The WHAT and WHY of the self sustaining ecosystem

ECOSYSTEM

A balanced, self-sustaining ecosystem will be produced.

The biotic and abiotic factors will work together. The abiotic factors are the physical features like the water, water temperature, soil, heat, light from the sun and the air. The biotic factors are the plants and animals. If there isn't enough light or water or if the soil doesn't have the right nutrients, the plants will die. If the plants die, animals that depend on them will die. If the animals that depend on the plants die, any animals that depend on those animals will die.

All the parts of the ecosystem will work together to make a balanced self-sustaining system over an 8 week period. It is very important that all parts work together as shown below.

TERRA ZONE

Nutrient rich soil from Luke Baker’s granny’s vegetable garden was used. This soil was placed on a layer of fine gravel which allows drainage and prevents the soil from becoming waterlogged. Soil is a critical part of the ecosystem. The soil will provide important nutrients for the plants. It anchors the plants to keep them in place and it absorbs and retains water for plants and animals to use. It provides a home for the living organisms.

The following plants were planted in the soil: Gazania, oregano, daisy, mondo grass, variegated plectranthus.

These green plants are the producers. They will make their own food using a process called photosynthesis. During photosynthesis, these plants will trap light energy from the sun with their leaves and use this energy of the sun to change water and carbon dioxide from the atmosphere into a sugar called glucose. Glucose is used by plants for energy and to make other substances like cellulose and starch. Cellulose is used in building cell walls. Starch is stored in seeds and other plant parts as a food source. These plants contain a pigment called chlorophyll which is used in photosynthesis. Chlorophyll traps the sun's energy and turns it into chemical energy.

Photosynthesis : carbon dioxide + water + [light energy] → oxygen + glucose

During photosynthesis oxygen is released into the air for the animals to breathe.

In order to use the food they have made, plant cells must perform cellular respiration. The cells use oxygen and glucose to create water, carbon dioxide, and energy.

Animal cells also perform cellular respiration and animals breathe in oxygen and breathe out carbon dioxide.

Respiration happens all the time, not just in the daylight. Plants produce oxygen for the animals to breathe during photosynthesis but they also have to use it themselves for cellular respiration. The rate of photosynthesis is faster than respiration, so a plant produces more oxygen than it needs for itself. It also produces more sugar than it needs right away, which is stored. Animals use the oxygen to perform cellular respiration.

Cellular Respiration: Glucose (sugar) + Oxygen →Carbon dioxide + Water + Energy (as ATP)

The ecosystem will be placed so that the light from the sun will reach and penetrate the see-through plastic bottles. The heat keep will keep plants and animals warm.

The air will provide oxygen and carbon dioxide for the plants and animals in the ecosystem.

Water is essential for life and without water all life would die. Dam water from the dam at Luke Baker’s home, Kenrock Estate, was collected and used to water the plants. Water is an important part of the cells that make up all living organisms. Water will be used by the plants to carry and distribute the nutrients they need to survive.

Consumers are animals and they get their energy from the producers or from organisms that eat producers. Grasshoppers (including 1 very large one) were placed in the terra zone. Animals that eat only plants are called herbivores. Grasshoppers are herbivores. Herbivores have teeth adapted to chewing plants. Their big molars are designed to help them grind up leaves, seeds and twigs.  A small praying mantis was also placed in the terra zone. The praying mantis is a carnivore. Carnivores are meat eaters. The praying mantis eats grasshoppers and other insects. It waits very quietly for its prey and doesn't move. When its victim gets close enough, the praying mantis jumps out and grabs its prey. The front legs of the praying mantis have little spikes that help to keep the prey from getting away.

Bacteria will be present in the water and the soil and the air. Unseen bacteria will be everywhere. Bacteria are consumers and decomposers. These bacteria will break down dead plants and animals in this zone into organic materials that go back into the soil as nutrients.

One earthworm was added to the terra zone soil. Earthworms are decomposers. In addition to breaking down organic materials and adding nutrients to the soil, earthworms will also help loosen the soil so air can circulate. This will help the plants to grow. The nutrients in the soil will be partially digested by the worms, making them easily used by the plants. The nutrients are thus broken down to be used by plants and the soil is aerated to bring more oxygen to the roots of the plants.

DECOMP ZONE

Decomposers are plants and animals like bacteria, fungi and earthworms that break down dead plants and animals into organic materials that go back into the soil.

Nutrient-rich compost mixed with some soil was placed in the Decomp zone and was placed on a layer of gravel to allow drainage. Dead beetles, a dead fly, dead ladybirds were placed in the decomp zone as well as an apple core, a plum pip and dried out leaves and a granadilla half. Eight earthworms were also placed in the decomp zone.

When plants and animals die, they become food for decomposers like bacteria, fungi and earthworms. Decomposers recycle dead plants and animals into chemical nutrients like carbon and nitrogen that are released back into the soil, air and water.

Bacteria will be everywhere in the decomp zone. They live in the water, the air and soil. Bacteria are consumers and decomposers.

Fungi will also exist in the compost. They don't have chlorophyll so they can't make their own food. Fungi release enzymes that decompose dead plants and animals. Fungi absorb nutrients from the organisms they are decomposing. Fungi are decomposers.

Eight earthworms were placed in the decomp zone. They are hermaphroditic, which means they have both male and female organs. The worms eat the bacteria and fungi that are in the dirt. Earthworms are thus consumers and decomposers.

Earthworms need moist environments to survive. If they dry out, they have trouble burrowing into the soil and they will die. Water from the dam was used to moisten the compost/soil mixture. Moisture is very important for worms. They can’t survive without it. Worms breathe through their skin. The worm’s skin must remain moist at all times to allow it to breathe in much needed oxygen. If their skin dries out, they will suffocate and die.

Earthworms eat dead plants and animals. When they eat, they also take in soil and tiny pebbles. They take in nutrients from microorganisms in the material they ingest. Earthworms then excrete wastes in the form of casts. Casts are rich in nutrients like nitrogen, phosphorus, and potash.

AQUA ZONE

This zone was created using dam water from Luke Baker’s Estate dam at Kenrock Estate. A layer of gravel was placed on the bottom. The dam water contains algae, bacteria and water weeds.

Bacteria exist in the water. Bacteria are consumers and decomposers.

Algae are producers. As the sun hits the water this will help the algae to grow. Algae produces oxygen for animals and provides food for microscopic animals. The microscopic animals absorb oxygen and expel carbon dioxide.

Water weeds will use the sun and carbon dioxide to grow. Water weeds are producers.

Although plants generally get the credit for producing the oxygen we breathe, some 75% or more of the oxygen in the planet’s atmosphere is actually produced by photosynthetic algae. Algae also play an important role as the foundation for the aquatic food chain. Thus, if the algae disappeared the ecosystem would be impacted