Gross Primary production is the rate at which the products of photoynthesis are formed. GPP takeaway the amount of glucose used in respiration is the Net production , which is the energy available to the next consumer in the food chain.
The sun is the rpimary source of energy as it is the energy source for photosynthesis.Plants are always at the start of food chains as they trap energy from light , they are autotrouphs.The next consumers are herbivores who feed only on vegetation.The next organisms are omivores or carnivores. These are are hetrotrouphic organisms. There are always losses between each trophic level becuase animals may not eat the whole plant or animal ( for example the roots and woody parts or bones/fur). There are also losses due to heat lost from respiration.Carnivores are more efficient than herbivores as protein is far more easily digested. Herbivores lose 60% of their energy from urine and faeces where as carnivores only lose 20%.
A large amount of energy from the sun is not used because it is the wrong wave length or it is reflected by the leaf. Transmission where light goes through the leaf also occurs . Secondary productivity is the rate at which consumers accumulate energy in the form of tissues and cells.
Primamry succession is where the area is collenised for the first time such as bare rock behind a glacier in this case soil will be created as larger organisms colonies.
Secondary sucession is where the area is recolenised after a fire for example and starts with soil.
When an area is stable it will each a climax community and in most cases this is mature wood land once enough soil is pesent to support them.This can be prevented by the introduction of sheep or farming of the land deforestation and soil erosion.For a community to get the the stage of a climax community it will take many years.
Grazing by sheep , farming of the land and soil erosion, deforestation prevent the formation of a climax community.The pioneer plants which first colenise an area are used to growing in tougher conditions perhaps will little water or in areas where soil is not as deep.
Pyramids of energy
Pyramids of biomass
These show the weight of the organisms ( bar water mass). They can become inverted as one tree will provide for many insects for example.
Pyramids of numbers
Shows the numbers of organisms that the one that the number of organisms in the trophic level before can support.
Pyramids of energy
show the energy at each trophic level, the 'step' up to the next trophic level shows the amount of energy which is lost between the 2 levels.