Lecture 2 Types of Ecosystem

8/6/2019 Lecture 2 Types of Ecosystem

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LECTURE 2 TYPES OF ECOSYSTEM

ECOSYSTEM

What is an Ecosystem?

An ecosystem is a natural unit consisting of all plants, animals and micro-organisms

(biotic factors) in an area functioning together with all of the non-living physical (abiotic)

factors of the environment.

Within all species, individuals interact with each other - feeding together, mating

together, and living together. Some species have a pecking order as well, and eachindividual has a role to play within it.

However, it is not only individuals within a species that interact. Different species of

animals interact with each other all the time. For instance, animals eat other animals

through their interactions in a food web. But plants are included in this web as well as

they, too, are eaten by animals.

What would happen if the weather were really cold all the time? Well, not all species of

animals, plants and bacteria would be able to survive. What differences are there

between species who live in the Rocky Mountains and those who inhabit the Sahara

desert? Landscape also determines where plants and animals might live. But what,

exactly, is an ecosystem? An ecosystem is a geographical area of a variable size where

plants, animals, the landscape and the climate all interact together.

The whole earth's surface can be described by a series of interconnected ecosystems.

All living beings form and are part of ecosystems. They are diverse and always

changing. Within an ecosystem, all aspects of the environment (both living things and

their non-living settings) interact and affect one another. Every species affects the lives

of those around them.


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A small ecosystem in the boreal forest might look something like this: in the

summertime, trees in forests (that produce oxygen used by living things through

photosynthesis) lower the temperature in the forest for communities in the hot summer

months. In turn, some members of the communities will probably feed upon the tree to

gain nourishment, thus affecting or stunting the tree's growth.

Conclusion

Ecosystem is a natural unit with interacting communities in a habitat usually changing

but it may be balanced without the interference of human. It is well organized with the

organisms forming populations and communities living in niches, habitats in the biome

or biosphere.

HOW DO THE ECOSYSTEM FUNCTION ?

1. An ecosystem is an association of organisms and their physical environment,

interconnected by an ongoing flow of energy and cycling of materials through it.

2. An ecosystem is an open system, with inputs, internal transfers, and outputs of bothenergy and nutrients.

3. Energy flows in only one direction through every ecosystem. Most commonly, energy

flow begins when photosynthetic autotrophs harness sunlight energy of the ecosystem

can use. Autotrophs a primary producer organisms for the ecosystem.

4. Energy rich organic compounds are stored forms of energy, and they serve as the

foundation for the ecosystems food webs. Such webs consist of a number of

interconnected food chains.

5. Each chain in a food web is a linear sequence from producers through various

consumers, decomposers and detritivores.

6. Overtime, most of the energy that enters a food web is lost to the environment,

mainly in the form of metabolic heat. Most nutriens are cycled within food webs, but

some amounts are lost to the environment.


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Ecosystems are made up of abiotic (non-living, environmental) and biotic components,

and these basic components are important to nearly all types of ecosystems.

Components of an Ecosystem

We can clarify the parts of an ecosystem by listing them under the headings "abiotic"

and "biotic".

ABIOTIC COMPONENTS

Sunlight

Temperature

Precipitation

Water or moisture

Soil or water chemistry (e.g., P, NH4+)

etc.

BIOTIC COMPONENTS

Primary producers

HerbivoresCarnivores

Omnivores

Detritivores

etc.

By and large, this set of environmental factors is important almost everywhere, in all

ecosystems.

Usually, biological communities include the "functional groupings" shown above. A

functional group is a biological category composed of organisms that perform mostly the


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same kind of function in the system; for example, all the photosynthetic plants or

primary producers form a functional group. Membership in the functional group does not

depend very much on who the actual players (species) happen to be, only on what

function they perform in the ecosystem.

Abiotic Components in an Ecosystem

1 Abiotic components are the non-living physical and chemical factors that make up the

environment.

2 The abiotic factors include:

(a) pH

(b) temperature

(c) light intensity

d) humidity

(e) topography

(f) microclimate

pH

1 The pH value of the environment, for example, water, soil or bark of a tree trunk can

affect the distribution of a particular organism.

2 Many organisms live in habitats where the range of pH of the environment is 6.5 to

7.5.

3 Some plants, for example, rose and pineapple plants, grow well in acidic soil. Other

plants, such as coconut plant, grow well in alkaline soil:

4 (a) Acid rain causes acidification of soil and water in rivers and Lakes.

(b) Acidic soil solution dissolves the toxic metals, for example, aluminium and mercury

from the soil and rocks. These substances are absorbed by the plants and cause

damage to the plants.


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(c)When pH of water is lower than 5.0, the acidic water kills many of the algae and

plants, insects, invertebrates, eggs, fry and adult fish.

Temperature1

1. Temperature has a direct influence on living organisms as it affects the rate of

enzyme-controlled biochemical reactions.

2 It also affects the rate of evaporation of water.

3 Large bodies of water such as oceans, seas and lakes have a fairly stable

temperature for aquatic organisms. Terrestrial habitats show wider daily and seasonal

fluctuations in temperature.

4. Most living organisms can survive within a range of temperatures between 0C - 45C

Light Intensity

1 Light intensity varies with season, time of day, latitude and aspect of slope.

2 Light is required by green plants for photosynthesis. Plants are usually found in areas

where there is suitable light intensity. Light tolerantplants are found in areas with higher light intensity. Liverworts, mosses

and smaller animals are found in more shady and moist areas. Heterotrophic organisms

which depend on the plants are also found in the same locality.

3 Competition for light can result in stratification (layered structure) of

. different plants in the forests.

4 Aquatic plants are usually found in surface layers of water.

5 Soil animals live in shady and moist areas to avoid dehydration.

6 Some animals show responses to changing light intensity during the seasons by

migration and hibernation.

Humidity


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1 Humidity is the amount of water vapour in the atmosphere.

2 Relative humidity in the atmosphere is usually lower during the day due to higher

temperature.

3 (a) The relative humidity in the atmosphere affects the rate of water loss by plants and

animals.

(b) When the environmental relative humidity is low, water evaporates rapidly from a

moist surface to the surrounding.

4 (a) Living organisms that have a relatively large thin moist surface area would lose

water rapidly to their surroundings.

(b) These organisms, for example, liverworts, mosses and frogs, are found in the more

shady and humid areas.

(c) The woodlice with a thin exoskeleton are normally found living under decaying leaf

litter or tree trunk where conditions are dark and moist to prevent dehydration.

Topography

1 Topography refers to the features of a place or region.

2 Three main features of topography that may influence the distribution of living

organisms are altitude, aspect and gradient.3 Altitude (height)

(a) At higher altitudes where the temperature and atmospheric pressure are

lower, there is greater wind speed and more rainfall. This may result

in zonation of different plant species at different altitudes.

(b) Mountains and hills also act as physical barriers to dispersal and

migration. They may isolate and restrict animal and plant species to

certain regions.

4 Aspect (the direction it faces)

Aspect of a slope or area would determine the amount of sunlight, light intensity,

temperature and amount of rain received by the slope or area. The slope that faces the

winds normally receives more rain.


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5 Gradient (steepness or angle of slope)

(a) The gradient influences water flow and amount of erosion.

(b) The steeper slopes are drier due to faster water drainage and run -off.

The soil is less fertile as there is rapid erosion of fertile thin top layer.

(c) Plants are commonly found in areas with slope angles less than 35.

Microclimate

1 Microclimate refers to the special local climatic conditions of a

particular small area or microhabitat.

2 Some of the factors that can affect the microclimate are light intensity, temperature,

wind, moisture or water availability, aspect of the place, type of surface and presence or

absence of shelter.

3 The microclimate may be different from the macro climatic conditions of the larger

surrounding area and influences the distribution of plants, animals and microorganisms.

4 For example, the microclimatic conditions beneath the leaf litter under a big tree are

different from the climatic conditions surrounding the big

tree.

Biotic Components of an Ecosystem

1 Biotic components are the components of an organism's environment that consists of

other living organisms. All these organisms together form the biotic environment.

2 Biotic components may affect an organism in many ways, for example, as symbionts,

parasites, predators or prey, or as competitors for light, food and shelter.

3 The abundance and distribution of an organism is affected by its interrelationships

with the biotic components

Feeding Relationships of the Biotic Components


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1 Feeding relationships are one of the important interactions between

living organisms. .

2 Primary producers are the green plants, algae and photosynthetic bacteria. They are

autotrophs and trap light energy during photosynthesis and converts it to chemical

energy stored in organic molecules such as carbohydrates, lipids and proteins. The

producers supply almost all the chemical energy used by living organisms.

3 Primary consumers are the herbivores which feed on the plants. They obtain energy

from the organic molecules synthesized by the plants.

4 Secondary consumers feed on primary consumers. They are the carnivorous

animals which feed on the herbivores.

5 Tertiary consumers are carnivores which feed on the secondary consumers.

6.. Decomposers are the saprophytic bacteria and fungi which feed on dead, decaying

organisms. They break down complex organic substances into simpler substances.

Decomposers play an important role :n geochemical cycles, for example, carbon cycle.

7- Detritivores are animals that feed on detritus. Detritus are fragments of organic

matter derived from dead and decaying plants and animals. Detritivores break down

detritus into smaller particles. Examples are woodlice, millipedes, centipedes and

earthworms.

Food Chains, Food Webs and Trophic Levels

1. A food chain or a food web involves the transfer of energy in an ecosystem. It shows

the feeding relationship between living organisms in the ecosystem.

2. A food chain is the transfer of energy from the primary producers (usually green

plants or phytoplanktons) to several levels of consumers. There are usually three or four

consumers in a simple food chain.

3 A trophic level is the position that an organism occupies in a food

Chain.


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4. Primary producers obtain the energy from sunlight to synthesise organic molecules

during photosynthesis. The solar energy is converted to chemical energy and stored in

the organic molecules.

Autotrophs such as the green plants, algae, photosynthetic bacteria

.and cyanobacteria are the primary producers. They occupy the fIrst

trophic level in the food chain.

5. The primary consumers occupy the second trophic level. Energy is transferred from

the primary producers to the primary consumers.

6 The secondary consumers occupy the third trophic level. Energy is transferred from

the second trophic level to the third trophic level.

7. The tertiary consumers occupy the fourth trophic level.

8 (a) As energy is transferred along a food chain, about 90% of the energy is used and

lost through respiration, excretion and egestion.

(b) Each trophic level receives less energy than the trophic level below it.

(c) Only a small amount of energy is left at the fourth or fifth trophic

level. This may be insufficient to support more trophic levels.

(d) Therefore, there are commonly about four or five trophic levels in one food chain.

9 . (a) A food web consists of several food chains that are linked with one another.

(b) In a food web, a particular organism may feed at more than one trophic

(c) For example, eagles can be the secondary, tertiary or quaternary consumers in the

rice field ecosystem


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10. The number of organisms in each trophic level can be represented by a pyramid of

numbers.

11. In an ecosystem, the producers and consumers mutually interact with one another

through the food chains and food webs.

Interactions between Biotic Components

1 The abundance and distribution of an organism is affected by its interaction with the

biotic components.

Symbiosis

1 Symbiosis is a close or permanent interaction between two or more organisms of

different species for an extended period.

2 The symbiotic relationship mayor may not be beneficial to the symbionts.

3 The three common types are:

(a) commensalism (b) parasitism (c) mutualism

4: Some types of symbiotic interaction are obligatory where one or both the symbionts

cannot survive without the other.
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Commensalism

1. Commensalism is a close interaction between two different living

species where one organism (commensal) benefits and the other (host)

is unaffected, neIther harmed nor benefIted.

.2 Examples are:

(a) epiphytic orchids (e.g. pigeon orchid) and ferns (e.g. staghorn fern, bird's nest fern)

growing on the trunks and branches of trees. Epiphytes are plants which grow on other

plants for support but not to obtain nutrients. The epiphytes are photoautotrophs and

can carry out photosynthesis.

(b) epizoics are non-parasitic animals that attach themselves to the ' outer surface of

other animals. For example, barnacles are found " attached to the skin of a whale. The

whale carries them from place to place. Barnacles feed on food fragments in the water

around the whale's mouth. Some barnacles can also live attached to shells of crabs,

rocks, pilings in the sea and at the bottom of ships.

(c) The remora fish are commonly found attached to sharks. They benefit by using the

shark as transport and protection. They also feed on leftover fragments from the shark.

The shark is not affected by the presence of the remora fish.

(d) Clown fish live among the stinging poisonous tentacles of sea anemones. The fish

obtain food remnants from the sea anaemones as well as protection from enemies. The

sea anemones are not affected.

Parasitism

1 Parasitism is a symbiotic relationship in which one organism


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shade and structural support, and absob water and minerals from the surrounding for

the algal cells produce food during photosynthesis. In return, the fungal hyphae obtain

sugars and other food synthesised by the algae during photosynthesis.

(c) rabbits ingest plant materials but cannot digest the cellulose.

Mutualistic bacteria and protozoa living mainly in the large caecum secrete the enzymes

needed to break down cellulose into sugars. The sugars are absorbed and assimilated

by the rabbit. In return, the host rabbit provides nutrients, space and shelter for the

mutualistic microorganisms.

Saprophytism

1 Saprophytism is a type of interaction in which living organisms obtain soluble organic

nutrients from dead, decaying organic matter.

2. Many bacteria and fungi are saprophytes, for example, mushroom, Rhizopus, Mucor

and Saccharomyces (yeast).

3 Saprophytes act as decomposers. They break down dead plants and animals torelease nutrients and elements for recycling.

4 Saprozoites are animals or protists that feed on digested organic matter An example

is the protozoan Opalina in the frog's intestine.

Predation

1 Predation is an interaction between two animal populations. The

predators are carnivorous animals which hunt, capture, kill and feed

on the prey.

2 Predators are usually larger and fewer in number than their prey.

3 Predator-prey interaction is important in regulating the natural


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population sizes of both the predators and prey although there is a

cyclic fluctuation in the population number.

4 (a) An increase in the prey population provides food for the predators.

(b) This causes an increase in the predator population.

(c) The increased predation leads to a decrease in the number of prey

organisms.

(d) Therefore, it causes a competition for the limited food resources

(prey). Many predators die due to food shortage and also diseases.

This leads to a decline in the predator population.

(e) The prey population starts to increase as there is less predation

5 The predator-prey oscillation is most liable to occur when a species of the predator is

specialised in feeding only one particular type of the prey. However, many predator

animals have alternative prey so their numbers may not fluctuate so widely..

Competition

1 When resources are in limited supply, organisms living in the same area or habitatmust compete for the same limited resources.

2 No species benefit during the period of the competition.

3 Eventually the competing species evolve either

(a) to aggressively reduce or eliminate the other competitor

(b) to avoid each other or one of them moves to another area

4 Animals compete for food, space (territory, nesting sites), shelter an~ breeding mates.

5 Plants compete for space, light, water and mineral ions.

6 Competition between individuals of the same species is known as intraspecific

competition.

7 Competition between individuals of different species is known as interspecific


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competition.

Ecosystem Ecology

In ecosystem ecology we put all of this together and, in so far as we can, we try to

understand how the system operates as a whole. This means that, rather than worrying

mainly about particular species, we try to focus on major functional aspects of the

system. These functional aspects include such things as the amount of energy that is

produced by photosynthesis, how energy or materials flow along the many steps in a

food chain, or what controls the rate of decomposition of materials or the rate at which

nutrients are recycled in the system.

Ecosystem ecology is the integrated study of biotic and abiotic components of

ecosystems and their interactions within an ecosystem framework. This science

examines how ecosystems work and relates this to their components such as

chemicals, bedrock, soil, plants, and animals. Ecosystem ecology examines physical

and biological structure and examines how these ecosystem characteristics interact.

The relationship between systems ecology and ecosystem ecology is complex. Much of

systems ecology can be considered a subset of ecosystem ecology. Ecosystem ecology

also utilizes methods that have little to do with the holistic approach of systems ecology.However, systems ecology more actively considers external influences such as

economics that usually fall outside the bounds of ecosystem ecology. Whereas

ecosystem ecology can be defined as the scientific study of ecosystems, systems

ecology is more of a particular approach to the study of ecological systems and

phenomena that interact with these systems.

Systems ecology

Systems ecology is an interdisciplinary field of ecology, taking a holistic approach to the

study of ecological systems, especially ecosystems. Systems ecology can be seen as

an application of general systems theory to ecology. Central to the systems ecology

approach is the idea that an ecosystem is a complex system exhibiting emergent


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profundal (bottom or deep water); benthic (bottom substrates); intertidal (the area

between high and low tides); estuaries.

Salt Water Ecosystems

A coral reef near the cool Hawaiian Islands is an example of a complex marine

ecosystem.

Marine ecosystems cover approximately 71% of the Earth's surface and contain

approximately 97% of the planet's water. They generate 32% of the world's net primary

production.[1] They are distinguished from freshwater ecosystems by the presence of

dissolved compounds, especially salts, in the water. Approximately 85% of the

dissolved materials in seawater are sodium and chlorine. Seawater has an average

salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different

marine ecosystems.

Marine ecosystems can be divided into the following zones: oceanic (the relatively

shallow part of the ocean that lies over the continental shelf); profundal (bottom or deep

water); benthic (bottom substrates); intertidal (the area between high and low tides);
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estuaries; salt marshes; coral reefs; and hydrothermal vents (where chemosynthetic

sulfur bacteria form the food base).

Classes of organisms found in marine ecosystems include brown algae, dinoflagellates,

corals, cephalopods, echinoderms, and sharks. Fish caught in marine ecosystems are

the biggest source of commercial foods obtained from wild populations.

Environmental problems concerning marine ecosystems include unsustainable

exploitation of marine resources (for example overfishing of certain species), water

pollution, and building on coastal areas.

Freshwater ecosystems

Freshwater ecosystems cover 0.8% of the Earth's surface and contain 0.009% of its

total water. They generate nearly 3% of its net primary production. Freshwater

ecosystems contain 41% of the world's known fish species.[3]

There are three basic types of freshwater ecosystems:

Lentic: slow-moving water, including pools, ponds, and lakes.

Lotic: rapidly-moving water, for example streams and rivers.

Wetlands: areas where the soil is saturated or inundated for at least part of the time.

Lake ecosystems can be divided into zones: pelagic (open offshore waters); profundal;littoral (nearshore shallow waters); and riparian (the area of land bordering a body of

water). Two important subclasses of lakes are ponds, which typically are small lakes

that intergrade with wetlands, and water reservoirs. Many lakes, or bays within them,

gradually become enriched by nutrients and fill in with organic sediments, a process

called eutrophication. Eutrophication is accelerated by human activity within the water

catchment area of the lake.[1]

The major zones in river ecosystems are determined by the river bed's gradient or by

the velocity of the current. Faster moving turbulent water typically contains greater

concentrations of dissolved oxygen, which supports greater biodiversity than the slow

moving water of pools. These distinctions forms the basis for the division of rivers into

upland and lowland rivers. The food base of streams within riparian forests is mostly

derived from the trees, but wider streams and those that lack a canopy derive the


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majority of their food base from algae. Anadromous fish are also an important source of

nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution

and introduced species.

Wetlands are dominated by vascular plants that have adapted to saturated soil.

Wetlands are the most productive natural ecosystems because of the proximity of water

and soil. Due to their productivity, wetlands are often converted into dry land with dykes

and drains and used for agricultural purposes. Their closeness to lakes and rivers

means that they are often developed for human settlement.

Pond ecosystems

This is a specific type of freshwater ecosystem that is largely based on the autotroph

algae which provide the base trophic level for all life in the area. The largest predator in

a pond ecosystem will normally be a fish and in-between range smaller insects and

microorganisms. It may have a scale of organisms from small bacteria to big creatures

like water snakes, beetles, water bugs, and turtles.

Functions of aquatic ecosystems

Aquatic ecosystems perform many important environmental functions. For example,

they recycle nutrients, purify water, attenuate floods, recharge ground water and provide

habitats for wildlife. Aquatic ecosystems are also used for human recreation, and are

very important to the tourism industry, especially in coastal regions.

The health of an aquatic ecosystem is degraded when the ecosystem's ability to absorb

a stress has been exceeded. A stress on an aquatic ecosystem can be a result of

physical, chemical or biological alterations of the environment. Physical alterations

include changes in water temperature, water flow and light availability. Chemical

alterations include changes in the loading rates of biostimulatory nutrients, oxygen

consuming materials, and toxins. Biological alterations include the introduction of exotic

species. Human populations can impose excessive stresses on aquatic ecosystems.


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Abiotic characteristics of aquatic ecosystems

An ecosystem is composed of biotic communities and abiotic environmental factors,

which form a self-regulating and self-sustaining unit. Abiotic environmental factors of

aquatic ecosystems include temperature, salinity, and flow.]

The amount of dissolved oxygen in a water body is frequently the key substance in

determining the extent and kinds of organic life in the water body. Fish need dissolved

oxygen to survive. Conversely, oxygen is fatal to many kinds of anaerobic bacteria.

The salinity of the water body is also a determining factor in the kinds of species found

in the water body. Organisms in marine ecosystems tolerate salinity, while many

freshwater organisms are intolerant of salt. Freshwater used for irrigation purposes

often absorb levels of salt that are harmful to freshwater organisms. Though some salt

can be good for organisms.

Biotic characteristics of aquatic ecosystems

The organisms (also called biota) found in aquatic ecosystems are either autotrophic or

heterotrophic.

Autotrophic organisms

Autotrophic organisms are producers that generate organic compounds from inorganic

material. Algae use solar energy to generate biomass from carbon dioxide and are the

most important autotrophic organisms in aquatic environments. Chemosynthetic

bacteria are found in benthic marine ecosystems. These organisms are able to feed on

hydrogen sulfide in water that comes from volcanic vents. Great concentrations of

animals that feed on this bacteria are found around volcanic vents. For example, there

are giant tube worms (Riftia pachyptila) 1.5m in length and clams (Calyptogena

magnifica) 30cm long

Heterotrophic organisms


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Heterotrophic organisms consume autotrophic organisms and use the organic

compounds in their bodies as energy sources and as raw materials to create their own

biomass Euryhaline organisms are salt tolerant and can survive in marine ecosystems,

while stenohaline or salt intolerant species can only live in freshwater environments.

Human ecosystem

Human ecosystems are complex cybernetic systems that are increasingly being used

by ecological anthropologists and other scholars to examine the ecological aspects of

human communities in a way that integrates multiple factors as economics, socio-

political organization, psychological factors, and physical factors related to the

environment.

The human ecosystem concept draws from disciplines such as ecology, anthropology,

sociology, philosophy, political science, cybernetics, and psychology, seeking to

understand the complex system of relationships in which humans interact. These

relationships exist within nested hierarchies of context with which individuals and human
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aggregates interact with differentially. Most analysis of human ecosystems focuses on

particular contexts of relationship, such as biological, individual, socio-cultural,

environmental et cetera.

Ecology (from Greek: , oikos, "household"; and , logos, "knowledge") is the

scientific study of the distribution and abundance of life and the interactions between

organisms and their environment.

Sociology (from Latin: socius, "companion"; and the suffix -ology, "the study of", from

Greek , lgos, "knowledge" [1]) is the scientific or systematic study of society,

including patterns of social relationships, social interaction, and culture.

Philosophy considers such general and fundamental questions as the sorts of things

that exist, the nature, scope, and limits of knowledge and moral judgments, and the

nature of mind and of language.

Political science is a branch of social science that deals with the theory and practice of

politics and the description and analysis of political systems and political behavior.

Political Science is often described as the study of who gets what, where, when and

why. Discovering a proper balance between the individual, the society and its

Government for civilization and human progress is paramount.Cybernetics is the interdisciplinary study of the structure of complex systems, especially

communication processes, control mechanisms and feedback principles. Cybernetics is

closely related to control theory and systems theory.

Example of cybernetic thinking. On the one hand a company is approached as a system

in an environment. On the other hand cybernetic factory can be modeled as a control

system.

Psychology is an academic and applied discipline involving the analytic and scientific

study of mental processes and behavior. Psychologists study such phenomena as

perception, cognition, emotion, personality, behavior, and interpersonal relationships..


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Urban ecosystem

Urban ecosystems are the cities, towns and urban strips constructed by humans.

This growth in the urban population and the supporting built infrastructure has impacted

on both urban environments and also on areas which surround urban areas. These

include semi or 'peri-urban' environments that fringe cities as well as agricultural and

natural landscapes.

By considered urban areas as part of a broader ecological system, scientists can

investigate how urban landscapes function and how they effect other landscapes with

which they interact. In this context, urban environments are effected by their

surrounding environment but also impact on that environment. Knowing this may

provide clues as to which alternative development options will lead to the best overall

environmental outcome.

.

Rainforest Ecosystem

.
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The Daintree Rainforest near Cairns, in

Queensland, Australia.

Rainforests are forests characterized by high rainfall, with definitions setting minimum

normal annual rainfall between 1750-2000 mm (68-78 inches).

Rainforests are home to two-thirds of all the living animal and plant species on Earth. It

has been estimated that many hundreds of millions of species of plants, insects and

microorganisms are still undiscovered. Tropical rainforests have been called the "jewels

of the Earth," and the "world's largest pharmacy," because of the large number of

natural medicines discovered there.

The undergrowth in a rainforest is restricted in many areas by the lack of sunlight at
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ground level. This makes it possible to walk through the forest. If the leaf canopy is

destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth

of vines, shrubs and small trees called a jungle. The two types of rainforest are:

Tropical rainforests are rainforests in the tropics, found near the Equator (between the

Tropic of Cancer and Tropic of Capricorn) and present in southeast Asia (Myanmar to

Indonesia and Papua New Guinea, northern and eastern Australia), sub-Saharan Africa

from Cameroon to the Congo, (Congo Rainforest), South America (the Amazon

Rainforest) Central America (Bosaws, southern Yucatn Peninsula-El Peten-Belize-

Calakmul), and on many of the Pacific Islands(such as Hawaii). Tropical rainforests

have been called the "Earth's lungs," although it is now known that rainforests contribute

little net oxygen additions to the atmosphere through photosynthesis

Temperate rainforests are rainforest in temperate regions. They can be found in North

America (in the Pacific Northwest, the British Columbia Coast, and in the inland

rainforest of the Rocky Mountain Trench east of Prince George), in Europe (in coastal

areas of Ireland, Scotland and southern Norway, parts of the western Balkans along the

Adriatic coast, and coastal areas of the eastern Black Sea, including Georgia and

coastal Turkey), and in East Asia (in southern China, Taiwan, much of Japan and

Korea, and on Sakhalin Island and the adjacent Russian Far East coast), and also

Australia and New Zealand.

Savanna


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Typical subcoastal Eucalyptus/Melaleuca savanna in Northern Australia demonstrating

the high tree density and regular spacing characteristic of many savannas.

A savanna or savannah is a grassland ecosystem with scattered trees or shrubs. In

savannas trees are small or widely spaced so that the canopy does not close. It is oftenbelieved that savannas are characterized by widely spaced, scattered trees, however in

many savanna communities tree densities are higher and trees are more regularly

spaced than in forest communities. The open canopy allows sufficient light to reach the

ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.[1]

Savannas are also characterised by seasonal water availability, with the majority of
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rainfall being confined to one season of the year. Savannas can be associated with

several types of biomes. Savannas are frequently seen as a transitional zone, occurring

between forest and desert or prairie.

Although the term savanna is believed to have originally come from a Native American

word describing "land which is without trees but with much grass either tall or short"

(Oviedo y Valdes, 1535), by the late 1800s it was used to mean "land with both grass

and trees". It now refers to land with grass and either scattered trees or an open canopy

of trees.

Chaparral

.Chaparral is a shrubland or heathland plant community found primarily in the U.S. state

of California and in the northern portion of Lower California, Mexico. It is shaped by a

Mediterranean climate (mild, wet winters and hot dry summers) and wildfire. Similar

plant communities are found in the five other Mediterranean climate regions around the

world, including the Mediterranean Basin (where it is known as maquis), central Chile

(where it is called matorral), South African Cape Region (known there as fynbos), and in

Western and Southern Australia.
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The word chaparral is a loan word from Spanish. The Spanish word comes from the

word chaparro, which means both small and dwarf evergreen oak

A typical chaparral plant community consists of densely-growing evergreen scrub oaks

and other drought-resistant shrubs. It often grows so densely that it is all but

impenetrable to large animals and humans. This, and its generally arid condition, makes

it notoriously prone to wildfires. Although many chaparral plant species require some

fire cue (heat, smoke, or charred wood) for germination, chaparral plants are not

"adapted" to fire per se. Rather, these species are adapted to particular fire regimes

involving season, frequency, intensity and severity of the burn.

Coral reef

Coral reefs are aragonite structures produced by living organisms, found in shallow,

tropical marine waters with little to no nutrients in the water. High nutrient levels such as

those found in runoff from agricultural areas can harm the reef by encouraging the
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growth of algae. In most reefs, the predominant organisms are stony corals, colonial

cnidarians that secrete an exoskeleton of calcium carbonate. The accumulation of

skeletal material, broken and piled up by wave action and bioeroders, produces a

massive calcareous formation that supports the living corals and a great variety of other

animal and plant life. Although corals are found both in temperate and tropical waters,

reefs are formed only in a zone extending at most from 30N to 30S of the equator.

Reef-forming corals do not grow at depths of over 30 m (100 ft), and temperature has

less of an effect on distribution but it is generally accepted that no corals exist in waters

below 18 C.

Desert

A desert is a landscape or region that receives very little precipitation. Deserts can be

defined as areas that receive an average annual precipitation of less than 250 mm (10

in), or as areas in which more water is lost than falls as precipitation. In the Kppen
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climate classification system, deserts are classed as BWh (hot desert) or BWk

(temperate desert). In the Thornthwaite climate classification system, deserts would be

classified as arid megathermal climates.

Greater Yellowstone Ecosystem

Greater Yellowstone is the last remaining large, nearly intact ecosystem in the northern

temperate zone of the Earth[1] and is partly located in Yellowstone National Park.

Conflict over management has been controversial, and the area is a flagship site among

conservation groups that promote ecosystem management. The Greater Yellow

Ecosystem (GYE) is one of the world's foremost natural laboratories in landscape

ecology and geology and is a world-renowned recreational site. It is also home to the

animals of Yellowstone.

Taiga
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The taiga is found throughout the high northern latitudes, between the tundra, and the

steppes.Taiga (pronounced / ta g/, from Turkic[1] or Mongolian) is a biome characterized by

coniferous forests. Covering most of inland Alaska, Canada, Sweden, Finland, inland

Norway and Russia (especially Siberia), as well as parts of the extreme northern

continental United States (Northern Minnesota, Michigan, Upstate New York, New

Hampshire, and Maine), northern Kazakhstan and Japan (Hokkaid), the taiga is the

world's largest terrestrial biome. In Canada, boreal forest is the term used to refer to the

southern part of this biome, while "taiga" is used to describe the more barren northern

areas of the Arctic tree line.

Since North America, Europe and Asia were recently connected by the Bering land

bridge, a number of animal and plant species (more animals than plants) were able to

colonize both continents and are distributed throughout the taiga biome (see

Circumboreal Region). Others differ regionally, typically with each genus having several

distinct species, each occupying different regions of the taiga. Taigas also have some

small-leaved deciduous trees like birch, alder, willow, and aspen; mostly in areas

escaping the most extreme winter cold. However, the deciduous larch is coping with the

coldest winters on the northern hemisphere in eastern Siberia. The southernmost part of

the taiga also has trees like oak, maple, and elm scattered among the conifers.

Tundra


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In physical geography, tundra is an area where the tree growth is hindered by low

temperatures and short growing seasons. The term "tundra" comes from Kildin Sami

tndr 'uplands, tundra, treeless mountain tract'. There are two types of tundra: Arctic

tundra (which also occurs in Antarctica), and alpine tundra[1]. In tundra, the vegetation

is composed of dwarf shrubs, sedges and grasses, mosses, and lichens. Scattered

trees grow in some tundra. The ecotone (or ecological boundary region) between the

tundra and the forest is known as the tree line or timberline.

Arctic tundra
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Arctic tundra occurs in the far Northern Hemisphere, north of the taiga belt.The word

"tundra" usually refers only to the areas where the subsoil is permafrost, or permanently

frozen soil. (It may also refer to the treeless plain in general, so that northern Spmi

would be included.) Permafrost tundra includes vast areas of northern Russia and

Canada [1]. The polar tundra is home to several peoples who are mostly nomadic

reindeer herders, such as the Nganasan and Nenets in the permafrost area (and the

Sami in Spmi).

The Arctic tundra is a vast area of stark landscape, which is frozen for much of the year.

The soil there is frozen from 25-90 cm (9.8-35.4 inches) down, and it is impossible for

trees to grow. Instead, bare and sometimes rocky land can only support low growing

plants such as moss, heath, and lichen. There are two main seasons, winter andsummer, in the polar Tundra areas. During the winter it is very cold and dark, with the

average temperature around 28 C (18.4 F), sometimes dipping as low as 50 C

(58.0 F). However, extreme cold temperatures on the tundra do not drop as low as

those experienced in taiga areas further south (for example, Russia's and Canada's

lowest temperatures were recorded in locations south of the treeline). During the

summer, temperatures rise somewhat, and the top layer of the permafrost melts,

leaving the ground very soggy. The tundra is covered in marshes, lakes, bogs and

streams during the warm months. Generally daytime temperatures during the summer

rise to about 12 C (54 F) but can often drop to 3 C (37 F) or even below freezing.

Arctic tundras are sometimes the subject of habitat conservation programs. In Canada

and Russia, many of these areas are protected through a national Biodiversity Action

Plan.
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The tundra is a very windy area, with winds often blowing upwards at 4897 km/h (30-

60 miles an hour). However, in terms of precipitation, it is desert-like, with only about

1525 cm (610 inches) falling per year (the summer is typically the season of

maximum precipitation). During the summer, the permafrost thaws just enough to let

plants grow and reproduce, but because the ground below this is frozen, the water

cannot sink any lower, and so the water forms the lakes and marshes found during the

summer months. Although precipitation is light, evaporation is also relatively minimal.

The biodiversity of the tundras is low: 1,700 species of vascular plants and only 48 land

mammals can be found, although thousands of insects and birds migrate there each

year for the marshes. There are also a few fish species such as the flat fish. There are

few species with large populations. Notable animals in the Arctic tundra include caribou

(reindeer), musk ox, arctic hare, arctic fox, snowy owl, lemmings, and polar bears (only

the extreme north).

Due to the harsh climate of the Arctic tundra, regions of this kind have seen little human

activity, even though they are sometimes rich in natural resources such as oil and

uranium. In recent times this has begun to change in Alaska, Russia, and some otherparts of the world.

A severe threat to the tundras, specifically to the permafrost, is global warming. The

melting of the permafrost in a given area on human time scales (decades or centuries)

could radically change which species can survive there.

Another concern is that about one third of the world's soil-bound carbon is in taiga and

tundra areas. When the permafrost melts, it releases carbon in the form of carbon

dioxide, a greenhouse gas. The effect has been observed in Alaska. In the 1970s the

tundra was a carbon sink, but today, it is a carbon source.

Antarctic tundra


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Antarctic tundra occurs on Antarctica and on several Antarctic and subantarctic islands,

including South Georgia and the South Sandwich Islands and the Kerguelen Islands.

Antarctica is mostly too cold and dry to support vegetation, and most of the continent is

covered by ice fields. However, some portions of the continent, particularly the Antarctic

Peninsula, have areas of rocky soil that support plant life. The flora presently consists of

around 300-400 lichens, 100 mosses, 25 liverworts, and around 700 terrestrial and

aquatic algae species, which live on the areas of exposed rock and soil around the

shore of the continent. Antarctica's two flowering plant species, the Antarctic hair grass

(Deschampsia Antarctica) and Antarctic pearlwort (Colobanthus quitensis), are found on

the northern and western parts of the Antarctic Peninsula[5] In contrast with the Arctic

tundra, the Antarctic tundra lacks a large mammal fauna, mostly due to its physical

isolation from the other continents. Sea mammals and sea birds, including seals and

penguins, inhabit areas near the shore, and some small mammals, like rabbits and cats,

have been introduced by humans to some of the subantarctic islands.

The flora and fauna of Antarctica and the Antarctic Islands (south of 60 south latitude)

are protected by the Antarctic Treaty.[6]Tundra also occurs on Tierra del Fuego and southern Argentina.[7] Notable plant and

lichen species of this tundra include Neuropogon aurantiaco, Azorella lycopodioides,

Marsippospermum reichei, Nardophyllum bryoides, and Bolax gummifera.

Alpine tundra
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Alpine tundra is an ecozone that does not contain trees because it has high altitude.

Alpine tundra occurs at high enough altitude at any latitude on Earth. Alpine tundra also

lacks trees, but the lower part does not have permafrost, and alpine soils are generally

better drained than permafrost soils. Alpine tundra transitions to subalpine forests below

the tree line; stunted forests occurring at the forest-tundra ecotone are known as

Krummholz. Alpine tundra occurs in an alpine zone.

Alpine tundra does not map directly to specific World Wide Fund for Nature ecoregions.

Portions of Montane grasslands and shrublands ecoregions include alpine tundra.

Because alpine tundra is located in various widely-separated regions of the Earth, there

is no animal species common to all areas of alpine tundra. Some animals of alpine

tundra environments include the Kea parrot, marmot, Mountain goats, chinchilla, and

pika.

Large sections of the Tibetan Plateau include alpine tundra.

Ecosystem services
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Ecosystem services are fundamental life-support services upon which human

civilization depends, and can be direct or indirect. Example of direct ecosystem services

are: pollination, wood, erosion prevention etc. Indirect services could be considered

climate moderation, nutrient cycles, detoxifying natural substances and many more.

Function and biodiversity

From an anthropological point of view, many people see ecosystems as production

units that of goods and services. Among some of the most common goods produced by

ecosystems, is wood by forest ecosystems and grass for cattle by natural grasslands.

Meat from wild animals, often referred to as bush meat in Africa, has proven to be

extremely successful under well-controlled management schemes in South Africa and

Kenya. Much less successful has been the discovery and commercialization of

substances of wild organism for pharmaceutical purposes. Services derived from

ecosystems are referred to as ecosystem services.

They may include

(1) facilitating the enjoyment of nature, which may generate many forms of income and

employment in the tourism sector, often referred to as eco-tourisms, (2) water retention,thus facilitating a more evenly distributed release of water,

(3) soil protection, open-air laboratory for scientific research, etc.

A greater degree of species diversity or biological diversity - popularly referred to as

Biodiversity - of an ecosystem may contribute to greater resilience of an ecosystem,

because there are more species present at a location to respond to a factor of change

and thus "absorb" or reduce its effects, thus reducing the effect before its structure is

fundamentally changed to a different state. This is not universally the case and there is

no proven relationship between the species diversity of an ecosystem and its ability to

provide goods and services on a sustainable level: Humid tropical forest produce very

little goods and direct services and are extremely vulnerable to change, while many

temperate forests readily grow back to their previous state of development within a


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lifetime after felling or a forest fire. Some grasslands have been exploited sustainably

for thousands of years (Mongolia, Africa, European peat and mooreland communities).

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Lecture 2 Types of Ecosystem

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