Biotic Zones
We began this study with a set of basic rules for the development of intelligent tool using life – as we know it. We said conditions must allow for,
a)  the availability of liquid water, b) the planet would need to have an average surface temperature between 0º and 60ºC, the freezing point of water and the temperature at which protien is denatured, and c) the  planet’s mass should fall within the range of 0.25 and 3x Earth’s mass.
We went on to determine cloud cover, albedo and the associated range of solar constants.
We learned how to calculate the planet’s orbital radius, it’s day and year length.
We considered the intelligent alien’s morphology, it’s height, body build and general need for protective skin pigmentation.
We determined what class of main sequence stars could support a life giving ecosphere and learned how long these stars would remain stable for life to develop.
Now it time for our mind’s eye to float down and settle on these alien worlds.
As a child awakening in a new world, we’ll begin to tie together the things we learned from, a) conditions on mother Earth, b) our understanding of bio-organic chemistry, astronomy, atmospheric physics, etc.
Using the SRAPO construct, we’ll now begin to draw and label images for what we may expect to theoretically find on a given alien planet.
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Within complexity lies basic uniformity and structure is related to function. Structural shifts occur within the matrix of complexity, but the matrix remains uniform in function. Mr Larry

The patterns of temperature, precipitation and atmospheric circulation carve out the basic land environments on Earth; we can expect these factors to play equally important, roles on other worlds.
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As we go through our early years of schooling, we learn to associate terms like, ‘equatorial wet forest’ with an area that is hot, wet and jungle like. We call the Sahara, Gobi and Mohave deserts-‘deserts’. Our language can tend to limit our understanding of alien worlds, because we tend to classify environments with a name associated with a mental picture of that environment.
When we are creating planetary models, we need to associate environments with wholistic patterns, combining average planetary surface temperature, atmospheric circulation, illumination levels across the latitudes and biological adaptation. We need to think of an environment as a  process and biological adaptions as shifts with in the matrix of interplay between the given planetary and solar parameters.

By definition, a desert is a region left unoccupied; waste, barren; it is also an arid region lacking the moisture to support much vegetation. Our perceptions of a ‘desert’ relate to the later narrow description, yet in a broader context we can define other deserts, as;
•  Aquatic Nutrient Desert:  Where there is a lack of available nutrients; such conditions exist on Earth’s ocean surface, beyond the continental shelf.
•  Cold Desert:  The continent of Antarctica.
•  Arid Desert:  The arid Gobi, Sahara, Kalahari, Rub Al Kahali, Mohave deserts, etc.
•  Heat Desert:  As located on some of our warmer planetary models; heat is the biologically limiting factor.
•  Illumination Desert: Located near 90º latitude on very warm, low axial inclination planets. Perpetual, extremely low levels of illumination are biologically limiting factors, unless nutriens feed into the illumination desert from biologically active areas.
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The pattern in which each of Earth’s biological communities have developed was influenced by temperature, precipitation, atmospheric composition and circulation, axial inclination, planetary mass, stellar spectral class, the existence of other orbiting bodies (‘moon’, binary star system), etc. If we shift the values of any of these variables on  Earth, there would be a direct impact on the morphology, size and distribution of our biological community, changing them away from what we hyave considered the norm. The norm that we find on extraterrestrial worlds will have developed under their own interplay of planet-star conditions. Intelligent, tool using creatures may seem quite different from what we’re accoustomed to at first glance, but only because they developed from their own unique mix of conditions. They are products from within the same matrix of physical proscesses, just shifted from what is found and called ‘normal’ on Earth. The greater the shift with in the matrix, the more uniusual they will seem, at first.

Equatorial Wet Forest
On worlds with low to medium axial inclination and moderate APST, we can expect to find wet forests in equatorial regions. This zone will have an average temperature 5ºC to 15ºC (9ºF to 27ºF) above the APST and a precipitation rate 50% greater than the planetary average. When compared with the planet’s polar region, the equatorial wet forest will have a greater variation between day and night temperatures, but would remain nearly constant, or only gradually changing on a day to day seasonal basis. Since precipitation would be relatively plentiful, the plant community would have to compete primarily for  sunlight, as a result, some of the tallest plants on the planet would be growing here. If an aerial canopy develops, we could expect a wide variety of shade tolerant plants on the forest floor. The equatorial wet forests moist conditions would be ideal for bacterial and insect life, which would function to bring about the organic decomposition of plant and animal organic material.

Arid Desert Zone
In the high pressure zones above and below the Equatorial Wet Forest exist discontinuous belts of relative arid Desert. The extent  of the Arid Desert across the planet’s land mass will depend on the planetary mass, APST and axial inclination. On our model worlds, any area receiving about 10 inches or less of annual rainfall may be considered an arid desert. Keep in mind that ‘annual’ refers to Earth’s 365 day year. If the model planet has a Sidereal Period twice Earth’s and day length remained the same) the arid desert would only receive half as much precipitation.

Arid Deserts on Earth occupy 14% of the terrestrial environment. They characteristically have a temperature range of 4ºC to 32ºC (39ºF to 89ºF) with an average of 23ºC (73ºF). The Arid desert has a hot, dry climate and is found to register the planets hottest surface temperatures. Plant life which has adapted to the dry, hot climate display biological adoptions for water collection and retention. On the hottest planets,  many desert plants may display reverse phototropism; an hour after the sunrises, the plant may close its leaves, only to reopen them an hour or so before sunset. Succulent plants would have either a small leaf or no leaf at all, with photosynthesis occurring through the plant stem, as in the Barrel cactus and Saguaro cactus. The bulk of the trunk in these plant’s are composed of water storage cells; while the volume of the shoot is large, the surface area is small. This results in a large storage area for the areas biologically limiting factor, water, and a relatively small area from which they can lose their precious liquid reserves.

Non succulent plants will be modified with leathery leaves, thick cuticle layers on the outer surfaces of their leaves, they may have the ability to fold and curl, also leaves will likely be small. An example of a plant displaying many of these characteristics is the Creosote bush found commonly in the US southwestern arid desert.

In arid deserts, both succulent and non succulent plant species would have extensive root systems for water collection and potentially as locations for water storage.

Chemical inhibitors may also be used to maintain territory. This would result visually, in a more or less even spacing of the plants across the desert.

Other plants which have adapted to the Arid Desert might undergo their entire life cycle in that brief period when moisture was available. These ‘annuals’, with their fast growing shoots would die after the end of the moist season, leaving their seeds and/or a viable root system to lie dormant until the next moist period.

Animal life in the Arid Desert would tend to be either the small burrowing variety or larger, but thin. Due to the extreme temperatures, large animal life would have small body volume to large surface area ratios.

In these climatic conditions, both plant and animal life will have made specialized adoptions to reduce water loss; these adoptions may be biological or by technique or both.

Prairie & Grasslands
The condition of a temperate climate coupled with erratic and limited rainfall can extend grassland communities from the equator to near the polar region. On Earth, the grasslands have an annual precipitation rate that falls between 25%  (10 inches) and 75% (30 inches) of the planets average. These areas are typified by small short lived plants, mainly annual and perennial herbs, relatively little rain, good fertile soil and numerous large herbivores.

In temperate regions on alien worlds which receive similar precipitation, we might expect to find similar types of biological adoptions. We might also expect to find such regions under agricultural use as fields or pasture amongst intelligent species.

While the plants and animal living in these zone will certainly look exotic, we will understand from their distribution and general adaptations to the limiting factors in the environment that they fill the same or similar roles in the ecology of the communities in which they live.
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Cool Forest The temperate forest regions of Earth’s mid latitudes are extremely complex in their makeup and adoptions to temperature and moisture availability. Across broad regions of our own planet, the cool temperate forest experience temperatures ranging from -34ºC to 27ºC (-29ºF to 81ºF) with an average of 3ºC (37ºF) and precipitation rates of 10 to 60 inches per year.

The ability of a plant to survive freezing temperatures is called ‘frost resistance’, this ability varies widely among different species and is normally seasonal.

On cool and mild APST planets with low rates of axial inclination, frost resistant species would be found primarily in the mid to higher latitudes. As we encounter increased rates of axial inclination, frost resistance would tend to migrate closer to the equator. On planets with a very high  degree of axial inclination and mild temperatures, we would  find most plant species specialized with both frost resistance and heat tolerance. On such worlds, we might find plants going through a growing cycle where their cells are partially filled with an electrolyte during the winter, forming a biological antifreeze. As winter gives way to spring and spring to summer, the electrolyte might gel into a paste, reducing water loss. Then as the climate cooled, the paste would dissolve back into antifreeze.

Ice Caps, Tundra and Snow Fields
On many of our model worlds, we should expect to find the existence of ice caps. On the cooler worlds we will find thicker ice caps in the polar regions, with snow fields extending in various coverage down to mid latitudes. Cooler planets with a low degree of axial inclination will have permanent ice caps. Warmer planets, with a high degree of axial inclination, will have ice sheets and snow fields that migrate with the season, similar to winter snow across northern latitudes on Earth. On planets with a high degree of axial inclination the plant and animal life with have a high degree of cold and heat tolerance, species migration may be an important part of many large animal life forms and hibernation a retreat from the cold for most of the smaller less mobile creatures.

Ice caps are bordered by Tundra in terrestrial environments. As we move up through the APST range, we could find the Tundra and Ice Caps at progressively higher latitudes. Eventually the ice cap is replaced by diminished snow fields. As the APST approaches 60ºC, the Snow fields melt away and are replaced by a low illumination environment.

If we compared two planets of the same mass and axial inclination, the planet with the higher APST would have the smallest ice cap. If we compared two planets of same mass and APST, the planet with the smallest axial inclination would have the largest permanent snow fields.

On warm planets with moderate to high axial inclination, the ice cap may completely disappear during that hemisphere’s summer. The activity of the biotic community on alien worlds will be similar to that on Earth as each season is experienced. The hemisphere entering Spring, a time of increases sunlight and warmth,  will come out of winter dormancy and experience growth.

In the hemisphere entering Fall, the biotic community will be gearing down for the approaching Winter. The plants will winterizes, the animals will migrate, build up energy reserves, prepare for hibernation and/or utilize other adaptive mechanisms.

On planets with approximately a 30ºC APST, we may find the absence of true ice caps. In their place may exist the relatively more temperate permafrost fields with perennially frozen ground or nearly permanent frost.

Frost caps require an annual temperature of about -3ºC (26ºF) or less in order to exist; however, the temperature range over the entire area may run from -36ºC to 4ºC (-32ºF to 39ºF). Precipitation in these regions is under 15 inches per year. Climatic conditions in the permafrost zone is are cold and dry, with long winters and cool summers.
[Illustration at right: Ice Cap & Snow Field expansion on a cool planet with varying degrees of axial inclination.]

On any world with a permafrost region either covering the poles or circumventing the icecap, an explorer would find large expanses of flat land and rounded hilly terrain, where the effects of freezing and thawing would have reduced rocks to small particles. The soils of these regions would be poorly drained and poorly aerated on planets with low axial inclination and just the opposite planets with high axial inclination.

Remember, if the planet were orbiting a relatively cool G9 or K0 spectral class star, it’s orbit would be near the star, providing a short year. If the planet orbited a much hotter, F24 or F4 star, its orbit would fall further from the star giving it a year perhaps twice as long as our own, hence a ‘quarter year’ of about 6 months- plenty of time for small 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

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 Centigrade) with latitude for each of our planetary models.
Earth equivalent biotic zones have been colored into the chart showing the migration of  plant life related to APST.
The temperatures given in the table were calculated as follows:

Example #1: 140ºF (hot planet’s APST) – 68ºF (Earth’s APST) = 72ºF difference (on hotter planet)
Therefore, 72ºF hotter (in general) + 81ºF at Earth 0º latitude (equator) = 153º F at 0º latitude (equator) on hot ASPT planet.

Example #2:  68ºF (Earth’s APST) – 32ºF (cold planet’s APST) =  -36ºF cooler difference (on cooler planet).
Therefore,  -36ºF cooler (in general) + (-4ºF on Earth at 70º latitude) = -40ºF at 70º latitude on the cold planet.

Look across the top of the Biotic Zone Table to locate 113ºF, then read down the column to find the approximate surface temperature at a given latitude. On a planet with an APST of 113ºF, the equatorial temperature would be about 126ºF, at 60º latitude it would be a warm 80ºF  and a cool 41ºF at 70º latitude.

Drawn to overlay the preceding table are the color coded, approximate temperature and latitude boundaries, of the various biotic communities found on Earth. I’ve extended the APST range an additional 15ºC on either side of the conditions used in this study to demonstrate the serious deterioration of the planets habitability, see double blue and double red verticle lines toward either side of the chart.
In the column at far right, Earth’s APST (average planetary syrface temperature) and general biotic conditions per latitude have been included for comparison.
Note that the biotic community we are accustomed to on Earth, would be seen to shift toward the planets equator with a reduction in the average planetray surfave temperature; conversely, the biotic zones would shift toward the poles with an increase in APST.

In order to better understand the migration of biotic zones and the general climate of our model planets, I’ve included the illustrations below showing and equatorial and polar view for each 15ºC change in APST within the SRAPO filter parameters. An Earth model has been included for comparative reference.

Model illustrations on the left, provide an equatorial view of the planet with latitudes shown on the extreme left and temperatures on the right.
The models on the right, are shown in a polar view. The numbers entered above the pole are latitude and number below are the average temperatures for the given latitude.

ILLUSTRATION: APST, LATITUDE and ENVIRONMENT MODELS.

Environmental Limiting Factors & The Plant Community
The planetary models we looked immediately above, have no axial inclination, we were determining the average temperature for a latitude;  the length of the day to night cycle made no contribution. The parent star will rise and set in the same locations daily. Each day at local noon, the sun will have risen to it’s highest point in the morning sky and will begin its move lower in the afternoon sky. The elevation the sun rises to above the horizon al local noon will depend on ones latitude on the planetary surface.

On a planet with no axial inclination and 0ºC APST, plants in the equatorial zone, below 25º latitude, would be exposed to nearly perpendicular sunlight at local noon.

On planets with0 to 30ºC APST, most of the plant communities exist below 60º latitude. In these locations, the noon sunlight comes from a position relatively high in the sky. This results in the tropical and cool forest developing ‘ vertical light gathering stratification’. Hence we would find fungi located in the lower strata, rising above the fungi would be the shade lovers, then the shade tolerant and finally a canopy of sun seekers.

On 0º axial inclination planets, with 45ºC to 60ºC APST, the  majority of the plant community exists above 45º latitude. Under these  conditions, the tropical and cool forest would tend to develop ‘horizontal light gathering stratification’. On the equatorial side of the forests reaching deeper and deeper into the hotter zones, plants would decrease in size or biomass, attempting to adapt to extreme temperatures. On the polar side of the forests, plant life would again decrease in size or biomass, but this time light would be the limiting factor.

The following, illustration, Relative Plant Size and Biomass Per Unit Area, uses APST, latitude and various biological limiting factors to assist in developing a feeling for plant height and /or biomass per unit area, for various latitudes across a planet’s surface.

Also, remembered that gravity affects height, so that the largest or tallest plants on a 3.0 Earth mass planet will be considerably shorter than the tallest plants on a 1.0  or 0.5 Earth mass planet—that is, if all parameters are equal except planetary mass.

The  0ºC APST’ model in the  illustration shows short plants growing at around 30º latitude, this planets tundra zone. This biologically limiting, cold environment, rapidly gives way to a cool forest which extends from about 25º ‘north (and south’) latitude to the equator. With the sun passing nearly over the habitable equatorial zone, we would expect to find the plant communities of the cool temperature forest well developed into vertical light gathering strata.
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Illustration: Relative Plant Size and Biomass Per Unit Area

The 60ºC APST (140ºF average planetary surface temperature) model has short, ‘shade loving’ plants in the biologically limiting, dimly lit, twilight like polar region. With a decrease in latitude and subsequent increase in elevation of the mid day sun, the cool temperature forests develop a fierce competition for light. Around 60º latitude, the damp. Warm and fairly well illuminated conditions produce a tropical type forest canopy which carries the tallest plants on the planet. Below 60º latitude, increasing temperatures tend to overcome moisture availability where upon plant size or biomass per unit area must be reduced to thwart starvation.
Approaching 30º latitude, the high pressure system creates arid conditions. This area is not only arid, but extremely hot, with air temperatures 10ºF above that required to destroy protein. From about 30º latitude and down to the equator, temperatures tend to become the biologically limiting factor. (Note: For comparison, its recommended that we turn adjust the water temperature in our home hot water tank from 140ºF to about 120ºF to reduce the chance of being scalded).

On a planet with a large mass, i.e. 2.0 to 3.0 Earth mass, the dry land area is quite small compared with the area covered by water, therefore, at 60ºC APST, a dry land area located at 30º latitude would not be arid, it would be for us, an environment of extreme heat and severe humidity. On such a world, at 30º latitude, our bodies would feel like they were in a 140ºF sauna. We wouldn’t feel comfortable until we relocated to 70º latitude where 70ºF air temperatures would be found; equivalent to being above our ‘Arctic Circle’, in Finland, Alaska, northern Russia, northern Canada, Greenland.

Continued in Chapter 9: Data Correlation