Some of these microhabitats are enormously specialised. Bracket
fungi in particular provide homes for a number of different insects. A small black beetle,
Dorcatoma ambjoerni, is a real specialist as it has been found only inside
hollow beeches, in the fruiting bodies of the bracket fungus, Inonotus cuticularis.
Even living trees can be attacked by different
kinds of fungi. Heartrot fungi decay the already dead heartwood in the centre of the
living tree, producing hollow cavities. These may provide nest holes for birds, roosts for
bats and microhabitats for a great variety of wood decay invertebrates.
This bonanza of invertebrate life in the
plethora of rotting wood occurring in woodlands, accounts for the presence of birds such
as the Greater Spotted Woodpecker which feed on them. However, invertebrates are not
confined to rotting wood or to the soil. Different species are also to be found all over
the trees and the many other, perhaps less noticeable plants, equally characteristic of
Of course the trees themselves provide a
habitat for a great variety of other living things. Hundreds of different lichens clothe
their bark. Mixed in amongst these are yet more species of algae, microfungi, mosses and
liverworts. Many invertebrates live in this wonderful epiphytic microhabitat. A small
piece of moss taken from a tree trunk and placed under a microscope is absolutely hopping
The invertebrates feeding on all the plants
in the wood attract our small woodland birds, such as Nuthatches, Treecreepers and Blue
Tits, and these in turn are the reason why Sparrowhawks can be found there.
Larger animals such as Roe deer also roam
through the wood. While we are unlikely to actually see them, the signs of their presence
will be all around, from the territorial scratchings of the males, made on saplings, to
the dung which they deposit as they go. While this dung may be undesirable waste to us,
there is no such thing as waste in nature and it will be eagerly colonized as soon as it
falls. As many as 350 different species of invertebrates are associated with the dung of
hoofed mammals in Britain alone. The rich resource of invertebrates living in and emerging
from the dung provides food for any number of predators, such as beetles, birds, small
mammals and bats.
We are now beginning to get a feel for the
enormous biodiversity or variety of life present in a single habitat such as a woodland,
which before we learnt how to look seemed so empty of life. If we extrapolate this to
encompass all the available habitats in the world, which in itself would be a staggering
list, some idea of the unbelievable variety of life on earth starts to emerge.
In spite of hundreds of years of scientific
investigation we still have little idea of the exact numbers of species contained within
habitats. We have even less idea of the many complex interactions going on between them.
As a result of this ignorance it is essential
to conserve whole habitats and their ecosystems rather than tinkering with individual
parts of them.
Habitats are the basic essential for
biodiversity to exist. They guarantee life on earth.