Abiotic Components Abiotic components are non-living geological, physical and chemical factors in the environment which affect ecosystems.

Abiotic components can be categorized as condition or resources. It includes : • Soil

• Atmospheric a. Light

b. Temperature

c. Wind

d. Water

e. Atmospheric gases

• Physiographic Factor

Plants growth requirements

Plants Req. Light

Soil

Heat

Water

Air

http://www.youtube.com/watch?v=d26AhcKeEbE&NR=1

Soil / Edaphic Factor

Besides these factors Soil microbes and Decaying

matter is also affecting .

• Soil Texture : The size of soil particles varies from

microscopic particles called clay to larger particles

called sand.

• Loam soil is a mixture of sand and clay particles. •

• Sandy soils are suitable for growing plants because

they are well aerated, excess water drains away

quickly, they warm up quickly during the day and is

easy to cultivate, whereas its unsuitable because

they does not retain much water and soon dry out

and contain few soil nutrients required for plant

growth.

• Clay soils are suitable for plant growth

because they hold large quantities of water

and are rich in mineral nutrients. But they

are unsuitable as they are badly aerated,

soon becomes waterlogged and it also gets

cold during winter. •

• Loam soils possess desirable properties of

both sand and clay - it has a high water

retaining capacity, good aeration, good

nutrient content .

http://www.physicalgeography.net/fundamentals/10t.html

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPLANTHORM.html

• Soil air : Soil air is found in those spaces between

the soil particles that are not filled with soil water.

The amount of air in a soil depends on how firmly

the soil is compacted. In well-aerated soil at least

20% of its volume is made up of air. •

• Soil temperature : Soil temperature is an important

ecological factor. It has been found that the

temperature of soil below a depth of about 30cm is

almost constant during the day but seasonal

temperature differences do occur. At low

temperature there is little decay by decomposers.

• Soil water: Soil water can be classified into three

types, namely hygroscopic, capillary and

gravitational water:

a. Hygroscopic water occurs as a thin film of

water around each soil particle.

b. Capillary water is that water held in the small

spaces between the soil particles and

c. Gravitational water is the water which drains

downwards through the soil.

• Soil solution :Soil solution is the decaying

remains of plants and animals, together with

animal excretory products that form humus.

This increases the fertility of the soil.

Task 3, 1 point Should be submitted within one week

• Compare between sandy and clay soils in

term of:

– Particles size

– Soil air

– Water holding capacity

– Water retention

– Tillage and cultivation

– Temperature and freezing

– Etc

• Soil pH : Acidity or alkalinity of soil (the

pH of the soil) influences the biological

activity in soil and the availability of certain

minerals. Thus the pH of soil has a greater

influence on the growth and development

of plants. Some plants e.g. ferns grow best

in acid soils ( soils with a pH below 7),

while xerophytes (desert ) grow better in

alkaline soils (soils with a pH above 7).

Light

• Sun is the major source of light and heat on

earth.

• The variation of this solar energy creates day

and night and the great change in climate

from the baking deserts to the freezing poles.

• The earth spins on its axis of rotation every

24 hours, so that most of the world has 24

hours cycle of day and night.

• Why there is difference between equator and

poles ???

Length of day and night

SunriseSunset

Sunrise Sunset

Sunrise Sunset

Summer Spring and Autumn Winter

• As the energy passes through the

atmosphere, about 20%-40% of it is

absorbed by gases, dust and water vapor in

the atmosphere.

• The energy which reaches the poles has

more atmosphere to travel compared to

earth thus more energy is lost before it

reaches poles. Over a year equator gets

twice as much as energy as either poles

(Woodward 1987)

Direct

solar

rays26% Atm.

Absorpt

ion14%

Reflect

ion 4%

Atm.

ref.7%

Sky

radiatio

n atm

11% Sky rad.

Clouds

14%

Cloud sur

ref24%

• It is the energy that is used by green plants

(which contain chlorophyll) during the

process of photosynthesis. Visible light is of

the greatest importance to plants because it

is necessary for photosynthesis. Factors

such as quality of light, intensity of light and

the length of the light period (day length)

play an important part in an ecosystem.

• Light requirements of plants differ and as a

result distinct layers, or stratification, can be

observed in an ecosystem. Plants which

grow well in bright sunlight are called

heliophytes (Greek helios, sun) and plants

which grow well in shady conditions are

known as sciophytes (Greek skia, shade )

Temperature

• The opening of the flowers of various plants

during the day and night is often due to

temperature difference between the day and

night.

• The seed of some plants (biennials) normally

germinate in the spring or summer; this

phenomenon is well observed in carrots and is

called vernalization الحث

• Some fruit trees such as the peach require a cold

period each year so that it can blossom in the

spring.

• Deciduous trees األوراق متساقطة نباتات lose

their leaves in winter and enter into a state

of dormancy, where the buds are covered

for protection against the cold.

• The seeds of many plants, e.g. peach and

plum, must be exposed to a cold period

before they germinate; this chilling ensures

that seeds don't germinate during autumn,

but after winter, when the seedlings have

better chances to survive.

• In animals, a distinction is made between

ectothermic "cold-blooded” animals and

endothermic "warm-blooded“ animals.

• In desert conditions, there is greater

temperature variation between day and night

and organisms have distinct periods of activity,

for e.g. many cacti الصّبار flower at night and are

pollinated by nocturnal ليلي insects.

• Seasonal movements (migration) occur in some

animals; examples of such animals are

migratory locusts الجراد, butterflies and various

marine animals like whales and penguins.

• Seasonal changes have also a great influence

on animal life in an ecosystem; torpor in سبات

winter is common in reptiles and some

mammals in South Africa, but a winter sleep

occurs in bears of the northern hemisphere;

some animals collect fat or other resources

during favourable periods (often summer and

autumn) and become dormant this is called

hibernation الشتوي السبات , there are also animals

that are dormant during warm and dry conditions

and this is known as aestivation ; الصيفي السبات

examples of such animals are snails القواقع and

the African lung-fish.

Water

Plants can be classified into 3 groups

according to their water requirements:

– Hydrophytes: Hydrophytes are plants which grow

in water e.g. water-lilies and rushes.

– Mesophytes: Mesophytes are plants with

average water requirements e.g. roses,

– Xerophytes: Xerophytes are plants which grow in

dry environments where they often experience a

shortage of water e.g. cacti and often succulents.

Aloes are xerophytes.

Hydrophytes' Lotus

Mesophytes Rose

Xerophytes Aloe vera

Water requirements of animals: Terrestrial animals are also exposed to desiccation

تجفيف and just a few interesting adaptations are

mentioned here:

• Chitinous body covering of insects, the scales

ريش of reptiles, the feathers حراشف of birds and the

hair of mammals prevent the water loss.

• The tissues of animals may be tolerant to water

loss e.g. a camel can live without water for long

periods because its body tissues have this

adaptation.

Water cycle

• Condensation of water vapor in the air

leads to precipitation the rain.

• Evaporation returns water vapor to the

atmosphere.

• Infiltration of rainwater replenishes يغذي

groundwater supplies.

• Surface runoff of rainwater replenishes

surface water supplies.

http://www.buffer.forestry.iastate.edu/Photogallery/illustrations/Images/Hydrologic-Cycle.jpg

Wind

• Winds carry water vapour which may condense

and fall in the form of rain/snow .

• Wind plays a role in pollination and seed dispersal

of some plants, as well as the dispersal of تشتيت

some animals, such as insects.

• Wind erosion can remove and redistribute topsoil,

especially where vegetation is less.

• Warm dry winds may cause a fire hazard.

• Plants grown in strong winds are usually smaller

than those in less windy conditions.

Physiographic

• These factors are associated with the

physical nature of the area, such as altitude,

slope of land and the position of the area in

relation to the sun or rain-bearing winds.

• Altitude االرتفاع plays a role in vegetations

zones.

• Slopes are important when considering the

temperature of the soil surface on land with a

northern slope, on level and on land with

south facing slopes, thorn scrub is شجيرات

often found growing on these slopes .

Atmospheric gases

• The most important gases used by plants

and animals are oxygen, carbon dioxide and

nitrogen.

• Oxygen: It is used by all living organisms

during respiration.

• Carbon Dioxide: It is used by green plants

during photosynthesis.

• Nitrogen: It is made available to plants by

certain bacteria and through the action of

lightning.

Oxygen cycle

• Essential for animals during respiration,

released by plants as by product of

photosynthesis.

• Cycles much like the carbon cycle.

• Deforestation, ocean pollution is harmful

for oxygen cycle.

http://www.ba.ars.usda.gov/bpdlkids/oxygen_graphic.html

Carbon Cycle

• CO2 is taken up by plants during photosynthesis

• CO2 is released by organisms during respiration and decomposition; fires, volcanoes

• CO2 is also released by vehicles and industries

• Carbon, present in all organic molecules, moves along the food chain as one organism eats another

• 78% of the volume of troposphere

• Most complex cycle

• N2 gas can’t be used so it must be ‘fixed’ so that organisms can use it

• Steps to the cycle:

– N Fixation – occurs in plant, by bacteria

– Ammonification (the conversion of organic nitrogen to ammonium (NH4

+) by the action of decomposers (bacteria).

– Nitrificationa nitro group is added to an organic compound

– Assimilation (The conversion of nutriments into أغذيةliving tissues)

– Denitrification

Nitrogen cycle

• N2 gas is modified by “nitrogen-fixing” bacteria in legumes into ammonia (NH3) – NITROGEN FIXATION – aids in production of sugars/starches

• Bacteria turn wastes and detritus into ammonia – AMMONIFICATION – released into atmosphere .

• NH3 is converted into nitrite (NO2-) which is

then used to produce nitrate (NO3-) -

NITRIFICATION

• Plant roots take up the ammonia and nitrate ions and converts it into amino acids, proteins, DNA/RNA = assimilation امتصاص

• nitrogen, present in proteins, moves through the food chain as one organism eats another .=Denitrification نزع النتروجين

Phosphorus Cycle

• Phosphorus is released as rocks erode

and plants assimilate this

• Very slow process

• Phosphorus passes from one organism to

another in the food chain

• Decomposers release phosphorus during

decomposition

• Mined for production of fertilizer. Mined in

Tampa, FL

http://arnica.csustan.edu/carosella/Biol4050W03/figures/phosphorus_cycle.htm

Thank you!