Misplaced Pages

#502497

90-575: Nyungwe Forest was established in 2004 and covers an area of approximately 1,019 km (393 sq mi) of rainforest , bamboo , grassland , swamps , and bogs . The nearest town is Kamembe, Rwanda , 54 km (34 mi) to the west. Mount Bigugu (2,921 m (9,583 ft)) is located within the park borders. In October 2020, the Rwanda Development Board signed an agreement with African Parks to assume management for an initial 20 years. In September 2023, Nyungwe Forest

180-560: A horizontal gene transfer process referred to as natural transformation . Some species form extraordinarily resilient spores , but for bacteria this is a mechanism for survival, not reproduction. Under optimal conditions bacteria can grow extremely rapidly and their numbers can double as quickly as every 20 minutes. Most living things that are visible to the naked eye in their adult form are eukaryotes , including humans . However, many eukaryotes are also microorganisms. Unlike bacteria and archaea , eukaryotes contain organelles such as

270-530: A closed and continuous tree canopy , moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforests can be generally classified as tropical rainforests or temperate rainforests , but other types have been described. Estimates vary from 40% to 75% of all biotic species being indigenous to the rainforests. There may be many millions of species of plants, insects and microorganisms still undiscovered in tropical rainforests. Tropical rainforests have been called

360-413: A few extremely rare exceptions, such as Thiomargarita namibiensis . Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies . Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle , or form clusters in bacterial colonies such as E.coli . Their genome

450-454: A healthy animal, and cause illness. Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates . Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today. The discovery of microorganisms such as Euglena that did not fit into either

540-498: A host they are known as pathogens and then they are sometimes referred to as microbes . Microorganisms play critical roles in Earth's biogeochemical cycles as they are responsible for decomposition and nitrogen fixation . Bacteria use regulatory networks that allow them to adapt to almost every environmental niche on earth. A network of interactions among diverse types of molecules including DNA, RNA, proteins and metabolites,

630-502: A large group of photosynthetic eukaryotes that include many microscopic organisms. Although some green algae are classified as protists , others such as charophyta are classified with embryophyte plants, which are the most familiar group of land plants. Algae can grow as single cells, or in long chains of cells. The green algae include unicellular and colonial flagellates , usually but not always with two flagella per cell, as well as various colonial, coccoid , and filamentous forms. In

720-435: A large industrial scale by microbial fermentation include acetic acid produced by acetic acid bacteria such as Acetobacter aceti , butyric acid made by the bacterium Clostridium butyricum , lactic acid made by Lactobacillus and other lactic acid bacteria , and citric acid produced by the mould fungus Aspergillus niger . Microorganisms are used to prepare bioactive molecules such as Streptokinase from

810-629: A large loss of Amazonian rainforest around 2050 due to drought , forest dieback and the subsequent release of more carbon dioxide. Tropical rainforests provide timber as well as animal products such as meat and hides. Rainforests also have value as tourism destinations and for the ecosystem services provided. Many foods originally came from tropical forests, and are still mostly grown on plantations in regions that were formerly primary forest. Also, plant-derived medicines are commonly used for fever, fungal infections, burns, gastrointestinal problems, pain, respiratory problems, and wound treatment. At

900-526: A membrane as in a eukaryote, and the presence of endosymbionts. This is seen to be the first plausible evolutionary form of microorganism, showing a stage of development from the prokaryote to the eukaryote. Archaea are prokaryotic unicellular organisms, and form the first domain of life in Carl Woese 's three-domain system . A prokaryote is defined as having no cell nucleus or other membrane bound - organelle . Archaea share this defining feature with

990-490: A moist layer of leaf litter, the presence of epiphytes and lianas and the absence of wildfire. The largest areas of rainforest are tropical or temperate rainforests, but other vegetation associations including subtropical rainforest , littoral rainforest , cloud forest , vine thicket and even dry rainforest have been described. Tropical rainforests are characterized by a warm and wet climate with no substantial dry season: typically found within 10 degrees north and south of

SECTION 10

#1732765469503

1080-423: A more open canopy layer than other rainforests, and are found in areas of lower rainfall (630–1,100 mm (25–43 in)). They generally have two layers of trees. A tropical rainforest typically has a number of layers, each with different plants and animals adapted for life in that particular area. Examples include the emergent, canopy , understory and forest floor layers. The emergent layer contains

1170-431: A mutualistic symbiosis between the two. However, these signals can be eavesdropped by other microorganisms, such as the soil bacteria , Myxococcus xanthus , which preys on other bacteria. Eavesdropping, or the interception of signals from unintended receivers, such as plants and microorganisms, can lead to large-scale, evolutionary consequences. For example, signaler-receiver pairs, like plant-microorganism pairs, may lose

1260-416: A narrow region known as the rhizosphere that supports many microorganisms known as the root microbiome . These microorganisms in the root microbiome are able to interact with each other and surrounding plants through signals and cues. For example, mycorrhizal fungi are able to communicate with the root systems of many plants through chemical signals between both the plant and fungi . This results in

1350-490: A national emergency. Amazon deforestation jumped by 69% in 2008 compared to 2007's twelve months, according to official government data. However, a January 30, 2009 New York Times article stated, "By one estimate, for every acre of rainforest cut down each year, more than 50 acres of new forest are growing in the tropics." The new forest includes secondary forest on former farmland and so-called degraded forest . Microorganism A microorganism , or microbe ,

1440-590: A pH of 2.0 or less. Piezophiles thrive at very high pressures : up to 1,000–2,000 atm , down to 0 atm as in a vacuum of space . A few extremophiles such as Deinococcus radiodurans are radioresistant , resisting radiation exposure of up to 5k Gy . Extremophiles are significant in different ways. They extend terrestrial life into much of the Earth's hydrosphere , crust and atmosphere , their specific evolutionary adaptation mechanisms to their extreme environment can be exploited in biotechnology , and their very existence under such extreme conditions increases

1530-496: A relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation , transformation and transduction , even between widely divergent species. This horizontal gene transfer , coupled with a high mutation rate and other means of transformation, allows microorganisms to swiftly evolve (via natural selection ) to survive in new environments and respond to environmental stresses . This rapid evolution

1620-437: A remnant genome. Like bacteria, plant cells have cell walls , and contain organelles such as chloroplasts in addition to the organelles in other eukaryotes. Chloroplasts produce energy from light by photosynthesis , and were also originally symbiotic bacteria . Unicellular eukaryotes consist of a single cell throughout their life cycle. This qualification is significant since most multicellular eukaryotes consist of

1710-478: A single cell called a zygote only at the beginning of their life cycles. Microbial eukaryotes can be either haploid or diploid , and some organisms have multiple cell nuclei . Unicellular eukaryotes usually reproduce asexually by mitosis under favorable conditions. However, under stressful conditions such as nutrient limitations and other conditions associated with DNA damage, they tend to reproduce sexually by meiosis and syngamy . Of eukaryotic groups,

1800-513: A small net impact on atmospheric carbon dioxide levels, though they may have other climatic effects (on cloud formation, for example, by recycling water vapour ). No rainforest today can be considered to be undisturbed. Human-induced deforestation plays a significant role in causing rainforests to release carbon dioxide, as do other factors, whether human-induced or natural, which result in tree death, such as burning and drought. Some climate models operating with interactive vegetation predict

1890-407: A small number of very large trees called emergents , 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 that occur above the canopy in some areas. Eagles , butterflies , bats and certain monkeys inhabit this layer. The canopy layer contains

SECTION 20

#1732765469503

1980-828: A study by Colin Turnbull , The Forest People , in 1962. Pygmies who live in Southeast Asia are, amongst others, referred to as " Negrito ". There are many tribes in the rainforests of the Malaysian state of Sarawak. Sarawak is part of Borneo, the third largest island in the world. Some of the other tribes in Sarawak are: the Kayan, Kenyah, Kejaman, Kelabit, Punan Bah, Tanjong, Sekapan, and the Lahanan. Collectively, they are referred to as Dayaks or Orangulu which means "people of

2070-488: A subfield of microbiology is virology , the study of viruses. Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3.5 billion years ago. Further evolution was slow, and for about 3 billion years in the Precambrian eon , (much of the history of life on Earth ), all organisms were microorganisms. Bacteria, algae and fungi have been identified in amber that

2160-437: A trend towards declining populations in rainforests, for example, reptiles that feed on amphibians and reptiles. This trend requires close monitoring. The seasonality of rainforests affects the reproductive patterns of amphibians, and this in turn can directly affect the species of reptiles that feed on these groups, particularly species with specialized feeding, since these are less likely to use alternative resources. Despite

2250-436: A very broad array of fauna , including mammals , reptiles , amphibians , birds and invertebrates . Mammals may include primates , felids and other families. Reptiles include snakes , turtles , chameleons and other families; while birds include such families as vangidae and Cuculidae . Dozens of families of invertebrates are found in rainforests. Fungi are also very common in rainforest areas as they can feed on

2340-573: A well-oxygenated filter bed such as a slow sand filter . Anaerobic digestion by methanogens generate useful methane gas as a by-product. Microorganisms are used in fermentation to produce ethanol , and in biogas reactors to produce methane . Scientists are researching the use of algae to produce liquid fuels , and bacteria to convert various forms of agricultural and urban waste into usable fuels . Microorganisms are used to produce many commercial and industrial chemicals, enzymes and other bioactive molecules. Organic acids produced on

2430-977: A wide range of chemicals and enzymes. They are invaluable in research as model organisms . They have been weaponised and sometimes used in warfare and bioterrorism . They are vital to agriculture through their roles in maintaining soil fertility and in decomposing organic matter. They also have applications in aquaculture, such as in biofloc technology . Microorganisms are used in a fermentation process to make yoghurt , cheese , curd , kefir , ayran , xynogala , and other types of food. Fermentation cultures provide flavour and aroma, and inhibit undesirable organisms. They are used to leaven bread , and to convert sugars to alcohol in wine and beer . Microorganisms are used in brewing , wine making , baking , pickling and other food -making processes. These depend for their ability to clean up water contaminated with organic material on microorganisms that can respire dissolved substances. Respiration may be aerobic, with

2520-608: Is 220 million years old, which shows that the morphology of microorganisms has changed little since at least the Triassic period. The newly discovered biological role played by nickel , however – especially that brought about by volcanic eruptions from the Siberian Traps – may have accelerated the evolution of methanogens towards the end of the Permian–Triassic extinction event . Microorganisms tend to have

2610-503: Is abundant. Many seedlings that will grow to the canopy level are present in the understory. Only about 5% of the sunlight shining on the rainforest canopy reaches the understory. This layer can be called a shrub layer , although the shrub layer may also be considered a separate layer. The forest floor , the bottom-most layer, receives only 2% of the sunlight. Only plants adapted to low light can grow in this region. Away from riverbanks , swamps and clearings, where dense undergrowth

2700-524: Is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells . The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from sixth century BC India. The scientific study of microorganisms began with their observation under the microscope in the 1670s by Anton van Leeuwenhoek . In the 1850s, Louis Pasteur found that microorganisms caused food spoilage , debunking

2790-438: Is considered to be one of the fathers of microbiology . He was the first in 1673 to discover and conduct scientific experiments with microorganisms, using simple single-lensed microscopes of his own design. Robert Hooke , a contemporary of Leeuwenhoek, also used microscopy to observe microbial life in the form of the fruiting bodies of moulds . In his 1665 book Micrographia , he made drawings of studies, and he coined

Nyungwe Forest - Misplaced Pages Continue

2880-419: 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, because the warm, humid conditions promote rapid decay. Many forms of fungi growing here help decay the animal and plant waste. More than half of the world's species of plants and animals are found in rainforests. Rainforests support

2970-507: Is high in oceans, deep sea-vents, river sediment and an acidic river, suggesting that many eukaryotic microbial communities may yet be discovered. The fungi have several unicellular species, such as baker's yeast ( Saccharomyces cerevisiae ) and fission yeast ( Schizosaccharomyces pombe ). Some fungi, such as the pathogenic yeast Candida albicans , can undergo phenotypic switching and grow as single cells in some environments, and filamentous hyphae in others. The green algae are

3060-414: Is important in medicine, as it has led to the development of multidrug resistant pathogenic bacteria , superbugs , that are resistant to antibiotics . A possible transitional form of microorganism between a prokaryote and a eukaryote was discovered in 2012 by Japanese scientists. Parakaryon myojinensis is a unique microorganism larger than a typical prokaryote, but with nuclear material enclosed in

3150-463: Is incorrect to assume that diseases appear one by one in humans. Disease infects by spreading from one person to another. This infection occurs through seeds that are so small they cannot be seen but are alive. In 1546 , Girolamo Fracastoro proposed that epidemic diseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances. Antonie van Leeuwenhoek

3240-504: Is usually a circular bacterial chromosome – a single loop of DNA , although they can also harbor small pieces of DNA called plasmids . These plasmids can be transferred between cells through bacterial conjugation . Bacteria have an enclosing cell wall , which provides strength and rigidity to their cells. They reproduce by binary fission or sometimes by budding , but do not undergo meiotic sexual reproduction . However, many bacterial species can transfer DNA between individual cells by

3330-948: Is utilised by the bacteria to achieve regulation of gene expression . In bacteria, the principal function of regulatory networks is to control the response to environmental changes, for example nutritional status and environmental stress. A complex organization of networks permits the microorganism to coordinate and integrate multiple environmental signals. Extremophiles are microorganisms that have adapted so that they can survive and even thrive in extreme environments that are normally fatal to most life-forms. Thermophiles and hyperthermophiles thrive in high temperatures . Psychrophiles thrive in extremely low temperatures. – Temperatures as high as 130 °C (266 °F), as low as −17 °C (1 °F) Halophiles such as Halobacterium salinarum (an archaean) thrive in high salt conditions , up to saturation. Alkaliphiles thrive in an alkaline pH of about 8.5–11. Acidophiles can thrive in

3420-610: The Albertine Rift montane forests ecoregion in Africa. In fact, the number of endemic species found here is greater than in any other forest in the Albertine Rift Mountains that has been surveyed. The forest, which reaches its maximum altitude of 3,000 m (9,800 ft), is of particular interest for the presence of colonies of chimpanzees ( Pan troglodytes ) and Angola colobus ( Colobus angolensis ),

3510-465: The Amazon rainforest ), Central America (e.g. Bosawás , the southern Yucatán Peninsula - El Peten - Belize - Calakmul ), Australia , and on Pacific Islands (such as Hawaiʻi ). Tropical forests have been called the "Earth's lungs ", although it is now known that rainforests contribute little net oxygen addition to the atmosphere through photosynthesis . Tropical forests cover a large part of

3600-525: The Charales , which are the algae most closely related to higher plants, cells differentiate into several distinct tissues within the organism. There are about 6000 species of green algae. Microorganisms are found in almost every habitat present in nature, including hostile environments such as the North and South poles , deserts , geysers , and rocks . They also include all the marine microorganisms of

3690-878: The Intertropical Convergence Zone . The broader category of tropical moist forests are located in the equatorial zone between the Tropic of Cancer and Tropic of Capricorn . Tropical rainforests exist in Southeast Asia (from Myanmar (Burma) ) to the Philippines , Malaysia , Indonesia , Papua New Guinea and Sri Lanka ; also in Sub-Saharan Africa from the Cameroon to the Congo ( Congo Rainforest ), South America (e.g.

Nyungwe Forest - Misplaced Pages Continue

3780-565: The animal or plant kingdoms, since they were photosynthetic like plants, but motile like animals, led to the naming of a third kingdom in the 1860s. In 1860 John Hogg called this the Protoctista , and in 1866 Ernst Haeckel named it the Protista . The work of Pasteur and Koch did not accurately reflect the true diversity of the microbial world because of their exclusive focus on microorganisms having direct medical relevance. It

3870-515: The cell nucleus , the Golgi apparatus and mitochondria in their cells . The nucleus is an organelle that houses the DNA that makes up a cell's genome. DNA (Deoxyribonucleic acid) itself is arranged in complex chromosomes . Mitochondria are organelles vital in metabolism as they are the site of the citric acid cycle and oxidative phosphorylation . They evolved from symbiotic bacteria and retain

3960-418: The equator . Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year. Average annual rainfall is no less than 168 cm (66 in) and can exceed 1,000 cm (390 in) although it typically lies between 175 cm (69 in) and 200 cm (79 in). Many of the world's tropical forests are associated with the location of the monsoon trough , also known as

4050-479: The human body , microorganisms make up the human microbiota , including the essential gut flora . The pathogens responsible for many infectious diseases are microbes and, as such, are the target of hygiene measures . The possible existence of microscopic organisms was discussed for many centuries before their discovery in the seventeenth century. By the 6th century BC , the Jains of present-day India postulated

4140-400: The oceans and deep sea . Some types of microorganisms have adapted to extreme environments and sustained colonies; these organisms are known as extremophiles . Extremophiles have been isolated from rocks as much as 7 kilometres below the Earth's surface, and it has been suggested that the amount of organisms living below the Earth's surface is comparable with the amount of life on or above

4230-456: The poles to the equator , in deserts , geysers , rocks , and the deep sea . Some are adapted to extremes such as very hot or very cold conditions , others to high pressure , and a few, such as Deinococcus radiodurans , to high radiation environments. Microorganisms also make up the microbiota found in and on all multicellular organisms . There is evidence that 3.45-billion-year-old Australian rocks once contained microorganisms,

4320-432: The protists are most commonly unicellular and microscopic. This is a highly diverse group of organisms that are not easy to classify. Several algae species are multicellular protists, and slime molds have unique life cycles that involve switching between unicellular, colonial, and multicellular forms. The number of species of protists is unknown since only a small proportion has been identified. Protist diversity

4410-440: The "jewels of the Earth" and the " world's largest pharmacy ", because over one quarter of natural medicines have been discovered there. Rainforests as well as endemic rainforest species are rapidly disappearing due to deforestation , the resulting habitat loss and pollution of the atmosphere . Rainforests are characterized by a closed and continuous tree canopy, high humidity, the presence of moisture-dependent vegetation,

4500-400: The 20th century and the area covered by rainforests around the world is shrinking. Biologists have estimated that large numbers of species are being driven to extinction (possibly more than 50,000 a year; at that rate, says E. O. Wilson of Harvard University , a quarter or more of all species on Earth could be exterminated within 50 years) due to the removal of habitat with destruction of

4590-417: The Earth, but one to two hundred feet above it, extending over thousands of square miles." A 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

SECTION 50

#1732765469503

4680-496: The ability to communicate with neighboring populations because of variability in eavesdroppers. In adapting to avoid local eavesdroppers, signal divergence could occur and thus, lead to the isolation of plants and microorganisms from the inability to communicate with other populations. A lichen is a symbiosis of a macroscopic fungus with photosynthetic microbial algae or cyanobacteria . Microorganisms are useful in producing foods, treating waste water, creating biofuels and

4770-676: The bacteria with which they were once grouped. In 1990 the microbiologist Woese proposed the three-domain system that divided living things into bacteria, archaea and eukaryotes, and thereby split the prokaryote domain. Archaea differ from bacteria in both their genetics and biochemistry. For example, while bacterial cell membranes are made from phosphoglycerides with ester bonds, Achaean membranes are made of ether lipids . Archaea were originally described as extremophiles living in extreme environments , such as hot springs , but have since been found in all types of habitats . Only now are scientists beginning to realize how common archaea are in

4860-759: The bacterium Streptococcus , Cyclosporin A from the ascomycete fungus Tolypocladium inflatum , and statins produced by the yeast Monascus purpureus . Microorganisms are essential tools in biotechnology , biochemistry , genetics , and molecular biology . The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe are important model organisms in science, since they are simple eukaryotes that can be grown rapidly in large numbers and are easily manipulated. They are particularly valuable in genetics , genomics and proteomics . Microorganisms can be harnessed for uses such as creating steroids and treating skin diseases. Scientists are also considering using microorganisms for living fuel cells , and as

4950-408: The blood of cattle that were infected with anthrax always had large numbers of Bacillus anthracis . Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, and this caused the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, then inject it into

5040-476: The broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur refuted the theory of spontaneous generation and supported the germ theory of disease . In 1876, Robert Koch (1843–1910) established that microorganisms can cause disease. He found that

5130-464: 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 or understorey layer lies between the canopy and the forest floor. It 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 and insect life

5220-417: The decomposing remains of plants and animals. The great diversity in rainforest species is in large part the result of diverse and numerous physical refuges , i.e. places in which plants are inaccessible to many herbivores, or in which animals can hide from predators. Having numerous refuges available also results in much higher total biomass than would otherwise be possible. Some species of fauna show

5310-418: The earliest direct evidence of life on Earth. Microbes are important in human culture and health in many ways, serving to ferment foods and treat sewage , and to produce fuel , enzymes , and other bioactive compounds . Microbes are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism . Microbes are a vital component of fertile soil . In

5400-426: The environment, with Thermoproteota (formerly Crenarchaeota) being the most common form of life in the ocean, dominating ecosystems below 150 metres (490 ft) in depth. These organisms are also common in soil and play a vital role in ammonia oxidation. The combined domains of archaea and bacteria make up the most diverse and abundant group of organisms on Earth and inhabit practically all environments where

5490-516: The existence of microorganisms as discovered by modern science. The earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a first-century BC book entitled On Agriculture in which he called the unseen creatures animalia minuta, and warns against locating a homestead near a swamp: … and because there are bred certain minute creatures that cannot be seen by

SECTION 60

#1732765469503

5580-434: The existence of tiny organisms called nigodas . These nigodas are said to be born in clusters; they live everywhere, including the bodies of plants, animals, and people; and their life lasts only for a fraction of a second. According to Mahavira , the 24th preacher of Jainism, the humans destroy these nigodas on a massive scale, when they eat, breathe, sit, and move. Many modern Jains assert that Mahavira's teachings presage

5670-440: The eyes, which float in the air and enter the body through the mouth and nose and they cause serious diseases. In The Canon of Medicine (1020), Avicenna suggested that tuberculosis and other diseases might be contagious. Turkish scientist Akshamsaddin mentioned the microbe in his work Maddat ul-Hayat (The Material of Life) about two centuries prior to Antonie van Leeuwenhoek 's discovery through experimentation: It

5760-699: The globe, but temperate rainforests only occur in a few regions around the world. Temperate rainforests are rainforests in temperate regions. They occur in North America (in the Pacific Northwest in Alaska , British Columbia , Washington , Oregon and California ), in Europe (parts of the British Isles such as the coastal areas of Ireland and Scotland , southern Norway , parts of

5850-422: The growth of vegetation in a tropical 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 colour and sometimes produces mineral deposits such as bauxite . Most trees have roots near the surface because there are insufficient nutrients below

5940-602: The hundreds in Nyungwe. In 1974, the last buffalo was killed in Nyungwe by hunters. In 1984, Nyungwe was divided into areas that allow for sustainable use and harvesting of timber. The Government of Rwanda developed a plan for a buffer zone that can still be seen today. In 1984, biodiversity surveys conducted by the Wildlife Conservation Society (WCS) with RDB documented colobus in groups of up to 400 members—an unheard of phenomenon. In 1987, development of

6030-473: The increasing deforestation rate, especially in Indonesia, is the expansion of oil palm plantations to meet growing demand for cheap vegetable fats and biofuels . In Indonesia, palm oil is already cultivated on nine million hectares and, together with Malaysia , the island nation produces about 85 percent of the world's palm oil. Several countries, notably Brazil , have declared their deforestation

6120-477: The interior". About half of Sarawak's 1.5 million people are Dayaks. Most Dayaks, it is believed by anthropologists, came originally from the South-East Asian mainland. Their mythologies support this. Tropical and temperate rainforests have been subjected to heavy legal and illegal logging for their valuable hardwoods and agricultural clearance ( slash-and-burn , clearcutting ) throughout

6210-514: The island of New Guinea is home to an estimated 44 uncontacted tribal groups. The tribes are in danger because of the deforestation, especially in Brazil. Central African rainforest is home of the Mbuti pygmies , one of the hunter-gatherer peoples living in equatorial rainforests characterised by their short height (below one and a half metres, or 59 inches, on average). They were the subject of

6300-619: The latter now extinct in Angola for the intense hunt to which they were subjected. Nyungwe Forest Reserve was established in 1933 by the Belgian colonial government. In the 1920s the colonial government had become concerned about the accelerating conversion of forest to pasture. The laws governing Rwanda's forest reserves prohibited clearing forests for agriculture, but maintained community rights to cut and collect firewood, and permitted commercial exploitation of valuable hardwood timber. Enforcement

6390-437: The majority of the largest trees, typically 30 metres (98 ft) to 45 metres (148 ft) 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. Epiphytic plants attach to trunks and branches , and obtain water and minerals from rain and debris that collects on

6480-498: The most immediate impact on microbiology by allowing for the cultivation of a wide range of microbes with wildly different physiologies. Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by microorganisms in geochemical processes. He was responsible for the first isolation and description of both nitrifying and nitrogen-fixing bacteria . French-Canadian microbiologist Felix d'Herelle co-discovered bacteriophages and

6570-473: The poor soil quality. First is that the soil is highly acidic. The roots of plants rely on an acidity difference between the roots and the soil in order to absorb nutrients. When the soil is acidic, there is little difference, and therefore little absorption of nutrients from the soil. Second, the type of clay particles present in tropical rainforest soil has a poor ability to trap nutrients and stop them from washing away. Even if humans artificially add nutrients to

6660-409: The potential for extraterrestrial life . The nitrogen cycle in soils depends on the fixation of atmospheric nitrogen . This is achieved by a number of diazotrophs . One way this can occur is in the root nodules of legumes that contain symbiotic bacteria of the genera Rhizobium , Mesorhizobium , Sinorhizobium , Bradyrhizobium , and Azorhizobium . The roots of plants create

6750-708: The rainforests. Another factor causing the loss of rainforest is expanding urban areas . Littoral rainforest growing along coastal areas of eastern Australia is now rare due to ribbon development to accommodate the demand for seachange lifestyles. Forests are being destroyed at a rapid pace. Almost 90% of West Africa 's rainforest has been destroyed. Since the arrival of humans, Madagascar has lost two thirds of its original rainforest. At present rates, tropical rainforests in Indonesia would be logged out in 10 years and Papua New Guinea in 13 to 16 years. According to Rainforest Rescue , an important reason for

6840-482: The same time, rainforests are usually not used sustainably by non-native peoples but are being exploited or removed for agricultural purposes . On January 18, 2007, FUNAI reported also that it had confirmed the presence of 67 different uncontacted tribes in Brazil, up from 40 in 2005. With this addition, Brazil has now overtaken the island of New Guinea as the country having the largest number of uncontacted tribes. The province of Irian Jaya or West Papua in

6930-550: The size of organism, gives an estimate of perhaps 1 trillion species on the planet, of which most would be microorganisms. Currently, only one-thousandth of one percent of that total have been described. Archael cells of some species aggregate and transfer DNA from one cell to another through direct contact, particularly under stressful environmental conditions that cause DNA damage . Like archaea, bacteria are prokaryotic – unicellular, and having no cell nucleus or other membrane-bound organelle. Bacteria are microscopic, with

7020-421: The soil, the nutrients mostly wash away and are not absorbed by the plants. Finally, these soils are poor due to the high volume of rain in tropical rainforests washes nutrients out of the soil more quickly than in other climates. A natural rainforest emits and absorbs vast quantities of carbon dioxide . On a global scale, long-term fluxes are approximately in balance, so that an undisturbed rainforest would have

7110-443: The supporting plants. 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

7200-442: The surface. Extremophiles have been known to survive for a prolonged time in a vacuum , and can be highly resistant to radiation , which may even allow them to survive in space. Many types of microorganisms have intimate symbiotic relationships with other larger organisms; some of which are mutually beneficial ( mutualism ), while others can be damaging to the host organism ( parasitism ). If microorganisms can cause disease in

7290-433: The surface; most of the trees' minerals come from the top layer of decomposing leaves and animals. On younger substrates, especially of volcanic origin, tropical soils may be quite fertile. If rainforest trees are cleared, rain can accumulate on the exposed soil surfaces, creating run-off, and beginning a process of soil erosion . Eventually, streams and rivers form and flooding becomes possible. There are several reasons for

7380-488: The temperature is below +140 °C (284 °F). They are found in water , soil , air , as the microbiome of an organism, hot springs and even deep beneath the Earth's crust in rocks . The number of prokaryotes is estimated to be around five nonillion, or 5 × 10 , accounting for at least half the biomass on Earth. The biodiversity of the prokaryotes is unknown, but may be very large. A May 2016 estimate, based on laws of scaling from known numbers of species against

7470-423: The term cell . Louis Pasteur (1822–1895) exposed boiled broths to the air, in vessels that contained a filter to prevent particles from passing through to the growth medium , and also in vessels without a filter, but with air allowed in via a curved tube so dust particles would settle and not come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within

7560-835: The theory of spontaneous generation . In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis , cholera , diphtheria , and anthrax . Because microorganisms include most unicellular organisms from all three domains of life , they can be extremely diverse. Two of the three domains, Archaea and Bacteria , only contain microorganisms. The third domain, Eukaryota , includes all multicellular organisms as well as many unicellular protists and protozoans that are microbes. Some protists are related to animals and some to green plants . Many multicellular organisms are also microscopic, namely micro-animals , some fungi , and some algae , but these are generally not considered microorganisms. Microorganisms can have very different habitats , and live everywhere from

7650-545: The trail system began at Uwinka. In 1994, war and genocide devastated the country and destroyed many of the research and tourist facilities in Uwinka. Most senior staff were forced to flee, but many junior staff members at Nyungwe stayed on to protect the park. The park began to rebuild in 1995, but security and stability were still uncertain. In 1999, the last elephant in Nyungwe was killed in the swamp by poachers. Rainforest Rainforests are forests characterized by

7740-761: The western Balkans along the Adriatic coast, as well as in Galicia and coastal areas of the eastern Black Sea , including Georgia and coastal Turkey ), in East Asia (in southern China , Highlands of Taiwan , much of Japan and Korea , and on Sakhalin Island and the adjacent Russian Far East coast), in South America (southern Chile ) and also in Australia and New Zealand . Dry rainforests have

7830-651: Was added to UNESCO World Heritage list. The Nyungwe forest has a wide diversity of animal species, making it a priority for conservation in Africa. The forest is situated in a region in which several large-scale biogeographical zones meet and the variety of terrestrial biomes provides a great span of microhabitats for many different species of plants and animals. The park contains 13 primate species (25% of Africa's total), more than 300 bird species including 30 Albertine Rift endemics, 1068 plant species, 85 mammal species, 32 amphibian and 38 reptile species. Many of these animals are restricted-range species that are only found in

7920-552: Was lax, and local people continued to use the forest for hunting, honey collection, woodcutting, subsistence farming, and gold mining. Rwanda became independent in 1962, and the country's forest reserves were managed by the Ministry of Agriculture. From 1958 to 1973, Nyungwe Forest was reduced by over 150 km² due to fires, woodcutting, hunting of animals, and small-scale agriculture. Nearby Gishwati and Virunga forests were cut in half at this time. In 1969, elephants still numbered in

8010-444: Was not until the work of Martinus Beijerinck and Sergei Winogradsky late in the nineteenth century that the true breadth of microbiology was revealed. Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques. While his work on the tobacco mosaic virus established the basic principles of virology, it was his development of enrichment culturing that had

8100-410: Was one of the earliest applied microbiologists. Microorganisms can be found almost anywhere on Earth . Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists , some fungi , as well as some micro-animals and plants. Viruses are generally regarded as not living and therefore not considered to be microorganisms, although

#502497