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LIGHT: Limiting factor, variation in different ecosystems, effects on plants and animals

212/3/2016

Content

•Introduction

•Variation of light in different ecosystem

•Effects of light on plant

•Effects of light on animal

•Case study

•References

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INTRODUCTION

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.

The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.

•The main source of light on Earth is the Sun.•Light is part of the electromagnetic spectrum, which ranges from radio waves to gamma rays. •Electromagnetic radiation can also be described in terms of a stream of photons which are mass less particles each travelling with wave like properties at the speed of light. 

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VARIATION OF LIGHT IN DIFFRETNT ECOSYSTEM

The intensity of light reaching the Earth’s surface varies with angle of incidence, degree of latitude and altitude, season, time of day, amount absorbed and dispersed by atmosphere

A number of climatic and topographic factors such as fog, clouds, suspended water drops, dust particles etc.

When the angle of incidence is smaller results into relative reduction in intensity.

Likewise, sun’s altitude changes due to differences in latitude, changes in the season and in the time of day.

The illumination (intensity) of daylight is greatly diminished by moisture, clouds, and dust in the atmosphere and also by forest vegetation.

The direction and slope of the mountain also affect light intensity. There will be no light on the one side of slope.

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Illumination is measured in lux.

About 10% of the sunlight which falls over the water surface, is reflected back and rest 90% of that pass down in the water

The phytoplankton, zooplankton, suspended organic and inorganic particles either reflect or absorb the light rays.

Depending upon the penetrating of light, oceans are divided into 1. euphotic zone (up to 50 meter depth)2. disphotic zone (up to 80 to 200 meters depth) 3. aphotic zone (below 200 meter of depth)

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•Without light, many of the plants would not be able to produce the energy needs to grow

•Sunlight provides the energy that green plants use to create sugars, which release energy into the living things

•Plants get energy from light through a process called photosynthesis, this process provides virtually all the energy used by living things

EFFECTS OF LIGHT ON PLANT

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Light affecting plants

IndirectlyDirectly

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1. Intensity2. Quality3. Duration4. Chlorophyll Production5. Stomatal movement6. Heating Action7. Distribution of plants8. Overall vegetative development of plant

Mainly plants are affected directly by light with,

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• Light effects on plants based on its intensity, quality and duration which are also known as limiting factor for plant growth.

1. Intensity: light intensity increases, the rate of photosynthesis will increase as long as other factors are in adequate supply. As the rate increases, eventually another factor will come into short supply. The graph below shows the effect of low carbon dioxide concentration.

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2. Quality: Normal plant growth requires white light or sunlight Light quality refers to the color or wavelength reaching the plant's surface. If we take an example of a prism (or raindrops) can divide sunlight into

respective colors of red, orange, yellow, green, blue, indigo and violet. Red and blue have the greatest impact on plant growth.Green light is least effective (the reflection of green light gives the green

color to plants). Blue light is primarily responsible for vegetative leaf growth. Red light,

when combined with blue light, encourages flowering.

Relative efficiency of various light colors in photosynthesis

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3. Duration: Photoperiodism : Total length of daily light period to which plants are exposed

Neutral day plant

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4. Chlorophyll Production: Mostly plants needs light for chlorophyll production. So survival of other life also depends upon light as they depend upon plants for food

5. Stomatal movementBasically opening and closing of stomata is regulated by lightIt is also related with transpiration and absorption

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6. Heating Action:By changes in light intensity, heating of plant parts get changes. As

higher the temperature it creates higher temperature in plant parts

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7. Distribution of plants:Light is the main reason by which the distribution of plants is takes places

in various places on Earth with different latitude.

8. Overall vegetative development of plant:Heliophytes: They are the plants growing best in full sun light Sciophytes: The plants which grow best in low sun light

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Plants are indirectly affected by light with,

1. Transpiration Rate2. Respiration3. Absorption

1. Transpiration Rate:By increasing the temperature light is indirectly affecting the transpiration rate of plant

body. It also affects the water absorption capacity.Thus, higher intensity of light is connected to dried habitat

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2. Respiration: With changes in stomata movement and transpiration rate respiration also gets affected indirectly with light

3. Absorption:As transpiration rate changes, absorption of water is also changes in plant growth rate

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EFFECTS OF LIGHT ON ANIMAL

•Light is affecting normal pattern of day and night are very important for most living things to function properly. •The waking and sleeping patterns of many animals are affected by the changes in light over 24 hours or during the year.•Many animals are diurnal, which means they will naturally wake up when it gets light and go to sleep when it becomes dark. •Nocturnal animals react in the opposite way. They sleep during the day and wake up at night-time. •There are also crepuscular animals that are active primarily during twilight, the time just before the sun sets or rises.

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1. Migration2. Hibernation3. Animal eyes4. Camouflage5. Bioluminescence6. Protoplasm7. Metabolism8. Photoperiodism and Biological clock (Biorhythms)

Mainly animals are affected by light with,

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1. MigrationMany animals are also affected by the change of season. The length of daylight

affects animals when to start migrating. Many birds migrate to countries thousands of kilometers away. They will use

the sun to help them find their way (navigate). Bees also use the position of the sun to navigate.

2. HibernationIn some colder countries, the shorter days trigger hibernation in animals like

bear. These animals eat a lot in the warmer months to build up fat before sleeping in a

burrow, cave or hole during the cold winter.

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3. Animal eyesInsects, such as flies, have compound eyes which is directly affected by light. Unlike humans, some animals can see infrared and ultraviolet light.Bees can see ultraviolet light which helps them see flowers that reflect

ultraviolet light from their petals. Other animals, such as the piranha, can see infrared light. Seeing infrared light

helps animals to catch their prey.

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4. Camouflage with pigmentation: Many animals have different colours and patterns on their fur or skin that make them

difficult to see. This means they are camouflaged. Other animals use colour to scare predators. Chameleons can change colour to fit in with the environment around them. Animals can do this by changing the size of the pigment cells in the skin. When these

pigment cells change size, they make different colours and patterns on the skin.

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5. BioluminescenceMany animals give out light. When animals make this light, it is call

bioluminescence.Some animals use chemicals or bacteria inside the cells of their body to create

light.The male Malaysian firefly is one insect that produces a particularly spectacular

show. Many fireflies sit on the same bush and all flash their light at the same time.

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6. Effect on Protoplasm:Some animals remain protected by some sort of body covering which is helping

to protect from solar radiation.Ultraviolet rays are known to cause mutational changes in the DNA of various

organisms.

7. Effect on metabolism:By increasing in light intensity results increase in enzymatic activity. Solubility of gases decreases with higher light intensity

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8. Photoperiodism and Biological clock (Biorhythms):Circadian rhythms:

• It is mainly working with the Earth’s rotation by working with day/ night with activity /sleep.

Circatidal rhythms:• In this rhythms, tidal activities are affecting the working of animal• By changes in high and low tides, the animals which are living in intertidal zone

alternately submerged in water and exposed to air.Circalunar rhythms:

• It is synchronized with the phases of moon. With the changes in phases animals are changes their color, size which is also known as heteronersis.

Semilunar rhythms:• It deals with spring tide and neap tide which is related to the second and fourth

quarter of moonCircannual rhythms:

• The activities of animals are also affected by seasonal changes during the year. Metabolic activities of animals are changes with seasonal changes.

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CASE STUDY

Impact of Light Intensity on Habitat Preference of Macro invertebrates in Carp CreekAccording to the study done in the region Carp Creek near Pellston, Michigan, the affect of light on macroinvertebrate was studied by Emma Kelly and members.The results shows that, 6 pairs of Mayfly and amphipod growth was changed due to the variation of light.

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Multiple Choice Questions

1. Illumination is measured in ______A. Nanometer B. centimeterC. Lux D. kilometer

2. ______ light is less affecting on the plant growthA. Red B. BlueC. Violet D. Green

3. Tidal activities are affecting the working of animal are known as __________A. Circatidal rhythms B. Circadian rhythmsC. Circalunar rhythms D. Semilunar rhythms

4. _________ is direct affect of light on plantsB. Absorption B. Chlorophyll ProductionC. Transpiration Rate D. Respiration

5. Crepuscular animals are highly active during _______C. Daylight B. DarklightC. Morninglight D. Twilight

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REFERENCES

•P. S. Verma, V. K. Agarwal. Cell Biology, Genetics, Molecular Biology, Evolution and Ecology. 10th ed. S. Chand & Company Ltd, 2010 •P. D. Sharma. Ecology and Environment. 10th ed. Rastogi Publication, 2010•http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1517&context=natrespapers•http://www.andor.com/learning-academy/what-is-light-an-overview-of-the-properties-of-light•http://www.rsc.org/learn-chemistry/content/filerepository/CMP/00/001/068/Rate%20of%20photosynthesis%20limiting%20factors.pdf•http://www.ext.colostate.edu/mg/gardennotes/142.html•http://www.skwirk.com/p-c_s-11_u-25_t-137_c-436/animals-and-light/nsw/science-technology/light-up-my-life/sensing-light

THANK YOU

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