Biological diversity is dependent on habitat. No two species can share exactly the same resources, each finds a niche. This is the force that drives increases in Biological diversity. The loss of any species can be determined mathematically due to percentage of habitat loss. [Harrison, 1993]. The smaller the area, the lower the chances of finding a niche. Because natural systems have tightly interrelationships between species, no one species can survive alone. Smaller populations are more vulnerable to disaster, they cannot migrate to better conditions and the number slowly decline. Even bird species, which can move on become locally extinct and therefore effect that area and any species dependent on them for food or fertilising or seed propagation.
Unfortunately 'developments' that occur within a forest have a greater effect than those slowly eating in from the boundaries. Some forest species cannot be moved on, some are dependent on certain species and perhaps, certain aged species (aged trees provide holes from fallen limbs, higher living quarters etc). To remove one type of species or only old wood can be detrimental to 100's species when we include the vital but not visual species such as insects. Terry Erwin shocked a great many insect students who were hoping to count and catalogue all species before the close of the next century, if the insects still existed. He estimated that there were up to or beyond 30 million species! From one forest tree he found 1200 beetle and 13 per cent were specific to that tree. [Harrison, 1993]
Biological diversity is not evenly spread across the globe - it occurs in greatest numbers in the tropics, where unfortunately there is the fastest population growth, the greatest need to drain wetlands, clear forest and harvest on the reefs.
Harrison notes that in Australia and Madagascar, a surge of extinctions followed the arrival of humans. [he cites Richard Cowen, The History Of Life 1990].
On the issue of Population control, we have to be careful not restrict people's rights, (recall Care of people ethic) and acknowledge that population growth in the Western worlds is far more damaging than in underdeveloped nations because of the high consumption levels.
We must aim more for careful consumption and different expectations. Today people work longer hours to buy additional goods that their fore-fathers didn't even wish for or want. We could build on those desires for cleaner air and beautiful surrounds.
Harrison writes on the Semai people in Musoh, central highlands of Malaysia:
"The Semai of Musoh are adapting to the modernizing economy around
them. They have kerosene lamps, pots and pans, blankets. One or two families
have bicycles and radios. Musoh even has its first television set, run
off an old car battery ...To buy all these goods, the Semai have to extract
more from the forest than they require for their own basic needs. The men
and boys cut rattan vines and porter them down to the lowlands, tails trailing
like brontosaurus. The women spend most of their spare time cutting up
pandanus leaves and weaving them into sleeping mats for sale. And so they
are losing their precious leisure, and their priceless culture. Old Basuloh
retains all the Semai mysticism towards nature.
Baboi his eldest son, though he has inherited all his father's hunting
prowess, already has a more pragmatic view. Batom the seventeen-year-old
.. has no interest in learning and would far rather watch his neighbour's
..television or go to discos in the nearest town. He wears flashy trainers,
which he bought by catching rare butterflies and leaf insects and selling
them to Chinese traders....Within two generations a culture has been destroyed.
And the destruction of the culture proceeds hand in hand with the destruction
of nature."
Some of the benefits of modernism include higher education (the information revolution which you, the reader and us, the writers are part of right now), which usually leads to better health; medicine to improve quality of life, and ease suffering. Most of the costs are not to the consumer directly and are hidden (pollution, waste, over-use and dependence) and there is evidence of increasing abandonment of preventive measures - Such examples include
References : Paul Harrison The Third Revolution: Population,
Environment and a Sustainable World. Winner of a 1992 Population Institute
Global Media Award. Pub. Penguin London. 1992, 1993
Beryl Morris CSIRO Biotechnology Cambridge Press UK 1995