Education Is The Key To Success: Chapter No.11 : Ecosystems - Botany - For HSC Part 2 (XII)

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Q.4: Explain the climatic factors of an ecosystem.
Ans: CLIMATIC FACTORS OF AN ECOSYSTEM:
It consists of::

1. LIGHT:

i) LIGHT INTENSITY:

Light intensity varies with seasons by light intensity.
Opening and closing of stomata and permeability of cell membrane is affected by light intensity.
Intense light destroys chlorophyll.
The plants growing In light arc called helophytes while those growing in shade are called sclophytes.

ii) LIGHT DURATION:

The light duration or photoperiod has marked-effect on flowering, leaf fall and dormancy in plants.
In animals, behavioral activities (biological rhythms) such as court ship display, nesting and other behaviours are also effected by light.
In spring, migration of certain groups of birds depend upon photoperiod.

iii) LIGHT QUANTITY:

The visible light which ranges from 400-780 mn, consists of seven colours. The chlorophyll absorbs red and blue green colour for photosynthesis.
Light with shorter wavelength carries more energy but destroys micro-organisms and also causes sunburn in human beings.

2. TEMPERATURE:

A moderate temperature favours the growth and other activities of plants and animals.
Life exists, from 0°C to 50°C.
Different animals found at different places are due to variation in temperature.
Temperature below freezing. point or high temperature kills the living organisms or damage them.
Optimum temperature is required for enzymes efficiency.

3. WATER:

Water is the most important factor of ecosystem and is an important need of all the living organisms.
According to the availability of water, plants are grouped into XEROPHYTES, HYDROPHYTES and MESOPHYTES.
Water is abundant in aquatic ecosystem while it becomes limited in terrestrial ecosystem.
Water Is needed for all the physiological activities of plants and animals.
It is one of the raw materials needed for photosynthesis.
In terrestrial ecosystem, rainfall is the main source of water.
Plants absorb it from soil, however its availability is related to many factor like edaphic factors of soil and kind of vegetation.
In nature continuous cycling of water also takes place, it is culled hydrological cycle.

4. ATMOSPHERE AND WIND:

Atmosphere is u store house of CO₂, O₂, N₂ and vapours of water.
O₂ is used In respiration.
CO₂ in used in photosynthesis and N₂ is a major component of protein.
Wind current distributes these gases and brings atmospheric circulation of water vapours.
Wind also favour pollination and dispersal of seeds.
Wind with high velocity breaks the branches and plants.
Wind also influences the migration of flying birds and restricts timberline.
At high altitude the air pressure and percentage of oxygen is low that's why in these areas mammals cannot live.

5. FIRE:

Fire is n physical factor, which brings a sudden change in ecosystem.
A Fire may be caused by lightening, volcanic activities rind mutual friction between trees such as bamboos and mostly by man.
A forest which is established and created in centuries is destroyed in few minutes by fire.
Fire favour the competition among trees and set new species as climax.
Fire recycles various nutrients and new growth is stimulated.
Fire also favours the growth of some fungi. These fungi are called Pyrophilous Fungi.
Pyrophilous fungi decompose unborn dead plants or animals.
Men made fires are set to clear ground for agriculture or making mud but this is the destruction of ecosystem.