structure and function of forest ecosystem
I. Biotic components:
The various biotic components, representatives from the three functional groups, of a forest ecosystem are:
- In a forest, the producers are mainly trees.
- Trees are of different kinds depending upon the type of forest developed in that climate.
- Apart from trees, climbers, epiphytes, shrubs and ground vegetation.
- Dominant species of trees in major types of forest ecosystems are:
- Tectona grandis, Acer, Beulah, Picea, Pine, Cedrus.
2.Consumers: In a forest, consumers are of three main types.
- These are Herbivores which feed directly on producers.
- Ants, Beetles, Bugs, spiders etc. feeding on tree leaves.
- Larger animals such as Elephants, Deer, giraffe etc. grazing on shoots and/or fruits of trees.
b.Secondary Consumers: These are carnivores and feed on primary consumers.
Eg: Birds, Lizards, Frogs, Snakes and Foxes.
- These are secondary carnivores and feed on secondary consumers
- These include top carnivores like Lion, Tiger.
- These include wide variety of saprotrophic micro- organism like;
- Bacteria (Bacillus Sp., Clostridium sp., pseudomonas.
- Fungi (Aspergillus sp., Ganoderma sp., Fusarium.
- Actinomycetes (Streptomyces).
- They attract the dead or decayed bodies of organisms & thus decomposition takes place.
- Therefore, nutrients are released for reuse.
II. Abiotic components: The way in which plants and animals grow and carry out their different activities is a result of several abiotic factors. These factors are light, temperature, water, atmospheric gases, wind as well as soil (edaphic) and physiographic (nature of land surface) factors.
- These include basic inorganic & organic compounds present in the soil & atmosphere.
- In addition dead organic debris is also found littered in forests.
Light: Light energy (sunlight) is the primary source of energy in nearly all ecosystems. It is the energy that is used by green plants (which contain chlorophyll) during the process of photosynthesis; a process during which plants manufacture organic substances by combining inorganic substances. Visible light is of the greatest importance to plants because it is necessary for photosynthesis. Factors such as quality of light, intensity of light and the length of the light period (day length) play an important part in an ecosystem.
Quality of light (wavelength or colour):
Plants absorb blue and red light during photosynthesis. In terrestrial ecosystems the quality of light does not change much. In aquatic ecosystems, the quality of light can be a limiting factor. Both blue and red light are absorbed and as a result do not penetrate deeply into the water. To compensate for this, some algae have additional pigments which are able to absorb other colours as well.
Light intensity ("strength" of light):
The intensity of the light that reaches the earth varies according to the latitude and season of the year. The southern hemisphere receives less than 12 hours of sunlight during the period between the 21st March and the 23rd of September, but receives more than 12 hours of sunlight during the following six months.
Day length (length of the light period):
Certain plants flower only during certain times of the year. One of the reasons for this is that these plants are able to "measure" the length of the night (dark periods). However, it was thought that it is the day length (light periods) to which plants reacted and this phenomenon was termed photoperiodism. Photoperiodism can be defined as the relative lengths of daylight and darkness that effect the physiology and behaviour of an organism.
Short-day Plants: These plants flower only if they experience nights which are longer than a certain critical length. The chrysanthemum (Chrysanthemum sp.), the poinsettia ( Euphorbia pulcherrima) and the thorn-apple (Datura stramonium) are examples of short day plants.
Long-day plants: These plants flower if they experience nights which are shorter than a certain critical length. Spinach, wheat, barley, clover and radish are examples of long plants.
Day-neutral plants: The flowering of day-neutral plants is not influenced by night length. The tomato (Lycopersicon esculeutum) and the maize plant (Zea mays) are examples of day-neutral plants.