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Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited. In other words, it is the gradual growth of an ecosystem over a longer period. In contrast, secondary succession occurs on substrate that previously supported vegetation before an ecological disturbance from smaller things like floods, hurricane's, tornadoes, and fires which destroyed the plant life. ==Occurrence== In primary succession pioneer species like lichen, algae and fungi as well as other abiotic factors like wind and water start to "normalize" the habitat. Primary succession begins on rock formations, such as volcanoes or mountains, or in a place with no organisms or soil. This creates conditions nearer optimum for vascular plant growth; pedogenesis or the formation of soil is the most important process. These pioneer plants are then dominated and often replaced by plants better adapted to less odd conditions, these plants include vascular plants like grasses and some shrubs that are able to live in thin soils that are often mineral based. For example spores of lichen or fungus, being the pioneer species, are spread onto a land of rocks. Then, the rocks are broken down into smaller pieces and organic matter gradually accumulates, favouring the growth of larger plants like grasses, ferns and herbs. These plants further improve the habitat and help the adaptation of larger vascular plants like shrubs, or even medium- or large-sized trees. More animals are then attracted to the place and finally a climax community is reached. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「primary succession」の詳細全文を読む スポンサード リンク
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