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Role Of Organisms On A Tropical Ecosystem Video

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S bmw. Keystone species play an important role, both in maintaining species diversity and the health of an ecosystem. A keystone species is an organism that helps maintain species diversity within an ecosystem by keeping the numbers of other species in an ecosystem constant. In ecology, two parameters are used to measure changes in ecosystems: resistance and resilience. The ability of an ecosystem to remain at equilibrium in spite of disturbances is called resistance. The speed at which an ecosystem recovers equilibrium after being disturbed, called its resilience. Ecosystem resistance and resilience are especially

Tropical rainforestalso spelled tropical rain forestluxuriant forest found in wet tropical uplands and lowlands around the Equator. This article covers only the richest of rainforests—the tropical rainforests of the ever-wet tropics. Tropical rainforests represent the oldest major vegetation type still present on the terrestrial Earth. Like all Trppical, however, that of the rainforest continues to evolve and change, so modern tropical rainforests are not identical with rainforests of the geologic past.

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Tropical rainforests grow mainly in three regions: the Malesian botanical subkingdom, which extends from Myanmar Burma to Fiji and includes the whole of ThailandMalaysiaIndonesiathe PhilippinesPapua New Guineathe Solomon Islandsand Vanuatu and parts of Indochina and tropical Australia ; tropical South and Central Americaespecially the Amazon basin ; and West and Central Africa see biogeographic region. Smaller areas of tropical rainforest occur elsewhere in the tropics wherever climate is suitable. The principal areas of tropical deciduous Role Of Organisms On A Tropical Ecosystem or monsoon forests are in India, the Myanmar— Vietnam —southern coastal China region, and eastern Brazilwith smaller areas in South and Central America north of the Equatorthe West Indiessoutheastern Africa, and northern Australia.

The flowering plants angiosperms first evolved and diversified during the Cretaceous Period about million years ago, during which time global climatic conditions were warmer and wetter than those of the present.

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Only later—during the middle of the Paleogene Periodabout 40 million years ago—did cooler, drier climates develop, leading to the development across large areas of other vegetation types. It is no surprise, therefore, to find the greatest diversity of Tropicap plants today in the tropical rainforests where they first evolved.

Of particular interest is the fact that the majority of flowering plants displaying the most primitive characteristics are found in rainforests especially tropical rainforests in parts of the Southern Hemisphere, particularly South Americanorthern Australia and adjacent regions of Southeast Asiaand some larger South Pacific islands. Of the 13 angiosperm families generally recognized as the most primitive, all but two— Magnoliaceae and Winteraceae —are overwhelmingly tropical in their present distribution. Three families—Illiciaceae, Magnoliaceae, and Schisandraceae—are found predominantly in Northern Hemisphere rainforests. Organismw

Five families—Amborellaceae, Austrobaileyaceae, Degeneriaceae, Eupomatiaceae, and Himantandraceae—are restricted to rainforests in the tropical Australasian region. This has led some authorities to suggest that the original cradle of angiosperm evolution might lie in Gondwanalanda supercontinent of the Southern Hemisphere thought to have existed in the Mesozoic Era to 66 million years ago and consisted of Africa, South America, Australia, peninsular India, and Antarctica.

An alternative explanation for this geographic pattern is that in the Southern Hemisphere, especially on islands, there are more refugia—i.

The first angiosperms are thought Tropixal have been massive, woody plants appropriate for a rainforest habitat. Most of the smaller, more delicate plants that are so widespread in the world today evolved later, ultimately from tropical rainforest ancestors. While it is possible that even earlier forms existed that await discovery, the oldest angiosperm fossils — leaveswood, fruitsand flowers derived from trees—support the view that the earliest angiosperms were rainforest trees.

Further evidence comes from the growth forms of the most primitive surviving angiosperms: all 13 of the most primitive angiosperm families consist of woody plants, most of which are large trees. As the world climate cooled in the middle of the Cenozoic, it also became drier.

This is because cooler temperatures led to a reduction in the rate of evaporation of water from, in particular, the surface of the oceans, which led in turn to less cloud formation and less precipitation. The Oeganisms hydrologic cycle slowed, and tropical rainforests—which depend on both warmth and consistently high rainfall—became increasingly restricted to equatorial latitudes. Within those regions rainforests were limited further to coastal and hilly areas where abundant rain still fell at all seasons.

In the middle latitudes of both hemispheres, belts of atmospheric high pressure developed. Within these belts, especially in continental Role Of Organisms On A Tropical Ecosystem, deserts formed see desert: Origin. In regions lying between the wet tropics and the deserts, climatic zones developed in which rainfall adequate for luxuriant plant growth was experienced for only a part of the year. In these areas new plant forms evolved from tropical Topical ancestors to cope with seasonally dry weather, forming tropical deciduous forests.

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In the drier and more fire-prone places, savannas and tropical grasslands developed. Retreat of the rainforests was particularly rapid during the period beginning 5, years Organiss leading up to and including the Pleistocene Ice Ages, or glacial intervalsthat occurred between 2, and 11, years ago. Climates fluctuated throughout this time, forcing vegetation in all parts of the world to repeatedly migrate, by seed dispersal, to reach areas of suitable climate. Not all plants were able to do this equally well because some had less-effective means of seed dispersal than others.]