Ecosystems

Geography ecosystems

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Basics

Ecosystem: set of relationships between all organisms (biotic factors) and non-living (abiotic) factors in an area. Eg. Forest: trees, animals, water, soil.
Organisms depend on physical factors and each other to survive = relationships.
Ecosystems vary in size.

Biome is an area with distinctive climate and vegetation.
They contain different ecosystems and are large areas, often cover multiple countries.

Energy enters by photosynthesis. Suns energy used by plants to grow and reproduce. Energy stored in plants and passed up food chain when plant is eaten. Process continues throughout ecosystem.

Food webs and chains have trophic levels.
Producers (plants) make own food
Primary consumers (herbivores/omnivores) eat producers
Secondary consumers (carnivores/omnivores) eat consumers
Tertiary consumers (top carnivores and omnivores) eat consumers

Biomass is the total mass of living matter and decreases at each trophic level.

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Basics

As you go up trophic levels, energy decreases.
90% is lost at each level.
It is lost between sunlight and autotrophs because less than 50% of sunlight is used in photosynthesis.
Lost by consumers because only 10% is passed from autotrophs to herbivores.

Living organisms need lots if carbon, hydrogen, oxygen, nitrogen and sulphur. These elements are constantly recycled through ecosystems between plants, animals and the atmosphere.

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Succession

It is the process by which an ecosystem changes over time. Biotic conditions change as abiotic conditions change. Occurs in stages called seres. There are two types of succession;

Primary: on land that's newly formed or exposed. Abiotic conditions are harsh. First species to colonise (pioneer species) are the first sere. They can grow as are specialised to harsh conditions. Pioneer species change abiotic conditions as the they which forms soil. Condiments become less hostile so new organisms can grow.

Secondary: land that's been cleared of all pans but soil remains. Starts at a later sere so pioneer species are larger plants.

Different plants and animals that are better adapted for conditions move in and out-compete species to become dominant. Ecosystems become complex and species diversity increases.

Final sere - climax community - is when biotic and abiotic factors are in balance - climatic climax.

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Lithosere - bare rock to woodland

Pioneer species (lichens) colonise as they can live with little water.

They break down rock releasing minerals.

As rock gets more damp, mosses grow and weather the rock surface.

Mosses and lichens die, forming soil.

Soil deepens, larger plants move in. Shrubs, ferns and small trees grow.

They become dominant.

Soil is rich with nutrients to support the large dominant trees, reaching the climatic climax.

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Psammosere - bare sand to woodland

Pioneer species colonise bare sand.  Roots bind sand together.

Pioneer species die and decompose, forming soil.  Other species move in.

Soil is very alkaline as it contains shell fragments and salt from seawater.

Soil deepens, becoming less alkaline as more organic matter forms.  Small and large plants move in.

Soil deeps as larger plants die and decompose.  Shrubs and small trees out-comptete small plants.

Soil eventually supports large trees.

Pine, birch, ash and oak become dominant climax species..

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Hydrosere - fresh water to woodland

Pioneer species colonise water surface.

They die and sink to bottom, accumulating with other sediments.

Water gets shallower, aquatic plants move in.  They are rooted in lake bed, trapping more sediment.

Water becomes very shallow, swamp and marsh plants move in.  Marsh plants generate plant litter, building up and forming wet soil.

Larger plants and tree seedlings move in.  These decrease the soil moisture by transpiration, until soil is no longer water logged.

Soil deepens and becomes drier, providing suitable conditions for large climax tree species.

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Halosere - salt water to woodland

Pioneer species that can tolerate being submerged in saltwater colonise intertidal zone.

Roots trap mud bought in by tidal water.

Pioneer species die and decompose, forming soil.

Accumulation of decaying material and mud makes salt water move in.  

Roots trap and hold more sediment.

Ground level continues to rise and soil deepens as decomposing plants build up.

Shrubs and small trees move in and out-compete smaller plants.

Soil deepens and large climax trees become dominant.

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Succession

UK Climatic Climax is temperate deciduous woodland biome.

Canopy layer = trees 30ft tall (dominant).  Wider at crown and broad leaves.  Deciduous = Reduces water loss when roots struggle to take water from frozen soil and low light slows photosynthesis. Epiphytes grow on trees in all layers.

Shrub layer = smaller trees 5-20ft tall.

Herb layer = mosses and leaf litter carpet.  Decomposers break it down, nutrients return, make fertile.  Undergrowth dense.  Flowering plants frow in Spring as trees have not regrown leaves = spring window.

Human activity stops or deflects succession = plagioclimax.

Deforestation/ get wood or timber or fuel, make space for farming/ reduces soil quality (fewer plants grow) = hardy shrubs

Animal grazing/ meat/ small plants eaten = fast growing mosses

Clearance by fire/ clear for farming and control plants, improve soil/ plants destroyed (fastest recolonise) = fast growing plants

Afforestation/ timber/ cleared for new, only 1 species = managed areas, humans control plagioclimax

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Succession

North York Moors - Heather Moorland

Created by human activities:

Was oak forest, small amounts of heather

5000 yrs ago, hunting and gathering began to clear

4-2000 yrs ago, remaining woodland cleared = reduced soil quality

Few plants grew - heather hardy as less competition

1000 yrs ago, sheep grazing prevented regrowth, heather fast growing

Maintained by human activities:

National park maintanied for environmental and economic

Without active management would be temperate deciduous

Sheep grazing and controlled burning

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Tropical ecosystems - Human activity

Deforestation: cattle farming; commercial agriculture; commercial logging; small scale farming; mineral extraction; new settlements; dams.

Environmental: habitat loss; flooding; degrades soil; removes nutrients; reduces rate of evapotranspiration; global warming.

Social: more jobs; traditional livelihoods destroyed; natives forced to move out; risk from new diseases; conflict.

Economic: jobs; money from industry; destroys resources dependant on.

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Tropical ecosystems - Human activity

Overhunting: indigenous people hunt for own use; populations increase so demand is higher; hunting commercialised.

Climate change: drought; species die; kill 85% of rainforest if 4 degree increase.

Poaching: animals killed illegally for valuable skins and tusks.

Poaching and overexploration impact biodiversity, leading to decline and extinction.            In Malaysia, the tiger, tapir, elephant, leopard are endangered.                                          Loss of species could effect other species; Brazil nut, agouti burries, it grows.

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Tropical ecosystems - Sustainable management

Make human activity more sustainable: conserve for natives and renewable resources; sustainable:

Selective logging: old trees only; removed with horses or helipcopters.

Replanting: new trees planted; same type of tree; expensive so only in places like Aus.

Ecotourism: doesnt harm and benefits locals; small number of visitors at one time, conserve water and dispose water properly; income for locals; awareness of conservation (funding); don't have to log/farm for money anymore which is incentive to conserve; little money recieved by host country; jobs menial and low paid.

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Tropical ecosystems - Sustainable management

Legally protected:

Environmental law: ban unsustainable use of wood; control land use; hard to manage in large areas.

Protection: national parks and nature reserves; damaging activities monitored/prevented; educated about importance of conservation; difficult to enforce restrictions over large area.

International community can help:

Reducing demand for hardwood: certain tree; rarer; reduce demand; banning sale/ lots of tax if imported; ban logging of it.

Reducing debt: LEDC's; borrow money to cope with floods/development; paid back with interest; industrial activities pay back; debt can be cancelled; have to make sure money is spent on conservation.

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Urban Ecosystems

Organism's "niche" = role in ecosystem

Expansion of urban areas = new niches .E.G. plants - eaten by insects/birds; woodlice - eat dead plant material; birds - waste dumps - human waste

Small scale ecosystems

Urban gardens & Parks: large variety of plants = increases biodiversity; invertibrates feed off plants; birds eat invertibrates and plant seeds and nest in trees\shruvs; ponds = aquatic insects, fish, amphibians etc; mammals live in/visit

Sports fields: dominated by grass, daisies, dandilions; invertibrates eat plants; birds eat seeds/insects

Roads: plants on roadside, verges (carried by cars), exhausts boost; plants managed - mowing reduces biodiversity, planting increases biodiversitt, supports invertibrates; birds nest, hunt/scavenge along roadside; animals travel = wildlife corridor

Railways: plants (ox rag, clover) carried seeds by train; wetland plants (rushes), railway beds drain water away from tracks = mini wetlands; hardy shrubs (hawthorn, brambles) side of tracks, railway companies cut vegetation back these grow quickest; invertibrates = bird food; mammals = wildlife corridor

Roads and railways are routeways = man-made paths and tracks hosting ecosystems.

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Urban ecosystems

Rural/urban fringe = urban area meets rural

Variety of land uses = variety of ecosystems

  • Populations increase = new developments = destroy ecosystems .E.G. high demaand for water = grassland flooded to create resovoir
  • Rural ecosystems broken up by developments by surrounding woods, cutting it off or separate populations of organisims
  • Increased populations = air and water pollution.  Water pollution from waste reduces biodiversity as it affects birds feeding as well
  • Recreational activities = disturb wildlife, increase soil erosion - dropping litter, destroying wildlife (picking flowers), vandalism. fires

Some developments create new ecosystems - wetland on derelict industrial sites

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Urban ecosystems

Deliberately introduced species:

  • farming (wheat)
  • game (rainbow trout, Canadian geese)
  • forestry (douglas fur)
  • biological control (japanese knotweed psyllid to control japanese knotweed)
  • novelty (grey squirrels)

Unplanned

  • spreading from gardens (oxford ragwort)
  • escaped animals (ring-necked parakeets)
  • imported (harlequin ladybird on flowers)

Harmful species are invasive.  Negative impacts:

  • non-native can out-compete native (grey squirrels and red squirrels)
  • native plants damaged (squirrels strip bark)
  • farm ecosystem disrupted
  • non-native eat native
  • tranfer diseases (squirrel pox)

Buddleia provides food for butterflies and bees so it is good

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Urban Ecosystems

Wasteland in urban areas is quickly colonised

It is abandoned land from deindustrialisation and is in poor condition

Base for ecosystems through succession

The wasteland characteristics affect the sere that develops

EG. drainage, acid/alkali conditions, pollution levels

Roadside verges and railway sidings are colonised in the same way.  Succession starts at a later stage as soil is already there

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Urban Ecosystems

Ecological conservation areas - areas of land granted a protected status to ensure ecosystems are preserved and enhanced

Mersey forest (woodlands and green spaces):

  • managed by public, private and voluntary organisations
  • range of habitats so huge number of species
  • Aims: to provide green space for locals, protect ecosystems and preserve biodiversity, and bring money through sustainable forestry and tourism

Urban areas

  • Green Streets set up community groups to plant and care for trees = more attractive and bird habitats
  • 3000 hectares new woodland and 8 million trees

It has been successful and they want to improve landscape on derelict sites

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Urban Ecosystems

Environmental benefits

  • creates habitats; increases biodiversity
  • 800 hectares non woodland, 90km hedgerows
  • reduction in pollution
  • reduces soil erosion
  • wildlife corridors

Social

  • 60% of 1.5million locals use it = improves health
  • educational activities

Economic

  • improved image = boosted economy, house prices increased
  • sustainable forestry = 150 new jobs since 1994
  • increased tourism, leisure and recreation = jobs and money to area
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Global Ecosystem Issues

Bodiversity - variety of organisms in an area.  Not evenly distributed - increases from poles towards equator: 50% world's animals live in tropical rainforests (warmer, moist, stable).  Plants grow better so food chain works.

Human activities reduce biodiversity

  • deforestation (habitat loss)
  • draining wetlands (habitat loss)
  • pollution (damage habitats and harm species)
  • global warming (changes abundance and distribution)
  • rising sea levels (habitat loss)
  • overexploitation (reduces population)

Ecosystems need high level biodiversity.  A range of species maintains ecosystem (1 dies - all effected).  Helps ecosystem adapt to changing physical conditions (high bio, more survival).  Creates feedback loops.

Fragile environment = easily damaged (by human acts and natural disasters) and can't adapt.  Very difficult to repair damage.

EG. coral reefs: water temp change and quality - coral can go bleached

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Global Ecosystem Issues

Fragile ecosystems are rich in natural resources but cause conflict over exploitation and conservation

Amazon rainforest: resources to feed subsistence farmers and natives; renewable resources; important for exploiting for developing economy

Difficult to get balance between conservation and exploitation because:

  • cross international borders (Amazon in 9 countries) so difficult to agree
  • LEDCs so lack of money/expertise to manage/conserve properly
  • countries depend on natural resources from fragile ecosystems
  • exploit as no alternative/don't understand need to conserve
  • need to introduce non-native species as food but out-compete native

People trying to restore fragile environments by replanting, coral nurseries, restoration projects - some can't be restored as they're so bad

Indian Ocean tsunami damaged coral reefs and mangrove swamps so they are replanting mangrove

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Global Ecosystems - Serengeti

Savanna, gassland. 30k km2 Tanzania & SW Kenya. Grazing animals and predators. Grasses, shrubs and acacia trees.

Hunting and poaching: for sport and food and to sell.  1970s-1980s black rhino fell to 2 animals.  Legislation 1989 banned trade of ivory.  Still illegal hunting for meat.

Increasing population: land use conflicts, settlements, crops, grazing.  Colonised and farmed = habitats lost.  Increased hunting.

Fire: controlled fires sustain, prevents woodland growth, burns dead grass, fertilises, new shoots = food.  Uncontrolled fires damage trees and roots.

Invasive species: cause damage.  Mexican poppy out competes native plants and crops, unsuitable for farming.  Animal disease 1994 domestic dogs virus killed 1/3 Serengeti lions.

Serengeti national park.  15000km2 in Tanzania.  1951.  To preserve wildlife and reduce environmental damage.  Managed by TANAPA

  • monitoring ecosystem; priority species protection (anti poaching patrols - black rhino)
  • disease monitoring and vaccination programmes
  • controlled burning; conservation education projects
  • 4 wildlife management areas - sustainabe use of resources; tourism
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Global Ecosystems - Serengeti

How it helped:

  • WMA's - food source, income, legally traded products
  • poaching declined - species increasing
  • tourism income - to national park, boosts economy, ranger precense defers poaching
  • disease monitoring - prevention

Still threats

  • human population growing = conflict
  • locals reluctant to joing WMA
  • outside WMA's, poaching still big

Tourism

  • construction of infrastucture = environmental impact
  • vehicles and aeroplanes = pollution
  • waste disposal = problems
  • disturb and distress animals
  • increase demand for water = water shortages

Clear code of conduct and limits try to reduce these impacts

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Global Ecosystems - Amazon

Deforestation - 13% forest cleaered for mining, logging, subsistence farming, cattle ranching (60%+ 2000-2005).  Causes forest fires, soil erosion, decreased biodiversity

Overhunting and overfishing - traditional lifestyle, population growth means increase, hunting for bushmeat- unsustainable as primates reproduce slowly and many endangered

Central Amazon Conservation Complex CACC (2003) by 4 Brazilian reserves.  Protects biodiveristy, maintains ecosystems, use forest in sustainable way.  49000km2, variety habitats, managed by IBAMA, local gov, research institutes, mining & tourism workers.  Schemes to balance conservation and sustainable development:

  • zones: total protection, buffer zones, sustainable use, rehab, experimental use.  Activity in these strictly controlled: total protection - access heavily restricted.  Sustainable use - quotas to limit logging, hunting, fishing,
  • 2 sustainable development reserves (SDRs) where hunting and logging only for subsistence - limit to number caught
  • economic alternatives programmes - sustainable schemes by locals who receive direct income for work - fisheries managment, ecotourism, sustainable farming, handicrafts
  • education projects
  • increase community involvement with conservation
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Global Ecosystems - Amazon

Sustainable development initiatives successful.

  • CACC protected surrounding area from major development (no dams, mines, pipelines, commercial logging & none planned)
  • SDRs improved biodiversity - black caiman increased by 100%
  • economic alternatives programmes promote sustainable activities and reduced poverty: increased income 50-99%, farmers and craftsmen join Producer's Association
  • ecotourism = source of income and conservation
  • local education and health improvement successful

Protecting large area is difficult.

  • reserves large and understaffed
  • restricting access to total protection is difficult due to area size and lack of staff
  • population growth = stress on ecosystem = deforestation on edges of CACC
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