Ecosystem made up of plants and animals and the physical factors affecting them. It also includes how they affect each other and interact.

Transcription

1 Living World Ecosystems Ecosystem made up of plants and animals and the physical factors affecting them. It also includes how they affect each other and interact. Major functions of an ecosystem 1. Transfer of energy Ø The Sun is the source of energy for all life on Earth (heat and light energy) Ø This energy is transferred through the system by consumption Primary producers (plants which capture sunlight and convert it to energy via photosynthesis) Consumers (animals which eat others in the food chain) Ø Energy may be stored as biomass for a period of time Ø Energy may leave the system via respiration or other life processes which use energy Ø The transfer of energy can be shown through a food chain each level in the food chain is called a trophic level there is great energy loss between the levels Ø The transfer of energy in an ecosystem can be shown in more depth with a food web many food chains drawn together to show the complex interactions between components

2 2. Nutrient Cycling Ø The recycling of nutrients between living organisms and the environment can be seen through Gersmehl s model Ø Nutrients are foods that are used by the plants and animals to grow, such as nitrogen and potassium. 3. Decomposers Ø bacteria and fungi in the soil that break down the remains of plants and animals, and release the chemicals for plants to use again. Case Study: Hedgerow Biotic components Hedgerow shrubs (variety of vegetation e.g. beech, wild rose) Occasional tall trees (e.g. oak) Field layer of grasses (e.g. blackberry) Insects (e.g. ladybugs) Birds (e.g. robins) Mammals (e.g. badgers) Abiotic components Fertile, brown earth soils Warm, damp summers/ cool wet winters Human components Trimmed by farmers Local people collect berries/ roses Distribution of Ecosystems 1. Tropical Rainforests around the equator (within the tropics) e.g. Indonesia, Northern Australia, Congo, Brazil 2. Hot Desert around the tropics all continents e.g. Sahara, Australian, Gobi 3. Deciduous Forest Northern Hemisphere (mostly) outside the tropics (between 40 and 50 ) further North on the Western side of continents (where winters are warmer) e.g. North America, New Zealand

3 Tropical Rainforests Climate Tropical rainforests are based around the equator and, as a result, have an equatorial climate. This includes: Ø high temperatures (day and night) Ø little seasonal variation Ø regular and high rainfall (in afternoons) Ø high humidity e.g. Manaus, Brazil Annual rainfall: 2100mm Average temperature: 27 C Temperature range: 2 C Soil The soil in a tropical rainforest is called a latosol. High temperatures and rainfall combined with biotic activity causes the thick litter layer (from vegetation) to decompose quickly, leaving a thin humus layer. A horizon contains a dense root mat which takes up almost all nutrients released by the decomposing organic matter, leaving nutrient levels low. Heavy rainfall causes the release of iron and aluminum from parent material as well as leaching, which inhibits the formation of many horizons. Vegetation One third of the world s trees grow in rainforests, making it so that they have to fight for sunlight. In addition to this structure, there are: Ø lianas (creepers) climbing between trees, trying to get as high as possible Ø epiphytes which grow over other trees and plants, but do not derive nourishment from them Adaptations Ø Lack of sunlight trees grow very tall have no branches (conserves energy for height) lianas loop around the tree trunks and can grow up to 200m leathery leaves to withstand UV ferns are able to survive in very dark conditions dense undergrowth develops where sunlight can reach (e.g. near rivers) Ø A lot of rain drip-tip leaves shed water so they do not rot

4 Ø Poor soil below A horizon trees grow shallow, but expansive roots trees grow buttress roots above surface for support and shallow roots are not enough for such tall trees Deforestation in Malaysia Causes of deforestation Ø Slash and burn small scale deforestation by indigenous populations burning of cut trees adds to the fertility of soil, and they move on after it has lost its fertility relatively small scale, however Ø Farming and Commercial Ranching the rapid expansion of oil palm plantations has led to huge increases in deforestation in Malaysia, because of the need for space began in 1970s, it was promoted by government with 10-year tax break for plantation owners in 2011, it reached 5 million ha of space commercial ranchers are only interested in replacing forest with pastures often do not even sell the wood Ø Logging tree loggers often only want one type of tree, but in order to reach them, they must clear the entire area Malaysia has one of the best rainforest protection policies in the region with only fully grown trees allowed to be felled and those with important ecological qualities are left unharmed (but much illegal logging still takes place) Ø Mineral extraction and mining mining has been widespread in Peninsular Malaysia with tin mining and smelting dominating areas of rainforest have had to be cleared for the construction of roads drilling for oil and gas has started on Borneo Ø Energy e.g. $2 billion Bakun Dam in Sarawak (completed in 2011) the flooding of 1,000s of Ha of forest. Approximately 230km 2 of virgin forest was cut down. It has a capacity of 2,400 mega watts. Ø Population increase and settlement increase of population: 13.7 million in million in 2010 a greater need for energy, housing and jobs all of which require the forests Ø Building roads more settlements and industry require more roads to be built these require trees to be felled

5 Effects of deforestation Economic Environmental Social Political Sarawak has a plan to grow its economy by factor 5 Malaysia was the world s largest producer of palm oil until 2006 Loss of habitat causes extinction: Sarawak boasts more than 28,000 species, including endangered ones (e.g. Borneo Gibbon). But 230km 2 of this habitat was cut down for the project. Deforestation leads to global warming adds carbon dioxide to the atmosphere destroys valuable carbon sinks Green energy is produced by the hydroelectric dams Bakun dam has a 2400 megawatt capacity Indigenous populations are relocated e.g. 10,000 indigenous people were located for the Bakun dam The resources indigenous populations rely on are destroyed e.g. Penans a hunter-gatherer tribe depend on the forest for their livelihoods Deforestation has lost the government the support of local peoples Penans protested in 2003 against the encroachment of a logging company, but were taken no notice of, instead some were imprisoned Sustainable Management Sustainable management allowing the rainforests to be used to meet our needs without compromising those of the future s Ø Selective Logging only some trees are felled less damaging to the forest as the overall structure is kept (canopy intact so soil erosion does not occur) forest is able to regenerate horse logging and helilogging is even less damaging as heavy trucks are avoided Malaysia: restricted use of bulldozers (entry tracks are 1 km apart), helilogging, companies employing clear-felling methods do not get their licenses renewed Ø Replanting when new trees are planted to replace the ones that are cut down will be trees for the future important that the same types of tree are planted so that the variety is maintained

6 Malaysia: the Community Forestry Development scheme replants not only in rainforest, but also in villages (fruit trees to ensure a food supply) and in urban areas (to stabilize temperatures) Ø Reducing demand hardwood (e.g. mahogany, teak, ebony) is in high demand from consumers in MEDCs this means that some tropical hardwood trees are becoming endangered richer countries can take action to reduce demand heavily taxing it banning its sale countries with the rainforest can also take action ban logging of hardwood species Ø Education some local people are unaware of the environmental impacts of deforestation, but still make money from it educating them about their impacts, how to reduce them, and alternative ways to make money (e.g. ecotourism, rubber tapping) may make them reduce their impact education of the international community reduces demand for products that lead to deforestation (e.g. hardwood and palm oil) puts pressure on governments to reduce deforestation Ø Ecotourism a tourism that does not harm the environment and benefits the local people it provides a source of income for locals so that they do not have to engage in deforestation relatively small scale, so only helps a few people and a small area Ø Reducing debt most tropical rainforest is in poorer countries with a lot of debt these countries allow deforestation in order to pay back the debt if debt is reduced, they would not have to do this, so sometimes debt is cancelled by countries or organizations however, there is no guarantee that this money will be spent on conservation conservation swaps (debt-for-nature swaps) guarantee this Ø Protection environmental laws can be used to protect rainforests laws that ban certain types of logging nature parks and reserves can be set up where damaging activities are restricted however, a lack of funds can make it difficult to police Malaysia: Taman Negara National Park, 14% of Peninsular Malaysia s forest is protected from development Why is international cooperation needed? many countries that have rainforests are LEDCs most pressure on rainforests come from MEDCs, therefore cooperation is needed to bridge this gap LEDCs need funding in order to afford sustainable management

7 Hot Deserts Climate Deserts have both extremes of temperature: very hot in the day, and cold at night. They are also extremely dry. e.g. In Salah, Algeria Average daytime temp: 26 C Average nighttime temp: 9 C Annual range: 25 C Annual rainfall: 18mm Soil The soil in the desert is called a desert soil. They have the following characteristics: overall: very thin, lacks structure and grey in color thin crust caused by high-intensity rainfall and/or desert pavement (small stones) thin humus layer (due to lack of vegetation) solid bedrock (due to lack of weathering) capillary action pulls water upwards through the profile, with salts and bases, making the soil salty and alkaline Vegetation Very sparse vegetation. The plants that do survive are very well adapted: Vegetation adaptations: Ø Little rainfall succulents store water in flesh spiky leaves deter animals roots can either be very shallow but widespread so absorb large quantities of water in short periods of time very long to tap into groundwater supplies e.g. cacti and agaves drought-tolerant (xerophytic) dry out, lose leaves etc. in order to reduce metabolism to near zero when rain arrives they resume growth very deep and extensive roots take moisture from where evaporation is not a problem e.g. desert ferns drought evaders (ephemerals) short life cycles so that they sprout in only very specific circumstances, germinate and then die within two weeks when the conditions are dry again seeds have a thick case protecting a pulpy center so they can lie dormant for months e.g. desert marigolds

8 Ø Extreme temperatures small leave have a larger surface area so stomata do not need to be kept open in order to maintain temperature (reduces transpiration) some plants can turn their leaves to minimize surface area to the Sun Economic Activity in Deserts MEDC Case Study: The Australian Outback Location: Australia, a very large island between the Indian and Pacific oceans, is mostly desert Economic development and challenges: Ø Hunting and gathering Australia s aboriginal people traditionally survived this way does not produce enough food to support the whole population Ø Farming the modernized way Australia gets their food difficult due to low moisture and nutrient levels Ø Tourism Uluru is a popular tourist destination: 400,000 people in 2005 but environmentally sensitive and aboriginal culture is exploited Ø Mining Australia has 70% of the world s opal, and has quality reserves of iron ore and silver however, very hot and dangerous Ø Retirement Migration becoming increasingly popular to retire to the warm climate Management and challenges: Ø Water and Farming in order for farms to profit, they must be huge travel between areas can be long farms use dams and reservoirs to store water for sheep and cattle but, water can be lost through evaporation farmers use bore holes to tap into underground water groundwater stores are very slow to fill and may be used quicker than it fills Ø Tourism and Aboriginal Culture Uluru Aboriginal Cultural Center educates visitors about culture and history the income goes to the local community, and 30 employees are aboriginal people this allows the culture to continue to thrive

9 LEDC Case Study: The Sahara Location: The Sahara is located in Northern Africa. It covers many countries including Morocco, Algeria, Tunisia, Libya, Egypt and Sudan. Economic Development and Challenges: Ø Energy large oil and gas reserves underneath the Sahara: in Algeria the extraction of it accounts for half of GNI but very hard to find, let alone reach and extract e.g. Hassi Messaoud oil field 40,000 workers must transport workers and supplies by plane Ø Farming the heavily irrigated Nile Valley is fertile, and able to be used for agriculture but, Egypt has a rapidly growing population and 32% of Egypt s population is employed in agriculture, so overcultivization and overgrazing has led to desertification (land quality declines to such an extent that it has turned to desert) more land is needed Management and challenges: Ø Energy world s first solar power plant in the Sahara Desert electricity difficult to transport: wires must be placed under Mediterranean Ø Farming tried to irrigate other pieces of land salinity caused by irrigating water containing mineral salts; makes plants die reducing the number of farm animals fewer animals mean less economic return- unfeasible for the long term diversifying farming to have crops and animals animal manure can be used to fertilise the soil and then help plants grow. This is fairly sustainable as one elements supports the other. building dams and reservoirs water may be lost via evaporation

10 Temperate Deciduous Forests Climate Temperate deciduous forests have a moderate climate with no extremes: Ø summers warm, but not too dry Ø winters cool, but rarely dip below freezing Ø long growing season (up to 7 months) Ø rainfall throughout the year, exceeding 1,000mm annually e.g. Greensborough, USA average temperature: 13 C temperature range: 20 C total annual rainfall: 1045mm Soil The soil in a temperate deciduous forest is called a brown earth soil. O-horizon Ø there is a large leaf litter layer (especially in the autumn) due to the leaf fall Ø which ferments due to the moderate temperatures soil biota earthworms Ø to give a large humus layer as well A and B horizons: Ø there is a lack of clear boundaries due to leaching earthworms Ø reddish-brown colour throughout due to leaching of minerals such as iron and aluminium C horizon: Ø there are fragments of rock due to chemical weathering (from the presence of water and moderate temperatures) biological weathering (from tree roots) of the bedrock Vegetation The temperate deciduous forest has four layers: 1. Canopy layer (20-30 m) oak, beech, sycamore, chestnut, ash 2. Sub-canopy layer hawthorn, holly, hazel 3. Field layer bluebells, wild garlic, bramble 4. Ground layer moss

11 Adaptations Ø Seasonal variation of moderate temperatures trees shed leaves can conserve water as less transpiration will occur photosynthesis would not be as efficient flowering plants bloom in spring before the canopy has developed so light can penetrate often have bulbs to aid survival during cold weather or drought leaves are not waxy Management of a temperate deciduous woodland Case Study: Epping Forest Land use Ø wildlife 70% of land is deciduous forest, but also other habitats such as marshes and grasslands habitat of many species (including fallow deer, woodpecker and the stag beetle) Ø recreation walking, golf (18-hole course), horse-riding (50km), coffee shops Ø education courses for adults and children (e.g. Children s Wanstead Nature Club) field studies centre Ø grazing English Longhorn cattle were reintroduced in 2002, promoting biodiversity this is sustainable management as it provides income to farmers while helping the forest continue to thrive Management Ø conservation City of London balances the environmental and social needs of Epping Forest e.g. controlling recreation allows people to have fun, and for the forest to remain undestroyed e.g. only permitting each dog walker 3 dogs provides compromise between the environment and people s wants e.g. pollarding: pruning system in which the upper branches of a tree are removed, promoting new growth allows wood to be obtained both now and in the future Ø protection the majority of the forest has been designated as Site of Special Scientific Interest (SSSI) Special Area of Conservation (SAC) this gives protection by the EU and is sustainable management as it allows the park to be available to future generations