Picture says a thousand words. In this case, using charts will better explain all the 'technical' aspects for those of you whom are interested in know how a terrarium works.

We are going to go through the water cycle in a terrarium's ecosystem.

Terrarium Ecosystem – Water cycle

Starting from the plant itself:

  1. Plant Transpires - This means the exchange of gas between the environment. This also means gas in the form of water vapour, as technically, water behaves like gas in this stage of the water cycle.
  2. Water Condenses - Water vapour given out by the plant condenses into water droplets. These water droplets may form on the wall of the enclosure or in the air itself as mist. Usually mist will form during cooler temperature. However, if the terrarium is overly watered, water droplets on the water will be visible throughout the day. This is when you need to 'air' the plant.
  3. Soil Wets - Mist in the air and water droplets on the wall sips into the soil. This of course includes you watering the soil. Always use a sprinkler so as to maintain top soil layer's landscape.
  4. Water Absorption - Water is taken into the roots following a few methods.
    • Osmosis – This happens when there is a lower concentration of salt in the soil than in the plant at the root. Water basically flows into the roots along the concentration gradient, from a lower salt concentration to a higher salt concentration. This process does not take up energy.
    • Reverse Osmosis (RO) – This takes place when there is a higher concentration of salt in the soil than in the plant at the root. Not to be mistaken by dryness of soil, a relatively dry soil can still be low in salt concentration. This process requires the use of energy in the form of ATP (Adenosine Triphosphate). ATP is manufactured in the leaves during photosynthesis.
    •  Capillary Action – This action takes place simultaneously during Osmosis or RO. Basically it makes use of surface tension and suction effect to draw water. The molecular forces in the Plant's stem attracts water molecules on it's inner surface and draws water up against gravity. Transpiration of the plant also creates a suction effect (think sucking water through a straw) which suck up water on the surface of tubes in the stem

This lesson on the water cycle happening in a terrarium ecosystem does not take into account how the plant makes use of the water ( will be in our next more indepth installation). However, it gives you a basic idea of the water cycle. Let's work on some terrarium now or check out our creations and Keep on Thriving!

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