Relationship of species with physical environment


Ecology studies the interactions between organisms and their physical and biotic environment. The physical environment can be built (i.e., created by people) or it can be natural (i.e., trees, rivers, etc.).

The physical environment includes land, air, water, plants and animals, buildings and other infrastructure, and all of the natural resources that provide our basic needs and opportunities for social and economic development. Plant growth and geographic distribution are greatly affected by the environment.

Climatic factor:

It is related to climates such as light, temperature, atmosphere, precipitation (snow, fog, rainfall), and wind. Climatic factors act directly on the growth, survival, reproduction, and movement of individuals

Edaphic factor:

It is related to the soil such as soil texture, soil structure, soil moisture pH of soil depth, and ingredients of soil, such as water, minerals, salt, gases, acidity, etc. For example, very alkaline soil may be an edaphic factor limiting the variety of plants growing in a region.

Topographic factor:

Arrangement of natural and artificial physical features of Earth i.e. plains, mountains, valleys, water bodies, etc. Every habitat has a different set of environments. Every specie living in that environment should respond to these factors in different ways.

Basic requirements:

Every specie whether it is a plant or animal show a response and required a certain amount of water, light, temperature, and salts. Water is essential for plants. According to water requirements plants are categorized into three classes.

(i) Aquatic  (ii) Mesic (iii) Xeric

1) On the basis of water: –

On the basis of water, plants are of three types.


The aquatic plants are called hydrophytes. These plants do not face water shortage condition. They have large leaves with a large number of stomata to increase the rate of transpiration. These plants have access to water availability.

For example Water lily.


The plants living in a moderate water environment are called Mesophytes. These plants have moderate water availability.

For example Hydra.


The plants living in dry Terrestrial environment is called Xerophytes. These plants have minute leaves and awesome time they shut shed their lives to reduce the rate of transpiration. These plants have a shortage of water.

For example Cactus.

On the basis of light: –

On the basis of light plants are of two types:


Showing adaptation to bright sunlight. They are also called sun-loving plants, which are those that require for their optimum growth full exposure to the sun. E.g., Mango


Also called shade-loving plants, these are those plants that require reduced light intensity. These plants have larger photosynthetic units than heliophytesSciophytes are also known as photophobous plants and they reach their saturation level in only 20% sunlight.

On the basis of temperature: –

On the basis of temperature plants are of two types:


It requires less amount of temperature.


It requires a higher amount of temperature.

Ecological Amplitude:

Is range in which a plant flourishes in an ecosystem or in a community is called ecological amplitude.

  • Variation in organisms.
  • Ecotype and biotype.
Variation in organisms:

Ecological amplitude is firstly dependent upon variation in organisms. The plants or other species live in an area; all are morphologically or physiologically different.

Ecotype and biotype:

A Group of organisms which are selected by nature and adapted themselves to the environment is called ecotypes. For example Tall trees. These are not produced artificially.


A Group of organisms within the ecotype produced by variations caused by gene recombination is called by biotype. In the biotype, those organisms produced have the gene variation. The greater the number of ecotypes and biotypes in Species, the wider the ecological amplitude.

Importance of ecological amplitude:

a) Geographical distribution:

The natural arrangement of various forms of animals and plants are in different regions and localities of Earth. Ecological amplitude regulates the distribution. Different animals and plants are present in the area and adapted to their physical environment.

b) Phonologicalbehavior:

The occurrence of any phenomenon during any time is called “phonological behavior”. For example, some of the plants show flowering in the summer season and some of the plants show flowering in the winter season.


The appearance of species in different areas is zonation. Different zones are formed in an area, such as tall trees, shrubby plants vegetation occurs.

Capacity to use resources:

Certain species are more efficient to use resources, such as minerals, water, nutrients, etc. than others. This is because of their efficient “phylogicare system” produced under the influence of genetic recombination.

For example, Tall trees absorb more sunlight and their roots are deeply penetrating and absorb more nutrients than other small shrubby plants.

Relation of organisms with the same species or different species:

Based on interrelationships that exist between the organisms of the same species or different species, this species shows the following characteristics:


Groups of individuals which can interbreed in nature and produce fertile offspring are known as species.


A Group of individuals of the same species occupying the same place at the same time is called a population.


The individual or organisms of a specie compete for the resources available to them such as water, light, space, and mineral salts.


It is the type of relationship in which one population inhibit or reduce the other population by producing other harmful Chemicals is called ammensalism.

For example Algal blooms


It is the type of relationship in which both organisms get benefit from each other.

For example, Lichen is composed of fungi and algae.


It is the type of relationship in which one organism get benefit and other organisms neither get benefit nor harm.

For example Nest on trees.


A relationship in which one of the individuals called a “parasite” receives benefits at the expense of another organism card the “host” is called parasitism.

For example The species of Cuscuta.


It is an interaction in which one organism called a “Predator” eats another organism called “prey”.

For example, Lion eats a deer.


The transfer of pollen grains from one plant to another is known as pollination/ the transfer of pollen grains from the anther to the stigma. A large number of plants depends upon insect or Birds for pollination.

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