|
|
Ecosystem Type
|
Net Primary Productivity
(Kilocalories /
square meter / year)
|
Approximate
Kilocalories
per square meter per day
|
Growing Season # of Frost
Free nights |
Rainfall per year in
inches |
Type of Land |
% of Earth's Land Surface |
| Tropical Rain
Forest |
9000
|
25
|
365 days
|
More than 60
|
|
11% |
| Estuary
(the place where a river meets the
sea) |
9000
|
25
|
.varies |
varies |
Marshland
swamps
lakes
streams
|
3% |
| Swamps and
Marshes |
9000
|
25
|
. varies |
.varies |
| Savanna (grass, scattered
trees, little or no winter snow) |
3000
|
8
|
356 days but
limited by drought |
30 - 40 during rainy
season |
Grassland
Savanna
Prairie
|
21% |
| Temperate
Grassland (cold
winters) |
2000
|
6
|
70-100 days |
10-30 |
| Deciduous
Temperate Forest |
6000
|
16
|
more than 120
days |
25-60 |
Temperate Forests
|
22% |
| Boreal
Forest (Evergreen Coniferous
Forest) |
3500
|
10
|
less than 120
days |
12-33 |
| Polar Tundra
Alpine
Tundra |
600
|
2
|
50-60 days
up to 180 |
Less than 10 |
Barren ice, sand tundra desert
|
13%
20% |
| Desert |
< 200
|
1
|
|
Less than
10 |
|
Cultivated Land,
which has generally been forest or tall grassland before its
cultivation, now covers 9% of the earth's land surface. It
produces 14% of the land's biomass.
Agriculture that supports humans requires at least 20 inches
of rainfall a year, although sometimes, when rainfall is
insufficient, the natural rainfall may be supplemented with
irrigation. |
| The total
primary productivity of the ocean is about 8 times the primary
productivity of all the land surface. This is about three times
as much production in the ocean as the average for dry land for
the same area. This productivity varies widely from season to
season and place to place. |
This table is from http://www.geog.ouc.bc.ca/physgeog/contents/9l.htmlan
online Geology course created by Dr. Michael Pidwirny at Okanagan
College, British Columbia, Canada and http://www.sph.edu/ies/land.htm
Land Use and Net Primary Productivity
(Dr
Viau's additions are in red.)
The Primary Productivity number tells us how many kiloCalories
of organic material the plants in this biome make in a year. The organic
materials that the plants make include leaves, stems, petals, roots, stems,
thorns, seeds, etc. All these structures are made of
organic molecules. Organic molecules are molecules which
combine other elements with carbon. These molecules are the basis of
Carbon Life Forms (we are carbon life forms) and are made by plants, which
capture carbon dioxide from the air and use the carbon atoms as building blocks
in the carbohydrate molecules that they synthesize.
All the material that the plants make
can be used by animals or detritovores, fungi and Bacteria that eat
dead or rotting material. However, obviously if all the
material got eaten the plants would not survive for long.
Overuse of the plant resources, sometimes called overgrazing, can
destroy the natural productivity of a biome.
To learn more about this, go to
Carrying Capacity.
|