1.1 The Ecosystem of the Natural Forest

The ecosystem of the natural forest is a perfect and complete system. In the natural forest there are a huge number of species of plants, animals and micro-organisms. Living (biotic) and non-living (abiotic) things exist within certain relationships and in a certain balance. The ecosystem describes the pattern of relationships and interactions among living and non-living things. Therefore, it is very important for us to understand this first.

1.1.1 The Nutrient Cycle (Regenerative System)

In ecology, all living things are placed in one of three categories: producers, consumers or decomposers.
The main point of understanding the ecosystem is learning the interaction between producers, consumers, decomposers and other non-living things (sun, water, air, minerals, etc.).

The Nutrient Cycle

Producers are plants which have green leaves containing chlorophyll. They produce food (carbohydrates) for themselves and all other living things by using sun energy (the only energy from outside) and taking nutrients (minerals, water, carbon dioxide, etc.). This production process is called photosynthesis. It is very important to note that nothing can produce food for living things except plants. That is why they are called producers.

Consumers are animals which live by eating the products (carbohydrates) of producers directly and indirectly. Consumers are divided into four groups: first order, second order, third order and top carnivorous animals The first order includes herbivorous animals (e.g. insects) which eat the products of the producers directly. The second order are carnivorous animals (e.g. spiders, frogs) which eat mainly animals of the first order. The third order are carnivorous animals (e.g. snake) which eat mainly animals of the second order. The top carnivores are animals (e.g. eagle, tiger) which eat mainly animals of the third order. No animals eat top carnivores. Man is categorized as a consumer. (Note: The actual relationship among animals is more complicated. This classification shows the basic relationship only.)

Decomposers are micro-organisms (fungi, bacteria, virus, etc.) which live by eating organic matter such as the waste of producers and consumers(e.g. fallen leaves, dead body and dung of animals, etc.). There are huge numbers of micro-organisms living in the soil (more than 100,000,000 in 1 gram of fertile soil). The most important function of decomposers is to change organic matter into humus through decomposition and minerals through mineralization. Humus is indispensable for making and improving the soil. Minerals are absorbed again by producers as nutrients. (From another angle, the work in the soil, the soil is kept clean and healthy, otherwise, the surface of the planet would be full of the waste matter of producers and consumers.)

As the diagram shows, the more producers (plants) produce carbohydrates, the more consumers (animals) can live. The more organic matter is supplied to the soil from producers and consumers, the more decomposers (micro-organisms) become active and the more nutrients are supplied to the producers. The producers increase and more sunlight is used for carbohydrate production. This system is called the nutrient cycle.

It may also be called the carbon cycle, ni9trogen cycle, mineral cycle, etc. The deference is in the focus. When the focus is on carbon, then it is called the carbon cycle.

Through the nutrient cycle, all living things increase and the soil becomes fertile. Every living and non-living things interacts in nature-there is nothing useless or unnecessary. They are all tied together in relationships of needing and supporting one another. If one piece is disturbed, the whole system reacts. For instance, if organic matter is not supplied to the soil, micro-organisms (decomposers) become inactive and the soil becomes infertile and plants (producers) cannot produce well in the infertile soil. The low production of producers consequently reduces the numbers of animals (consumers).

1.1.2 The Ecological Pyramid

The ecological pyramid is another perspective of the relationships and balance between living things - especially consumers - and how nature controls and balances the nubers in each group.; The shape of the pyramid shows the allocation of numbers (bottom to top large to small).

The Ecological Pyramid

For instance, so-called harmful insect are consumers of the first order. (herbivores) that eat producers (green plants) directly. However the number of insects is controlled by consumers of the second order,(bird, frog, spider, etc.) and kept within certain limits. Therefore, the second are eaten by consumers of the third order (snake etc.) and the third are eaten by top carnivores (eagle, tiger etc.). In this way, each order of consumer is naturally held to certain limited numbers by the control of upper orders and quantity of food supply form lower orders. Consequently, the shape of the ecological pyramid is formed by the numbers of each order and the producer and shows very clearly that basic foundation are the producers. If the producers increase in number, the consumers can also increase in numbers. But a decrease in producers results in a decrease in consumers.

This relationship (eating and being eaten) between producers and consumers is called the food chain. The food chin is an ecosystem which is very delicately balanced and disturbances at any one stage upsets this. For example, if snakes are destroyed in large number for their skin, then mice and rats would proliferate. If frogs decrease greatly in number for export of frog legs, an increase in the population of insects and reduction in crop yield would result.