Ecology xi

Ecology (oikos -home; logous - study )

Study of interrelationships between living beings and environment is called ecology 

Term ecology for the first time used by H. Reiter

There are two branches of ecology _

A. Synecology 

Study of relationship between living community and environment 

B.Autecology:

Study of interrelationships between individual of species or its population with environment

Ecological factors :

The environmental components that influence growth, reproduction, migration etc. are called environmental factors.

There are two types of ecological factors-

1. Abiotic factors and 

2. Biotic factors 

1. Abiotic factors:

They are nonliving components of the environment that influence life 

They are of three types 

a. Climatic factors 

b. Edaphic factors and 

c. Topographic factors 

a. Climatic factors:

Related with atmosphere which may be light, temperature etc.

Light:

Most important environmental factors without which nolife exists  accept some chemoautotrophic bacteria 

The continuous source of light on earth is sun

Effect of light on plant:

It is essential for photosynthesis of organic food by chlorophyll 

All animals depends on plants for food 

It influences closing and opening of stomata, transpiration, flowering, seed germination  etc.

Plants grow in direct strong sunlight are called heliophytes whereas those which grow in suffused  light is called sciophytes

Effect on animal:

It influences migration, movement, size of the eye, reproduction, pigmentation of skin etc.

Water and humidity:

It determines the amount of ground water, type of vegetation and distribution of animals 

Rainfall throughout the year causes tropical evergreen forest

Good rainfall one or two  season causes deciduous forests 

Moderate rainfall one or two season causes grassland 

Least or no rainfall causes deserts 

b. Edaphic factors 

Study of soil is called pedology

The uppers weathered surface of earth crust which contains organic and inorganic matters in which microorganism lives and plant can grow is called soil 

Soil also provides habitat for terrestrial animal and water, minerals and fixation to the plant 

Plant may be lithophyte, samophyte, oxalophyte i.e. grow on rock, sandy soil and acidic soil respectively. 

The various components of soil which affect vegetation are as follows 

I. Soil air and soil water:

Water and air found in interparticles space of soil 

Soil air helps in respiration of microorganism and root in soil 

Plant absorbs capillary water through which minerals also get absorbed

Ii. Soil temperature:

Very high and low temperature is injurious for root 

Soil temperature influences root formation, absorption of water and seed germination 

Iii. Soil organic matters:
Dead organic matters present in soil is called humus. It makes the soil porous, increase fertility, aeration and water holding capacity of the soil.

Iv. Soil microorganism:
Some bacteria and fungi such as Nostoc, Anabaena, Spirulina, Clostridium  etc. increases fertility of the soil 

V. Soil pH:
Some plants require acidic whereas other needs alkaline soil for there normal growth therefore soil pH influences distribution of plants

Vi. Soil type:
Loam soil is better than any other soil for cultivation of crops

C. Topographical factors:
It is the description about the structure  of earth's surface 
It includes mountains, valleys, plain, altitudes, direction of slopes etc 
The temperature and pressure decreases with increase in altitudes 
Low temperature favours the formation of cloud and rainfall therefore mountain and hills are favourable for plant growth and causes different types of forests due to climatic variation  
The sunward faces of the mountains have better vegetation than opposite faces 
Slopes causes corrosion and quick movement of water therefore valleys and plains are good for cultivation due to slow movement of the surface water and gets direct sunlight for long duration of time.