7 There is a tremendous loss of energy between one trophic level and the one above. It takes an enormous amount of vegetation to support one herbivore; and a lot of herbivores to support one predator. So big predators need vast territories. Inevitably, then, the big animals are few in number; and so they are easily driven to extinction.
15 The ecological niche of an organism depends not only on where it lives but also on what it does. By analogy, it may be said that the habitat is the organism's "address", and the niche is its "profession", biologically speaking.Odum - Fundamentals of Ecology - W B Saunders 1959Oak trees live in oak woodlands; that's common sense. The oak woodland is the habitat. So if Odum was writing a letter to an oak tree he would address the letter to:Sir Deciduous Oak Tree, The Oak Forest, England, U.K.
16 What do oak trees do? If you can answer that question you know the oak trees "profession" or its ecological niche.Perhaps you think that oak trees just stand there looking pretty and not doing very much, but think about it.Oak trees:absorb sunlight by photosynthesis;absorb water and mineral salts from the soil;provide shelter for many animals and other plants;act as a support for creeping plants;serve as a source of food for animals;cover the ground with their dead leaves in the autumn.
17 A TASK!These organisms fit into the food web above.Moth caterpillars: Tawny owls: Squirrels: Aphids: Trees (leaves, flowers, fruits, bark): Beetles: Bank voles: Foxes: Sparrows: