Ecosystems: Change and Challenge (Key Terms and Ideas)

Ecosystems: Change and Challenge

All the key terms for the topic (excludes case studies)

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What is an ecosystem?
A system that includes all living organisms in an area, as well as its physical environment, functioning together as a unit.
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What are biotic factors?
Influences on an ecosystem from living things e.g. plants, animals, bacteria
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What are abiotic factors?
Influences on the ecosystem from non living things (sunlight, water, humidity, soil etc.)
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Where does all energy used by living things come from?
Ultimately, the sun. Energy enters living things as a result of photosynthesis by plants (and some bacteria)
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How much incoming sunlight is captured?
Less the 4%. Of this, more than half the energy captured by plants is used in resperation/ lost as heat.
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What is a herbivore?
Any organism that eats only plant tissue (a primary consumer), for example a rabbit. They feed on the plant whilst it is alive.
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What is a decomposer?
An organism which feeds on dead matter. Examples include fungi and bacteria.
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Where does the majority of energy go to in most ecosytems?
The decomposers.
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How do herbivores use most of their energy intake?
They use almost all of their energy intake on resperation and maintaining their body temperatures.
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What is biomass?
The total mass of living biological organisms in a given area.
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What is a carnivore?
Secondary Consumers. They are organisms that divise most of their energy and nutrient requirements from a diet almost exclusivly of animal tissue (e.g. a lion.)
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What are nutrients?
Nutrients are the chemical elements and compounds needed for organisms to grow and function. Plants cannot grow (make new cells) if essential nutirents are absent.
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What is Nutrient Cycling?
The movement of the nutrients within an ecosystem.
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In what three components are nutrients stored within an ecosystem?
In soil (a mixture of air, water, weathered rock and decomposed organic matter on the earths surface), in litter (the dead organic matter on the top of the soil), and in biomass (the total of plant and animal life within an ecosystem.)
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What is a Gersmehl Diagram? What are its features?
A diagram to illustrate the mineral nutrient cycle. When applied to an ecosytem, the size of circles is proportionate to the amount of nutrients they store. Nutrient transfers are shown by arrows.
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What are autotrophs?
An autotroph is any organism that can synthesis its food from inorganic substances, using heat or light as an energy source.
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What is a food chain?
An arrangement of the organisms in an ecosystem in the order in which they eat each other. Each organism uses the lower organism as a source of energy. Each layer of the food chain is known as a trophic level.
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What are Producers?
Organisms that can manafacture food from inorganic raw materials. Another term for an autotroph.
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What are Primary Consumers?
Herbivores. They feed on producers.
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What are Secondary Consumers?
Carnivores that feed on herbivores.
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What are Tertiary or Higher Consumers?
Carnivores that feed on other Carnivores.
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What is a food web?
A scheme of feeding relationships, resembing a web. They show interconnections between an ecosytem not shown in a food chain, as animals generally consume a varied diet whilst serving as food for a variety of other creatures.
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What is a plant succession?
The term used to signify the changes in a community of plants over time. It also refers to the sequence of communities which replace one another in a given area.
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What is a primary succession?
A succession that develops by the gradual colonisation of a lifeless aibiotic surface. Also known as a PRISERE.
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What is colonization?
The ecological process by which a species spreads to new areas.
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What is a sere?
The entire sequence of stages that a succession goes through (referred to as SERAL STAGES)
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What is a lithosere?
A succession that starts on newly exposed bare rocky surface such as newly erupted and solidifies volcanic lava.
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What is a psammosere?
A succession that starts on bare ground (e.g. coastal sand dunes such as Bridlington Sands.)
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What factors are required for a sand dune system to develop?
A plentiful supply of sand, strong winds to transport the sand particles, and an obstacle to trap the sand particles (e.g. a plant, hence why plants are so vital in the formation and growth of sand dunes.)
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What are the charactaristics of the pioneer stage of a psammosere?
Plants growing at the back of the beach cause a local drop in wind speed, so small sand piles begin to form. These are colonised by pioneer species such as lyme grass, which is tolerant to salt. Their roots stabilizes the new dunes.
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What are the characteristics of the building stage of a psammosere?
The humus created by decaying pioneer plants who are outcompeted makes more fetile growing conditions. Soil becomes less alkaline as pioneers grow and trap rainwater. Less hardy plants shade out pioneers. The dune turns from yellow to grey.
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What are the characteristics of the climax stage of a psammosere?
Plants such as trees and heather can now grow. Plants from earlier stage die out as they are outcompeted for light and water. As the water table reaches the surface, dune slacks may occur. Water tolerant plants may grow here.
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What eventually happens as the psammosere develops over time? (May take hundreds of years)
Furthest inland, on the oldest dune, the climatic climax will be reached. This will be temperate deciduous woodland.
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What is the climatic climax?
A biological community of plants and animals which, through ecological succession, has reached equilibrium of climate and soils.
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When did plant succession in the UK reach its climatic climax?
Around 8000 years ago. Around 5000 years ago, forest clearance resulted in a plagioclimax.
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What is a plagioclimax?
The plant community that exists when human interference prevents the climatic climax vegetation being reached.
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Which four layers are charactaristic of the temperate deciduous woodland (oak woodland)?
The tall tree canopy layer, the shrub layer, the field layer and the ground layer.
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What characterizes the tall tree canopy layer?
Oak (the tallest at over 30m), birch, sycamore and ash. They shed their leaves in winter. Some woodland is so heavily dominated by the dense canopy, that light is prevented from reaching lower layer. This reduces the biodiversity in the lower layers.
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What characterizes the shrub layer?
Small trees such as hawthorn, hazel, buckthorn and rowan.
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What characterizes the field layer?
Dominated by woodland flowers such as bluebell and wood anenome and primrose, along with woodland grasses and sedges.
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What characterizes the ground layer?
You may find mosses, liverworts and tree seedlings. You will also find fallen, decaying wood and leaf litter, which are important for fungi.
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What is deforestation?
The deliberate clearing of forest by cutting and/or burning.
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What is a secondary succession?
Succession taking place on a formerly vegetated area, but the vegetation has since been lost.
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Why is heather moorland a plagioclimax?
It has been created by forest clearence in upland areas. Reduced soil fetility allows plants such as heather to dominate. Grazing of the black faced sheep and controlled burning of heather (muirburn) prevents secondary succession.
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What does urban growth alter in an ecosystem?
Soil drainage, water flow, climate and light availability are all altered through urbanistation..
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What types of habitats might you find in an urban area?
Urban forests (e.g. Mersey Forest), playing fields, golf courses, derelict land, flower beds to botanical gardens (e.g. Kew Gardens.)
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Other cards in this set

Card 2


What are biotic factors?


Influences on an ecosystem from living things e.g. plants, animals, bacteria

Card 3


What are abiotic factors?


Preview of the front of card 3

Card 4


Where does all energy used by living things come from?


Preview of the front of card 4

Card 5


How much incoming sunlight is captured?


Preview of the front of card 5
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Also excludes the rainforest biome stuff. I'll add this later.

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