Biosphere to Ecosystems - Biomes, Nutrient Cycles - PDF

BIOSPHERE to ECOSYSTEMS TOPIC 1 Textbook pg 134 - 161  Biodiversity Biodiversity is the greatest treasure we have… Its diminishment is to be prevented at all cost. Thomas Eisner  What is ? The existence of a large variety of different kinds...

BIOSPHERE to ECOSYSTEMS TOPIC 1 Textbook pg 134 - 161  Biodiversity Biodiversity is the greatest treasure we have… Its diminishment is to be prevented at all cost. Thomas Eisner  What is ? The existence of a large variety of different kinds of living organisms which makes a balance environment Organisms include animals, plants, fungi and microorganisms that work together in ecosystems forming an intricate web which maintains and supports life. There are three levels of biodiversity; Ecosystem diversity, species diversity and genetic diversity It is estimated that there are between 3 and 30 million species currently living on Earth.  Loss of Loss of biodiversity is the decrease in the number of species within an ecosystem. Humans need to strive for sustainable development – we need to use resources wisely and conserve them in order to maintain the balance in ecosystems. Loss of biodiversity seriously effects the earth and its ability to maintain life including HUMAN life. Reduced biodiversity means: ◦ Food supply might be vulnerable (overfishing, pests) ◦ Fresh water supply interruption and shortages ◦ Humans are more vulnerable to natural disasters ◦ Increase in zoonotic diseases (disease transmitted from animal to human)  What is a Biome? BIOME: Geographical region with a distinct climate which supports plants and animals that live in that area. Due to the distinctive climate (average yearly rainfall and temperature) in that area and soil type - plants which are adapted to those conditions will grow there. Specific animal species will be supported by those plant types. Climate Plants/ Animals and soil vegetation  What is a Biome? Biomes can be identified by the type of vegetation (plants) found in that area. ENDEMIC SPECIES: Plants or animals which are restricted to ONLY a specific area or biome (they are not found anywhere else). Climate = average rainfall & temperature of an area. Biomes are classified as either: Terrestrial biomes (land) Aquatic biomes (water)  Biomes in South Africa South Africa has 8 terrestrial biomes. We live in a country which is one of the richest, most species diverse areas in the world, even though it is a relatively small region. Each of the biomes is home to many different plants and animals that are all very well suited to adapted to living in that region.  WHAT TO STUDY: Know the location on the map of the Biomes of South Africa 8 terrestrial biomes. 1 2 3 4 5 6 7 8 Desert  Fynbos Fynbos biome is known for its very high biodiversity (over 8500 species) and also for having a very high number of endemic species (found only in Fynbos biome)  WHAT TO KNOW: Link climate/soil to type of plant in Fynbos Biome biome to animals in biome ‘Fynbos’ refers to the small shrubs with fine leaves found in this biome. Fynbos occurs almost only in the south-western and southern parts of the Western Cape Province. The biome is a World Heritage Site. With at least 8 570 species of flowering plants, it is one of the most diverse floras in the world with 68% endemic plants, many found only in very small areas: Climate: Cold, wet winters and hot, dry summers with strong winds and regular fires (winter rainfall) Soil: Sandy and alkaline coastal soil, further inland it becomes more acidic Fynbos consists of low shrubs with fine leaves, such as ericas, and leafless, tufted, grass-like plants such as restios. Some proteas can grow into large bushes. Trees are rare and grasses are a small part of this biome. Fynbos plants are adapted to survive in poor soil and hot dry conditions by having small leathery leaves (small surface area of leaves reduces water loss by transpiration) OR by having succulent leaves which store water. Fynbos has low nutrient levels and does not support large numbers of animals. The animals which live in the fynbos biome are also smaller herbivores/carnivores. Fynbos biome needs fire for the life cycle of many plant species. Fynbos has 4 main plant types = proteoids, restoids, ericoids & geophytes. Fynbos biome is under threat due to human impact – loss of habitat due to agriculture, increasing urban areas, too frequent fires. Savanna  WHAT TO KNOW: Link climate/soil to type of plant in Savanna biome biome to animals in biome ‘Savanna’ refers to vegetation that is mixed grassland and trees. 46% of South Africa is savanna. Climate: Summer rainfall; extremely hot temperatures in summer; cold winters with little rain. Soil: Soil is varied - Some areas have porous, sandy soil which supports broad leafed plants, other areas have nutrient rich clay which supports small-leaved plants and thorn trees. Richer soils provide nutrients which support a large plant variety including grasses and trees. Typical tree species Acacia, marula, baobab, mopani & bushwillow. Plants support many large herbivores like elephant, rhino, zebra, wildebeest, anterlope etc which provide food for large carnivores. Savanna biome is well known for having the ‘BIG 5’ animals which attracts tourists to visit these areas. Savanna biome is threatened by human activities such as loss of habitat due to agriculture, livestock grazing and poaching as well as long droughts. Wetlands Wetlands Wetlands are areas with waterlogged soils, or areas covered with a shallow layer of water. They may be permanently or seasonally covered with water. They are important because they: ◦ are essential to water security ◦ play an important role in the water cycle ◦ are flood controllers because they slow down flood water ◦ are filters that improve water quality by trapping sediments ◦ hold nutrients such as phosphorus and nitrogen, and even harmful bacteria ◦ are wildlife habitats – they provide food, shelter and breeding areas for many animals. Sadly, 50% of South Africa’s wetlands have been lost as a result of human influence, with only a fraction of what remains being conserved. To ensure water security into the future, we need to safeguard our existing wetlands and help rehabilitate others, where practical. Test your knowledge 5 4 6 8 2 3 7 1 Activity 1. Identify Biomes labelled 1-8 2. Name THREE main groups of plants found in the Fynbos biome? 3. Why are there no large animals found in the fynbos biome? 4. Suggest ONE reason why the Savanna biome is good for agriculture. 5. What is the difference between indigenous and endemic? Use your textbook or phone to research this. BIOSPHERE to ECOSYSTEMS The BIOSPHERE The biosphere can be defined as that part of the earth where the living organisms are found. This is 8km upward from the earth’s surface and 11km downwards into the crust. The Biosphere includes interactions with: ◦ Atmosphere (air) ◦ Hydrosphere (water) ◦ Lithosphere (rock and soil) The ATMOSPHERE The atmosphere is a layer of gases around the earth, held in place by earth’s gravity. It is made of 78% Nitrogen, 21% oxygen and 0.03% Carbon dioxide and very small amounts of other gases. The atmosphere supports life on earth: ◦ It is important as it forms a “blanket” around the earth trapping some of the radiant energy from the sun. This keeps the earth’s temperatures moderate. This is called the GREEN HOUSE EFFECT and makes life on earth possible. ◦ The ozone layer within the atmosphere reflects some of the harmful UV radiation from the sun. ◦ Contains oxygen which is used by many life forms on earth. The LITHOSPHERE The lithosphere is all the soil and rocks that makes up the upper layers of the earth’s surface. The SOLID, OUTER layer which forms the CONTINENTS which include ◦ Mountains ◦ Landforms ◦ Plateaus ◦ Coastal plains Has a thin layer of soil (weathered rock) which provides plants with minerals and holds water. The HYDROSPHERE ALL the WATER on the planet ◦ Oceans ◦ Rivers ◦ Lakes ◦ Vapour ◦ Underground water 97% of the hydrosphere is the OCEAN 3% is fresh water (only 1% is fit to consume) Water is essential for life on earth Ecosystems An ecosystem is an area in which there exists relationships between living organisms and the living organisms and the non-living environment. Ecosystems can be large or small. Some examples of ecosystems: a river, a grassland, a fallen rock. Ecology = The study the interactions of organisms to one another and to their physical surroundings. Terminology Organism/Individual = Individual animal/organism (eg. single elephant) Population = group of organisms of the same species living in the same place (eg. herd or several herds of elephant living in the Kruger Park) Community = all animal and plant populations in an area (eg. elephant, giraffe, tree species, grass species, aquatic animals etc) Habitat = particular place where an organism lives Terminology 1. Ecosystem = Community + non-living environment 2. Ecosystem + ecosystem + ecosystem = biome 3. Biome + biome + biome = biosphere Therefore….from smallest to biggest….. Organism → population → community → ecosystem → biome → biosphere  Terminology 1. Species: A group of organisms with similar physical and biological characteristics that can breed together/interbreed and produce fertile offspring. 2. Population: Group of organisms of the same species living in the same area and able to interbreed with each other. 3. Community: Group of different populations (all living plants and animals) living in the same area. 4. Ecosystem: An area in which plant and animal populations (community) interact with the non-living environment. 5. Biome: Group of ecosystems with a distinct climate and a similar community of plants and animals. 6. Endemic: Species of organism found restricted (unique) to a region. 7. Symbiotic: Interaction between two different organisms living in close physical association. 8. Mutualism: Type of symbiotic relationship between two organisms in which both organisms benefit. 9. Lichen: A close association (mutualism) between an algae and fungi. 10. Abiotic: Non-living chemical and physical factors of an ecosystem. 11. Biotic: Living component of an ecosystem. 12. Habitat: The area where an organism lives Ecosystems Ecosystems are made of the community of organisms (different species) and the non-living environment. We call all the living factors = biotic factors. ◦ Interact with one another and rely on abiotic factors. We call all the non-living factors = abiotic factors. ◦ Physical and chemical factors that influence the living components of an ecosystem.  Ecosystem Biotic factors Abiotic factors Producers Physiographic factors Edaphic factors Physical factors (autotrophs) (GEOGRAPHY) (SOIL) (CLIMATE) Consumers Type & Aspect Light (heterotrophs) texture Decomposers Altitude pH Temperature (saprophytes) Slope Air content Water Soil Atmospheric temperature gases Nutrients Wind & Fire (minerals) Humus Water  Abiotic factors - Physiographic factors (Geography) 1. Aspect: The direction in which a surface faces in relation to the sun. North and South facing slopes (In the Southern hemisphere - the north slope gets more sunlight hours, so it is warmer, but also dryer) 2. Slope: The gradient of the land. Gentle or steep (water runs off a steep slope too fast for plants to absorb it and causes erosion) 3. Altitude: Height of land above sea level (high altitudes are colder with less oxygen) TEXTBOOK: Page 145  North-facing slope gets more direct Aspect sunlight for longer periods = Warm, dry, less decomposition South-facing slope receives less direct sunlight = Cool, moist, more decomposition therefore more lush vegetation  North-facing slope Aspect Sparsely vegetated. Xerophytes like aloes adapted for hot, dry conditions are found. South-facing slope More lush vegetation, taller plants adapted to cooler, moist conditions.  Abiotic factors - Edaphic factors (SOIL) Soil determines the type and amount of plants growing in an area. Plants absorb water and minerals from soil. 1. Type and texture of soil TERMINOLOGY HUMUS: Is formed by the ◦ Sandy: Large particles with lots of air spaces. Low humus decomposition of dead content and poor water retention (can’t hold water for long) plants and animals. Benefits of humus: (infertile) Makes soil more fertile Releases nutrients from ◦ Clay: Very small particles, very small air spaces, low humus decaying matter content. High water retention can cause plants roots to rot Allows for air spaces between soil particles (infertile). Improves water retention ◦ Loam: Mixed particle size, both large and small results in well aerated soil. High humus content, with both moderate water retention and drainage makes this the most fertile soil,  Soil types and textures Property of soil Sandy Clay Loam Particle size large very small mixed Air content high very low good/moderate Humus low low high Water retention low/poor high good/moderate Water drainage too fast too slow good TERMINOLOGY WATER RETENTION: Soil’s ability to hold water. WATER DRAINAGE: How quickly water runs through the soil. Edaphic factors (SOIL) 2. pH (how acid/alkaline the soil is). pH determines the type of plant which will grow. Most plants prefer neutral soils, but there are exceptions. 3. Air content (number and size of air spaces found between soil particles). Air spaces provide space for roots to grow and supports earthworms and a diversity of microorganisms in the soil. 4. Soil temperature (influences by aspect, water content, colour of soil and other factors) Soil temperature below 20-40cm remains relatively constant. ◦ Low temp= unfavorable for plants and animal decay. ◦ Higher temp = increased decay of organic matter if soil is moist & BUT dry soil has less decay. Edaphic factors (SOIL) 5. Nutrient content (minerals – minerals come from the type of rocks in the lithosphere). Nitrogen, phosphorus, potassium, sulphur, iron, magnesium & calcium are essential for plant growth. 6. Humus content: organic component of soil formed by the decomposition of plants and animals. Releases nutrients like nitrogen which can be taken up by plants and separates the soil particles allowing air spaces. Humus also improves water retention of soil.  Abiotic factors - Physical factors (CLIMATE) 1. Light and length of day The amount of light and length of daylight received affects plants and animals. Some examples include: ◦ Animal and plant behaviour: ◦ Diurnal (animals active in the day) ◦ Nocturnal (animals active at night) animals ◦ Plant growth: photoperiodism is the main stimulus that plants use to detect the time of year. Depending on the number of sunlight hours received, this can trigger flowering, germination, leaf drop and other processes in the plant. Plants co-ordinate their activity with seasons. ◦ Tropism: Phototropism is a plant growth response due to uneven (one-sided) light stimulus. Plants grow towards the light to receive brighter light for more efficient photosynthesis. Physical factors (CLIMATE) 2. Temperature Temperature is closely related to amount of sunlight. Temperature affects the distribution of plants and animals. Animals adapt to temperature changes in various ways. Different temperature regulating mechanisms of animals: ◦ Endothermic animals ◦ Ectothermic animals Animals have different mechanisms for surviving extreme temperatures: Migration – movement from one area to another, caused by seasonal changes. E.g. swallows. Hibernation – reduced winter activity and winter ‘sleep’. Aestivation – summer inactivity and summer ‘sleep’. Dormancy – some plant species survive cold seasons by becoming dormant. E.g. Deciduous plants lose their leaves in winter and slow down metabolic processes in the plant in order to withstand the cold temperatures and drier conditions in winter. COLD and WARM BLOODED ECTOTHERMIC ENDOTHERMIC COLD blooded WARM blooded Cannot regulate their body temperature Brain regulates their body temperature and become inactive in extreme to maintain a constant body temperatures as their temperature temperature varies with the environment ◦ Heat is produced during cellular ◦ Animals often lie in the sun to respiration increase their body temperature ◦ Sweat produced by sweat glands http://image.desk7.net/Animal%20Wallpapers/7530_1280x800.jpg evaporates to cool the body ◦ Fat for insulation Aestivation vs Hibernation AESTIVATION HIBERNATION DORMANCY IN INSECTS, AMPHIBIANS DORMANCY IN ENDOTHERMIC AND FISH TO WITHSTAND VERY HIGH ANIMALS TEMPERATURES OR DRY PERIODS INACTIVITY, DEEP SLEEP, SLOW METABOLISM TO WITHSTAND LOW FOOD SUPPLY IN WINTER IN VERY COLD CLIMATES Abiotic factors - Physical factors (CLIMATE) 3. Water Water availability affects the amount, frequency & distribution of plants and animals. Water is constantly cycled between oceans, atmosphere and land. ◦ Humidity = amount of water vapour in the air. In dry areas this is a source of water for plants and animals. High humidity slows down water loss through transpiration. ◦ Plants are classified according to the amount of water they need to grow. ◦ Xerophytes, Hydrophytes, Mesophytes  TEXTBOOK: Page 142 and page 140 (succulent karoo biome) for examples of adaptations of xerophytes and hydrophytes Availability of water XEROPHYTE MESOPHYTE HYDROPHYTE Have adaptations to Adapted to survive with Have adaptations to prevent water loss in a moderate water live in water. dry conditions. supply. Abiotic factors - Physical factors (CLIMATE) 4. Atmospheric gases The atmosphere is a source of Carbon dioxide for plants and oxygen needed by plants and animals for cellular respiration. Carbon dioxide, water vapour and methane and the main greenhouse gases which gas trap some of the sun’s radiation (heat) from escaping into space. This is called the greenhouse effect and is essential for life on earth. Due to human activity carbon dioxide levels have increased resulting in an ENHANCED greenhouse effect. This has resulted in an increase in average atmospheric temperatures which is causing GLOBAL WARMING. GLOBAL warming results in climate change. Abiotic factors - Physical factors (CLIMATE) 5. Wind – Moving air currents ◦ Wind influences rainfall, which in turn affects the types of plants and animals living in an ecosystem. ◦ Strong winds damage plants and increases water loss through transpiration. ◦ Wind can be an important factor in pollination and seed dispersal ◦ Some plants have adapted to survive the effects of wind by having needle-like leaves and thick waxy cuticles 6. Fire Some plants require fire as part of their life cycle. Some species of protea need fire in order to prepare seeds for germination.  Wind Seed dispersal Plant growth Wind pollination affected by wind Harsh conditions  Ecosystem Biotic factors Abiotic factors Producers Consumers Decomposers  BIOTIC FACTORS The biotic factors are the living components of an ecosystem – plants, animals, fungi and microorganisms. They interact with one another through feeding relationships as well as with the abiotic factors of the ecosystem. 3 Categories: 1. PRODUCERS 2. CONSUMERS 3. DECOMPOSERS BIOTIC FACTORS Biotic factors interact with each other in different ways. Symbiosis is the close association between two living organisms: Examples of these interactions are: mutualism – both organisms benefit; E.g. clown fish and anemone commensalism – one organism benefits, the other is not affected; E.g. barnacle on whale parasitism – one organism benefits (parasite) and the other is harmed (host); E.g. humans and tapeworms  PRODUCERS (AUTOTROPHS) Living organism that have the ability to make their own food. All plants and photosynthesizing phytoplankton are producers. Producers change the sun’s radiant energy into chemical energy (glucose) – they capture the sunlight and produce glucose through the process of photosynthesis. Most of this energy is used to carry out the plant’s life activities. The rest of the energy is passed on when plants are eaten to primary consumers and is the basis of all food chains. 𝐂𝐡𝐥𝐨𝐫𝐨𝐩𝐡𝐲𝐥𝐥 + 𝐂𝐚𝐫𝐛𝐨𝐧 𝐝𝐢𝐨𝐱𝐢𝐝𝐞 𝐂𝐎𝟐 + 𝐖𝐚𝐭𝐞𝐫 𝐇𝟐𝐎 Glucose (C6H12O6) + Oxygen (O2) 𝐑𝐚𝐝𝐢𝐚𝐧𝐭 𝐞𝐧𝐞𝐫𝐠𝐲  CONSUMERS (HETEROTROPHS) Organisms that CANNOT produce their own food and need to consume other organisms (plants or animals) to get energy to live. Primary consumer: Animals that eat plants (also called herbivores) Secondary consumer: Animals that feed on primary consumers (can be omnivores or carnivores) Tertiary consumer: Animals that feed on secondary consumers. Usually larger carnivores that feed on smaller animals. HERBIVORES eat plants OMNIVORES eat plants and meat CARNIVORES eat meat PREDATORS kill prey SCAVENGERS eat carrion (dead animals) INSECTAVORES eat insects DECOMPOSERS (SAPROPHYTES) Organisms that break down dead and decaying organic matter to obtain energy and return the nutrients to the soil. They are important in removing waste material. ◦ Use enzymes in the process. ◦ Play a vital role in the recycling of nutrients. ◦ Examples are bacteria and fungi FUNGI BACTERIA Videos Ecosystems are not always as simple as we may think. Watch this video for greater understanding: How Wolves Change Rivers (4:17 min) https://www.youtube.com/watch?v=oSBL7Gk_9QU ENERGY FLOW IN ECOSYSTEMS Energy flow in ecosystem All organisms need energy for life processes like movement, growth, reproduction etc. Green plants or other producers (phytoplankton in the sea) trap the sun’s energy and make glucose during photosynthesis. This energy is passed in food from one organism to the next. Energy flows in ONE direction through the ecosystems. Energy is transformed from one form to another – new energy cannot be created and energy cannot be destroyed. Each consumer depends on the trophic level below it for energy. Not all energy is transferred to the next level when organisms are eaten. Energy is lost as heat, used up in cellular respiration to maintain body processes and through urination and defecation (we do not draw this lost energy into the pyramid). This loss of energy limits the length of food chains to 4-5 levels. Decomposers feed on dead material from producers and consumers (we do not show these on the pyramid) Food CHAINS and Food WEBS Food Chain: Shows movement of energy through feeding (trophic) levels from one organism to the next in a sequence of food and energy transfers (ONE PATH ONLY) Food Web: Consists of all the interlinking food chains in an ecosystem. It shows a more accurate picture of feeding relationships in an ecosystem. (ALL possible PATHS of energy flow) Savanna food web  Top carnivore Typical marine food chain What is the producer? Food chains & Food webs RULES: Arrows = represents energy flow (arrow points into the mouth of the animal eating) Trophic level = each feeding level/ step in a food chain or food web. Primary Consumer = The first consumers in a food chain, usually herbivores, Secondary Consumer = Second consumers, feed on herbivores, can be omnivores or carnivores. Tertiary Consumer = Carnivores that feed on secondary consumers. Top Carnivore = The carnivore at the top of a food chain (not all food chains have this 5th trophic level). Food Chain drawing: Draw horizontally from left to right on the page. No need to drawings. Although sunlight is the source of energy needed for photosynthesis, the sun is NOT shown in the food chain. Food /Ecological pyramids Food webs and chains do not show how many organisms or how much energy is supported at each trophic level. This information can be shown in an ecological pyramid. There are 3 different types of ecological pyramids: 1. Pyramid of number: Shows the number of organisms at each level. It is like a bar graph on its side and the size of the bar represents the number of organisms in that trophic level. The actual number of organisms are used. 2. Pyramid of biomass: Shows the mass of living material at each level. Biomass is the total amount of living tissue at each level and shows the potential food at each level (you have to add up the mass of all the organisms). Biomass is expressed as mass of organic matter per unit area (usually kg/m2) 3. Pyramid of energy: Shows the amount of energy transferred from one trophic level to the next. Energy is measured in kilojoules (kj) per unit area (usually kj/m2)  Drawing pyramids ◦ You can draw pyramids as a triangle or separate bars like a bar graph on its side. Remember if you have an unusual pyramid of numbers (like the example of the fleas or the baobab tree in the textbook pg 152), to make the bar size proportional to the number. ◦ ALWAYS label the trophic levels, feeding relationships (producer, primary consumer etc) and organism name ◦ Check UNITS for pyramid of biomass/energy. Make sure all the units are the same! TERTIARY TERTIARY CONSUMER 4th trophic level CONSUMER SECONDARY SECONDARY 3rd trophic level CONSUMER CONSUMER PRIMARY PRIMARY CONSUMER 2nd trophic level CONSUMER PRODUCER 1st trophic level PRODUCER Ecological pyramids TOP CARNIVORE 5th trophic level TERTIARY CONSUMER 4th trophic level SECONDARY CONSUMER 3rd trophic level PRIMARY CONSUMER 2nd trophic level PRODUCER 1st trophic level Pyramid of number (see examples on pg 152) A single rabbit can support many fleas, so this The number of individuals decreases at each pyramid does not decrease at each level. level, so it has the appearance of a pyramid. Pyramids of number do not take into account the mass of organisms at each level. Pyramid of Biomass (kg/m2) (see examples on pg 153) The total mass of all the organisms at each trophic level is represented as Kg/Km2 in this example. Calculating BIOMASS You may be asked to calculate the BIOMASS of a trophic level. To do this you need to multiply the number of organisms by the mass of ONE organism. 2 Eagles 10 Sparrows E.g) An eagle has a mass of 3000g and a caterpillar has a mass of 4g. Calculate the biomass of the trophic levels in the food pyramid 100 Caterpillars below: Biomass of caterpillars: 100 x 4g = 400g or 0.4kg 1000 Leaves Biomass of eagles: 2 x 3000g = 6000g or 6kg Pyramid of energy 42 kJ The total energy transferred to the next trophic level is 418 kJ shown. For some terrestrial pyramids only about 10% is transferred. In this example kJ is shown 4184 kJ and not kJ per unit area.  Leaf = 3g Beetle = 5g Activity Lizard = 56g Owl = 90g Acacia tree = 250 000g Caterpillar = 4g Please complete Activity on textbook page 153 African hoopoe = 60g Changes from textbook: Flea = 0.05g NOTE the correction to the table in the textbook: Remember 1kg = 1000g Desert food chain Savannah food chain Producer 200 decaying leaves 1 acacia tree Herbivore Primary consumer 50 beetles 200 caterpillars Primary Secondary consumer 2 lizards 5 African hoopoes Secondary Tertiary consumer 1 pearl spotted owl 100 fleas Question 1.1 – Draw and label a pyramid of numbers for each food chain. Question 1.2 – Draw and label a pyramid of biomass each food chain. NUTRIENT CYCLES Nutrient cycles All organisms are made up of chemicals found in the food we eat. There is only a fixed amount of matter (atoms) on earth and these are cycled between organisms and spheres. Matter cannot be created or destroyed! Its amazing to think that the same atoms that were on earth during the times of the dinosaurs are still cycling around today. For example: ◦ The rocks of the lithosphere weather and break down to form soil. ◦ Minerals in the soil are absorbed by plants and used to form the plant tissues. ◦ These minerals are transferred to animals when the plants are eaten. ◦ Nutrients are later released back into the environment when animals defecate or when living things die. Nutrient cycles We will be discussing 4 nutrient cycles in this section: 1. The WATER cycle 2. The OXYGEN cycle 3. The CARBON cycle 4. The NITROGEN cycle Make sure you know the processes in each cycle and could explain the cycle in words or fill in missing pieces of the cycle.  1. Evaporation – heat from the sun causes evaporation from ocean and water bodies. 2. Transpiration – Water is lost by plants through stomata on their leaves. 3. Condensation – as the moist air rises it cools and condenses forming Water cycle clouds. 4. Transportation – movement of water through the atmosphere. 5. Precipitation – water is released from clouds in the form of rain, sleet, snow or hail. 6. Run off – water runs off the land surface and collects in rivers, lakes and the ocean. 7. Infiltration - water soaks into the subsurface soils (percolation is the movement of water through the soil itself) 8. Groundwater – some of the water that infiltrated into the soil becomes ground water.  Oxygen cycle The oxygen cycle is the movement of oxygen between the atmosphere, the biosphere (oceans, plants and animals) and the lithosphere. Oxygen is released into the atmosphere by: 1. Plants during PHOTOSYNTHESIS. 2. PHOTOLYSIS – UV radiation from the sun breaks down atmospheric water and nitrates to release oxygen. 3. WEATHERING of limestone releases oxygen. Oxygen is taken out of the atmosphere by: 1. RESPIRATION: Plants, terrestrial and aquatic animals use oxygen for cellular respiration. 2. DECOMPOSITION: Oxygen is required by decomposing organisms. 3. Dissolved in water & used by aquatic organisms to make calcium carbonate shells (CaCO3). 4. COMBUSTION: Oxygen is needed for combustion. 5. WEATHERING: Oxygen is used in the weathering of rocks (eg rusting) Oxygen cycle PHOTOSYNTHESIS RESPIRATION PHOTOLYSIS ATMOSPHERE Dissolved to form CaCO3 shells COMBUSTION BIOSPHERE LITHOSPHERE DECOMPOSITION WEATHERING  Carbon cycle The element carbon is found in the organic molecules carbohydrates, proteins, fats and nucleic acids (DNA and RNA) and makes up the ‘bodies’ or tissue of all living things. Carbon is found in the atmosphere as carbon dioxide (CO2). This Carbon is ‘trapped’ during photosynthesis to form sugars (carbohydrates) in the plant and then the carbon is transferred along the food chain. Carbon cycles between the atmosphere, biosphere and lithosphere. Processes that release carbon into the atmosphere: 1. CELLULAR RESPIRATION: by of animals and plants 2. COMBUSTION: Burning of fossil fuels 3. DECOMPOSITION: Decomposers feed on dead plants and animals and release carbon back to the environment Processes that take carbon out of the atmosphere: 1. PHOTOSYNTHESIS: by plants, algae and phytoplankton. Carbon is then passed along the food chain. Animals get their carbon by eating and digesting plants and other animals. 2. Dissolved carbon dioxide in water. Some is used by aquatic animals to make Calcium carbonate shells (CaCO3) 3. Formation of fossil fuels (FOSSILISATION) captures carbon in the soil as coal and oil Carbon cycle Balance of the OXYGEN and CARBON cycles The main processes that drive BOTH the oxygen and carbon cycles are photosynthesis and respiration. These cycles balance the amount of oxygen and carbon dioxide in the atmosphere. There is an INCREASE in human activities which increase carbon dioxide in the atmosphere (burning fossil fuels, industrialisation). There is a DECREASE in activities which take carbon out of the atmosphere like planting trees. Overall this has resulted in an increase in atmospheric carbon dioxide (from 0.03 – to almost 0.04%) The OXYGEN and CARBON cycle ensure atmospheric carbon (as CO2) & oxygen (O2) remain in balance  N2 in atmosphere Nitrogen cycle Converted to Nitrates absorbed by plant nitrates in soil & used to make proteins ALL living things need nitrogen as the element nitrogen is used to form proteins (proteins are the building blocks of Proteins tissues and form enzymes which control many life eaten processes) Nitrogen is found in the atmosphere at 78% (N2 gas) BUT Proteins plants and animals CANNOT use the nitrogen from the eaten atmosphere. Plants can absorb NITRATES (NO3) which contain nitrogen from the soil, but the atmospheric nitrogen (N2) must be Proteins converted to nitrates before it can be used. eaten Animals can only get nitrogen via the FOOD CHAIN by eating proteins from plants or eating the proteins of another consumer.  Nitrogen cycle (see diagram on page 157) Nitrogen cycles between the atmosphere, biosphere and lithosphere. So how is the atmospheric nitrogen converted into NITRATES which can be absorbed by plants? Processes that TAKE nitrogen from the atmosphere: 1. NITROGEN FIXING BACTERIA called Rhizobium that live in the root nodules of legume plants fix atmospheric nitrogen to make nitrates for plants to absorb. 2. NITROGEN FIXING BACTERIA that live freely in the soil called Clostridium and Azotobacter fix atmospheric nitrogen to make nitrates for plants to absorb. 3. ELECTRICAL FIXATION: Lightening converts atmospheric nitrogen into nitrogen oxides, these are dissolved in rain and fall to the ground where nitrates are added to the soil. 4. INDUSTRIAL FIXATION: Humans have developed processes to manufacture ammonia and nitrogen fertilizers. Fertilizers replace depleted nitrogen in the soil and boost crop growth. Processes that RETURN nitrogen to the atmosphere: 1. DENITRIFICATION by bacteria Pseudomonas and Thiobacillus (often in waterlogged soil) convert nitrate to atmospheric nitrogen (NO3→ N2). If farmers have spent money on fertilizers, this would be a waste!  Nitrogen fixing bacteria FREE–LIVING NITROGEN FIXING BATERIA (Azotobacter and NITROGEN FIXING BATERIA Clostridium) – Live in the soil (Rhizobium) - Live in legume root nodules – mutualistic relationship (both plant and bacteria benefit) Nitrogen cycle How is the nitrogen contained in the proteins of dead animals and plants recycled? 1. AMMONIFICATION Decomposing fungi and bacteria release ammonia from decaying plants and animals and the decomposition of faeces. 2. NITRIFICATION: Nitrifying bacteria convert ammonia to nitrates. This occurs in 2 stages: ◦ Nitrosomonas bacteria convert ammonia to nitrite ◦ Nitrobacter bacteria convert nitrite to nitrate These nitrates can then be absorbed by plants. Nitrogen is taken up and used to make proteins in plant tissues – this is called ASSIMILATION.  Nitrogen cycle N2 NITROGEN IN N2 ATMOSPHERE NITROGEN IN ATMOSPHERE ELECTRICAL FIXATION INDUSTRIAL FIXATION NITRATE NITRATE NITRATE NITRITE AMMONIA NITRATE DENITRIFICATION NITRIFICATION