter is called productivity. Distinguish between primary and secondary productivity.

Energy enters the living component of the ecosystem through producers. The rate of accumulation of energy producers in the form of organic matter that can be used in foods, is called the primary product. This indicator is determined the total energy flux through the live component of the ecosystem, and hence the amount (biomass) of living organisms that may exist at its expense in the ecosystem.

In primary productivity distinguish gross and net productivity. Gross primary productivity - is the rate at which plants accumulate chemical energy in photosynthesis. Part of it - about 20% - they are spending on the breath - to maintain their own life, which is then in the form of heat released into the environment and lost to the ecosystem. The rate of accumulation of organic matter producers less the cost of breathing is called net primary productivity. The energy that organisms can use the following trophic levels.

ecological pyramid - this graphical models (usually in the form of triangles), reflecting a number of individuals (pyramid of numbers), the amount of biomass (biomass pyramid) or the energy contained in them (pyramid energy) at each trophic level and indicate the reduction in all indicators increasing trophic level.

There are three types of ecological pyramids.

pyramid of numbers

Pyramid of numbers (number) reflects the number of individual organisms at each level. In ecology numerical pyramid is rarely used, since due to the large number of individuals at each trophic level is very difficult to map the structure of biocenosis in the same scale.

pyramid of biomass

Pyramid of biomass - the relation between producers and consumers, and expressed in their mass (total dry weight, energy content or other measure total living matter). Usually in terrestrial biological communities total weight producing more than of consumers. In turn, the total weight of the first order of consumers is greater than the second order of consumers, etc. If organisms are not too different in size, then the graph is usually obtained with a stepped pyramid tapered tip.

pyramid energy

Pyramid energy reflects the value of the energy flux, the rate of passage of food through the mass of the food chain. On the structure of biocenosis largely affects not fixed amount of energy, and the rate of production of food.

All ecological pyramid built one rule, namely: at the base of the pyramid are all green plants, and the construction of the pyramids considered regular decrease from its base to the top of the number of individuals (pyramid of numbers), their biomass (biomass pyramid) and passing through dietary energy Exalt (pyramid of energy).

 

32. Changes of ecosystems under the influence of internal factors, generally as a result of activity of organisms making them, it is accepted to call a suksessiya.

Thus, the suktsessiya is a consecutive change of communities in this area (in one ecosystem), caused by internal factors for an ecosystem.

Yu.Odum (1975) points to three parameters, characterizing a suktsessiya:

Natural succession

Left alone most habitats in Britain will eventually turn into woodland. Bare earth and rock, will first be colonised by mosses, lichens and plants of sparse ground. Other flowers and grasses will follow, with scrub and trees coming in afterwards. In wetter habitats waterside vegetation is rapidly colonised by tree species.

As vegetation cover increases, there is a build up of soil and nutrients and the early colonisers are overrun by more vigorous plants. As tree cover increases this process accelerates as woodland develops. The early stages of this process support a rich assemblage of flower and insect wildlife which soon disappears as more vegetation develops.

it is the ordered development of community connected with changes in time of specific structure and processes proceeding in community; it is definitely directed and is thus predictable;

the suktsessiya results from change of the physical environment under the influence of community, i.e. the suktsessiya is supervised by community, despite that the physical environment defines character of a suktsessiya, change speed, and often and sets limits which the developed can reach;

the culmination of development is the stabilized ecosystem in which the maximum biomass is the share of unit of an available stream of energy (or high contents of information) and the maximum number of symbiotic communications between organisms.

Stability of an ecosystem - ability of an ecosystem and its separate parts to resist to fluctuations of external factors and to keep the structure and functional features. On the contrary, degree of inability of an ecosystem to resist to harmful external effects means its vulnerability. For example, in this ecosystem the amount of precipitation goes down for 50% in comparison with average annual values, but production of plants decreases thus only by 25%, and the number of population of herbivorous organisms - only for 10%.

Relative attenuation of fluctuations in process of their passing on food chains serves in the environment as a measure of internal stability of an ecosystem - its abilities to resist to changes. Thus stability of an ecosystem can be caused by existence of stocks of moisture in the soil, and in case of rather long drought - partial replacement of grassy plants sensitive to a drought with drought-resistant types. This ability of ecosystems is important when studying consequences of impact on them anthropogenous factors. In particular, the most vulnerable are ecosystems where mosses and the lichens which are most sensitive to pollution of atmospheric air dominate. In ecology the concept of stability is quite often considered as a stability synonym.

 

33. Changes of ecosystems under the influence of internal factors, generally as a result of activity of organisms making them, it is accepted to call a suksessiya.

Thus, the suktsessiya is a consecutive change of communities in this area (in one ecosystem), caused by internal factors for an ecosystem.

Yu.Odum (1975) points to three parameters, characterizing a suktsessiya:

anthropogenic succession

ecological succession, which occur due to human activity. AS caused either by a permanent external factor (grazing, trampling, pollution), or represent the recovery of ecosystems after human disturbance (overgrowing deposits, restoring pastures after the cessation of intensive grazing, forest regeneration on the cutting, etc.). In the modern biosphere 's Certificate play a huge role. Environmental monitoring needs Certificate of Authorship purpose of forecasting their future development and development management approaches 's Certificate to reduce the harm that person causes the biosphere. AS very diverse. They may have different durations (from years to millennia), to be progressive (accompanied by an increase in biological production of ecosystems and their species richness) or regressive (reduced values ​​of these parameters).

Stability of an ecosystem - ability of an ecosystem and its separate parts to resist to fluctuations of external factors and to keep the structure and functional features. On the contrary, degree of inability of an ecosystem to resist to harmful external effects means its vulnerability. For example, in this ecosystem the amount of precipitation goes down for 50% in comparison with average annual values, but production of plants decreases thus only by 25%, and the number of population of herbivorous organisms - only for 10%.

Relative attenuation of fluctuations in process of their passing on food chains serves in the environment as a measure of internal stability of an ecosystem - its abilities to resist to changes. Thus stability of an ecosystem can be caused by existence of stocks of moisture in the soil, and in case of rather long drought - partial replacement of grassy plants sensitive to a drought with drought-resistant types. This ability of ecosystems is important when studying consequences of impact on them anthropogenous factors. In particular, the most vulnerable are ecosystems where mosses and the lichens which are most sensitive to pollution of atmospheric air dominate. In ecology the concept of stability is quite often considered as a stability synonym.

 

34. Primary succession - starting on substrates undisturbed soil-forming processes (rocks, lava, sand dunes). So, after the retreat of the glacier (in the south of Alaska) at this locality primary succession consists of the following stages. At the beginning of settled mosses, which are then replaced by sedges, and creeping shrub willows are replaced by thickets of alder and Sitka spruce, and in the end there is some forest formations (of spruce and hemlock). This is relatively quick succession: alder thicket stage is reached within 10-20 years, and 100 years later the habitat is covered with high fir trees.

Secondary succession - takes place in established biological communities after disturbances (forest fires, deforestation, drought, etc.). J. Odum (1986) gives the example of secondary succession in the Piedmont (USA): in place of abandoned farmland had developed the following steps: weeds (aster, beaver), which were replaced by grasses, then settled with fast-growing pine hardwood (amber, tulip tree) with a touch of oak and hickory, and finally, after 150-200 years it formed climax forest (oak and hickory). The newly created lakes, reservoirs and ponds are now experiencing secondary succession, and they are filled by sediments begin to form terrestrial ecosystems.

Stability of an ecosystem - ability of an ecosystem and its separate parts to resist to fluctuations of external factors and to keep the structure and functional features. On the contrary, degree of inability of an ecosystem to resist to harmful external effects means its vulnerability. For example, in this ecosystem the amount of precipitation goes down for 50% in comparison with average annual values, but production of plants decreases thus only by 25%, and the number of population of herbivorous organisms - only for 10%.

Relative attenuation of fluctuations in process of their passing on food chains serves in the environment as a measure of internal stability of an ecosystem - its abilities to resist to changes. Thus stability of an ecosystem can be caused by existence of stocks of moisture in the soil, and in case of rather long drought - partial replacement of grassy plants sensitive to a drought with drought-resistant types. This ability of ecosystems is important when studying consequences of impact on them anthropogenous factors. In particular, the most vulnerable are ecosystems where mosses and the lichens which are most sensitive to pollution of atmospheric air dominate. In ecology the concept of stability is quite often considered as a stability synonym.

 

35. Homeostasis-relative dynamic constancy of the internal environment (blood, lymph, tissue fluid) and the stability of the basic physiological functions (blood circulation, respiration, thermoregulation, metabolism, and so on) of humans and animals. Regulatory mechanisms that support a physiological state or properties of cells, organs and systems of the whole organism at an optimal level, called homeostatic.

Large ecosystems, and stablest of them – the biosphere are the steadiest, and young ecosystems are most unstable. This results from the fact that in big ecosystems the self-regulating homeostasis at the expense of interaction of circulations of substances and energy streams is created.

At the level of ecosystems the set of types, structure and complexity of the trophic networks, the steadiest forms of interaction between specific populations reflect fitness to the most fundamental features of the environment and are directed on steady maintenance of biogene circulation in these conditions – on homeostasis maintenance. Violations in an ecosystem, environments occurring against invariable average characteristics, cause the functional adaptations of compensatory type keeping basic structure of a biocenosis. For example, the diverse reversible changes of trophic, topichesky or parasitic communications caused by fluctuations of number of separate types. At more essential violation of structure of a biocenosis there are unstable communities replacing each other – process, ideally the leader to restoration of initial type of an ecosystem. Ecological suktsessiya such – one of the brightest expressions of action functional adaptations at the level of biocenoses and homeostasis action.

Various levels of a gomeostazirovaniye of biological systems and the biosphere as a whole developed throughout long geological history of our planet. Recently situation sharply changed: within nearly one-one and a half centuries "scientific and technical explosion" in development of human society led to that activities of mankind for scales of influence on biospheric processes became comparable to the natural factors defining before development of the biosphere.

36. Homeostasis-relative dynamic constancy of the internal environment (blood, lymph, tissue fluid) and the stability of the basic physiological functions (blood circulation, respiration, thermoregulation, metabolism, and so on) of humans and animals. Regulatory mechanisms that support a physiological state or properties of cells, organs and systems of the whole organism at an optimal level, called homeostatic.

Under a biocenosis (from armor. Bios life, ценоз the general) understand set of the live organisms occupying a certain territory and being characterized by certain relations among themselves and adaptations to habitat. The term "biocenosis" was offered by the German hydrobiologist K.Myobius in 1877.

All sum of influences which are made at each other by living beings, call biotic factors. The direct live environment of an organism makes its biotsenotichesky environment. Site of the abiotic environment which occupies a biocenosis, call a biotope.

Scales of biotsenotichesky groups of organisms are various - from communities of lichens on trunks of trees or a decaying stub to the population of the whole landscapes: woods, steppes, deserts, etc.