Fragile environments

Fragile envrionements are ecosystems that are easily disturbed and can't adapt to change. E.g. coral reefs, costal wetlands, polar environments, savanna grassland and tropical rainforest.
Fragile environments are easily damages by changes brought about by human activities, e.g. loss of habitat due to deforestation, species loss due to overfishing or damage to habitats due to water pollution.
1. Changes in natural envrionement also affect fragile environments, e.g. extreme weather events like floods and doroughts, or longer term changes such as increasing or decreasing erosion or sedimentation.
2. Small changes can cause a lot of damage to fragile envrionemnts:
  1. Coral reefs are sensitive to changes in water temperature and quality- they grow in salt water between 21 and 29C. If temperature increases the coral becomes bleached- the coral cant provide enough nutrients to supposrt the algae that live in it, and forces them out instead. The coreal needs thse algae to provide oxygen and nutrients- without them they will eventually die.
  2. Polar environments are sensitive to temperature changes- small incerases can melt vast areas of ice, which can destroy habitats and threaten species. E.g. Polar bears need sea ice to hunt seals, which are their main food course. As ice melts, polar bears cannot feed and their numbers decline.
  3. Costal wetlands are sensitive to changes in sea level and sedimentation- species are adaped to live in certain depths of soil and water, smallchanges can destroy may species' habitats.
Fragile ecosystems are often rich in natural resources e.g ingredients for medicines, and often have high biodiversity. Exploitation Vs Conservation
Management
1. Can be difficult to find balance between conservation and expolitation.
2. Some fragile envrionments cross international borders. For example the Amazon rainforest covers an areas across 9 different countries. This makes it very difficult to agree on and carry on a management stratergy across the whole rainforest.
3. Many fragile envrionments are located in less developed countries that lack the money or expertise needed to conserve them properly. Consequently people that live in these areas may exploit it because they have no alternative or because they don't understand the need to conserve it.
4. Countries that depend on natural resources from fragile environments for income are reluctant to stop these activities, because it would damage their economy and slow development. E.g. in Brazil the mining industry damages the rainforest, but brings money to the country. ( $9 billion in 2006.)
5. In some areas there is a need to introduce non-native species (e.g. as a food crop), but these can out-compete native species, and be extremly difficult to remove. For example, in Arizona an invasive plant, Tamarisk, was introduced as a windbreak. But it out-competes native plants and is difficult to control, making it a threat to the desert ecosystem.
Restoration
1. Indonesian government has invested in replanting areas of rainforest, and the Coral Restoration Foundation has set up coral nurseries and restoration projects in many ares where reefs have been damaged. However restoration of fragile environments can be difficult.
2. Some cannot be restored. Clearing land in a rainforest causes soil quality to decline. Even if land is replanted, the degraded soil means that rainforest vegetation can't easily regrow.
3. Natural hazards (floods, droughts) cna cause damge to fragile environment which take a long timescale to recover. the Indian Ocean Tsunami in 2004 destroyed areas of coral reefs and mangrove swamps. Akthough some countries affeted by the tsunami are undertaking schemes to replant mangroves it could take hundreds of years for the ecosystems to fully recover.

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	Creado por nadia-ouachan hace casi 10 años