Biomes are the composite of all species within a large scale ecological community. In the natural environment, these assemblies have typically co-evolved, so that they have a natural arrangement in terms of their positioning to compete for sunlight, water and nutrient resources; in some cases these associations are symbiotic, but in most cases they are simply optimal spatial arrangements to take advantage of all the resources available in a given habitat. For example, there is typically a vertical tiering, where plants of differing light requirements can occupy canopy, mid-level or forest floor niches; the same theory applies even in a grassland, where the canopy is simply the tallest of the grasses or herbs.

In the case of water competition, depth of rooting and tolerance to arid soils are chief determinants for spatial arrangement; as far as nutrient competition, plants will compete to determine the most robust competitor for a given edaphic niche. While the outcome geometry for the plant palette usually appears random, there is a complex network of ecological theory at work that determines the layout of the assembled community. The same concept applies to aquatic communities as to terrestrial systems, with some plants having immersed roots and others, either macrophytes or phytoplankton, floating or immersed at varying levels suitable for their sunlight needs.

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Namibia Last Updated on 2014-07-07 16:10:29 Namibia is a nation of over two million people in southern Africa, bordering the South Atlantic Ocean, between Angola to the north and South Africa to the south. Namibia is mostly high plateau with the Namib Desert along the coast and the  Kalahari Desert in east. It is one of the least densly populated nations in the world. Namibia's major environmental issues include: limited natural fresh water resources; desertification; wildlife poaching; habitat fragmentation; and, land degradation which has led to few fully protected intact conservation areas. Most of the country is susceptible to prolonged periods of drought. South Africa occupied the German colony of Southwest Africa during World War I and administered it as a mandate until after World War II, when it annexed the territory. In 1966 the Marxist Southwest Africa People's... More »
Biodiversity and ecosystem services Last Updated on 2014-07-02 13:43:42 Biodiversity is being threatened at an unprecedented scale by global environmental change brought about by human societies. In addition to the many moral reasons to preserve it for its own sake, biodiversity provides numerous ecosystem services that are crucial to human well-being at present and in the future. Ecosystem services (also called environmental services or nature’s services) are benefits provided by ecosystems to humans, that contribute to making human life both possible and worth living. Biodiversity can affect ecosystem services directly. For example, humans derive most of their essential food and fibers from animals and plants. Certain plants and animals are at the core of traditional knowledge systems. In many areas of the world, fields covered in colorful flowers provide enjoyment to locals and visitors, and support important tourist industries (Figure 1).... More »
Swamp Last Updated on 2014-06-30 15:21:13 A swamp is any wetland dominated by woody plants. There are many different kinds of swamps, ranging from the forested red maple, (Acer rubrum), swamps of the Northeast, to the extensive bottomland hardwood forests found along the sluggish rivers of the Southeast. Swamps are characterized by saturated soils during the growing season, and standing water during certain times of the year. The highly organic soils of swamps form a thick, black, nutrient-rich environment for the growth of water-tolerant trees such as cypress (Taxodium spp.), Atlantic white cedar (Chamaecyparis thyoides), and tupelo (Nyssa aquatica). Some swamps are dominated by shrubs, such as buttonbush or smooth alder. Plants, birds, fish, and invertebrates such as freshwater shrimp, crayfish, and clams require the habitats provided by swamps. Many rare species, such as the endangered American crocodile depend on... More »
Registan-North Pakistan sandy desert Last Updated on 2014-06-28 00:07:20 The Registan-North Pakistan sandy desert is an ecoregion spanning southern Afghanistan; the extreme eastern portion of Iran; part of northwest Pakistan, covering a total land area of approximately 107,100 square miles. This ecoregion is classifed within the Deserts and Xeric Shrublands biome. There is considerable vertebrate species richness within the Registan-North Pakistan sandy desert, although endemism among this group is only represented by five reptilian taxa. Situated in the southernmost portion fo Afghanistan, the far east of Iran and along part of the northwest Pakistan border area, this ecoregion is an arid element of the palearctic landscape. The Khash Desert is a major feature ot the ecoregion. The Registan-North Pakistan sandy desert includes: Zohary’s Iranian steppes of Artemisietea herbae-albae iranica east of the Kuh-e Gamsidzai and the Kuh-e Palangan;... More »
Desert willow Last Updated on 2014-06-26 17:20:22 Desert willow (Chilopsis linearis) Sometimes plant names are just plain confusing. The desert willow is not a true willow, but it does grow in deserts. Actually, desert willow is in the trumpet creeper family (Bignoniaceae), which has many showy-flowered species found mostly in the tropics. Catalpa (Catalpa bignonioides and Catalpa speciosa) and trumpet creeper (Campsis radicans) are native North American species closely related to desert willow. Desert willow, which grows as a shrub or small tree, is at home in desert arroyos. An arroyo (literally creek in Spanish) is a usually dry creek bed or gulch that temporarily fills with water after heavy rains. Each rain gives the desert willow a good watering and it responds with a spurt of new growth and new flower clusters at the end of its branches. It may have two or three growth spurts during a wet summer. Desert willow has... More »