Geoecology Option (Q16-18) Examine the factors that influence soil characteristics. (Latosols) Soils result from the weathering of rocks and the redeposit ion of weathered material. Soil is a layer of loose material that lies on the surface of the land it is made up of organic and inorganic matter.
There is a wide variety of soils around the world due to the influence of climate, parent material, relief, vegetation, soil organisms, time and human interference
Climate is long term series of weather patterns e.g. Mediterranean, cool temperate oceanic. Climate effects both vegetative production and the activity of organisms. Climate influences the rate of weathering which in turn controls soil thickness. Weathering occurs most quickly in tropical areas where temperatures are high and rainfall is high e.g. the Tropical broadleaf evergreen rainforest. Climate affects the amount of leaching. This is the process whereby minerals are washed downwards leaving the top layer of soil without minerals.
The type of parent material determines the amount and type of minerals in the soil. These minerals then provide nutrients and food for plants. Parent material also influences soils depth, colour, texture and PH.
Relief also influences soil characteristics. Mountainous regions are steep and so soil cannot build up due to mass movement e.g. landslides. Upland areas are characterised by thin heavily leached soils. High rainfall in upland areas mean more leaching. High ground means less vegetation and less organic content.
Vegetation and soil organisms influence soil characteristics. Decayed vegetation becomes hums and humus is vital for good growth. When leaves fall they turn into humus which gives further growth. If there is no vegetation the soil will be infertile e.g. the dessert plants binds the soil together to retain moisture and reduce soil erosion. Soil organisms help soil fertility in many ways e.g. earthworms aerate the soil. Bacteria change nitrogen into a form that plants can absorb and fungi changes decayed vegetation into humus.
Finally human’s interference can remove or increase soil depth by deforestation this is getting rid of forests e.g. the slash and burn technique.Deforistation means less vegetation, less transpiration, less moisture and soil dries out e.g. the Amazon basin Brazil.Overcropping is intense farming. This leads to less vegetation, dry soil and increased erosion e.g. The American Dustbowl.Overgrzing is more animals than the land can support e.g. The Sahel Africa.
There are many factors that can influence the soil type found in any one region. These factors can be natural and influenced by humans. Different combinations of these factors create the different soil types found on this planet.
Examine the factors that influence soil characteristics, with reference to one soil type you have studied (Latosols) (Another version of above essay)
Soil is a thin layer of loose material that covers most of Earths land surface. It is composed of organic (living) and inorganic material. Soils constitute parts consist of 45% Rock particles, 25% Water, 25% Air and 5% leaves (organic material). The soil type I will discuss is Latosols. Latosols originate from the humid tropical and equatorials zones. Soil research has shown that soil profiles are influenced by seven separate, yet interacting factors: However I will focus on four in detail 1) Climate, 2)Parent Material and Time, 3) Soil organisms and Vegetation and 4) Human Interference.
Climate is a long-term series of weather patterns. 45% of soil is made of rock particles. Climate controls the rate of weathering (the break down of rocks). Types of weathering include Biological, Physical and Chemical. Latosols are affected in this way. Latosols are formed by the process of Leaching. Leaching is the process where rainwater carries minerals down through the soil. Latosols quickly lose their fertility under crop cultivation because excessive leaching has removed the plant nutrients in all but a thin surface layer. Desertification also affects Climate. Desertification is the spread of the desert conditions into new areas. Decertified soils are dry, dusty and lack humus. Their fertility is reduced and they are affected by soil erosion. Africa is the continent most at risk from desertification although Southern Europe, especially Southern Spain is also at risk. Desertification often occurs as a result of a combination of drought, over- cropping and deforestation. High population growth in countries such as Sudan contributes to desertification due to the increased demand for food and fuel. Drought conditions increase the chance of desertification occurring when the soil is already stressed by over cropping and over grazing. In Sahelian countries such as Chad and Niger, Cotton and Cashew nuts are grown as cash crops on huge plantations as part of economic reforms in return for debt relief. People are removed from their land at the edge of the plantations. This land is overgrazed and over-cropped and trees are cut down for fuel and building materials.
Soil parent material is the material that soil develops from, and may be rock that has decomposed in place, or material that has been deposited by Wind, Water and Ice. The character and chemical composition of the parent material plays an important role in determing soil properties, especially during the early states of development. Variations of the latosols have been described as yellowish-brown lateriatic and reddish-brown lareiatic soils. Large upland areas of Africa and India within the tropical wet-dry climate regime have black and dark grey tropical soils. These dark soils may be related to special conditions of underlying bedrock. For example, the dark soils of peninsular India coincide rather well with the Deccan Plateau, underlain basalts. Parent material also controls Soil colour, Soil PH, Soil texture and Soil depth. It takes up to 400 years to form 1cm of soil e.g. Surtsey Island. The more time available, the more vegetation cover and more weathering. This is how Latosols are formed.
Soil developed on parent material that is coarse grained and composed of minerals resistant to weathering are likely to exhibit coarse grain texture. Fine grain soil develops where the parent material is composed of unstable minerals that readily weather. Parent material composition has a direct impact on soil chemistry and fertility. Parent materials rich in soluble ions-calcium magnesium, potassium and sodium are easily dissolved in water and made available to plants. Limestone and basaltic lava both have a high content of soluble basses and produce fertile soil in humid climates. If parent materials are low in soluble ions, water moving through the soil removes the bases and substitutes them with hydrogen ions making the soil acidic and unsuitable for agriculture.
3. Soil Organisms and Vegetation
Soil Organisms include Fungi, worms and bacteria all help soil fertility. How? Earthworms aerate the soils. E.g. Latosols. Fungi change decayed vegetation into humus. Humus is very good for growth. When leaves fall they turn to Humus, which gives further growth. If there is no presence of Humus then in turn there is no vegetation and soil is left infertile. Plants also bind soil together roots. Vegetation type is important for soil type. Deciduous hardwoods (Oaks, Ash, Elm) give brown earth soils. Podzols soils form mainly under coniferous forests e.g. (pine needles- low organic content). Latosols are found only in warm, humid regions and hence correspond closely with the wet equatorial climate and the tropical wet-dry climate.
4. Human Interference
Soil is a renewable resource. However factors such as Deforestation, which means less vegetation, less transpiration, less moisture and in turn Soils dry out e.g. Latosols- Amazon basin, Brazil. Over cropping by humans has led to intensive farmed vegetation where soil is exhausted. The soil becomes depleted in Nitrogen thereby hampering growth. Continued Over cropping will only lead to increased erosion like The American Dustbowl in the 30’s when even the economy felt the strain. Another effect is over cropping, where there are more animals then the land can support. Soil becomes unprotected against Aeolian wind erosion. This increased erosion can be witnessed in The Sahel, Africa.
The Greenhouse effect has caused an increase in global temperatures and increased evaporation rates. Drier soils mean more erosion. Even though the fertilisation of land with added minerals such as Nitrogen will increase growth however the problem of Eutrophication occurs where slurry or pesticides contaminate the cleanliness of the water flowing into the rivers and seas. However some efforts have been made to help human’s carbon footprint with the introduction of Irrigation when water is added to soil to increase growth. Carbon credits have become popular in giving something back to nature. When we buy forest to try to counter balance are carbon usages we help reduce our carbon footprint. Forests use CO2 and release oxygen, which is good for our planet. Also forests bind soil thus preventing erosion.
There are many factors that can influence the soil type found in any one region. These factors can be natural and influenced by humans.
Examine the characteristics of one Biome you have studied In this essay I will discuss the characteristics of the tropical broadleaf evergreen rainforest. I will discuss the climate, soils, flora and fauna of this biome. A biome is a large global ecosystem. Each biome has a similar pattern of climate, vegetation etc. Biomes are normally named after their vegetation types e.g. desert biome. The tropical rainforest as I will now refer to it as is found around 10 degrees north and south of the equator (the tropics) e.g. South America, South East Asia, Central America and Africa.
Climate: The tropical rainforest experiences a tropical climate. Temperatures are high (average 27 degrees Celsius) and show little variation meaning there is no difference between the seasons. This biome experiences high levels of convectional rainfall (up to 6600cm of rainfall per annum) This type of rainfall occurs as the sun’s rays are directly overhead and heat the ground and plants, resulting in high levels of evaporation. This water vapour then condenses resulting in heavy daily rainfall. As a result tropical rainforests are very humid (70% to 80% humidity) its climate is due to its position near the equator. The sun’s rays are very direct so there is no real change between seasons. Sunrise and sunset is at 6 o clock. Only 2% of sunshine reaches the forest floor. Convectional rainfall happens usually once a day, the sun which is directly overhead heats the ground rapidly and causes moist humid air to rise. This air cools at height and condenses; this causes torrential rainfall, sometimes with lightning.
Soil: The climate has determined the soil type in this biome. The soil that develops in tropical rainforests is known as latosols. These soils endure high rates of weathering due to high rainfall. This rainfall also leads to rapid leaching. Most minerals in the soil are removed except for iron. Layers of iron build up and this is called laterisation. If this iron is exposed to air it turns to iron oxide, giving the soil its red colour. This soil becomes infertile and acidic and if vegetation is removed it becomes useless for growth. Tropical rainforests have low levels of humus because of huge amounts of decomposers (ants, fungi etc.) Because plants grow so fast they absorb the available humus immediately using their shallow roots. These soils are, therefore, dependant on the climate, plants and animals for its supply of nutrients. There is a fine balance between the soil and the climate of this biome. If the trees are cut down the soil is deprived of its supply of nutrients and renders it unusable.
Flora: The rainforest has a huge floral biodiversity. Rainforests have been called “earth’s lungs”. Many species of plants are yet unknown to science. These plants may contain cures needed by the modern medical society. Many rainforest plants have made adaptations to fit into this biome. Rainforest trees that need extra support in shallow soils have buttresses, which are broad woody supports at the base of the trees. Plants develop large drip tip leaves which catch more sunlight and are adapted for high rainfall amounts to run off. Epiphytes are plants that grow on other plants to get more sunlight and to avoid herbivores. Lianas are woody vines that grow up tree trunks to get to the light; there are over 2500 different species of lianas. The plants in the rainforest grow in 4 distinctive layers. The emergent layer is the tallest of the layer of trees, which can reach heights of 80m. The trunks of these trees are thin as they don’t require protection from frost. The tops of these trees have umbrella shaped outlines. Between 20m and 40m is the canopy layer. Plants in this layer have a canopy of vegetation. Plants found in this layer include vines and epiphytes. An epiphyte is a plant that grows on another plant but is not parasitic, such as a fern. The understory is under the canopy. Plant growth in this layer is limited because of lack of sunlight. Ferns and vines grow in this layer also. Vegetation in the tropical rainforest is dependent on the heavy, daily rainfall and hot, humid conditions.
Fauna: Rainforests are home to more species than all other biomes combined. 82% of the worlds known biodiversity can be found in tropical rainforests, even though this biome only takes up 8% of the worlds land surface. Animals have had to make adaptations to help them live in hot, humid conditions. Rainforests canopies contain a larger variety of animal life than in the rest. Birds such as the toucan and mammals including the howler monkey and jaguars live in this layer of the forest. On the forest floor snakes and insects can be found. Many animals eat in the cool of night and need the intense heat during the day to speed up metabolism. Animals use techniques such as camoflage to protect themselves from predators. One of the most common is looking like a leaf. Plants and animals depend on each other to survive and the growth of plants is dependant on the climate, therefore, all aspects of the tropical rainforest are interdependent.
Impacts of human activity on a biome
A biome is a global ecosystem. Each biome has a similar pattern of climate, soils, vegetation and animal life. Biomes are usually named after their vegetation type eg. Desert Biome. The biome I have studied is the tropical broadleaf evergreen forest (rainforest). Tropical rainforests are found between 5 degrees north and south of the equator. Examples of the tropical rainforests can be found in the amazon basin in Brazil and Indonesia. Human activity has both a positive and negative impact on rainforests.
The rate of felling in rainforests has increased rapidly in recent years. In 1800 there were 2.9 billion hectares of rainforest. Now there is only 1.5 billion hectares remaining. It has got so bad that 1 and a half hectares are lost every second. Experts believe that the last remaining rainforests will be consumed within 40 years. There are many reasons for the clearance of rainforests such as agriculture, development and commodities.
Clearance for agriculture is the main threat to our rainforests. Slash and burn techniques are used to clear the rainforest. This consists of cutting down and burning sections of the rainforest. This cleared land id then used to create fields for agriculture or pasture for livestock. Once the vegetation is removed there is no humification and the soil becomes low fertile soil. There is great controversy as western countries buy meat that is produced on this land. Eg. McDonalds. This adds to the funding for the clearance for agriculture.
Rainforests are also cleared for commodities. Very often rainforests will be cleared to meet the increasing demands of richer countries for products such as coffee beans and cocoa. These used to be sourced in a sustainable way and there was no need for large farms. There is also a huge demand in the industrialised rich for tropical hardwoods such as teak and mahogany. These trees take up to 70 years to grow so it is difficult to source them sustainably. Also rainforests are cleared for the mining of gold.
The Brazilian government have attempted to move people out of the over populated east to the Amazonas state. This means that more rainforests have to be cleared. Eg. The development of Manaus. Also the development of the Trans-Amazonian highway has opened up the region to settlers and illegal loggers. The Trans-Amazonian Highway was inaugurated on August 30, 1972. It is 5,300 km long, making it the third longest highway in Brazil. The highway was intended to integrate this region with the rest of the country, and with Colombia, Peru and Ecuador.
The rapid felling of tropical rainforest has many effects such as soil erosion. Tropical soils were originally shallow. The vegetation being removed means there are no roots to bind the soils together. The soil is then removed by heavy rainfall. What remains is a dry infertile laterised soil. Intensive farming leads to exhausted soils.
Rainforests have huge biodiversity with many species still unknown to science. Experts estimate that we are losing 137 animals plants and insects everyday due to tree felling. Tribal groups are also lost. Eg. Amazonian Indians. Fragmentation occurs when a road or cleared area of the forest fragments plant and animals into smaller areas and eventually leads to extinction. Eg. Sumatran white rhino, orang utang and silver back gorilla are near extinction.
Rainforests act as huge carbon stores. When the trees are cut down they release the carbon dioxide into the atmosphere and increases the rate of global warming. Global warming is the increase in the average temperature of Earth. It leads to climate change and sea levels rising.
Humans also have a positive impact on rainforests. A non-governmental organization (NGO) was formed to protect the rainforest and their biodiversity. The idea was to work with local producers and multi-nationals to make sustainable rainforest friendly products. It is known as the rainforest alliance. They work with local farmers to make sure agricultural practices are sustainable. No child labour is allowed. The rainforests tourism division makes sure tourism companies are preserving the rainforest and not damaging the forest. They certify companies that are responsible and promote sustainable tourism.
Access the impact of human activity on a biome you have studied.
A Biome is a large global ecosystem. Each Biome has a broadly similar pattern of Climate, Vegetation (Flora), Soil type and Animal life (Fauna). One biome I have studied is the Tropical evergreen broadleaf rainforest biome. Countries where this biome is found are the Congo, Brazil, and Indonesia. Tropical rainforests are found between 5 degree North and South of the equator. However further human activity on this biome may hinder its existence. In this essay I will access the impact of the human activity on the Tropical evergreen broadleaf rainforest biome.
There are many reasons for this rapid clearance of rainforests such as 1.Clearance for Agriculture.
Intensive farming involves a high use of chemicals such as fertilisers and pesticides. These chemicals run off into rivers increasing acidity levels in the biome. This threatens the survival of many Flora and Fauna. Slash and burn techniques are used to clear the rainforest. Whereby, farmers clear the jungles vegetation. This Vegetation dries out months after and leads to low fertile soil, as there is no humification as vegetation is removed. This cleared land is then used for cattle ranches where cattle are let to graze the land further depleting the soil of its minerals. Also, controversy spread globally as Western countries buy the beef produced on the land. Multinational franchise restaurants e.g. McDonnells and KFC are encouraged to buy this beef in the rainforests as its inexpensive yet ruining their reputation.
2.Clearance for Commodities
Very often rainforests will be cleared to supply the demands of richer Western countries for products such as Coffee and Cocoa beans. They are used to be sourced in a sustainable way, meaning no need for large farms. The rate of tree felling has increased rapidly (1800-2.9billion hectares, today only 1.5billion hectares remain). One and one –half acres of rainforest are lost every second. Large scale felling threatens the sustainability of the forest as land use for farming yields higher profits. These trees take up to 70 years to grow so difficult to source sustainably.
Huge demand in the rich industrialised countries for tropical hardwoods such as Teak, Mahogany rosewood. The process of illegally cutting down trees throwing them down the river and hoping they retrieve them with many logs getting caught in the river. Also mining for Gold, Bauxite and Aluminium has increased exploitation.
3.Clearance for development
The Brazilian government have attempted to move people out of the overpopulated eastern cities to Amazonas State. This means more rainforests cleared. The rapid development of the city Manause has made way for more towns and cities to develop. Manause is in the heart of the Amazon, surprisingly appearing like a mini New York with skyscrapers and massive buildings. The construction of motorways such as the Trans- Amazonian highway has opened up the region to settlers to easily access from east and west Brazil but also has left access to illegal loggers to the interior.
Whatever the reasons, the rapid felling of tropical rainforests has many effects.
1. Soil Erosion
The soils in the tropical rainforest are shallow, very poor in nutrients and almost without soluble minerals. Rapid weathering and leaching plays a key role in the development of the soils, called latosols found here. The process of leaching removes minerals, except iron oxides, below the reach of the plant roots. This layer of iron oxides builds up and laterisation occurs. The soil becomes infertile acidic. If the iron is exposed to oxygen the soils, through the process of oxidation will develop a red colour. What remains is a dry infertile laterised soil. Intensive farming leads to soil exhaustion. This leads to Over cropping and Overgrazing whereby the soil is depleted of valuable minerals and the influx of Fauna has reduced vegetation cover leaving soil unprotected, devoid of humus and open to erosion.
2. Loss of Biodiversity
Rainforests have huge biodiversity with many plants and animals as yet unknown to science. Exports estimates that we are losing 137 plant, animal and insect species every single day due to rainforest deforestation. The loss of tribal groups, Amazonian Indians, Papa New Guinea in tropical rainforests decreases this human ethnic group and may even become extinct. The process of Fragmentation carried out by humans has had a massive detrimental effect on this tropical rainforest biome. Fragmentation occurs when a road or a cleared area of forest fragments plant and animal populations into smaller areas. Eventually leading to little or no procreation and then extinction. E.g. of species: Sumatran White Rhino, Oranutang and the Silver back gorilla. These animals are then used as bush meat meant for human consumption.
3. The Worlds largest Pharmacy
The tropical rainforests of this earth are abundant with herbal and medicinal properties yet unknown to scientists. More than 25% of Western pharmaceuticals are derived from rainforest ingredients e.g. Aloe Vera, Cocoa Butter, Echinasia. Less than 1% of these tropical trees and plants have been tested by scientists. With continuous Fragmentation and Tree felling, we humans are depriving ourselves of potential cures for the future for long threatening diseases such as Cancer and other illnesses instead we should nurture this vegetation and preserve it.
4. Global warming and rainforests
Rainforests act as huge carbon stores. When this tree is cut down this carbon is released into the atmosphere and increases the rate of global warming. Global warming leads to climate change and sea levels rising due to melting ice caps. This will place large areas of densely populated regions at risk of flooding, e.g. Sao Paulo and other major cities. Therefore, we as humans to reduce the fragmentation and cutting down of our rainforests.
However, in recent years, humans have learnt to work collectively with the rainforest proposing some positive initiatives bringing humans one with nature.
The introduction of the Rainforest Alliance and NGO that aims to protect rainforests and their biodiversity. The idea is to work with local producers and multinationals to make sustainable rainforest- friendly products, e.g. Lipton Tea, Lyons Tea and Kenco coffee are a few of the many products stamped with the Rainforst Alliance certification. The Rainforest Alliances also has a sustainable agricultural division where the organisation works with local farmers to make sure agricultural practices are sustainable. They advocate an end to child labour. Multinational companies can enter “The ethnical food market”. Recently, McDonalds made all the McCafe coffee certified. The Tourist division makes sure tourism companies are preserving the rainforest and are not damaging the forest. It certifies companies that are responsible and promote sustainable tourism.