Biome
From Palaeos
The biome is a major terrestrial assemblage of plants, animals, and microorganisms that has a characteristic appearance and occurs over large geographical areas on the earth's surface.
Biomes are largely determined by combination of temperature (in term determined by latitude) and rainfall.
Biomes correspond rather well to subdivisions distributed along the latitudes, from the equator towards the poles, with differences based on to the physical environment (for example, oceans or mountain ranges) and to the climate. Their variation is generally related to the distribution of species according to their ability to tolerate temperature and/or dryness. For example, one may find photosynthetic algae only in the photic part of the ocean (where light penetrates), while conifers are mostly found in mountains.
Though this is a simplification of more complicated scheme, latitude and altitude approximate a good representation of the distribution of biodiversity within the biosphere. Very generally, the richness of biodiversity (as well for animal than plant species) is decreasing most rapidly near the equator and less rapidly as one approaches the poles.
Biomes can be divided up in several ways, but it is most usual to list six or seven: (from tropical to polar): tropical rainforest, savanna, desert, grassland, temperate deciduous forest, taiga (boreal forest), tundra. These ecosystems differ dramatically from one another, largely because of climatic factors.
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The ocean can be considered an eighth biome, or even a succession of biomes, determined by depth and proximity to the continental shelf. Sometimes freshwater ecosystems are also considered biomes..
The biomes mentioned above are those currently in existence on earth. However, some of them have not always been around. The first forests appeared during the late Devonian, modern deciduous trees in the Cretaceous, and grasslands only in the Miocene epoch. Biomes during the Jurassic, the Permian or the Carboniferous were very different. Fern savannas for example seem have served as vast prairies which provided food for herds of grazing sauropod dinosaurs.
During the Holocene biomes have changed radically. Two artificial biomes could be added, the agricultural and the urban landscapes, as environments modified by man
[edit] Links
- World Wide Biome project
- Biome Basics
- Biome Resources
- Biomes - annotated list of links
- Biomes - huge list of links
- Biomes - list of links
- Modern Ecosystems - has material on Biomes
- Global land environments since the last interglacial by Jonathan Adams
