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A2 geography ecosystems
AQA physical geography - GEOG3
Terms in this set (44)
The study of communities of living organisms and the relationship among the members of those communities and between them and the physical and chemical constituents of their surrounding.
A major global ecosystem. It will contain a climatic climax community of plants and animals and a zonal soil. It will have its own distinctive climate with one dominant vegetation type.
A set of interacting and interdependent, living and non-living components or sub systems.
The total mass of living organisms in a community at a given moment - plants, animals, soil micro - organisms. It is expressed as the dry weight per unit area or km/m²
Dead Organic Matter
Dead or decaying plant and animal remains (DOM)
The non-living things in the environment eg water, light, temperature, carbon dioxide etc
Living things in the environment eg plants, animals, bacteria, people etc.
The process in green plants and certain other organisms by which carbohydrates are synthesised from carbon dioxide and water using absorb light energy. It releases oxygen as a by product. These carbohydrates are used as a food by organisms.
Plants which can produce its own food through photosynthesis.
-or primary consumer- animals and occasionally plants, that obtain their energy by eating green plants.
-or secondary-meat eaters
-organisms that eat both plants and meat.
Organisms that take the remains of dead plants and animals as well as their excreta (poo) and converts them back into carbon dioxide and nutrients.
The level at which energy, in the form of food, is transferred from one group of organisms to another in the food chain. Level 1 is formed of autotrophs (Plants), which produce their own food. Level 2 is formed of primary consumers that feed on Level 1 plants. Level 3 feeds Level 2 etc. Few chains have more than 5 or 6 levels as much as 90% of energy is lost as heat as each step.
The sequence of energy transfers, in the form of food, from one organism in a trophic level to those in another, achieved when organisms eat or decompose others.
More complex than a food chain, but more common as simple food chains are rare. In a food web there are a variety of different sources of food at each trophic level and most animals in the food web have more than one source of food and/or provide food for more than one consumer in the level above
Gross Primary Production
GPP - the process of absorbing light energy by plants - also called photosynthesis.
6CO²+ 6H²O + light energy → sugar + Oxygen
Net Primary Production
NPP - The amount of gross primary production which is used to produce new plant tissue or the amount of energy fixed is photosynthesis minus the energy lost by the respiration in plants, measured in gms per metre sq. per yr.
The loss of water from the soil via plants into the atmosphere
The whole process of succession from initial colonisation by pioneer species through to climax vegetation
A stage in the development of vegetation of an area over a period of time
A distinctive group of species within a sere, possessing larger biomass and a greater number of species than the previous
A series of changes that take place in a plant community over time.
The whole process of plant succession through individual seral stages but beginning on a fresh, non-biologically modified site eg new volcanic island - Krakatoa, SE Asia
The whole process of plant succession but on a previously vegetated site which has been disturbed eg an abandoned clearing created by shifting cultivation
A plant community at the end of the sere and in equilibrium with it's environment - no further succession will take place. Usually climatic climax - where the vegetation has evolved in a climate region uninterrupted by human activity, tectonic forces etc. It is in equilibrium with the prevailing climate.
If succession is prevented from progressing to it's climax because of some local arresting factors.
Soil limits succession
Relief is the local control
Water eg through impeded drainage
Humans or animals (through grazing) interfere with succession
When a climatic climax reverts back to a previous phrases
Primary succession in coastal salt marshes - Blakeny, Norfolk
Primary plant on sand dunes - Holkham Bay, Norfolk
Primary succession on fresh water margins - FenDrayton Nature Reserve, Cambridgeshire
Primary succession on exposed rock - Krakatoa, SE Asia
The place of each species within an ecosystem. This includes the space that it occupies and also the role that it carries out within the community and it's relationship with other species living around it.
Preservation of the natural environment
The management of resources in such a way that the ability of the system to replace itself its greater than the level of exploitation
The variety of species within an ecosystem
Soluble bases are removed from the soil by the downward - percolating water in environments where precipitation exceeds evaporation
Outer most layer of the earth's crust, providing the foundation of all plant life. Soil is made up of organic, mineral and animal remains, differentiated into layers or horizons of variable depth. It is created by the interaction of physical, chemical and biological processes
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