Ecozones – Food Chain – Niche Concepts

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Ecozones

Ecoregions are grouped into both biomes and ecozones. An ecozone is the broadest biogeographic division of the Earth’s land surface, based on distributional patterns of terrestrial organisms. Ecozones delineate large areas of the Earth’s surface within which organisms have been evolving in relative isolation over long periods of time, separated from one another by geographic features, such as oceans, broad deserts, or high mountain ranges, that constitute barriers to migration. As such, ecozone designations are used to indicate general groupings of organisms based on their shared biogeography. Ecozones correspond to the floristic kingdoms of botany or zoogeographic regions of zoology.

Ecozones are characterized by the evolutionary history of the organisms they contain. They are distinct from biomes, also known as major habitat types, which are divisions of the Earth’s surface based on life form, or the adaptation of plants and animals to climatic, soil, and other conditions. Biomes are characterized by similar climax vegetation. Each ecozone may include a number of different biomes. A tropical moist broadleaf forest in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by plants and animals with very different evolutionary histories.

Major Ecozones

A total of 14 Major Habitat Types reflect the diverse array of organisms adapted to life on land. These habitats range from the wettest of forest types to the driest and hottest desert conditions. Moreover, terrestrial communities represented here include the full extent of continental topographic relief: from mangrove forests by the sea to the alpine meadows of the Himalayas.

  1. Deserts and xeric shrublands
  2. Tropical and subtropical moist broadleaf forests
  3. Tropical and subtropical dry broadleaf forests
  4. Tropical and suptropical coniferous forests
  5. Temperate broadleaf and mixed forests
  6. Temperate Coniferous Forest
  7. Boreal forests / Taiga
  8. Tropical and subtropical grasslands, savannas and shrublands
  9. Temperate grasslands, savannas and shrublands
  10. Flooded grasslands and savannas
  11. Montane grasslands and shrublands
  12. Tundra
  13. Mediterranean Forests, woodlands and scrubs
  14. Mangroves

Ecological Niche

The ecological niche is defined as the sum total of the adaptations of an organismic unit, or as all of the various ways in which a given organismic unit conforms to its particular environment. As with environment, we can speak of the niche of an individual, a population, or a species.

The difference between an organism’s environment and its niche is that the latter concept includes the organism’s abilities at exploiting its environment and involves the ways in which an organism actually interfaces with and uses its environment.

Difference between Niche and Habitat

The most basic and the most difficult thing to understand is the ecological niche. This is the study of how organisms relate or fit in the ecosystem that it belongs to. The physical structure of the organisms is one of the very important factors for this concept or study. The physical attributes of the organisms are called the morphology. The psychological and behavioral ways of adaption of these organisms to their ecological community is also very important in studying the ecological niche concept.

The habitat, on the other hand, is focused more on the location or the place in the environment where the organisms live. The resources available to each species, whether physical or biological, are very important in this study or aspect.

The niche is the study that is more focused on the response of the organism to the limited resources of the environment and their competitors. On the other hand, the habitat is more focused on where the organisms live and how their environment affects them

Ecological Equivalents

Unrelated organisms that occupy similar habitats and resemble each other. Ecological equivalents result from convergent evolution. For example, sharks (fish) and dolphins (mammals) live in a marine habitat and superficially resemble each other.

Broad Niche

If an organism has adapted to an extensive range of environmental conditions for survival, it has a broad niche. This wide range of adaption and survival skills indicates that the organism can live in various different conditions. The reverse side of this would be a narrow niche, in which the organism must have very specific environmental conditions to survive and only plays a limited role in its habitat. A broad niche creature may also be called a generalist, while a narrow niche organism may be called a specialist.

The narrow niche species can only survive on fairly limited diets. Theythrive when conditions are just right. They fulfill a niche and are very affective with competing with other organisms. They have good mechanisms for coping with “known” risks, but if there living conditions change they are likely to go extinct. Specialist examples include the koala which lives almost entirely eucalyptus filling a niche that is toxic to most animals. Another specialist species is the orchid mantis this is a colorful mantis with limbs that resemble leaves and thrives only on orchids in the tropics.

Food Chain

A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A food chain starts with the primary energy source, usually the sun or boiling-hot deep sea vents. The next link in the chain is an organism that make its own food from the primary energy source — an example is photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are called autotrophs or primary producers. Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers — an example is a rabbit that eats grass.

The next link in the chain is animals that eat herbivores – these are called secondary consumers — an example is a snake that eat rabbits. In turn, these animals are eaten by larger predators — an example is an owl that eats snakes.

The tertiary consumers are are eaten by quaternary consumers — an example is a hawk that eats owls. Each food chain end with a top predator, and animal with no natural enemies (like an alligator, hawk, or polar bear).

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