Mesocosms (Practical 5)


Understanding:

• Ecosystems have the potential to be sustainable over long periods of time

Ecosystems describe the interaction between biotic components (i.e. communities) and abiotic components (i.e. habitat)

  • They are largely self-contained and have the capacity to be self-sustaining over long periods of time


There are three main components required for sustainability in an ecosystem:

  • Energy availability – light from the sun provides the initial energy source for almost all communities

  • Nutrient availability – saprotrophic decomposers ensure the constant recycling of inorganic nutrients within an environment

  • Recycling of wastes – certain bacteria can detoxify harmful waste byproducts (e.g. denitrifying bacteria such as Nitrosomonas)

Skill:

• Setting up sealed mesocosms to try to establish sustainability

Mesocosms are enclosed environments that allow a small part of a natural environment to be observed under controlled conditions

  • A terrarium is a small transparent container (e.g. glass or plastic) in which selected plants (or animals) are kept and observed



Making a Self-Sustaining Terrarium

A terrarium can be created using a glass or plastic bottle with a lid, according to the following steps:


  1. Building a verdant foundation

  • Add a bottom layer of pebbles, gravel or sand – this layer exists for drainage (smaller vessels require thinner rock layers)

  • Add a second thin layer of activated charcoal – this will prevent mold and help to aerate the soil

  • Spread a thin cover of sphagnum moss (or use an organic coffee filter) to create a barrier between the lower layers and soil

  • The final layer is the pre-moistened growing medium (i.e. potting mix)


  1. Selecting the right plants

  • Ideally, choose plants that are both slow growing and thrive in a bit of humidity (e.g. most ferns, club moss, etc.)

  • Inspect the plant thoroughly for any signs of disease or insects before introducing to the terrarium


  1. Maintaining appropriate conditions

  • Ensure the terrarium is placed in a location that provides a continuous source of light

  • Locate the terrarium in a place that does not experience fluctuating temperature conditions (i.e. avoid direct sunlight)

  • Do not initially over-water the plants – once the right humidity is established, a terrarium can go months without watering

  • Occasional pruning may be required – however, as level of soil nutrients decrease, plant growth should slow down







Lesson 11-18.pptx

Some pictures of the making of the mesocosm:

Mesocosm story