plants to go through their life cycle, or even a couple of generations.
Permafrost environments are typically a low energy areas offering little year around food to the larger animals. Most of the animal life consists of small burrowing types with insulated feet and various seasonal visitors. I suspect that small animals would inhabit permafrost regions on planets orbiting cool stars. Larger migrating species would be more important on planets orbiting hotter stars, where the growing season is longer, where a larger deposit of biomass has accumulated and where the season length would allow the larger species to migrate.
Small (short height) plant life would only have a few months, depending on the planets sidereal period (length of year) to carry out their life cycle before
reduced temperatures would bring about dormancy.
Planetary Bio-Zones, Plant Growth & Limiting Factors
On all of our model worlds, we could expect to encounter a mix of the following environments: cold, warm or hot arid deserts, rivers, marsh land, fresh water lakes, bays, hills, meadows and plains. We would expect to find a vast assortment of analogous physical surface structures, i.e., rock, sand, gravel, humus with partially decayed organic material, cliffs, etc. We would see common atmospheric phenomena, the parent sun in the sky, stars visible at night, fog, rain, snow, wind, clouds, storms-all with great variation in quantity, frequency and intensity as the stellar and planetary parameters were varied.
The biological community whose evolutionary histories track back through a particular environment, will display adoptions peculiar to that environment. It’s also reasonable to believe that similar environments on different alien worlds will tend to carry life forms who share somewhat similar morphological and very general behavioral patterns.
Atmospheric Circulation & Biotic Zone Diagram
The following Illustration: Atmospheric Circulation and Biotic Zones provides a general view of the effects of precipitation and atmospheric circulation.
This 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 on