Ecosystems

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Definitions & Energy Flow

An ecosystem is a system where organisms interact with each other and with their environment. There are two parts: the entire complex of organisms, or biome, living in harmony and the habitat in which the biome exists.

Biotic: Living factors (plants/animals) e.g. fires, deforestation
Abiotic: Non-living e.g. geology, climate, altitude, and soil type and pH levels.
Albedo: (Absobtion/reflection of light) Climate (P.P.T)
Biomes: Polar, Tundra, Boreal Forest, T. Woodland, T Grassland, Mediteranien, Desert, Rainforest

Sun is the driving force, drives water cycle. key to photosynthesis & provides energy. 
Inputs: Sun, animals, water. Process: Nutrients transferred from 1 store to another
Stores: Vegetation, plants, litter & soil. Output: Migration, evaportranspiration, throughflow 
Photosynthesis: plant uses energy which is then passed on as food to others. 
Loss of energy through respiration or general transfer of heat. Loss of energy at each trophic level, further up there is a decrease in biomass and loss of energy 
N.P.P = amount of energy available for G.P.P.
G.P.P = All energy produced in ecosystems in 1 year by producers (g/m2/yr-1 or kg/km2/yr-1)

Energy, Nitrogen, Carbon & Nutrient Cycle must be known.

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Plant Succession

Internal factors – autogenic factors. Initial colonisation, more plants prevent soil and wind erosion of the soil. More vegetation adds organic matter – this holds water and nutrients.
External factors - allogeneic factors (causes a change to the primary succession that has occurred naturally leading to secondary succession) Flooding & Human factors.
Primary & secondary succession, serial succession (sere’s)
Lithosere: Algae (autotroph) moss and lichen- birch (fast growing) replaced with ash/oak
Hydrosere: Phytoplankton feeds on themselves and decayed matter. Reeds- shrubs (produce shade) rushes, small trees occupy dry land away from water.

Factors affecting vegetation
Natural: Climate (Temp/Precipitation) Relief, Soil & Geology
Human: Deforestation, Fires, Liivestock Cultivation 

Succession Development 
Invasion, pioneer species die,
Colonisatiom: better conditions = more species as soil improves
Compeition for resources
Domination & Decline 

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Global Circulation

3 factors: Latitude, Altitude &Continentality 

GC
Hot air rises = areas of low pressure. Air rses and condenses to form clouds & creates rain
Cold air sinks creating high pressure - associated with calm weather

Polar Cell: Cold air sinks = high pressure, dry stable conditions
Ferrel Cell: Decending air giving cloudless stable conditions with cold air
Hadley Cell: Upper air cools as it moves north and sinks

ITCZ: convergence at trade winds: Uplift creating low pressure, high pressure is found at poles = divergence, convergence & uplift = low pressure (depressions)
 Horizontal movement by warm SW wind
Divergence & subsidence creates high pressure
Horizontal transfer by trade winds  

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Soil

Soil formation: Climate, organic matter, relief, parent material and time
Azonal: Soils determined by another local factor, rather than climate. E.g. local geology.
Intrazonal: Soils where climate is the dominant factor affecting their formation and development.
Zonal: Young, poorly developed soil. No one factor has dominated their formation.
Weathering: physical and chemical processes of rock breakdown & decay to provide soil with its mineral content.
Leaching: The downward movement of soluble nutrients in solution in soil water.
Humification: dead organic matter is broken down by bacteria, fungi and algae into a dark, amorphous mass called humus.
Capillary action: Upward movement of soil water caused by evaporation rates at the surface being higher than the precipitation rates.
Podsolization: Extreme form of leaching. Very acidic soil water is able to dissolve iron and aluminium, which is deposited later in distinct horizons and can form an iron pan.
Gleying: Soil becomes waterlogged and produces anaerobic conditions.

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Plagioclimax

Climatic Climax

Prisere succession adapts to take account of the interruptions that can affect succession,
Human interruptions = plagioclimax community that's managed maintained

Natura; interruptions can produce interupted succession & subclimax community
Subclimax: Topocliax controlled by relief e.g. volcanic eruption
Hydroclimax: controlled by drainage
Edaphic: controlled by soil chance e.g. salty winds affecting soil
Biotic controlled by animals e.g. grazing
Plagioclimax controlled by man e.g. burning/grazing  

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Ecologies along routeways & local scale

Railway: windborne seeds sucked in by trains, fences reduce human activity, route for animals
Roads: Verges provide habitat, nitrogen enhances some plant growth, mowing reduces abundance Canals: Variety of aquatic wildlife

Ecosystems on a local scale
Human: Increasing impervious surfaces, pollution, Building density alters the flow of air creating areas of turbulence.
Cities evolve as the outcome of myriad interactions between the individual choices and actions of human agents and biophysical agents. Human agents = household, business, developers and governments. Biophysical agents = climate & local geomorphology. Urban sprawl has effects on the area.
Urban niche: Within one urban site there are a number of different niches or microhabitats available for plants and animals to colonise.

Colonisation of waste land
Typically a Lithosere, 
Mosses and lichens develop on bare surface - Oxford ragwort - Tall herbs – Grassland - Scrub woodland
Colonisation depends on the following factors: Aspect, Moisture availability, Slope, Porosity, Surface roughness and Pollution levels.

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Rural - Urban Fringe

Ecological Niche: The place of each species within an ecosystem. This includes the space that it occupies and also the role it carries out within the community and its relationship with the other species living around it.
The fringe: Countryside immediately surrounding towns and cities. “The area of transition between well recognised urban land uses and the area devoted to agriculture.”
Greenbelt: an area of open land around a city, on which building is restricted. Biggest Green Belt in the UK is known as the Metropolitan Green Belt, around London

This principle was established in 1955. A certain area around a metropolis has certain controls against development in place.
Urban Blight: degradation of the rural-urban fringe.
Farmers face problems from fly-tipping & secondary succession may begin on untended fields.
Land banking is the practice of purchasing raw land with the intent to hold on to it until such a time as it is profitable to sell it on to others for more than was initially paid

Wildlife Corridoors: MILE END PARK
Small areas of isolated land, vital for conservation. Corridors can be through farmland.
MK new town built around a grid system of roads, along the road are rivers and green corridors separating the urban from the more rural areas.
2002 NEWCASTLE UPON TYNE, greenbelt taken out so development could occur, however the areas around those being developed had to be landscaped e.g. planting native species. Ouse burn forms green corridor that runs from the north right through to the old industrial heart of the city.  

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Ecological Conservation Areas

Increased pressure to protect the environment


Reasons: Altruistic (unselfish) motives, Encouraging wildlife back into cities, Making cheap use of an otherwise derelict area, encouraging businesses.


Work includes: planting trees and improving soil. Those involved: national trust, local authorities, users of the site and local inhabitants. Various view-points need to be considered and managed.


DULWICH UPPER WOOD originally Victorian Garden, ash & oak dominate, 40 bird species, herbs etc


TROOPERS HILL The site is in St George, east Bristol. The unusual geology of Troopers Hill is the reason for the site's ecological importance. The pennant sandstone on the hill results in acidic soils which support a heathland habitat found nowhere else in Bristol. Ling and bell heather cover the hill in purple flowers in late summer, with the attractive yellow flowers of broom seen earlier in the year.

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Issues on a global scale

Human activity: Something that people do or cause to happen.
Biodiversity: Range of plant and animal life in a particular habitat.
Sustainability: Sustainability is the ability of a process to be continued indefinitely without damaging and/or degrading the environment on which it depends.


As the world’s population continues to grow, increasing stress is being put on resources and environmental systems such as water, air and land. Population growth and economic development have resulted in spiralling demand for natural resources and a reduction in natural ecosystems and biodiversity.


   The UK government was one of the first to commit to protection of the environment, producing the UK Biodiversity Action Plan (BAP) in 1994. Aims and activities to cover a 20 year period: Protecting the best sites for wildlife – 10% of UK are designated SSSIs or ASSI’s Encouraging people to change their behaviour in relation to environmental issues. Ensuring the UK plays a proactive role in the development of multilateral environmental agreements and implementing them.

 

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