Saturday, December 26, 2009

3rd chapter - environmental science- btech biotechnology-2-2

The term ecosystem refers to the combined physical and biological components of an environment. An ecosystem is generally an area within the natural environment in which physical (abiotic) factors of the environment, such as rocks and soil, function together along with interdependent (biotic) organisms, such as plants and animals, within the same habitat. Ecosystems can be permanent or temporary. Ecosystems usually form a number of food webs. [1]
A biome is a large area with similar flora, fauna, and microorganisms. Most of us are familiar with the tropical rainforests, tundra in the arctic regions, and the evergreen trees in the coniferous forests. Each of these large communities contain species that are adapted to its varying conditions of water, heat, and soil. For instance, polar bears thrive in the arctic while cactus plants have a thick skin to help preserve water in the hot desert. To learn more about each of the major biomes, click on the appropriate heading to the right.
Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna and ecosystems in forests. The management of forests is known as forestry, silviculture, and forest serves as the home of wild animals and place where the plants usually live. A forest ecosystem is a natural woodland unit consisting of all plants, animals and micro-organisms (biotic factors) in that area functioning together with all of the non-living physical (abiotic) factors of the environment.[1]
Redwood tree in northern California redwood forest, where many redwood trees are managed for preservation and longevity.

Forest ecology is one branch of a biotically-oriented classification of types of ecological study (as opposed to a classification based on organizational level or complexity, for example population or community ecology). Thus, forests are studied at a number of organizational levels, from the individual organism to the ecosystem. However, as the term forest connotes an area inhabited by more than one organism, forest ecology most often concentrates on the level of the population, community or ecosystem. Logically, trees are an important component of forest research, but the wide variety of other life forms and abiotic components in most forests means that other elements, such as wildlife or soil nutrients, are often the focal point. Thus, forest ecology is a highly diverse and important branch of ecological study.

Forest ecology studies share characteristics and methodological approaches with other areas of terrestrial plant ecology. However, the presence of trees makes forest ecosystems and their study unique in numerous ways.

Grassland ecosystems in British Columbia generally occur in areas where the climate is hot and dry in summer and cool to cold and dry in winter. The parent material is often composed of fine sediments, and grasslands are most often in valley or plateau landscapes. The organisms that live in them include plants and animals that have adapted to the dry climatic conditions in a variety of ways.

Differences in elevation, climate, soils, aspect, and their position in relation to mountain ranges have resulted in many variations in the grassland ecosystems of British Columbia. The mosaics of ecosystems found in our grasslands, including wetlands, riparian areas, aspen stands and rocky cliffs, allow for a rich diversity of species.

An aquatic ecosystem is an ecosystem located in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.[1]

Food chains are representative of the eating relationships between species within an ecosystem or a particular living place. Many types of food chains or webs are applicable depending on habitat or environmental factors. Every known food chain begins with a type of autotroph, an organism that is able to manufacture its own food, whether it be a plant or some kind of unicellular organism

A food chain shows how each living thing gets its food. Some animals eat plants and some animals eat other animals. For example, a simple food chain links the trees & shrubs, the giraffes (that eat trees & shrubs), and the lions (that eat the giraffes). Each link in this chain is food for the next link. A food chain always starts with plant life and ends with an animal.

1. Plants are called producers because they are able to use light energy from the Sun to produce food (sugar) from carbon dioxide and water.

2. Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers. There are three groups of consumers.

1. Animals that eat ONLY PLANTS are called herbivores (or primary consumers).

2. Animals that eat OTHER ANIMALS are called carnivores.

* carnivores that eat herbivores are called secondary consumers

* carnivores that eat other carnivores are called tertiary consumers
e.g., killer whales in an ocean food web ... phytoplankton → small fishes → seals → killer whales

3. Animals and people who eat BOTH animals and plants are called omnivores.

4. Then there are decomposers (bacteria and fungi) which feed on decaying matter.

These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients.

Image Map of the Nitrogen Cycle - What happens in the soil?

Do you know why there are more herbivores than carnivores?

In a food chain, energy is passed from one link to another. When a herbivore eats, only a fraction of the energy (that it gets from the plant food) becomes new body mass; the rest of the energy is lost as waste or used up by the herbivore to carry out its life processes (e.g., movement, digestion, reproduction). Therefore, when the herbivore is eaten by a carnivore, it passes only a small amount of total energy (that it has received) to the carnivore. Of the energy transferred from the herbivore to the carnivore, some energy will be "wasted" or "used up" by the carnivore. The carnivore then has to eat many herbivores to get enough energy to grow.

Because of the large amount of energy that is lost at each link, the amount of energy that is transferred gets lesser and lesser ...

1. The further along the food chain you go, the less food (and hence energy) remains available.

An ecological pyramid (or trophic pyramid) is a graphical representation designed to show the biomass or productivity at each trophic level in a given ecosystem. Biomass pyramids show the abundance or biomass of organisms at each trophic level, while productivity pyramids show the production or turnover in biomass. Ecological pyramids begin with producers on the bottom and proceed through the various trophic levels, the highest of which is on top. In Ecological Pyramid the arrangements from below is producers then primary consumers then secondary consumers and on the top is decomposers.

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