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Forest fragmentation is a form of habitat fragmentation, occurring when forests are cut down in a manner that leaves relatively small, isolated patches of forest known as forest fragments or forest remnants. The intervening matrix that separates the remaining woodland patches can be natural open areas, farmland, or developed areas. Following the principles of island biogeography, remnant woodlands act like islands of forest in a sea of pastures, fields, subdivisions, shopping malls, etc.
Natural Causes of Forest Fragmentation
Forests may also be fragmented by natural processes such as fire and changes in climate.
For example, 300 million years ago in the Carboniferous the tropical rainforests in Euramerica were fragmented due to a change in climate. There was a great loss of amphibian diversity and simultaneously the drier climate spurred the diversification of reptiles. These changes however, occurred gradually over million of years, not like the human driven destruction of tropical rainforests today.
Forest fragmentation is one of the greatest threats to biodiversity in forests, especially in the tropics. The problem of habitat destruction that caused the fragmentation in the first place is compounded by :
- the inability of individual forest fragments to support viable populations, especially of large vertebrates
- the local extinction of species that do not have at least one fragment capable of supporting a viable population
- edge effects that alter the conditions of the outer areas of the fragment, greatly reducing the amount of true forest interior habitat.
The effect of fragmentation on the flora and fauna of a forest patch depends on a) the size of the patch, and b) its degree of isolation. Isolation depends on the distance to the nearest similar patch, and the contrast with the surrounding areas. For example, if a cleared area is reforested or allowed to regenerate, the increasing structural diversity of the vegetation will lessen the isolation of the forest fragments. However, when formerly forested lands are converted permanently to pastures, agricultural fields, or human-inhabited developed areas, the remaining forest fragments, and the biota within them, are often highly isolated.
Forest patches that are smaller or more isolated will lose species faster than those that are larger or less isolated. A large number of small forest "islands" typically cannot support the same biodiversity that a single contiguous forest would hold, even if their combined area is much greater than the single forest.
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms which previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of harvesting natural resources for industry production and urbanization. Clearing habitats for agriculture is the principal cause of habitat destruction. Other important causes of habitat destruction include mining, logging, trawling and urban sprawl. Habitat destruction is currently ranked as the most important cause of species extinction worldwide. It is a process of natural environmental change that may be caused by habitat fragmentation, geological processes, climate change or by human activities such as the introduction of invasive species, ecosystem nutrient depletion and other human activities mentioned below.
Impacts on organisms
In the simplest terms, when a habitat is destroyed, the plants, animals, and other organisms that occupied the habitat have a reduced carrying capacity so that populations decline and extinction becomes more likely. Perhaps the greatest threat to organisms and biodiversity is the process of habitat loss. Temple (1986) found that 82% of endangered bird species were significantly threatened by habitat loss. Endemic organisms that obtains limited ranges are most affected by habitat destruction, mainly because these organisms are not found anywhere else within the world and thus, have less chance of recovering. This is also contributed by that many endemic organisms obtains very specific requirements for their survival that perhaps can only be found within a certain ecosystem, resulting in their extinction. Habitat destruction can also decrease the range of certain organism populations. This can result in the reduction of genetic diversity and perhaps the production of infertile youths, as these organisms would have a higher possibility of mating with related organisms within their population, or different species.
Biodiversity hotspots are chiefly tropical regions that feature high concentrations of endemic species and, when all hotspots are combined, may contain over half of the worldâ€™s terrestrial species. These hotspots are suffering from habitat loss and destruction. Most of the natural habitat on islands and in areas of high human population density has already been destroyed (WRI, 2003). Islands suffering extreme habitat destruction include New Zealand, Madagascar, the Philippines, and Japan. South and east Asiaâ€”especially China, India, Malaysia, Indonesia, and Japanâ€”and many areas in West Africa have extremely dense human populations that allow little room for natural habitat. Marine areas close to highly populated coastal cities also face degradation of their coral reefs or other marine habitat. These areas include the eastern coasts of Asia and Africa, northern coasts of South America, and the Caribbean Sea and its associated islands.
Regions of unsustainable agriculture or unstable governments, which may go hand-in-hand, typically experience high rates of habitat destruction. Central America, Sub-Saharan Africa, and the Amazonian tropical rainforest areas of South America are the main regions with unsustainable agricultural practices or government mismanagement.
Areas of high agricultural output tend to have the highest extent of habitat destruction. In the U.S., less than 25% of native vegetation remains in many parts of the East and Midwest. Only 15% of land area remains unmodified by human activities in all of Europe.
Tropical rainforests have received most of the attention concerning the destruction of habitat. From the approximately 16 million square kilometers of tropical rainforest habitat that originally existed worldwide, less than 9 million square kilometers remain today. The current rate of deforestation is 160,000 square kilometers per year, which equates to a loss of approximately 1% of original forest habitat each year.
Other forest ecosystems ha
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Answers:It can be habitat fragmentation if the acid rain only damages patches of the forest. Exotic species may be involved and will be affected if the damage prevents them from moving around their original habitat. Destruction on a more evened-out scale will cause habitat degradation and those exotic species will ultimately perish. Good for them because sooner or later they will be affected by global warming problems caused by fragmentation and degradation of our habitats which are in turn caused by acid rain that comes most certainly from our own vehicles and factories. So you see, it is very clear here that both you and I are at a loss of what is happening so it would be best for the both of us along with the whole wide world we live in if you pay attention in class and start reading your books.
Answers:(1) Binary fission is the process by which prokaryotes divide into two identical daughter cells, which can eventually grow to the same size as the original parent cell. Such reproduction is characterized by exponential growth phases. A disadvantage is that there is little or no genetic variation, so habitat adaptation is not as rapid as would be expected with eukaryotic sexual reproduction. (2) Budding (also called burgeoning) is the formation of a new organism by the protrusion of part of another organism. This is very common in plants and fungi, but may be found in some animals as well, such as the Hydra. Usually, the protrusion stays attached to the primary organism for a while, before becoming free. The new organism is naturally genetically identical to the primary one (a clone), so, as with binary fission, there is not as much genetic variation in offspring as occurs with sexual reproduction. (3) Spore formation. A spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans. Spores are usually haploid and unicellular and are produced by meiosis in the sporophyte. Once conditions are favorable, the spore can develop into a new organism using mitotic division, producing a multicellular gametophyte, which eventually goes on to produce gametes. Two gametes fuse to create a new sporophyte. This cycle is known as alternation of generations, but a better term is "biological life cycle", as there may be more than one phase and so it cannot be a direct alternation. Haploid spores produced by mitosis (known as mitospores) are used by many fungi for asexual reproduction. A chief difference between spores and seeds as dispersal units is that spores have very little stored food resources compared with seeds. Because spores contain so few nutrition stores, they are not as nurturing to a developing individual as a seed, egg, or placenta. (4) Fragmentation or Clonal Fragmentation is a form of asexual reproduction or cloning where an organism is split into fragments. The splitting may or may not be intentional. Each of these fragments develop into mature, fully grown individuals that are a clone of the original organism. If the organism is split any further the process is repeated. Fragmentation is caused by mitosis. Meiosis is not involved in fragmentation. Fragmentation is seen in many organisms such as molds, some annelid worms, and starfish. Binary fission of single-celled organisms such bacteria, protozoa and many algae is a type of fragmentation. Molds, yeast, and mushrooms, all of which are part of the Fungi kingdom, produce tiny filaments called hyphae. These hyphae obtain food and nutrients from the body of other organisms to grow and fertilize. Then a piece of hyphae breaks off and grows into a new individual and the cycle continues. As with other types of asexual reproduction, fragmentation does not provide any genetic variation in offspring, and does not allow for any hybridization or heterosis. Thus, as with all forms of asexual reproduction, adaptation to new environemental conditions is not as rapid as with sexual reproduction. (5) Vegetative reproduction is a type of asexual reproduction found in plants, and is also called vegetative propagation or vegetative multiplication. It is a process by which new plant "individuals" arise or are obtained without production of seeds or spores. It is both a natural process in many plant species (as well as non-plant organisms such as bacteria and fungi) and one used or encouraged by horticulturists to obtain quantities of economically valuable plants. As with other types of asexual reproduction, vegetative reproduction does not provide any genetic variation in offspring, and does not allow for any hybridization or heterosis. Thus, as with all forms of asexual reproduction, adaptation to new environemental conditions is not as rapid as with sexual reproduction.
Answers:1 b 2 a 3 b 4 a 5 c