Ecosystem as a holistic system

 

 

 

 

 

 

 

 

Ecosystem as a holistic system

 

 

Prepared by:  Asangalieva

Dinara

Group: ITM-121 K/R

Checked by: Professor Kolbay I.S.

 

 

 

 

 

 

 

 

Almaty, 2012

Contents.

 

Introduction

 

I. The concept of the ecosystem.

II. Interrelations between Water cycle, Nitrogen cycle, Oxygen -Carbon cycle and anthropogenic factor.

  1. Water cycle

               2. Nitrogen cycle

               3. Oxygen cycle

               4. Carbon cycle

III. Self-sustaining mechanisms in ecosystems.

IV. Main changes in stocks caused by human activity.

               1. Abiotic factors

               2. Biotic factors

V. Homeostasis: maintaining the balance.

 

Conclusion

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Introduction.

 

     Ecology considers the interaction of living organisms and inanimate nature. This interaction is, first, is within a specific system (ecosystem), and second, it is not chaotic, but definitely organized by law.

     Ecosystem is the set of producers, consumers and decomposers, which interact with each other and with their environment by means of exchange of matter, energy and information in such a way that this one system is stable for a long time.                      Ecosystem necessarily represents the totality of living and non-living components.

     This report will consider the following items:

1) Within the ecosystem biogeochemical cycles are carried out. All cycles are interrelated.

2) The sustainable development of the ecosystem necessary self-sustaining mechanisms.

3) One of the main factors affecting on impaired balance in the ecosystem is the anthropological factor. The human impact on the environment is huge. In the modern world the person is no longer simply consumer who use natural products and, because the labor activity started to make products to himself. To survive in the natural environment people have to build its artificial human systems. To meet all of their evolving needs, they have to alter natural ecosystems and even destroy them.

4) Ecosystem is stable over time, which provides a certain structure of the biotic and abiotic components. Ecosystem as a whole is able to maintain stability at a relatively stable external environment and change as a result of changes in the environment and in the ecosystem itself. This revealed the meaning of homeostasis.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I. The concept of the ecosystem.

      

       Anywhere on the earth's surface dwells always complex species. In view of a rapidly deteriorating insulation condition of their existence, so the natures of individuals always live in the communities. Ecosystems, as well as population-based system, other than the "biological properties" inherent individual organisms possess a number of features that characterize the community at large. In addition, they have qualitatively new and unique features, the lack of a population system, part of them. Community - not just the sum of its constituent species, but also the totality of interactions between them, so it has emergent properties that are manifested only in the study of his own, but not its constituent populations.

     The first organisms on earth were heterotrophs. They would quickly run out of themselves if autotrophs didn’t appear. In the presence of these groups of organisms is possible primitive material cycle: autotrophs synthesize organic matter, and heterotrophic consume them. This results in the splitting of organic matter. If the cleavage products re-used autotrophs, there cycling between organisms that inhabit the ecosystem.

       Plants synthesize organic compounds using the energy of sunlight and nutrients from the soil and water. These compounds are the building blocks of the plants from which they form their tissues, and a source of energy they need to maintain their functions. In order to release the stored chemical energy of heterotrophs decompose organic compounds not on the original organic compounds - carbon dioxide, water, nitrates, phosphates, etc., thus completing the cycle of nutrients. Thus, the biotic and abiotic parts of the ecosystem connect continuous exchange of material - nutrient cycling, which supplies energy to the sun.

       The above allows us to define an ecosystem as follows: ecological system is a continuous changing any unity that includes all of the organisms on the site and interacting with the physical environment so that a flow of energy creates a trophic structure, species diversity and the cycling of matter in the system. Hence the following three criteria by which one can identify ecosystem: trophic structure, species diversity and the cycling of matter. 

      However, this definition does not take into account the time factor, and this fact is very important, because every ecosystem is developing for a long time, has a history. This aspect is taken into account in a different formulation: ecosystem - the historical system of sharing a certain set of organisms’ living spaces for the nutrition, growth and reproduction.

       Ecosystem - the basic functional unit of nature, because it includes and organisms and the abiotic environment, and each part affects the other and both are necessary to sustain life in the form in which it exists on earth.

       As a first approximation biotic part of the ecosystem must include the two main components: 1) the autotrophic component, characterized fixation of light energy, the use of simple inorganic substances, the construction of complex organic substances, and 2) the heterotrophic component, which is characterized by utilization of complex organic substances, their decomposition and reconstruction.

       In the second approximation in any ecosystem include the following components: 1) inorganic materials (carbon, nitrogen, carbon dioxide, water) that come in cycles, and 2) organic compounds (proteins, carbohydrates, lipids), linking the biotic and abiotic parts and 3) the climate regime (temperature and other physical factors), and 4) producers - autotrophic organisms, mainly green plants are able to create food from simple inorganic substances, 5) consumers - heterotrophic organisms, mainly animals that eat other organisms or particles of organic matter, and 6) decomposers - heterotrophic organisms, mainly bacteria and fungi that break down complex compounds into simple, suitable for use by producers.

         The first three groups - non-living components, and the rest are live weight - biomass. Location of the last three components of the flow of the solar energy is the structure of the ecosystem. Ecosystem structure consists of three levels (producers, consumers, decomposers) transformation of the energy cycle, and two - solid and gaseous substances .In ecosystem structure and function are embodied all activity of organisms included in this biotic community: the interaction with the physical environment and with each other. However, organisms live for themselves, and not to play any role in the ecosystem. Ecosystems are composed of properties due to the activity of its member plants and animals. Only with this in mind, we can understand the structure and function, and the fact that the ecosystem as a whole respond to changes in environmental factors.

 

II. Interrelations between Water cycle, Nitrogen cycle, Oxygen -Carbon cycle and anthropogenic factor.

 

Nutrients are recycled in global biogeochemical cycles. In these cycles, nutrients alternate between organisms and the environment. Humans can disrupt nutrient cycles in many ways, with profound impacts on ecosystems.

 

 

1. Water Cycle.

      

      Water is a part of a global recycling network known as a hydrological cycle or water cycle. The water cycle runs day and night, free of charge, collecting, purifying, and distributing water. Along its way, it serves humans and other living creatures in a multitude of ways.

The water cycle is a process by which water travels in a sequence from the air to Earth and returns the atmosphere. It moves through cloud formation in the atmosphere, precipitation, interception, and infiltration into the ground. The basic cycle consists of water rising to the atmosphere through evaporation and transportation and returning to the land and oceans through condensation and precipitation.

      The evaporation occurs when water molecules escape from surface waters, soil, and plants, becoming suspended in air. As the water molecules absorb energy from the sunlight, the kinetic energy they gain may be enough to allow them to break away from other water molecules entirely and enter the atmosphere. When water molecules depart, they leave behind impurities. The result of evaporation is  water vapor – water molecules in a gaseous state. The amount of water vapor in the air is the humidity. Humidity can be absolute and relative.  Condensation is the opposite of evaporation. It occurs when water molecules rejoin by hydrogen bonding to form liquid water. If the droplets form in the atmosphere, the result is a fog and clouds. If the droplets form on the cool surfaces of vegetation, the result is dew.

      Water that has evaporated eventually returns to the Earth through precipitation, this continuing the water cycle. Precipitation forms: rain, drizzle, snow, hail, sleet. Precipitation returns water to lakes, rivers, streams, or groundwater.

While the water cycle is itself a biogeochemical cycle, flow of water over and beneath the Earth is a key component of the cycling of other biogeochemical cycles. Runoff is responsible for almost all of the transport of eroded sediment and phosphorus from land to water bodies. The salinity of the oceans is derived from erosion and transport of dissolved salts from the land. Both runoff and groundwater flow play significant roles in transporting nitrogen from the land to water bodies. Runoff also plays a part in the carbon cycle, again through the transport of eroded rock and soil.

       Today, human activities affect almost all types of biogeochemical cycles. The main types of human impact on the water cycle is the increase in water consumption, including consumption irretrievable, the regulation regime of river water, the direction of flow, the construction of reservoirs. The results are an increase in precipitation in the industrial areas, due to tiny particles that accelerate water condensation. Also, this increase of water flow through the destruction of the vegetation cover, which keeps the water seeping into the ground, the result can be - flooding.

 

Table 1. Activity of water exchange in the hydrosphere:

 

Part of the Hydrosphere	Capacity, thousand km3	Active water exchange, the number of years
Ocean Groundwater (Including the zone of active Water exchange) Polar glaciers Surface water land River Soil moisture Water vapor atmosphere	1370000  60000  4000  24000  280  1,2  80  14	3000  5000  300  8000  7  0,03  1  0,027
All hydrosphere	1454000	2800

 

Data on the water cycle in the world allow us to calculate the activity of water exchange in various parts of the hydrosphere

 

 

 

2. Nitrogen Cycle.

 

      Nitrogen is an element that is essential to many important biological molecules, including amino acids, DNA and RNA.  Nitrogen is high demand by both aquatic and terrestrial plants. The nitrogen cycle is closely linked to the carbon cycle. Typically, nitrogen follows the carbon with which it is involved in the formation of protein substances.

      The main reservoir of nitrogen is the air, which is about 78 % nitrogen gas (N₂).The conversation of nitrogen to ammonia is known as a  nitrogen fixation. A number of bacteria and cyanobacteria can use nonreactive N and fix it.  Then ammonia is converted to nitrite, then to nitrate and reused. Denitrification is a microbial process that occurs in soils and sediments depleted of oxygen. And the denitrifying bacteria can take nitrate and use it as a substitute for oxygen. In so doing, the nitrogen is reduced to nitrogen gas and released back into the atmosphere.

       Humans alter the nitrogen cycle in a least four ways: 1) by applying excess nitrogen-containing fertilizer on farmland, much of which ends up in waterways; 2) by disposing of nitrogen-rich municipal sewage in waterways; 3) by raising cattle in feedlots adjacent to waterways; and 4) by burning fossil fuels, which release a class of chemicals known as nitrogen oxides into the atmosphere.

 

3. Oxygen Cycle.

 

      The major source of free oxygen that supports life is the atmosphere. There are two significant sources of atmospheric oxygen. One is breakup of water vapor through a process driven by sunlight. In this reaction, the water molecules are disassociated to produce hydrogen and oxygen. The other source of oxygen is photosynthesis.    Oxygen is produced by photosynthesis autotrophs and consumed by autotrophs and heterothrophs. Undercomposed organic matter in the form of fossil fuels and carbon in sedimentary rocks represent a net positive flux of oxygen to the atmosphere.  The other main reservoirs of oxygen are water and carbon dioxide.   All the reservoirs are linked through photosynthesis. Oxygen is also biologically exchangeable in such compounds from as nitrates and sulfates, which organisms transform from ammonia and hydrogen sulfide.

Because oxygen is so reactive, its cycling in the ecosystem is complex. As a constituent of carbon dioxide, it circulates throughout the ecosystem. Some carbon dioxides combine with calcium to form carbonates. Oxygen combines with nitrogen compounds to form nitrates. In these states, oxygen is temporarily withdrawn from circulation.

      Anthropogenic carbon dioxide released into the atmosphere, thus destroying the ozone layer, creating a greenhouse effect (along with other gases: such as oxides of nitrogen, CH₄,). The main consumer of carbon dioxide is a plant that is photosynthesis. Burning of fossil fuels, deforestation, reduction of vegetation, forest fires lead to a reduction of the gas processing photosynthesis and increase its concentration in the atmosphere. As a result of photosynthesis produces a huge amount of oxygen, which leads to a balance of the gas in nature, it is possible to breathe freely to all living beings on the planet. In general, the impact of anthropological factors on the cycling of oxygen in nature - it is the decline in the oxygen reduction of its natural resources.

      Oxygen and carbon cycles are usually linked and the two cycles are collectively called oxygen-carbon cycle. The movement of carbon and oxygen between the atmosphere, oceans, plants, animals and the ground is called the oxygen-carbon cycle. It moves from organisms to plants and back again and again.

 

4. Carbon Cycle.

     

       Carbon is a basic constituent of all organic compounds, is involved in the fixation of energy by photosynthesis. The source of all carbon is carbon dioxide in the atmosphere and the waters of Earth.  Carbon dioxide in the atmosphere is absorbed by plants and passed through the food chain. It released back into the environment as a result of the decomposition of the waste and dead remains of plants, animals, and other organisms. It is also released by cellular energy production and the combustion of organic materials such as coal, oil, gasoline and wood.

Since the industrial revolution, human activity has modified the carbon cycle by changing its component's functions and directly adding carbon to the atmosphere.

       The largest and most direct human influence on the carbon cycle is through direct emissions from burning fossil fuels, which transfers carbon from the geosphere into the atmosphere. Humans also influence the carbon cycle indirectly by changing the terrestrial and oceanic biosphere.

      Over the past several centuries, human-caused land use and land cover change has led to the loss of biodiversity, which lowers ecosystems' resilience to environmental stresses and decreases their ability to remove carbon from the atmosphere. More directly, it often leads to the release of carbon from terrestrial ecosystems into the atmosphere. Deforestation for agricultural purposes removes forests, which hold large amounts of carbon, and replaces them, generally with agricultural or urban areas. Both of these replacement land cover types store comparatively small amounts of carbon, so that the net product of the process is that more carbon stays in the atmosphere.

      Other human-caused changes to the environment change ecosystems' productivity and thus their ability to remove carbon from the atmosphere. Air pollution, for example, damages plants and soils, while many agricultural and land use practices lead to higher erosion rates, washing carbon out of soils and decreasing plant productivity.

      Higher temperatures and CO₂ levels in the atmosphere increase decomposition rates in soil, thus returning CO₂ stored in plant material more quickly to the atmosphere.

      Humans also affect the oceanic carbon cycle. Current trends in climate change lead to higher ocean temperatures, thus modifying ecosystems. Also, acid rain and polluted runoff from agriculture and industry change the ocean's chemical composition. Such changes can have dramatic effects on highly sensitive ecosystems such as coral reefs, thus limiting the ocean's ability to absorb carbon from the atmosphere on a regional scale and reducing oceanic biodiversity globally.

 

III. Self-sustaining mechanisms in ecosystems.

 

         Ecosystem resilience is the ability of ecosystems to maintain the structure and changes in the normal functioning of the environmental factors. Organisms adapt to changes in environmental factors to some extent, provide stability of ecosystems in which they belong, to a change in environmental factors of the environment.     However, as any more complex system, the ecosystem compared to the individual species of organisms have a higher degree of operational reliability in a changing environment, as at the system level are formed and developed new mechanisms to ensure system stability and viability of ecosystems, which were absent in some species. Such evolutionarily developed coping mechanisms of ecosystems to changes in habitat called adaptation of ecosystems.

      Consider the adaptation of ecosystems, consisting of adaptive mechanisms of two levels: the species level and the integration or system level. Species (lower) level of an appropriate mechanism in the "adaptation to the changing environmental factors." Form a system level adaptive mechanism that occurs due to the interaction of the species on the trophic chains and networks. The nature of this integration, system mechanisms for ecosystem sustainability is based on the cycle of matter, which is carried out by means of trophic chains.

     The existence of biogeochemical cycles creates an opportunity for self-regulation of ecosystems (or homeostasis), which gives the ecosystem stability over long periods. For example, the indicator of the strength of the global ecosystem associated with the cycling of matter is the following fact. It is known that 93% of body weight is 4 chemical elements: oxygen, carbon, hydrogen and calcium, which are, first, to include in the list of the eleven most common in geospheres earth chemical elements, and second, the four elements themselves form more than 56% of the mass geosphere.

     Species diversity - also one of the mechanisms of resilience of ecosystems to environmental stress. Diversity provides both a safety net, duplication stability. For example, the small form under unfavorable conditions for another broad-based form can dramatically increase their numbers, and thus fill the vacant space (ecological niche), keeping the ecosystem as a whole. This sequential change of the replacement of one or the other is called the ecological community succession.

 

IV. Main changes in stocks caused by human activity.

 

1. Abiotic Factors 

 

       Some human activities produce pollutants that contaminate the air, water and land, changing the chemical composition of the environment. Some air pollutants alter the climate. Changes to the chemical environment and the climate have profound impacts on other species as indicated by the lines connecting air pollution, water pollution, land pollution, and climate to plants, humans, and nonhuman animals.     These may stress organisms, making survival problematic. These may also impair reproduction, which lessens a population’s changes of survival; or they may kill organisms outright.  Some chemical pollutants may be identical to naturally occurring substances found in the environment. If their concentrations exceed an organism’s range of tolerance it may suffer. Nitrates and phosphates released from sewage treatment plants are good examples. Other chemical pollutants from human sources are entirely foreign to natural systems. 

       Pollution from human activities can also affect the physical conditions of ecosystems. Human activities often alter the chemical and physical nature of the environment; that is, the abiotic conditions, with profound effects both on us and on the species that share this planet this us.

 

2. Biotic factors

 

     Humans tamper directly with the biotic components of the natural world in many ways. We destroy habitat or severely alter it when we build homes and highways.       We impact on biotic components of ecosystems through introduction of foreign species, elimination of predators. Many human activities have a direct effect on the biotic components of ecosystems. Introduction of foreign species is particularly troublesome because these species may proliferate without the control, causing major economic and environmental damage.

     Human actions reduce degree isolation of biogeochemical cycles. Although it is quite high (for different elements and substances it is not the same), but still not absolute, as shown by the example of oxygen atmosphere.

Otherwise would have been impossible evolution (the highest degree of isolation of biogeochemical cycles observed in tropical ecosystems - the oldest and most conservative).

    Thus, we should not talk about changing the person that is not should be changed, but rather the human influence on the speed and direction changes and to expand their boundaries, break the rules measure conversion nature. Recently stated as follows: in the course of operation natural systems cannot exceed certain limits that allow these

The system saves the properties of self-maintenance. Violation measure as in a side increase or to decrease leads to negative results. For example, excess fertilizer as bad as it disadvantage. A sense of proportion is lost by modern man, who believes that in the biosphere everything is permitted.

 

V. Homeostasis: maintaining the balance.

    

      Ecosystem - historically established system - should not be considered as a simple sum of its parts, as a combination of separate its constituent populations. Ecosystem as a whole is able to maintain stability at a relatively stable external environment and change as a result of changes in the environment and in the ecosystem itself. The ability of the ecosystem to self-maintenance and self-regulation is called homeostasis. Homeostasis best describe as a fairly constant state. Scientists refer to homeostasis as a state of dynamic equilibrium. This means that conditions are dynamic – ever-changing – but they stay more or less the same over long periods.