ecosystems myself

ecology

name given to the study of relationships between organisms and their environment

ecosystems are…

made up of all living organisms and their interactions with one another in a defined area as well as the physical factors that are present in the region

Biotic factors?

usually supports the idea of competition between living organisms for food, territory / space or breeding partners

Examples of abiotic factors

• light availability

• temperature

• water availability

• oxygen availability

• edaphic (soil) factors

light availability

Plants are directly affected by light availability, as they require light for photosynthesis. Plants have developed to adapt to changing light availability.

• in areas of low light plants have larger leaves

• some plants have developed photosynthetic pigments which require less light to perform photosynthesis

• some plant reproductive systems only operate when light availability is at its optimum

Temperature

Temperature has the greatest effect on enzymes that control metabolic reactions. Plants will develop more rapidly with warmer temperatures, as do ectothermic animals

• changing temperatures come with changing seasons triggering migration and hibernation in some

• in plant species, temperature changes in seasons trigger leaf fall, dormancy and flowering

Water availability

In most plants and animals a lack of water leads to water stress which if severe will lead to death

Plants need water to

• keep cells turgid to keep the plant upright

• photosynthesise

Cacti are examples of xerophytes plants that have developed successful strategies to cope with water stress

oxygen availability

for aquatic organisms it is beneficial to have fast-flowing cold water because if the water is

• too warm

• or flows at a slow rate

resulting drop in oxygen concentration leads to the suffocation of aquatic organisms

in waterlogged soil the air spaces between soil particles become water filled leading to reduced oxygen availability to the plant

edaphic - different soil types

• clay

• foam

• sandy

clay soil

• fine particles

• easily waterlogged

• forms clumps when wet

foam

• different sized particles

• retains water

• doesn’t become waterlogged

sandy

• coarse well-separated particles

• allow free drainage

• doesn’t retain water

• easily eroded

Trophic levels

stages in the food chain (transfer of food in an ecosystem)

primary

secondary

tertiary etc

biomass

mass of material in an area or organisms without their water content

why isnt water considered as part of biomass

water levels can fluctuate depending on time of day or the environment - so its not a true representation of energy content

Measuring energy content and biomass

• Calorimeter - measures amount of calories

• Collect sample → kill organism → Oven at 80 degrees

reason - at 80 degrees ensures that most if the water can be removed by evaporation but not burning it at 100 degrees which would cause some organic material to decay or disintegrate

• continue to check mass - once mass stays the same all the water has been removed

Unit of biomass

• land animals - gm-²

• marine animals - gm-³

ecological efficiency

• efficiency in which biomass is transferred from one trophic level to the next (%)

• never 100%

why / how is energy lost from primary consumers to secondary consumers?

• Not all of the light is used in photosynthesis

• Sunlight is reflected (only 10% used in photosynthesis)

• Other factors affecting photosynthesis rate e.g water availability

• some energy is used up for photosynthesis in order for the reaction to occur

why / how is energy lost from secondary consumer to tertiary consumer ?

• Energy lost through heat during respiration

• Energy lost through excretion

• Some parts of food not eaten

Agricultural ways to increase ecological efficiency

• keep animals indoors

• keep fences - less movement

• feed them high-energy-content food so they can eat the whole thing - more energy being absorbed and less lost through excretion

• Vaccination - less energy going to immune system fighting infection

• Genetic engineering / selective breeding - can withstand infection and wont get sick