Ecosystems Revision Notes
Ecosystems
Defining Ecosystems
-ecosystems are all the living organisms hat interact with one another in a defined area
-also includes the physical factors present in that area
-range in size – can be a tiny bacteria colony or the entire biosphere of Earth
-boundaries of ecosystems are defined by the team carrying out the study (rock pool or playing field)
Factors Affecting Ecosystems
-all ecosystems are dynamic (constantly changing)
- 2 different factors affect ecosystems
Biotic Factors – living factors (presence of animals, competition for space, food and breeding partners)
Abiotic Factors – non-living factors (light, temperature, water availability)
Biotic Factors
-living factors
-interactions between organisms that are living)
Producers – plants (and some photosynthetic bacteria) supply chemical energy to all other organisms
Primary Consumers – eat the producers (herbivores)
Secondary Consumers – eat the primary consumers (carnivores/omnivores)
Decomposers – (bacteria and fungi) feed on waste material or dead organisms
-interactions often involve competition for food, territory and breeding partners
Abiotic Factors
-non-living factors
Light
-light availability will affect the rate of photosynthesis
-the greater the availability of light, the greater the success of plant species
-plants can develop strategies to cope with low light intensities (larger leaves, photosynthetic pigments that require less light)
Temperature
-temperature will affect the enzymes controlling metabolic reactions
-plants and ectothermic animals will develop more in warmer temperatures
-temperature changes can lead to behavioural/physiological changes (migration and hibernation in animals and leaf-fall and flowering in
plants)
Water Availability
-a lack of water will lead to water stress, if severe, will lead to death
-lack of water will calls plants to wilt as water is needed to keep cells turgid, keeping the plant upright
-xerophytes have developed successful strategies to cope with water stress
Edaphic (Soil) Factors
-different soil types have different effects on different organisms due to the soil’s particles size
Clay – fine particles that are easily clumped together and waterlogged
Loam – different sized particles that retain water but does not become waterlogged
Sandy – well-separated particles that does not retain water and easily eroded
Dynamic Ecosystems
-ecosystems are forever changing hence they are referred to being dynamic
-small changes can affect each organism
-e.g. if predator population increases, prey population decreases as there are more predators to eat them
-3 types of changes affect population size:
Cyclic Changes Directional Changes Unpredictable Changes
-changes that repeat them self -changes that go in one directional and last -changes that have no direction or rhythm
e.g. seasons, fluctuations in predator and longer than the organism’s life time e.g. flood, hurricanes, lightning
prey populations e.g. erosion of coast line
Ecosystems
Defining Ecosystems
-ecosystems are all the living organisms hat interact with one another in a defined area
-also includes the physical factors present in that area
-range in size – can be a tiny bacteria colony or the entire biosphere of Earth
-boundaries of ecosystems are defined by the team carrying out the study (rock pool or playing field)
Factors Affecting Ecosystems
-all ecosystems are dynamic (constantly changing)
- 2 different factors affect ecosystems
Biotic Factors – living factors (presence of animals, competition for space, food and breeding partners)
Abiotic Factors – non-living factors (light, temperature, water availability)
Biotic Factors
-living factors
-interactions between organisms that are living)
Producers – plants (and some photosynthetic bacteria) supply chemical energy to all other organisms
Primary Consumers – eat the producers (herbivores)
Secondary Consumers – eat the primary consumers (carnivores/omnivores)
Decomposers – (bacteria and fungi) feed on waste material or dead organisms
-interactions often involve competition for food, territory and breeding partners
Abiotic Factors
-non-living factors
Light
-light availability will affect the rate of photosynthesis
-the greater the availability of light, the greater the success of plant species
-plants can develop strategies to cope with low light intensities (larger leaves, photosynthetic pigments that require less light)
Temperature
-temperature will affect the enzymes controlling metabolic reactions
-plants and ectothermic animals will develop more in warmer temperatures
-temperature changes can lead to behavioural/physiological changes (migration and hibernation in animals and leaf-fall and flowering in
plants)
Water Availability
-a lack of water will lead to water stress, if severe, will lead to death
-lack of water will calls plants to wilt as water is needed to keep cells turgid, keeping the plant upright
-xerophytes have developed successful strategies to cope with water stress
Edaphic (Soil) Factors
-different soil types have different effects on different organisms due to the soil’s particles size
Clay – fine particles that are easily clumped together and waterlogged
Loam – different sized particles that retain water but does not become waterlogged
Sandy – well-separated particles that does not retain water and easily eroded
Dynamic Ecosystems
-ecosystems are forever changing hence they are referred to being dynamic
-small changes can affect each organism
-e.g. if predator population increases, prey population decreases as there are more predators to eat them
-3 types of changes affect population size:
Cyclic Changes Directional Changes Unpredictable Changes
-changes that repeat them self -changes that go in one directional and last -changes that have no direction or rhythm
e.g. seasons, fluctuations in predator and longer than the organism’s life time e.g. flood, hurricanes, lightning
prey populations e.g. erosion of coast line
