ECOSYSTEMBIOTIC AND ABIOTIC COMPONENTS

ECOSYSTEM• A region with a specific and recognizable landscape

form, such as a forest, grassland, desert, wetland, or coastal area

• A community and its physical environment• The concept of ecosystem was first put forth by A.G

Tansley in 1935• it can be temporary or permanent, natural or man

made, small or large • A very small ecosystem is called as microsystem

Importance of study• Gives information about the available essential

minerals and their recycling periods• Gross and net productivity of the ecosystem are

known• Provides knowledge about the web of interactions

and interrelations amongst the various populations as well as the between the population and the abiotic environment

• Helps humans to know about the conservation of resources, protection from pollution etc

STRUCTURE OF ECOSYTEM• By structure we mean,• The composition of biological community including

species, biomass, life history and distribution in space etc

• Quantity and distribution of non living materials such as water and nutrients

• Range or gradient of conditions of existence, temperature, light etc

• The structure of the ecosystem means the components

• The two major components are :-• Abiotic (non-living ) components• Biotic (living ) components

Abiotic Components

• Abiotic components are the non-living components of an ecosystem, affecting the life of organisms.

• Abiotic components can be harmful to the ecosystem

• Abiotic components are:– Temperature, light, water, soil, rocks, sulphur,

nitrogen, phosphorous, proteins, lipids, carbohydrates ,humic substances etc

• These specific abiotic factors represent the geological, geographical, hydrological and climatological features of a particular ecosystem

WIND

Many plants use the help of the wind to disperse seeds over long distances. Organisms disperse to find new habitats rich in needed resources. Strong winds can be very destructive

WATERWater is one of nature’s most important things is life. Essential to life, an organism’s survival depends an water. Water is necessary for digestion and absorption of food; helps maintain proper muscle tone-, supplies oxygen and nutrients to the cells; rids the body of water; and serves as a natural air conditioning system

SUNLIGHT

The sun provides light and warmth and it is the energy source for almost all ecosystems on Earth. Sunlight powers photosynthesis by plants, the main producer in most terrestrial ecosystems

TEMPERATURE

Most life exists within a fairly narrow range of temperatures, from about 0 C to about 50 C. Few organisms can maintain an active metabolism below 0 C for long, and most organisms’ enzymes are denatured (they lose their shape and stop working) above 50 C. However, extraordinary adaptations enable certain species to live at extreme temperatures

BIOTIC COMPONENT• The biotic components ranges from extremely

small bacteria, which live in the air, water and soil, algae which live in fresh and salt water, to the terrestrial plants which range from grasses and herbs that grow after the monsoon of every year to the giant long lived trees of the forest

• The living component of the animal world ranges from microscopic animals to small insects and larger animals such as fish, amphibians , reptiles, birds and mammals

• Biotic component is distinguished into autotrophs , heterotrophs and saprotrophs

• Autotrophs• Autotrophs are also called producers• These are photosynthetic plants, generally

chlorophyll bearing, which synthesize high-energy complex organic compounds (food) from inorganic raw materials with the help of sunlight, and the process is referred as photosynthesis.

• Autotrophs form the basis of any biotic system.

• In terrestrial ecosystems, the autotrophs are mainly the rooted plants. In aquatic ecosystems, floating plants called phytoplankton and shallow water rooted plants called macrophytes are the dominant producers.

Heterotrophs• Heterotrophs are called consumers, which are

generally animals feeding on other organisms

Consumer's also referred as phagotrophs (phago - to ingest or swallow) or macroconsumers are mainly herbivores and carnivores

Herbivores are referred as First order consumers or primary consumers, as they feed directly on plants . For e.g., Terrestrial ecosystem consumers like cattle, deer, rabbit, grass hopper, etc..

• Aquatic ecosystem consumers like protozoans, crustaceans, etc. Carnivores are animals, which feed or prey upon other animals

• Primary carnivores or Second order consumers include the animals which feed on the herbivorous animals. For e.g., fox, frog, predatory birds, smaller fishes, snakes, etc.

• Secondary carnivores or Third order consumers include the animals, which feed on the primary carnivores. For e.g., wolf, peacock, owl, etc.

• Saprotrophs are also called decomposers or reducers. They break down the complex organic compounds of dead matter (of plants and animals).

• Decomposers do not ingest their food.• Instead they secrete digestive enzymes into

the dead and decaying plant and animal remains to digest the organic material.

• Enzymes act upon the complex organic compounds of the dead matter.

Types of interactions

• The biotic environment is experienced by an individual as interactions with other organisms

• These include individuals of the same species ( intraspecific effects) and individuals of many other species (interspecific effects)

Intraspecific relationships

• Reproduction • One of the first phases is the location of a mate• This may occur by the advertisement by one sex

of its whereabouts such using scent, light or sound

• Selection of the mate often includes competition between individuals of the same sex , either males for females or rarely females for males

• Care of offspring• Offspring are usually cared for by their

parents; by the female only or by both parents• More rarely offspring are cared for by older

siblings. This occurs among colonial insects such as termites

• Care of offspring includes feeding, guarding, keeping them warm and transporting immature individuals

• Social behavior• Many social interactions are altruistic and

centre around finding food and defence• Guarding and defense of territories, young

and more vulnerable members of the group are also common in social animals

• Competition• This occurs between individuals within a

species for environmental resources such as food, space, light, water and mineral nutrients

• Here competition can occur at any time during the life cycle: between sperm or actively growing pollen tubes for the chance to fertilize an egg: between embryos in the womb for parental nutrients: between seedlings for light and space:

Interspecific relationships

• Reproduction• Pollination in many angiosperms and a few

gymnosperms involves a more mobile species as pollen transporter

• Such carriers include insects ,birds, bats and a few other mammals

• Care of offspring• Care of offspring by another species is rare• Example- European cuckoos which lay eggs in

the nests of small birds such as the meadow pipet, hedge sparrow and reed warbler

• The offspring are then reared by the owners of the nest

• This is a parasitic interaction as the foster parent usually loses all its own fledglings and gains nothing

• Mutualism• Where both the organisms gain benefits by

long term association with each other the relationship is said to be mutualistic

• Often one of the organisms gains food and the other protection

• Example- trees such as beech, oak and pine gain amino acids from fungal associations; the fungi in return receives carbohydrates and vitamins from the tree

• Parasitism and disease• Parasitism occurs where individuals of one

species live or reproduce using the food and other resources of an individual of other species

• The relationships between the parasites and hosts are many and varied

• Some parasites live within the host- endoparasites such as gut parasites and other outside the host- ectoparasites

• Predation• Apart from autotrophs, all organisms have to

feed on other organisms• Herbivores, insectivores and carnivores are all

involved in interspecific interactions• Protection• Many organisms attempting to avoid predation

use other organisms for protection Example- insects hide under tree bark, birds nest in holes in plants to protect their young

• Some organisms gain protection from predation by using the defence mechanism of another species

• Example-The cinnabar moth caterpillar eats the poisonous ragwort plant and concentrates the plant’s toxin in its own tissues

• The caterpillars are brightly colored with black and yellow stripes to warn birds that they are unpleasant to eat

• Some edible species even copy the warning colorations of harmful ones to gain protection

• Competition• Competition between the individuals of

different species is probably extremely important for determining the abundance, health, reproductive capacity and distribution of species within a community

• Competition probably occurs between similar or related species or between quite different species which need the same resources

• Defence• Organisms respond to predation, parasitism and

competition by using defence mechanisms• These includes mechanical defences like sharp

spines on cacti (protecting the plant, which contain a store of water, from thirsty desert animals), toxins in the ragwort for caterpillar

• Sometimes toxins are produced by plants to kill other plants in the surrounding vegetation

Energy flow in an ecosystem• A general energy flow scenario follows:

• Solar energy is fixed by the photoautotrophs , called primary producers, like green plants

• Primary consumers absorb most of the stored energy in the plant through digestion and transform it into the form of energy they need, such as adenosine triphosphate (ATP), through respiration

• A part of the energy received by primary consumers, herbivores, is converted to body heat (an effect of respiration), which is radiated away and lost from the system.

• The loss of energy through body heat is far greater in warm-blooded animals, which must eat much more frequently than those that are cold-blooded.

• Secondary consumers, carnivores, then consume the primary consumers, although omnivores also consume primary producers.

• Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion.

• As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration

• Again, some energy is lost from the system, since energy which the primary consumers had used for respiration and regulation of body temperature cannot be utilised by the secondary consumers

• tertiary consumers, which may or may not be apex predators then consume the secondary consumers, with some energy passed on and some lost, as with the lower levels of the food chain.

• A final link in the food chain are decomposers which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil.

• They also break down plants, herbivores and carnivores that were not eaten by organisms higher on the food chain, as well as the undigested food that is excreted by herbivores and carnivores.

• Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycle

TYPESaquatic ecosystem• It is an ecosystem in a body of water • Communities of organisms that are dependent

on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems

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

•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

• Marine ecosystems can be divided into many zones depending upon water depth and shoreline features.

• The oceanic zone is the vast open part of the ocean where animals such as whales, sharks, and tuna live.

• The benthic zone consists of substrates below water where many invertebrates live

• The intertidal zone is the area between high and low tides

• Other near-shore zones can include estuaries, salt marshes, coral reefs, lagoons and mangrove swamps.

• In the deep water, hydrothermal vents may occur where chemosynthetic sulphur bacteria form the base of the food web.

• freshwater ecosystems • It cover 0.80% of the Earth's surface and inhabit

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.

• There are three basic types of freshwater ecosystems:• Lentic: slow moving water, including pools, ponds,

and lakes.• Lotic: faster moving water, for example streams and

rivers.• Wetlands: areas where the soil is saturated or

inundated for at least part of the time.

terrestrial ecosystem• an ecosystem found only on landforms.• Six primary terrestrial ecosystems exist: tundra, taiga,

temperate deciduous forest, tropical forest, grassland and desert

•Terrestrial ecosystems are distinguished from aquatic ecosystems by the lower availability of water and the consequent importance of water as a limiting factor.

•Terrestrial ecosystems are characterized by greater temperature fluctuations on both a diurnal and seasonal basis than occur in aquatic ecosystems in similar climates.

•The availability of light is greater in terrestrial ecosystems than in aquatic ecosystems because the atmosphere is more transparent than water.

• Gases are more available in terrestrial ecosystems than in aquatic ecosystems.

• Those gases include carbon dioxide that serves as a substrate for photosynthesis, oxygen that serves as a substrate in aerobic respiration, and nitrogen that serves as a substrate for nitrogen fixation

• Terrestrial ecosystems occupy 28.2%, of Earth's surface.

• Although they occupy a much smaller portion of Earth's surface than marine ecosystems, terrestrial ecosystems have been a major site of adaptive radiation of both plants and animals.

• Major plant taxa in terrestrial ecosystems are members of the division Magnoliophyta (flowering plants), of which there are about 275,000 species, and the division Pinophyta (conifers), of which there are about 500 species.

• Members of the division Bryophyta (mosses and liverworts), of which there are about 24,000 species, are also important in some terrestrial ecosystems. Major animal taxa in terrestrial ecosystems include the classes Insecta (insects) with about 900,000 species, Aves (birds) with 8500 species, and Mammalia (mammals) with approximately 4100 species

• forest ecosystem• A terrestrial unit of living organisms (plants,

animals and microorganisms), all interacting among themselves and with the environment (soil, climate, water and light) in which they live.

• The environmental "common denominator" of that forest ecological community is a tree, who most faithfully obeys the ecological cycles of energy, water, carbon and nutrients.

• A forest ecosystem has definite boundaries and includes a forest of trees out to the limit of tree growth

• There are hundreds of thousands of defined and undefined ecosystems that can cover the broadest to the tiniest of areas.

• An ecosystem can be as small as a pond or a dead tree, or as large as the Earth itself

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