Ecology

Autotrophic beings are those that can produce their own food, i.e., that make organic material from inorganic compounds. Heterotrophic beings are those that need to incorporate organic material to nourish them. Therefore, heterotrophs depend on the production of the autotrophs.

Biome is a prevailing ecosystem constituted by similar biotic and abiotic factors present in one or more regions of the planet.

Autotrophic beings make organic material by photosynthesis or by chemosynthesis. There are photosynthetic autotrophs, like plants, and chemosynthetic autotrophs, like some bacteria.

Ecology is the field of Biology that studies the relations between living beings and between living beings and the environment.

Tropic levels correspond to positions on a food chain. Therefore, producers always belong to the first tropic level and decomposers to the last tropic level, consumers that eat directly the producers belong to the second tropic level and so on.

There is no limit regarding the number of tropic levels on a chain, since many orders of consumers can exist.

The energy flux along a food chain is always unidirectional, from the producers to the decomposers.

Food chain is the linear not branched sequence in which a living being serves as food for the other, from the producers until the decomposers.

Image Diversity: food chain

Heterotrophs are divided into consumers and decomposers. An ecosystem can exist without consumers but it cannot be sustained without decomposers. Without the decomposers, the organic material would accumulate causing environmental degradation and later death of the living beings.

In the vegetation of the tropical forests, broad-leafed evergreen trees predominate. On the top of the trees, epiphytes and lianas grow. Many varieties of pteridophytes can be found in these forests. Regarding the fauna, the abundance, and diversity is also great: there are monkeys, rodents, bats, insectivores, felines, reptiles, aves, amphibians, and invertebrates, mainly insects.

Deciduous trees are plants that lose their leaves in a period of the year. In the case of the deciduous of the temperate forest, the fall of the leaves occurs in the autumn. The loss of leaves is a preparation to face the cold months of the winter: roots, stem and branches are more resistant to low temperature and snow than the leaves; without leaves the metabolic rate of the plant is reduced; the decaying fallen leaves help to nourish the soil.

Biomes - Image Diversity: deciduous trees

Tropical rain forests, like the Amazon forest and the Congo forest, are typically located in low latitude, i.e., in the equatorial and tropical zones.

Biomes - Image Diversity: tropical forests

In the temperate forest, deciduous trees predominate. Mammals are found in great number, like bears and deers.

Biomes - Image Diversity: temperate forests

Taiga, or the boreal forest, is characterized by coniferous trees, pine forests. There are also mosses, lichens, small bushes, and angiosperms. In the taiga many mammals, like moose, wolves, foxes and rodents, migratory birds and great diversity of insects are found.

Biomes - Image Diversity: taigas

Tundras have vegetation formed mainly by mosses and lichens. In the fauna the dense furred animals, like caribous, musk oxen and polar bears, and migratory birds are found.

Biomes - Image Diversity: tundras

The major terrestrial biomes are tundras, taigas (or boreal forest), temperate forests, tropical forests, grasslands and deserts.

Species is the set of living beings able to cross among themselves generating fertile offspring.

This concept however does not apply to individuals of exclusive asexual reproduction and other definitions have been proposed. For example, "species is a set of living beings that evolve in a common manner all of them considered ancestors of the same type in relation to common descendants".

Population is the set of individuals of the same species found in a given place in a given time.

Abiotic factors are the nonliving elements that constitute a given environment, like light, temperature, minerals, water, gases, atmospheric pressure, etc.

Image Diversity: abiotic factors

Ecological niche is the set of peculiar activities, resources, and strategies that a species explores to survive and reproduce. Habitat is the place where the species lives to explore its ecological niche.

In other words, it can be said that habitat is the "address" of the species and the ecological niche is the "profession" of the species.

Biotic factors are the living beings (plants, animals, and microorganisms) that are part of a given environment.

Image Diversity: biotic factors