Ecology Day 1 and 2

Ecology

The term oekologie (ecology) was coined in 1866 by a German biologist, Ernst Haeckel from the Greek oikos meaning “house” or “dwelling”, and logos meaning “science” or “study”.

Thus, ecology is the “study of the household of nature”.

Haeckel intended it to encompass the study of an animal in relation to both the physical environment and other plants and animals with which it interacted.

Definition: Ecology is defined as “the scientific study of the interrelationships between living organisms and the environments in which they live”.

Why do we need to study ecology?

 It is important for humanity to understand its environment because we have the ability to modify the environment through the use of technology, and through over exploitation of natural resources as a result of greed or sheer pressure of numbers. Therefore, ecology is more than just the understanding of the interrelationships between organisms and their environment; it also has social, political, economic and technological dimensions.

History of Ecology

Our ancient Indian texts have references to ecological principles.

The classical text of Vedic period such as the Vedas, the Samhitas, the Brahmanas and Aranyakas-Upanishads contain many references to ecological concepts.

The Indian treatise on medicine, the Charaka Samhita and the surgical text Sushruta-Samhita show that people during this period had good understanding of plant and animal ecology.

Environment

The environment is defined as ‘the sum total of living, non- living components; influences and events, surrounding an organism’.

Concept of environment

The relationship and interaction between organism and environment are highly complex. No organism can live alone without interacting with other organisms and its immediate surroundings. So each organism has other organisms as a part of its environment. Each and everything with which we interact or which we need for sustenance forms our environment. The environment is not static. Both biotic and abiotic factors are in a flux and keep varying continuously.

Levels of organizations in Ecology.

Individual

Organism is an individual living being that has ability to act or function independently. It may be plant animal, bacterium, fungi etc.

Population

A population is a group of individuals of the same species inhabiting the same area. The main factors that make population grow are birth and immigration. The main factors that make population decline are death and emigration

Community

In order to survive individuals of any one species depend on individuals of different species with which they actively interact with several ways. Example: Animals require plants for food and trees for shelter. Plants require animals for pollination.

Ecosystem

An ecosystem is defined as structural and functional unit of biosphere consisting of community of living beings and the physical environment both interacting and exchanging materials between them.

An ecosystem is a complex set of relationship among the living resources, habitats and residents of that area.

Everything that lives in ecosystem is dependent on other species and elements that are also part of ecological community. If one part of an ecosystem is damaged, it has impact on everything else.

When ecosystem is healthy (i.e sustainable) it means that all the elements live in balance and are capable of reproducing themselves. Ecosystem can be as small as single tree or as large as entire forest.

Components of Ecosystem 

 The components of ecosystem is categorized into abiotic of non-living and biotic of living components. Both the components of ecosystem and environment are same.

1. Abiotic Components

Abiotic components are inorganic and non-living parts of the world. The abiotic part consists of soil, water air and light energy. It also involves large number of chemicals like oxygen, nitrogen etc and physical processes including volcanoes, earth quake, floods, forest fires, climates and weather conditions.

Abiotic factors are the most important determinants of where and how well an organism exists in its environment. Although these factors interact with each other, one single factor can limit the range of an organism.

Energy

Energy from sun is essential for maintenance of life. In the case of plants, the sun directly supplies the necessary energy. Since animals cannot use the solar energy directly they obtain it indirectly by eating plants or animals or both. Energy determines the distribution of organism in the environment.

Rainfall 

 Water is essential for living beings. Majority of biochemical reactions take place in aqueous medium. Water helps to regulate body temperature. Further water bodies form the habitat for many aquatic plants and animals.

Temperature

Temperature is critical factor of the environment which greatly influences survival of organisms. Organism can tolerate only certain range of temperature and humidity.

Atmosphere

The earth’s atmosphere is responsible for creating conditions suitable for existence of healthy biosphere on this planet. It is made up of 21% oxygen, 78% nitrogen, 0.038% carbon dioxide and other inert gases.(0.93 % Argon, Neon etc).

Substratum 

 Land is covered by soil and wide variety of microbes, protozoa, fungi and small animals (invertebrates) thrive in it. Roots of plants pierce through the soil.

Latitude and Altitude 

 Latitude has a strong influence on regions temperature, resulting in change of climate such as polar, tropical and temperate. These climates determine different natural biomes. From sea level to highest peak, wildlife is influenced by altitude. As the altitude increases the air becomes colder and drier affecting wild life accordingly.

2. Biotic components 

 Biotic components include living organisms comprising plants, animals and microbes and are classified according to their functional attributes into producers and consumers.

Primary producers – Autotrophs (Self nourishing)

Primary producers are basically green plants (and certain bacteria and algae).

 They synthesize carbohydrate from simple inorganic raw materials like carbon dioxide and water in the presence of sunlight by the process of photosynthesis for themselves and supply indirectly to other non producers.

Consumers – Heterotrophs or Phagotrophs.

Consumers are incapable of producing their own food(photosynthesis). They depend on organic food derived from plants, animals and both.

Macro consumers

They feed on plants and animals or both and are categorized on the basis of their food sources.

Herbivorous

These animals feed on herbs, plants, trees for their livelihood. Ex: Horse, Elephants, Giraffe, etc

Carnivorous

Carnivorous feed on secondary consumers are called tertiary consumers. Eg : Lion which eat wolves.

Omnivores

Omnivores are organisms that consume both plant and animals. Eg: Man

Micro consumers – Saprotrophs (decomposers or osmotrophs). They are bacteria and fungi which obtain energy and nutrients by decomposing dead organic substances (detritus) of plant and animal origin.

The products of decomposition such as inorganic nutrients by decomposing dead organic substances (detritus) of plant and animal origin.

Earthworms and certain soil organisms (such as nematodes and arthropods) are detritus feeders and help in the decomposition of organic matter and are called detrivores.

Classification of ecosystem

Natural Ecosystem.

Terrestrial

1.Forest

2.Grassland

3.Desert

Aquatic

1.Fresh Water

2.Saline Waters

 3. Estauries

Ecotone

Ecotone is a zone of junction between two or more diverse ecosystem.

For example: Mangrove forest represents an ecotone between marine and terrestrial ecosystem.

 Other examples are grassland, estuary and river bank.

Characteristics of Ecotone

1. It has conditions intermediate to the adjacent ecosystem. Hence it is zone of tension.
2. A well developed ecotone contains some organisms which are entirely different from that of adjoining communities.

Edge Effects.

In ecology, edge effects refer to the changes in population or community structures that occur at the boundary of two habitats.

Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range.

As the edge effects increase, the boundary habitat allows for greater biodiversity.

Niche 

A Niche is the unique functional role or place of a species in an ecosystem.

It is a description of all biological, physical and chemical factors that a species needs to survive, stay healthy and reproduce.

A niche is unique for a species which means no two species have exact identical niches.

Niche plays an important role in conservation of organisms.

If we have to conserve species in its native habitat we should have knowledge about the niche requirements of the species and should ensure that all requirements of its niche are fulfilled.

Types of Niche

Habitat niche – where it lives

Food niche – what it eats or decompose & what species it competes with.

Reproductive niche- How and when it reproduces.

Physical & chemical niche – temperature, land shape, land slope, humidity & other requirement.

Biome

The terrestrial part of the biosphere is divisible into enormous region called biomes which are characterized by climate, vegetation, animal life and general soil type.

No two biomes are alike. The climate determines the boundaries of a biome and abundance of plants and animals found in each one of them. The most important climatic factors are temperature and precipitation.

S. No	Name of Biome	Region	Flora and Fauna
1	Tundra	Northern most region adjoining the ice bound poles	Devoid of trees except stunted shrubs in the southern part of tundra biome, ground flora includes lichen, mosses .The typical animals are reindeer, arctic fox, polar bear, snowy owl, lemming arctic hare. Reptiles and amphibians are almost absent.
2	Taiga	Northern Europe, Asia and North America. Moderate temperature than Tundra. Also known as boreal forest.	The dominating vegetation is coniferous evergreen mostly spruce with some pine and firs.The fauna consists of small seed eating birds, hawks, fur bearing carnivores, little minks, elks, puma, Siberian tiger, Wolves
3	Temperate Deciduous Forest	Extends over Central and southern Europe, Eastern North America, Western china, Japan, New Zealand etc. Moderate average temperature and abundant rainfall. These are generally the most productive agricultural areas of the earth.	The flora includes trees like beech,oak, maple and cherry.Most animals are the familiar vertebrates and invertebrates.
4	Tropical rain forest	Tropical areas in the equatorial regions which is abound with life. Temperature and rainfall high.	Tropical rain-forest covers about 7 % of the earth’s surface & 40 % of the worlds plant and animal species. Multiple storeyof broad leafed evergreen tree species are in abundance. Most animals and epiphytes plants are concentrated in the canopy or tree top zones.
5	Savannah	Tropical region; Savannah is most extensive in Africa.	Grasses with scattered trees and fire resisting thorny shrubs.The fauna include great diversity of grazers and browsers such as antelopes, buffaloes, zebras, elephants rhinoceros; Carnivores include lion, Cheetah, hyena and mongoose and many rodents.
6	Grassland	North America, Ukraine etc. Dominated by grasses. Temperate conditions with rather low rainfall.	Grasses dominate the vegetation. The fauna include large herbivores like bison, antelope, cattle, rodents, prairie dog, wolves and a rich and diverse array of ground nesting bird.
7	Desert	Continental interiors with very low and sporadic rainfall with low humidity.The days are very hot but nights are cold.	The flora is drought resistance vegetation such as cactus, euphorbias, sagebrush.Fauna: Reptiles, mammals and birds.

Aquatic Zones

Aquatic systems are not called biomes. However they are divided into distinct life zones with regions of relatively distinct plant and animal life. The major differences between the various aquatic zones are due to salinity, levels of dissolved nutrients, water, temperature, depth of sunlight penetration.

S. No	Aquatic ecosystem	Characteristics
1.	Fresh Water Ecosystem	Fresh water ecosystems are classified as lotic (moving water) or lentic (still or stagnant water).Lotic water includes freshwater streams, springs, rivulets, creeks, brook and rivers. Lentic water bodies include pools, ponds, some swamps, bogs and lakes. They vary considerably in physical, chemical and biological characteristics.
2	Marine Ecosystem	Nearly three quarter of earth’s surface is covered by ocean with an average depth of 3,750 m and within salinity 35 ppt (parts per thousand) about 90 % of which is sodium chloride.
3.	Estuaries	Coastal bays, river mouths and tidal marshes form the estuaries. In estuaries fresh water from rivers meet ocean water and two are mixed by the action of tides. Estuaries are highly productive as compared to the adjacent river or sea.

Biosphere

Biosphere is a part of the earth where life can exist. Biosphere represents highly integrating and interacting zone comprising of atmosphere (air), hydrosphere (water) and lithosphere (land).

It is a narrow layer around the surface of the earth. If we visualize the earth to be size of an apple the biosphere would be as thick as its skin.

Biosphere is absent at extremes of the North and South poles, the highest mountain and deepest oceans because of hostile conditions which do not support life. Occasionally spores of fungi and bacteria do occur at great height beyond 8,000 mts, but they are not metabolically active and hence represent dormant life.

The energy required for the life within the biosphere comes from the sun. The nutrients necessary for living organisms comes from air, water and soil. The same chemicals are recycled over and over again for life to continue.

Living organisms are not uniformly distributed throughout the biosphere. Only few organisms live in the polar region while the tropical rain forests have an exceedingly rich diversity of plants and animals.

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