Rainforests

Rainforests are forests characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1750–2000 mm (68-78 inches).

Rainforests are home to two-thirds of all the living animal and plant species on Earth. It has been estimated, that many millions of species of plants, insects and microorganisms are still undiscovered. Tropical rainforests have been called the "jewels of the Earth", and the "world's largest pharmacy", because of the large number of natural medicines discovered there. Rainforests also supply 28% of the worlds oxygen, processing it through photosynthesis from carbon dioxide.

The undergrowth in a rainforest is restricted in many areas by the lack of sunlight at ground level. This makes it possible to walk through the forest. If the leaf canopy is destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth of vines, shrubs and small trees called a jungle. The two types of rainforest are:

Tropical rainforests are rainforests in the tropics
found near the Equator (between the Tropic of Cancer and Tropic of Capricorn) and present in southeast Asia (Myanmar to Indonesia and Papua New Guinea, northern and eastern Australia), sub-Saharan Africa from Cameroon to the Congo, (Congo Rainforest), South America (the Amazon Rainforest) Central America (Bosawás, southern Yucatán Peninsula-El Peten-Belize-Calakmul), and on many of the Pacific Islands(such as Hawaii). Tropical rainforests have been called the "Earth's lungs," although it is now known that rainforests contribute little net oxygen additions to the atmosphere through photosynthesis.

Temperate rainforests are rainforest in temperate regions
They can be found in North America (in the Pacific Northwest, the British Columbia Coast, and in the inland rainforest of the Rocky Mountain Trench east of Prince George), in Europe (parts of the British isles such as the coastal areas of Ireland, and Scotland, southern Norway, parts of the western Balkans along the Adriatic coast, as well as in the North West of Spain and coastal areas of the eastern Black Sea, including Georgia and coastal Turkey), and in East Asia (in southern China, Taiwan, much of Japan and Korea, and on Sakhalin Island and the adjacent Russian Far East coast), and also Australia and New Zealand.

Soils
Despite the growth of vegetation in a rainforest, soil quality is often quite poor. Rapid bacterial decay prevents the accumulation of humus. The concentration of iron and aluminium oxides by the laterization process gives the oxisols a bright red color and sometimes produces minable deposits such as bauxite. On younger substrates, especially of volcanic origin, tropical soils may be quite fertile.

Rainforest layers
Rainforest in the Blue Mountains, Australia
The rainforest is divided into four different parts each with different plants and animals, adapted for life in that particular area:

The 'emergent layer'
Contains a small number of very large trees which grow above the general canopy, reaching heights of 45-55 m, although on occasion a few species will grow to 70-80 m tall. They need to be able to withstand the hot temperatures and strong winds. Eagles, butterflies, bats and certain monkeys inhabit this layer.

The canopy layer contains the majority of the largest trees
typically 30-45 m tall. The densest areas of biodiversity are found in the forest canopy, a more or less continuous cover of foliage formed by adjacent treetops. The canopy, by some estimates, is home to 50 percent of all plant species, suggesting that perhaps half of all life on Earth could be found there. The fauna is similar to that found in the emergent layer, but more diverse. A quarter of all insect species are believed to exist in the rainforest canopy. Scientists have long suspected the richness of the canopy as a habitat, but have only recently developed practical methods of exploring it. As long ago as 1917, naturalist William Beebe declared that "another continent of life remains to be discovered, not upon the Earth, but one to two hundred feet above it, extending over thousands of square miles." True exploration of this habitat only began in the 1980s, when scientists developed methods to reach the canopy, such as firing ropes into the trees using crossbows. Exploration of the canopy is still in its infancy, but other methods include the use of balloons and airships to float above the highest branches and the building of cranes and walkways planted on the forest floor. The science of accessing tropical forest canopy using airships, or similar aerial platforms, is called dendronautics.

The understory layer lies between the canopy and the forest floor.
The understory (or understorey) is home to a number of birds, snakes, and lizards, as well as predators such as jaguars, boa constrictors, and leopards. The leaves are much larger at this level. Insect life is also abundant. Many seedlings that will grow to the canopy level are present in the understory. Only about 5 percent of the sunlight shining on the rainforest reaches the understory. This layer can also be called a shrub layer, although the shrub layer may also be considered a separate layer.

The forest floor layer receives only 2 percent of sunlight.
Only plants adapted to low light can grow in this region. Away from riverbanks, swamps, and clearings where dense undergrowth is found, the forest floor is relatively clear of vegetation because of the low sunlight penetration. It also contains decaying plant and animal matter, which disappears quickly due to the warm, humid conditions promoting rapid decay. Many forms of fungi grow here which help decay the animal and plant waste. It takes up to 20 minutes for rain to acutally touch the ground from the trees

from : http://en.wikipedia.org/wiki/Rainforest

Human Ecosystems

Human ecosystems are complex cybernetic systems that are increasingly being used by ecological anthropologists and other scholars to examine the ecological aspects of human communities in a way that integrates multiple factors as economics, socio-political organization, psychological factors, and physical factors related to the environment.

Central to the ecosystem concept is the idea that living organisms are continually engaged in a set of relationships with every other element constituting the environment in which they exist. The human ecosystem concept is then grounded in the deconstruction of the human/nature dichotomy, and the emergent premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope. Ecosystems can be bounded and discussed with tremendous variety of scope, and describe any situation where there is relationship between organisms and their environment.

A system as small as a household or university, or as large as a nation state, may then be suitably discussed as a human ecosystem. While they may be bounded and individually discussed, (human) ecosystems do not exist independently, but interact in a complex web of human and ecological relationships connecting all (human) ecosystems to make up the biosphere. As virtually no surface of the earth today is free of human contact, all ecosystems are pimpin can be more accurately considered as human ecosystems.

The human ecosystem concept draws from disciplines such as ecology, anthropology, sociology, philosophy, political science, cybernetics, and psychology, seeking to understand the complex system of relationships in which humans interact. These relationships exist within nested hierarchies of context with which individuals and human aggregates interact with differentially. Most analysis of human ecosystems focuses on particular contexts of relationship, such as biological, individual, socio-cultural, environmental et cetera.

Human ecosystems as complex cybernetic systems
Work by scholars such as Roy Rappaport, Gregory Bateson, and E.N Anderson has focused of transfer and transformation of information in human ecosystems. Inquiries as such have focused on the ecological and informational aspects of relationships in human ecosystems. In Steps to an Ecology of Mind (1972) Bateson discusses information as pattern and difference within complex cybernetic systems. In the 1990s Edwin Hutchins developed a school of psychology known as distributed cognition, which draws heavily from anthropology and sociology, emphasizing the social aspects of cognition. Distributed cognition is directly applicable to studies of human ecosystems, considering systems as sets of representations, and modeling the interchange of information between these representations. These representations can be either in the mental space of the participants or external representations available in the environment. In Cognition in the Wild (1994) Hutchins considers information processing within a bounded human ecosystem in a discussion of distributed cognition on board a naval vessel.

Aquatic Ecosystem

An aquatic ecosystem is an ecosystem located in water bodies. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.


Marine
Marine ecosystems cover approximately 71% of the Earth's surface and contain approximately 97% of the planet's water. They generate 32% of the world's net primary production. They are distinguished from freshwater ecosystems by the presence of dissolved compounds, especially salts, in the water. Approximately 85% of the dissolved materials in seawater are sodium andchlorine. Seawater has an average salinity of 35 parts per thousand (ppt) of water. Actual salinity varies among different marine ecosystems.

Marine ecosystems can be divided into the following zones: oceanic (the relatively shallow part of the ocean that lies over thecontinental shelf); profundal (bottom or deep water); benthic (bottom substrates); intertidal (the area between high and low tides);estuaries; salt marshes; coral reefs; and hydrothermal vents (where chemosynthetic sulfur bacteria form the food base).

Classes of organisms found in marine ecosystems include brown algae, dinoflagellates, corals, cephalopods, echinoderms, andsharks. Fish caught in marine ecosystems are the biggest source of commercial foods obtained from wild populations.

Environmental problems concerning marine ecosystems include unsustainable exploitation of marine resources (for exampleoverfishing of certain species), water pollution, and building on coastal areas

Freshwater
Freshwater ecosystems cover 0.8% of the Earth's surface and contain 0.009% of its total water. They generate nearly 3% of its net primary production. Freshwater ecosystems contain 41% of the world's known fish species.

There are three basic types of freshwater ecosystems:
Lentic: slow-moving water, including pools, ponds, and lakes.
Lotic: rapidly-moving water, for example streams and rivers.
Wetlands: areas where the soil is saturated or inundated for at least part of the time.

Lake ecosystems can be divided into zones: pelagic (open offshore waters); profundal; littoral (nearshore shallow waters); and riparian (the area of land bordering a body of water). Two important subclasses of lakes are ponds, which typically are small lakes that intergrade with wetlands, and water reservoirs. Many lakes, or bays within them, gradually become enriched by nutrients and fill in with organic sediments, a process called eutrophication. Eutrophication is accelerated by human activity within the water catchment area of the lake.

The major zones in river ecosystems are determined by the river bed's gradient or by the velocity of the current. Faster moving turbulent water typically contains greater concentrations of dissolved oxygen, which supports greater biodiversity than the slow moving water of pools. These distinctions forms the basis for the division of rivers into upland and lowland rivers. The food base of streams within riparian forests is mostly derived from the trees, but wider streams and those that lack a canopy derive the majority of their food base from algae. Anadromous fish are also an important source of nutrients. Environmental threats to rivers include loss of water, dams, chemical pollution and introduced species. Wetlands are dominated by vascular plants that have adapted to saturated soil. Wetlands are the most productive natural ecosystems because of the proximity of water and soil. Due to their productivity, wetlands are often converted into dry land with dykes and drains and used for agricultural purposes. Their closeness to lakes and rivers means that they are often developed for human settlement.

Functions

Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife. Aquatic ecosystems are also used for human recreation, and are very important to the tourism industry, especially in coastal regions.

The health of an aquatic ecosystem is degraded when the ecosystem's ability to absorb a stress has been exceeded. A stress on an aquatic ecosystem can be a result of physical, chemical or biological alterations of the environment. Physical alterations include changes in water temperature, water flow and light availability. Chemical alterations include changes in the loading rates of biostimulatory nutrients, oxygen consuming materials, and toxins. Biological alterations include the introduction of exotic species. Human populations can impose excessive stresses on aquatic ecosystems.

Ecosystems

Ecosystem is a natural unit consisting of all plants, animals and micro-organisms in an area functioning together with all of the non-living physical of the environment.

The ecosystem concept is the idea that living organisms are continually engaged in a set of highly interrelated relationships with every other element constituting the environment in which they exist. In a given area interacting with the physical environment so that a flow of energy leads to clearly defined trophic structure, biotic diversity, and material cycles within the system is an ecosystem."The human ecosystem concept is then grounded in the deconstruction of the human/nature dichotomy, and the emergent premise that all species are ecologically integrated with each other, as well as with the abiotic constituents of their biotope.
Ecosystems can be bounded and discussed with tremendous variety of scope, and describe any situation where there is relationship between organisms and their environment. If humans are part of the organisms, one can speak of a 'human ecosystem'. As virtually no surface of the earth today is free of human contact, all ecosystems can be more accurately considered as human ecosystems, or more neutrally as human-influenced ecoystems.

Examples :

1. Aquatic ecosystem
2. Chaparral
3. Coral reef
4. Desert
5. Greater Yellowstone Ecosystem
6. Human ecosystem
7. Large marine ecosystem
8. Littoral zone
9. Marine ecosystem
10. Rainforest
11. Savanna
12. Subsurface Lithoautotrophic Microbial Ecosystem
13. Taiga
14. Tundra
15. Urban ecosystem

National Park

National park is a reserve of land, usually declared and owned by a national government, protected from most human development and pollution. National parks are protected areas of IUCN category II.

Some countries also designate sites of special cultural, scientific or historical importance as national parks, or as special entities within their national park systems. Other countries use a different scheme for historical site preservation. Some of these sites, if they meet the criteria required, are awarded the title World Heritage Site by the UNESCO. In many countries, local government bodies may be responsible for the maintenance of park systems. Some of these are also called national parks.

Features preserved
National parks are usually located in places which have been largely undeveloped, and often feature areas with exceptional native animals, plants and ecosystems (particularly endangered examples of such), biodiversity, or unusual geological features. Occasionally, national parks are declared in developed areas with the goal of returning the area to resemble its original state as closely as possible.

In some countries, such as England and Wales, areas designated as a national park are not wilderness, nor owned by the government, and can include substantial settlements and land uses which are often integral parts of the landscape

Park mandates
Most national parks have a dual role as offering a refuge for wildlife and as serving as popular tourist areas. Managing the potential for conflict between these two roles can become problematic, particularly as tourists often generate revenue for the parks which, in turn, are spent on conservation projects. Parks also serve as reserves for substantial natural resources, such as timber, minerals and other valuable commodities. The balance of the demand for extraction of these resources, against the damage this might cause, is often a very important challenge in national park management. National parks have been subject to illegal logging and other exploitation, sometimes because of political corruption, or lack of law enforcement. For example, Lorentz National Park in Indonesia has no dedicated staff of guards. This threatens the integrity of many valuable habitats. Another example of indifference to wildlife conservation is the Romanian Parliament's discussions in September 2008 to open thirteen national parks to commercial hunting, in order to eliminate the wildlife from these areas. It is the first step toward an alleged dismantling of national parks in Romania and transformation into human settled areas

Wilderness

Wilderness is generally defined as a natural environment on Earth that has not been significantly modified by human activity. Wilderness areas and protected parks are considered important for the survival of certain species, ecological studies, conservation, solitude, and recreation. Wilderness is deeply valued for cultural, spiritual, moral, and aesthetic reasons. Some nature writers believe wilderness areas are vital for the human spirit and creativity. The word, "wilderness", derives from the notion of "wildness"; in other words that which is not controllable by humans. The word's etymology is from the Old English wildeornes, which in turn derives from wildeor meaning wild beast (wild + deor = beast, deer) (The Collins English Dictionary, 2000). From this point of view, it is the wildness of a place that makes it a wilderness. The mere presence or activity of people does not disqualify an area from being "wilderness." Many ecosystems that are, or have been, inhabited or influenced by activities of people may still be considered "wild." This way of looking at wilderness includes areas within which natural processes operate without human interference.
Large wilderness parks are currently protected by law and enforcement in many countries. Many new parks are currently being planned and legally passed by various Parliaments and Legislatures.

Conceptions of wilderness
Looked at through the lens of the visual arts, nature and wildness have been important subjects in various epochs of world history. An early tradition of landscape art occurred in the Tang Dynasty (618-907). The tradition of representing nature as it is became one of the aims of Chinese painting and was a significant influence in Asian art. Artists in the tradition of Shan shui (lit. mountain-water-picture), learned to depict mountains and rivers "from the perspective of nature as a whole and on the basis of their understanding of the laws of nature… as if seen through the eyes of a bird.” In the 13th century, Shih Erh Chi recommended avoiding painting "scenes lacking any places made inaccessible by nature. "The idea of wilderness having intrinsic value emerged in the Western world in the 1800s. British artists John Constable and JMW Turner turned their attention to capturing the beauty of the natural world in their paintings. Prior to that, paintings had been primarily of religious scenes or of human beings. William Wordsworth’s poetry described the wonder of the natural world, which had formerly been viewed as a threatening place. Increasingly the valuing of nature became an aspect of Western culture.
Wilderness was traditionally viewed as being a place to fear and avoid. It was the place where monsters and the unknown existed. Over the course of the 19th century wilderness became to be viewed not as a place to fear but a place to enjoy and protect, hence came the conservation movement in the latter half of the 19th century. Rivers were rafted and mountains were climbed solely for the sake of recreation, not to determine their geographical contexture. This was a profound shift in wilderness thought. It reached a pinnacle in the US in the 1960s with the passage of the Wilderness Act of 1964, that allowed for parts of U.S. National Forests to be designated as "wilderness preserves."
The 21st century has seen another slight shift in wilderness thought and theory. It is now understood that simply drawing lines around a piece of land and declaring it a wilderness does not necessarily make it a wilderness. All landscapes are intricately connected and what happens outside a wilderness certainly affects what happens inside it. For example, pollution from Los Angeles and the California Central Valley smog up Kern Canyon and Sequoia National Park. The national park has miles of "wilderness" but the air is filled with pollution from the valley. This then brings us to the paradox of what a wilderness really is, which is precisely the issue in 21st century wilderness thought.

Nature

Nature, in the broadest sense, is equivalent to the natural world, physical universe, material world or material universe. "Nature" refers to the phenomena of the physical world, and also to life in general. Manufactured objects and human interaction are not considered part of nature unless qualified in ways such as "human nature" or "the whole of nature". Nature is generally distinguished from the supernatural. It ranges in scale from the subatomic to the galactic.
The word nature is derived from the Latin word natura, or "the course of things, natural character." Natura was a Latin translation of the Greek word physis (φύσις), which originally related to the intrinsic characteristics that plants, animals, and other features of the world develop of their own accord. This is shown in the first written use of the word φύσις, in connection with a plant. The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socratic philosophers, and has steadily gained currency ever since. This usage was confirmed during the advent of modern scientific method in the last several centuries.

Within the various uses of the word today, "nature" may refer to the general realm of various types of living plants and animals, and in some cases to the processes associated with inanimate objects – the way that particular types of things exist and change of their own accord, such as the weather and geology of the Earth, and the matter and energy of which all these things are composed. It is often taken to mean the "natural environment" or wilderness – wild animals, rocks, forest, beaches, and in general those things that have not been substantially altered by human intervention, or which persist despite human intervention. This more traditional concept of natural things which can still be found today implies a distinction between the natural and the artificial, with the latter being understood as that which has been brought into being by a human consciousness or a human mind.

From : Wikipedia, the free encyclopedia