Transcript The Biosphere

The Biosphere
The Zone of Life
Getting the terms right
Getting the terms right 2
The Zone of Life
• The biosphere is that part of the Earth that
can support life. It is, relatively, thinner than
the shell of an egg.
• Is, first of all, very narrow about five miles
from top to bottom.
• It is made up of several component parts—all
of which host life forms of some sort: the
atmosphere, the hydrosphere, the lithosphere
and, the terrasphere.
• Air, water, rock and land.
The Component Parts
• The Biosphere is made up of many distinct
parts called Ecosystems
• They each represent the most stable and
efficient use of energy in that particular place
on the globe.
• They have evolved into this balance over a
long time, and are capable of adjusting if the
circumstances of energy adjust.
But…
• It is the interaction of all the elements
that makes up the Biosphere, not just
the total.
• Which is one reason most religions
stress harmony not adversity.
Ecosystems
• As we said, the world is divided into
broad, stable zones of distinctive fauna
and flora called Ecosystems.
The Three Characteristics
•
We normally evaluate any ecosystem
by three different parameters
1. Productivity
2. Diversity
3. Resilience
Productivity
• Any measure of productivity is always a
measure of output versus input.
• We measure the productivity of an
ecosystem by the weight of biological
(living) material it supports.
• However, we often distort this by asking
what weight of useful material does it
support?
But…
• As I said, we tend to measure
productivity in terms of useful energy, ie
how much food can this place produce.
• In that context, the temperate areas do
better, but at the cost of diversity.
• This has been achieved by massive
modification of the natural systems.
2. Diversity
• Nature builds diversity into everything.
• Every plant, even of the same species, is
genetically slightly different from its
neighbors.
• This is a survival mechanism
• If they were all the same, and there was a
virus, they would all die
• Indeed, lack of diversity is rare—think of
identical twins
2. Diversity
• In fact, when you think about it, it is
remarkable that, given there are six
billion people on earth, and we all have
two eyes, one nose etc., we can pick
out someone in a crowd we have not
seen for years
• And avoid them.
2. Diversity
• Since we discovered agriculture 10,000
years ago, we have been waging war
on natural diversity.
• We plant miles of the same crop
• And now we clone them, so there is no
diversity at all.
Diversity
• Biologists are not completely sure how many different
species live on the Earth. Estimates of how many
species exist on the Earth range from low of 2 million
to high of about 100 million. To date, about 2.1 million
species have been classified, primarily in the habitats
of the middle latitudes. Most of the unclassified
species on this planet are invertebrates. This group
of organisms includes insects, spiders, mollusks,
sponges, flatworms, starfish, urchins, earthworms,
and crustaceans. These species are often difficult to
find and identify because of their small size and the
fact that they live in habitats that are difficult to
explore. In the tropical rain forest, the cataloging of
species has been quite limited because of this later
reason. Scientists estimate that this single biome may
contain 50 to 90 % of the Earth's biodiversity.
Diversity
• The more species there are, then the
better Nature is able to cope with
change
• But Diversity is also associated with
competition as species may evolve to
the point where they are struggling to
fill the same space. Which led to the
Survival of the Fittest, not strongest.
3.Resilience
• Which means ability to withstand abuse
and bounce back.
• Over the millennia evolution has
allowed Nature to reach a point where
it copes with occasional extreme events
• But we throw things at Nature that it
has never seen before, and in
quantities, and at a speed, the cycles
cannot handle.
3.Resilience
•
•
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