Q&A: vegetation

What does the words you use in legends for vegetation zones mean?

The expressions roughly correspond to the climate zones of Monnyjja and Siminatessa.  Except for ice caps/cold deserts at the poles I make a distinction between five temperature zones:

• Alpine climate ‒ same as Martin Vahl’s tundra climate.
• Cold temperate climate ‒ the temperature range is the same as for Martin Valh’s coniferous forest climate.
• Warm temperate climate ‒ the temperature range is the same as for Martin Valh’s dedicious forest climate.
• Subtropical climate ‒ follows Martin Vahl’s definition.
• Tropical climate ‒ follows Martin Vahl’s definition.

In addition there are differences in precipitation and its distribution over the year.  The vegetation is the result of the combination of them:

• Mountains which peaks have permafrost ‒ the ground close the tops of the mountains stay frozen all year round.  On temperate and subtropical latitudes some of the soil thaws in the summer and on tropical latitudes in the daytime.  This soil is too little to allow trees to grow.  In contrast it is possible for the same kinds of low plants as on the tundra (see below).
• Scrubland on tropical mountains ‒ little or no difference in temperature between different parts of the year.  In contrast the differences are large between day and night.  The average is as low as in a temperate climate (-3º – +10º C or 27º – 50º F).  There is also defiance in precipitation.  These together limit the vegetation to mostly shrubs.
• Tundra ‒ the ground stays snow-covered up to two thirds of the year.  When the snow melts in summer the ground still remains frozen.  Only a thin layer of soil thaws every year.  It is too thin for trees to take root.  On Earth these zones are dominated by mosses and lichen.  Grasses, herbs and very low shrubs can also grow there.
• Cold temperate grassland ‒ warm enough for trees to grow but not enough precipitation.  The result on Earth is a mix of tundra, steppe and meadow plants.  This mix is called tundra-steppe.  It was widespread during the ice ages but does not exist today.  There is a project in Siberia to recreate the tundra-steppe.  If the project is successful it will show that tundra-steppe can exist even when it is not ice age.
• Cold temperate forest/woodland ‒ warm and wet enough for trees to grow.  On Earth is usually means coniferous forest or open woodland.  However, broadleaf forest also occurs in particular in the southern hemisphere.
• Warm temperate forest/woodland ‒ what can be compared to Martin Vahl’s dedicious forest climate.  The natural vegetation of such areas on Earth is usually broadleaf or mixed forest or open woodland.
• Warm temperate grassland ‒ comparable to Martin Vahl’s definition of temperate grassland climate.  The result is plains covered in low plants.
• Temperate desert ‒ roughly matches Martin Vahl’s definition of temperate climate.  However, the precipitation is too low for vegetation to cover the ground.  What little precipitation falls is very irregular, there can be years between rains or snowfalls.  Usually, there is also a large difference between day and night.
• Subtropical grassland with winter rain ‒ enough precipitation for vegetation to cover the ground yet not enough for forest.  If any trees grow at all they grow alone or in grooves.  The rainy season is in the winter.
• Subtropical forest/woodland with winter rain ‒ enough precipitation for forest to grow.  The relatively long rainy season is during the colder half of the year.  On Earth the vegetation consists of evergreen forest, open woodland or shrub.
• Subtropical forest/woodland with summer rain ‒ enough rain for forest to grow.  The relatively long rainy season is during the warmer half of the year.  The natural vegetation of such areas on Earth consists of deciduous forest or open woodland.
• Subtropical grassland with summer rain ‒ enough rain for vegetation to cover the soil.  However, it is not enough for forest.  If there are any trees at all they grow one and one or in small, spread out groups.  The rainy season is in the summer.
• Subtropical desert ‒ significant differences in temperature between different parts of the year.  The difference between day and night is also rather large.  Frosty nights occur in the winter.  The precipitation is too small for the soil to be covered by vegetation.
• Tropical desert ‒ only small differences in temperature between different parts of the year.  In contrast there are significant differences between day and night.  It does not rain enough for vegetation to cover the ground.
• Tropical grassland ‒ little or no differences in temperature over the year.  On the other hand there is a large difference between a rainy and a dry season.  It rains enough for vegetation to cover the ground.  Yet it is not enough for the landscape to be covered in woods.  On Earth the result is a tropical savanna or a frost-free steppe.
• Tropical forest with seasonal rain ‒ small to significant differences in temperature over the year.  The most important thing limiting vegetation is the difference between a rainy and a dry season.  On Earth this forest is called monsoon forest.
• Tropical rainforest ‒ about the same warmth all over the year.  It also rains all year round although the amounts of rain can vary.  The result is the densest and most lush forests imaginable.

I have not made any differences between forest and open woodland.  Neither have I made any difference between treeless plain and savanna.  The differences in climate due to temperature are more important to me.


© Lena Synnerholm.
Last changed the 9th of December 2016.
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