his planet’s biotic communities exist somewhat in bands that tend to change with latitude. Earth type vegetation has been symbolically drawn along the planets curvature in an attempt to trigger a conceptualization of the processes that occur in each biotic zone. While studying this illustration, keep in mind that:
• As the mass of the planet increases, gravity increases, resulting in generally shorter, more squat looking plants and animals. Also, the land to water ratio decreases-leading to less dry land and more water on the larger planet.
• If the APST were increased, the biotic zones would migrate toward the poles. Conversely, decreasing the APST would cause ice caps, tundra and snow fields to expand toward the equator pushing all other biotic zones before them. With a very low APST, the wet tropical forest might simply disappear, giving rise to an equatorial temperate forest.
• Biotic zones and land-to-water ratios expand or contract as we adjust the various parameters examined in this study.
Biotic Zone diagram
In relation to the Biotic Zone diagram, also see below, the Relative Precipitation-Solar Radiation-Vegetation diagram and the Latitude – Temperature Tables.
Relative Precipitation-Solar Radiation-Vegetation diagram
Latitude – Temperature Table
|High latitudes||Mid latitudes||Low Latitudes|
|Temperature may constrain life.||Combination (local climate)||Precipitation constrains life|
|High annual temperature variation.||Temperature variations greater inland than coastal.||Low annual temperature variation.|
|Low daily temperature variation.||High daily temperature variation.|
|Low storm activity.||Storm rates increase over land, decrease over sea.||High storm activity.|
Spring: Land heats up fast developing low pressure areas, sea develops a high pressure system.
Fall: Water remains warmer and develops a low pressure system, high pressure developers over land.
Planets with low to moderate axial inclination (little tilt) will generally provide increasingly lower temperature, stable temperature bands as one moves from the equator toward the poles.
Planets with a moderate degree of axial inclination will experience pronounced seasons as the year progresses. During the summer, that hemisphere tilted toward its sun will experience seasonably higher temperatures. A half of their year later, when the previously warmer hemisphere is tilted away from its sun, it will experience seasonably low temperatures. These seasonal temperatures create an overall average temperature for each latitude and region.
On a planet with no axial inclination, each latitude would still have a narrow annual average temperature between it’s ‘summer highs and winter lows’, this derives from the probability that the planet’s orbit is not a perfect circle about the parent star, a condition similar to Earths orbit. The extremes for all latitudes, on either side of the average, would be eliminated by the lack of axial inclination.
On Earth, the average annual temperature for a given latitude is that temperature the latitude would have if Earth had a 0º, instead of 23-1/2º axial inclination.
Shown in the Biotic Zone Table below, are the annual average planetary surface temperatures for each latitude. Since we have eliminated the temperature variation by using ‘average temperatures’, we can in effect say that if these temperatures were maintained throughout the year, that the planet has no axial inclination.
Lets now say that on any planet where there is no axial inclination, the temperatures vary with latitude just as they would on a Earth with no axial inclination. If this is so, we can compare temperatures with latitude for planets displaying all the APST used in this study. We should remember that the resultant temperature models provide:
• The annual average temperature for each latitude on a planet with 0º axial inclination, or,
• the annual average temperature for each latitude as derived from the overall seasonal variations on those planets with axial inclination.
In the Biotic Zone Table, compare temperatures (in degrees Fahrenheit and Centig