Abiotic Effects on an Ecosystem

The weather, soil, and such…

Biotic or Abiotic?

Biotic or Abiotic?

• Abiotic components: non-living components• Chemical, geological, physical factors

• Temperature• Light• Water• Oxygen Supply• Soil

• Biotic components: living components• Organisms and their relationships with other organisms

Role of the Abiotic Environment in Population Growth• Size and growth of population are affected by both biotic and

abiotic factors• Organisms are dependent on the abiotic factors of the

environment• They also modify these factors!

• Plants create shade, preserve water in the soil, consume carbon dioxide, and produce oxygen

Sunlight• Source of energy for almost all organisms

• Green plants need sunlight for photosynthesis• Adaptations occur to capture as much light as possible

• Water is divided into two zones• Photic zone: top layer where sunlight reaches• Aphotic zone: lower layer that sunlight does not

penetrate

Oxygen Supply• Air is composed of about 20% oxygen

• Easy for terrestrial organisms to obtain• Oxygen is returned to the air through photosynthesis

• Water contains dissolved oxygen in parts per million• Aquatic organisms extract this oxygen• Pollution can lower oxygen content

• Benefits some, harms some

Substratum• Soil or rock

• Acidity (pH)• Acid rain can make soil pH too low for many plants• Some plants like low pH (rhododenrons and pines)

• Texture of soil or clay content• Determine the quantity of water the soil can hold

• Minerals• Nitrates, phosphates, and other minerals

• Humus quantity• Determined by the amount of decaying plant and animal

life in soil

Chemical Cycles

• Within ecosystems, abiotic elements like nutrients are recycled and reused

• Nature has its own effective cycles of abiotic elements, and these cycles are crucial to every living organism on earth

• Carbon Cycle• Nitrogen Cycle• Water Cycle• Phosphorus Cycle

Carbon Cycle

Carbon Cycle• Gaseous carbon dioxide enters the living world via plants

• Photosynthesis uses carbon dioxide to produce glucose• Plants use glucose ot make starch, proteins, and fats• Animals eat plants and use digested nutrients to form carbs, fats

and proteins• Organic compounds are used in cellular respiration in plants and

animals and release carbon dioxide back into the air• The other organic carbons remains in an organism until death –

then the decaying process returns it to the air

Nitrogen Cycle

Nitrogen Cycle• Free nitrogen cannot be used by most organism• Free nitrogen is changed into usable, soluble nitrates by bacteria and

lightning strikes• Plants absorb the nitrates and synthesize nucleic acids and proteins• Animals eat the plants and synthesize animal proteins• Plants and animals give off wastes and eventually die• Nitrogen in wastes and dead tissue is released through decay as ammonia• Ammonia is converted into nitrites by chemosynthetic bacteria• Nitrites are converted into nitrates by nitrifying bacteria• Remaining ammonia is broken down to release free nitrogen

Water Cycle

Water Cycle• The sun heats up water in streams, lakes, oceans, etc• The water turns to vapor and moves into the air (evaporation)• Water vapor in the air cools and condenses into clouds• Eventually, the air cannot hold any more moisture and water

falls back to the Earth as precipitation• Water is collected in streams, lakes, oceans or as groundwater

Phosphorus Cycle

Phosphorous Cycle• Phosphorus is present in compounds that dissolve in water• Plants take in the phosphates from the water• Animals eat the plants and excrete waste that contains

phosphates, which are returned to soil or the ocean• When plants and animals die, decay returns more phosphates to

the soil or ocean