Environmental Factor of Ecology

Dosen pengampu:

1.      Dr. Hadi Suwono, M.Si

2.      Dr. Vivi Novianti, S.Si, M.Si.

Ecological Factors that Constitute the Environment of an Organism

In any eco-system, a living organism is influenced by a number of factors and forces. These environmental factors are known as eco- factors or ecological factors. These factors may be biotic (living) and abiotic (non­living).

A.    ABIOTIC

          I.     Climatic or Aerial factors:

(a)   Light

Light plays an important role in the species composition and development of vegetation. And, on an average approximately only 2-3% of this solar energy is used in Primary Productivity. Light intensity shows special variations due to the factors like atmos­pheric water layer, particles dispersed in the air, etc.

v Effect of Light on Plants:

1.      The synthesis of chloro­phyll in green plants can take place only in the presence of light. 

2.      The rate of photosynthesis is slower at lower intensity

3.      Respiration increases at higher light intensity and it decreases at lower light intensity.

4.      The process of opening of stomata (which depends upon light) leading to loss of water from the aerial surface of plants is known as transpiration.

5.      Light inhibits the synthe­sis of auxins or growth hormones

6.      The intensity of light largely influences the growth and de­velopment of flowers, fruits and vegetative parts of plants.

7.      Intense light helps in the formation of anthocyanin pigments in plants.

8.      Effect on Movement phototropism The leaves grow transversely to light.

9.      Effect on Photoperiodism The response of plants to the relative length of the day. clas­sified into Long Day Plants, Short Day Plants, Day neutral Plants

10.  The germination of seeds is largely influenced by light.

11.  The duration and intensity of light plays an important role in determining the distribu­tion of plants. 

v Effect of Light on Animals:

1.      The rate of metabolism in animals is largely influenced by light intensity through enzyme activity.

2.      the breeding activities are induced by light through its inoculating action over the gonads.

3.      Light induces the formation of pig­ments in animals.

(b)  Temperature

The cardinal temperature (The mini­mum, optimum and maximum temperatures) varies from species to species, and in the same individual from part to part. The distributions of plants, animals are also influenced by tem­perature.

v  Effects of Temperature on Plants and Animals:

1.      In the extremely low temperature, the protoplasm may be frozen. On the other hand, in the extremely high temperature, the protein may coagulate or denaturation.

2.      Respiration increase when temperature increase.

3.      The growth and development of plants and poikilothermic animals is influenced by tempera­ture.

4.      The transpiration increases with increase in atmospheric temperature

(c)   Water

The most important for life. All physiological process take place in the medium of water.

·         Depending on requirement of water, plants groped into:

1.      Hydrophytes: Plants living in water require large quanti­ties of water.

2.      Xerophytes: Terrestrial plants which cannot tolerate ex­tremely dry conditions and pass through long periods without-water.

3.      Mesophytes: Terrestrial plants require moderate quan­tity of water.

·         Depending on requirement of water, animals groped into:

1.      Hydrocoles: Aquatic animals which live in water and require large quantity of water.

2.      Xerocoles: Terrestrial animals which can tolerate ex­tremely dry conditions and pass long periods without water.

3.      Mesocoles: Terrestrial animals requiring moderate quan­tity of water.

(d)  Rainfall

The rainfall pro­vides water to plants and animals. Rainfall occurs due to inter­change of water between earth’s surface and the atmosphere. Annual rainfall determines the types of vegetation in any region. Different regions of the earth receive, different quantity of rain­fall depending upon the geographical features and the availability of moisture laden winds. The quantity, duration and intensity of rainfall regulate plant life.

(e)   Wind

The wind accelerates transpiration, removes solid moisture and at high velocities causes soil erosion. Erosion is the removal of the surface soil, rich in organic matter and fine mineral particles.

(f)    Humidity

Processes as transpiration, absorption of water etc. are influenced by atmospheric humidity. Humidity, thus, plays an important part in the life of plants and animals.

(g)   Atmospheric gases

Some principal gases like nitrogen, oxygen, carbon-dioxide, helium, hydrogen, methane, ozone etc. are found in atmosphere. In addition to these gases, there are water vapours. Industrial gases, dust, smoke particles, micro-organisms etc. are present in the atmosphere. These gases have important influence on the environment.

(h)  Salinity

Levels of salt affects the balance of water organisms through osmosis. The most aquatic organisms live in habitats of freshwater or salt because it has limited ability to osmoregulate.

    II.            Edaphic Factors

Edaphic factors deals with different aspects of soil, such as the structure and composition of soil, its physical and chemical fea­tures. Differences in soils is the main cause of occurrence of change of vegetation and animals. pH and physical structure also affects the distribution of animals and plants

Soil has mainly the following components:

(i) Mineral matter.

(ii) Soil organic matter or humus.

(iii) Soil water/soil solution.

(iv) Soil Atmosphere.

(v) Biological system (fauna of bacteria, fungi, algae, proto­zoa, ratifies, arthropods, etc.).

 III.            Topographic Factors

Its concerned with physical geography of the earth are known as topographic factors. These factors influence vegetation which causes variation in climate of a geographic region. The different topographic factors are:

1.      Altitude of the place

As the altitude above the sea level increases, there happens a decrease of temperature. Besides, the values of pressure, humidity, wind velocity etc. also changes. All these factors together give a definite pattern of vegetational zone.

2.      Steepness and exposure of the slope

The slope of mountain affects the nature of vegetation. In northern hemisphere, south facing slopes receives more solar radiation than the north facing slope. the steepness of slope accelerates the downward movement of surface water. The downward movement of water over the slope causes soil erosion and as a result, the vegetation disappears from that area.

3.      Direction of the mountain chains.

Its influences the rainfall in an area. If the moun­tain chains lie in the path of wind full of water vapour, then there is heavy rainfall on the wind striking side on the mountain chain.

B.     BIOTIC

The biotic factors constitute the living organisms of the environment and definitely they have their interactions. All types of interactions of living organism called symbiosis. It can devided into positive interaction and negative interaction.

1.      Positive Interaction

When the population help one another or both the species benefit.

(a)   Mutualism

Mutually beneficial inter-specific interactions with permanent and obligatory contact indispensable for their survival is termed as mutualism. Generally, two species (population) enter into some contact beneficial to each other. Example: Pollination by Animals (Bees, moths, butterflies etc. de­rive their food from plants and bring about pollination), Dispersal of fruits and seeds (The birds eat the fruits and the seeds contained in fruits are left through excrement at different places), Symbiotic nitrogen fixers (The bacterium Rhizobium forms nodules in the roots of leguminous plants and lives symbiotically with the host. Bacteria derive food from the higher plants and in return fix gaseous nitro­gen which is necessary for the plants.)

(b)   Commensalism

Its represents two or more populations living to­gether without entering into any kind of physiological exchange. In this process, one is benefited without any effect on the other.

2.      Negative Interaction

(a)   Antibiosis.

Through the production of some substances or environmen­tal conditions due to metabolic pathways, there is death of one organism by another.

(b)   Parasitism.

A parasite is the organism living on or in the body of another organism and deriving its food from its tissues.

(c)    Predation.

Predator is free living organism which kills and devours individuals of other species.

(d)   Competition.

When two organisms survive for something which is inadequate leads to competition. Its devided into:

·         Intra-specific.

Competition occurs between the members of same population.

·         Inter-specific.

Competition occurs between the populations of different species

MIND MAP

Refflection

I know that environmental factors in ecology are divided into two, namely biotic and abiotic component. Abiotic component consists of objects cannot live while biotic consists of living things. Biotic factors include, among others, is the light of the Sun, water, wind, temperature, humidity and soil. Whereas biotic factors consist of interacting living thing. The interactions that happen to be called positive or negative. Biotic and abiotic component factors so intertwined with each other for the balance of the ecosystem.

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