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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!