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.
WWF Terrestrial Ecoregions Collection
The Iberian sclerophyllous and semi-deciduous forests support a complex and diverse flora with a notable...
MutualismLast Updated on 2014-09-09 10:48:53
Mutualisms are ecological interactions between two species in which both benefit. Many mutualisms involve species living closely together (symbiosis); a species may be so dependent that it cannot live without its mutualistic partner (obligate mutualism). In other cases, a species can interact mutualistically with more than one partner (diffuse mutualism) or even live without its partner(s) under certain conditions (facultative mutualism). Although all species involved in a mutualistic relationship contribute to the partnership, we still expect each species to be "selfish" and to evolve traits that provide the maximum possible fitness benefit while minimizing cost.
1. Trophic mutualisms are interactions in which both species receive a benefit of resources. Organisms require both nutrients and energy to survive. In many trophic mutualisms, a plant provides energy... More »
PlantLast Updated on 2014-09-08 22:26:25
A plant is any one of the vast number of organisms within the biological kingdom Plantae; in general, these species are considered of limited motility and generally manufacture their own food. They include a host of familiar organisms including trees, forbs, shrubs, grasses, vines, ferns, and mosses. Conventionally the term plant implies a taxon with characteristics of multicellularity, cell structure with walls containing cellulose, and organisms capable of photosynthesis. Modern classification schemes are driven by somewhat rigid categorizations inherent in DNA and common ancestry.
Throughout most of the history of science from Aristotle to Linnaeus and into the 20th century, species were divided into two kingdoms: animals and plants. Driven by DNA characterizations and other modern analysis, fungi and bacteria have now been removed to separate kingdoms; in particular,... More »
NamibiaLast Updated on 2014-07-07 16:10:29Namibia 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;
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 servicesLast Updated on 2014-07-02 13:43:42Biodiversity 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 »
SwampLast 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 »
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