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Leaving Certificate Geography Geo-Ecology Higher Level 2009 Q 18 Q: Assess how biomes have been altered by human activity. (80 marks) From studying Geo-ecology, I have learned that biomes have been altered by human activity. These include early settlement and clearance of forests, industrial development, felling of tropical rain forests and intensive agricultural practices. 1. Early Settlement and Clearance of Forests In the temperate forest biome of Ireland, Irish land was deciduous mixed woodland growing undisturbed. About 7,000 years ago during the Neolithic times farmers first arrived in Ireland. They farmed lighter, grittier soils in the uplands. When the Celts arrived in 500BC, they brought their iron tools with them. They efficiently farmed the land by clearing only what they needed for settlement and farming. They farmed and grazed animals in the west of Ireland which lead to overgrazing the land and forced the soils to be exposed for example, the Burren in County Clare of exposed limestone bedrock. Deforestation also continued as the Vikings and the Normans made use of the forests in Ireland for building their boats, bridges and destructive settlements. In the 16th century, English and Scottish settlers arrived and cleared the forests to a greater extent. They tilled and cut down the old ancient forestry to make more room for farming, towns and roads. By 1921 at the end of the British rule less than 1% of Ireland was covered in forest. These forests are in Kenmare in County Kerry and Lough Gill in County Sligo. This lead to a great amount of animals distinct to the biome being extinct, for example the Irish elk and wolf. 2. Industrial Development in Europe Manufacturing industry can damage biomes in many ways. These range from the creation of acid rain and an increase in air and water pollution. Industrial activity in Europe is the main cause of acid rain. It is formed when emissions, such as sulfur dioxide that is released from fossil fuels, mix with rainwater forming a weak sulfuric acid. This rain then falls as rain with a pH less than 5.6, making acidic soil. There are many effects of acid rain on vegetation. It can cause leaf damage that reduces it's ability to photosynthesize. It leaves the plant vulnerable and weak. Seed germination (the growing of seeds) is reduced. Alluminium levels in the soil increase due to acidic rain. I t damages the tree's root hairs which affects the absorption of nutrients. In an effort to overcome these problems alkaline lime from limestone is added to bring the soil back to neutral after acid rain. I t is an expensive job as it takes 3 tonnes of lime to neutralize a field for 20 years. There are also effects of acid rain on animal life. For example, it has raised the pH of Sweden's waterways, killing off snails and larvae that feed frogs and fish there. Fish also die from alluminium poisoning due to being in the water. Acid rain has also killed millions of woodland animals in Europe. 3. Felling of Tropical Rain Forests In the Amazon rainforest in Brazil, deforestation is occurring at an alarming rate. This Equatorial biome provides high temperatures and plentiful rainfall all through the year. The forest is dense and luxuriant and it's trees form an almost continuous canopy over the land. Slash and burn cultivation refers to when people remove the vegetation layer by hand and then burn the left over scrub vegetation that wasn’t of any use to them. After it's burned the land is ploughed that returns the charred nutrients back to the ground to act as a fertilizer. Originally in the tropical rainforest, the natural native people like the Yanomani tribe practiced "slash and burn" and small areas of land were cleared for subsistence farming (growing enough to feed themselves). After some time the land was exhausted and the people moved on but due to the small size of the land, the forest took it over again and made it as good as new. This is called sustainable exploitation of the forest as it is managed well, causing very little harm to the forest biome. Deforestation is the clearance of forests. These clearances have normally been done by people outside the biome such as Europeans. Less than 2% of the natural rainforest along Brazil's Atlantic coast has survived. The tropical rainforest has decreased from 2.9 billion hectares to 1.5 billion hectares today. Logging is the process of cutting down trees and exporting them to make a profit. As Brazil is a rapidly developing country and economy, it uses it's mineral rich trees and as a result the government gets a portion of the timber profits. However, 80% of all timber logging activities are illegally done in the Brazilian rainforest to make outputs such as cheap plywood. Mining is another cause of felling tropical trees. Iron ore and copper are mixed in the rainforest which need hectares of cleared land to extract them. Much felling is carried out to provide settlement for Brazilians. Cleared land was given to poor settlers to build flavellas on due to overcrowding. Between the 1950's and 1960's the Brazilian government began building a new capital Brasilia in the rainforest, mainly to attract more people inland away from the overcrowded coastal cities. Today, 2.3 million people live in Brasilia, almost treble the population of Dublin. Reducing biodiversity is then a growing concern to the biome. It refers to the variety of plant and animal life in a biome. Unsustainable exploitation of the forest is an ongoing thing as 2,000 mature mahogany trees are cut down every minute. In this biome, tropical trees are home to 15 million species of plants and animals. 4. Intensive Agricultural Practices in Brazil Intensive agriculture needs the highest yield from the land. Some effects are related to farming, soil erosion and plant and animal habitats and indigenous people. Farming is ongoing in the biome. Deforestation of the tropical rain forests has made way for large cattle ranches and soya bean cultivation. These are mainly farmed by large multinational companies. Soils can be damaged due to the use of fertilizers and pesticides to kill all bugs around which throws the entire ecosystem out of balance, harming plants and animals. Now the Brazilian government encourages larger-scale clearances for agriculture as 40 hectares of rainforests are lost every minute to agriculture use. If this continues, it's estimated by 2050 only 40% of Brazil's rainforests will be left. Soil erosion is caused by the removal of the tree canopy (top layer of tree leaves). It can be in a case of 2-3 years a soil can lose it's fertility as it is deprived of it's foliage layer leading to a lack of humus. It is now called laterite soil as it has been baked in the sun and is useless to men. To prevent the cattle from starving, more land is felled to feed them as part of the vicious cycle. In the Brazilian biome, small habitats have been destroyed to the extinction of some animals and species for example the Panther, a large solitary black cat native to this biome. One quarter of all pharmaceutical drugs originated from the rainforest biome, such as Asprin from the cinchona tree for malaria. If the biome goes on to be destroyed, scientists wont be able to discover the plant species and cures for many of our diseases such as cancer and AIDS. The Indigenous people have suffered due to intensive agricultural practices. In Brazil, 90 tribes have been wiped out due to industrial and agricultural spread into the biome. Most were wiped out by diseases brought by man such as the Europeans to which they had no immunity, for example the common cold. The number of native tribes people in the region as been reduced to less than 250,000 in 2000 from nearly 6 million in the 1500's. In conclusion, biomes can be altered by human activity. In the Brazilian rain forest, the human activities such as early settlement, and the clearance of forests, industrial development in Europe, the felling of tropical rain forests and the intensive agricultural practices in Brazil have all helped to damage the ecosystems in the world’s forests.