Hello everyone,

As a continuation of last week’s topic, I am now going to talk a bit about plants in a closed environment. Last week, I have showed you, how I made a terrarium from a starter kit, and this week I would like to talk about the principle behind it.

So why is it an interesting experiment? First of all, it demonstrates in a micro environment how different organism work together to create an ecosystem. An ecosystem (as you can guess from its name) must something to do with interactions. To speak scientifically ecosystem is: An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system. (Wikipedia). This is simple and complex at the same time. Simple in sense to understand how it work, it is a circle of life/activities, and complex in terms of chemical and biological procedure – luckily nature invented it and it works perfectly. In this process are key non-living components like Water(H20), N2(Nitrogen), Oxygen(O2), Carbon Dioxide(CO2) and living components like plants, fungi, bugs and animals.

The nutrient cycle

In fact, you don’t need to make this experiment, you are already part of this experiment – by living on the planet. Nevertheless it is fun to see how a micro environment evolves.

So from now on, we will talk about the process in a terrarium. And let’s start from the bottom upwards…
There are 4 key elements to understand:
1. Drainage, it is key to avoid the rotting of the roots and keep the water sitting in the soil.
2. Charcoal layer, it cleans the water and soil fresh and removes toxins (unfortunately in my kit there was no such)
3. Soil, obviously one of the most important since plants need a growing medium. It needs to be clean, high in minerals and non-chemically treated.
4. Plants, to enable the ecosystem to cycle.

Afterwards, the only component you need to add, is water and ready to experience how our ecosystem works.

An overview

In action you can see, how it looks like:


Our planet works on the same principle and just like in the your glass jar, the earth consists of different layers – of course a little bit more complex


To simply explain I will use the explanation from

They divided it into 2 categories. 1. Water cycle and 2. Gaseous Exchange

1. 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. However, it gives you a basic idea of the water cycle.

2. Gaseous Exchange:


As mentioned at the beginning there are numerous important gases which are required to ensure a healthy ecosystem. CO2 and O2 you know they are important, but there is also another very important component, N2 – Nitrogen. It important to have in the the air of the terrarium, but too much will kill the life inside. As a solution, you can use lichen (as it was included in my starter kit).

All in all, having a sealed terrarium is easy to maintain – in theory – but in practice you see that the chemical and biological processes are very complex and too much or too little from one component can destroy the whole life.

Finally, I leave you with a thought to think about. Our planet. Our planet was engineered perfectly by nature, but one component – human activity (over exploitation of resources, pollution, over population, etc.) threatens the whole system. We can see how easily everything can collapse and everyone will experience the consequences!

Thank you for reading!


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s