Ecosystems Flashcards
Structure of an ecosystem
- Autotrophs/primary producer
- Primary consumer - herbivores
- Secondary consumer - carnivore
- Top predators/tertiary consumer - omnivores
Energy pyramid
Decreases each level as 90% lost in living processes.
Only 10% available for next level, hence why number of living organisms decreases with each trophic level.
Where energy goes
Most to decomposers
- receive most plant energy and use over half for life maintenance
- rest locked in soils or taken in by organisms that feed on decomposers
- all energy captured by plants is transformed and lost as heat (not recycled)
Nutrient cycling
Nutrients stored in three components
- biomass
- soil
- litter
Illustrated in gersmehl diagrams
Tropical rainforest nutrient cycle
Large biomass - rapid plant growth
Medium/small soil - fast reuptake for growth
Small litter - broken down quickly (hot+humid)
Tropical grasslands nutrient cycle
Large litter - lacks maoisture = slow decomposition
Small biomass - grasses die in dry season (limited accum)
Small soil - plant growth seasonal
Temperate deciduous woodland nutrient cycle
Large biomass - plant growth (not as fast as rainforest)
Medium soil - nutrients from litter in here by decomposers
Medium litter - slow decomposition in lower temps
Nitrogen Cycle
for construction of plant and animal matter
- present in atmosphere
- fixed in soil by some plants (taken up by roots of other plants, passes through ecosystem)
operates:
- over land/sea/in atmosphere
includes: inputs (volcanic eruptions), outputs (deep sea sediments)
Carbon Cycle
stored in: - coal/oil/gas/peat temporary stores: -plants/animals/soil burning fossil fuels + deforestation + destroy peat deposits = release C in atmosphere = greenhouse gases = global warming + climate change
food chains
link/show energy flow
trophic pyramids from simple FCs
most FCs interconnected = food webs
succession
change in a plant community through time
climatic climax
plant species living in perfect balance/equilibrium with the surrounding environmental conditions
primary succession
occurs on surfaces that have had no previous vegetation by the gradual colonisation of a lifeless abiotic surface.
e.g. lava flows, bare rock
xeroseres
form on dry land
lithoseres: bare rock
psammoseres: sand
hydroseres and haloseres
hydrosere: form in fresh water
halosere: form in salt water
two types of primary succession
xeroseres
hydroseres
secondary succession
follows destruction/modification of an existing plant community
- occur naturally (landslide)
- occur by human activity (deforestation)
sere
entire sequence of stages of a succession
seral stages
plagioclimax
when human influences prevent the ecosystem from developing further
stages (seres) of development of a succession
invasion pioneers compete colonisation domination decline (polyclimax theory)
Invasion sere of development of a succession
plants - bare ground - group/colony - 2 or more species survive (hardy plants/pioneer species)
e.g. long rooted, salt tolerant marram grass on sand dunes
Pioneers compete stage of development of a succession
as die, add organic matter - develop soil - affect microclimate
roots help weather surface - aid soil formation
Colonisation stage of development of a succession
immature soil - change balance of species - each stage better conditions for plant growth - inc no. species
Domination stage of development of a succession
- more species - added organic matter = imp water retention and soil qualities = taller and more agg plants - more demanding of space, water, nutrients
- taller plants (dominant plants) - shelter - other plants establish
- over time - stability = climax (dominants exclude rivals less suited)
Decline stage of development of a succession
once major dominants in place = saturation
climatic climax community (CCC)
vegetation stable balance with climate and soils in area
Example of a lithosere
Surtsey, Iceland (erupted 1963)
bacteria - lichens, mosses - herbs, grasses - ferns, bracken - large shrubs/small trees - large trees (birch, pine) - oak, ash trees
Lithosere develops in UK
Seral Stages
- Colonisation
- Establishment
- Competition
- Stabilisation
Seral Climax
Temperate Deciduous Woodland Location
UK: climatic climax - 8000yrs ago
Mid latitudes
Decent moisture
Oak + ash original dominants
Temperate Deciduous Woodland Climate
- winter 2-7C / summer 13-17C
- 500-2000mm precipitation/yr (most in winter)
- on-shore W winds: mod temp + bring moisture
- low pressure weather systems
Temperate Deciduous Woodland vegetation
- broadleaved deciduous trees (oak, ash) shed leaves in autumn
- soil temps fall, roots absorb less water: growth retarded
- heat loss dec transpiration + dec demand for water in cooler months
Temperate Deciduous Woodland soil
- 1.5m deep: brownearth, fertile zone, well drained
- autumn: leaf litter accu. - quickly decomposed by organisms, supports lots of fauna
- well mixed by earthworms (no clear layers)
- nutrient recycling: annual leaf fall
- aut+winter: some leaching - acidic soil = good for plant growth
Forest Structure
- Ground layer (mosses, seedlings, fallen decaying wood)
- Field layer (woodland (+grasses) + flowers, bluebell)
- Shrub layer (small trees, hazel, rowan)
- Tall tree canopy (oak 30-40m, ash, beech)
Some woods so dense + tall =light prevented reaching lower layers = fewer species
Effects of human activity on succession
4000BC: forests cleared
500BC: 1/2 woodland cleared-rest for timber+fuelwood
1086: everyone wood dependent
13th Cent: wood plantations (protected from grazing)
18th Cent: woodland clearance = parkland
19th Cent: industrial rev = wood major source fuel+building materials
1914: War = afforestation programme
1945: 1/3 remain woods cleared= agri + urbanisation
1975: little lost = conservation groups+tax incentive to replant
Effects of human activity on succession
Example: Caledonian Forest
Remnants of post-glaciation forest still exist:
- inaccessibility
- protection from deforestation, grazing, burning
Now protected by conservation legislation:
- mix of scots pine, birch, oak
- shrub layer: rowans
- field layer: heather
Plagioclimax
Interfering factors that stop a community from reaching climatic climax.
deforestation, agri = plagioclimax comm = dec biodiversity
UK:
- wood cleared for agri + settlement, industrial = pollution = acid rain = impacts veg + aquatic ecosystems in NW Europe
Plagioclimax UK: Heather Moorland
- deforestation, soil deteriorated = hardy plants dominate
- sheep grazing prevents regen = destroy saplings
- controlled: managed burning = eliminate less fire resistant = heather dominates = conserve nutrients
(- if burning not continued: trees grow + heather degenerates)
Heather Cycle
- Pioneer Phase: 0-6 yrs, small shoots
- Building Phase: 6-15yrs, heather dominate
- Mature Phase: 12-28yrs, colonisation other plants
- Degenerate Phase: 20-30yrs, gaps enlarged, mosses + lichens
(after stages 2,3,4 burning to take back to pioneer phase)
(after 20-30 yrs natural succession= young birch = succession to woodland)
Tropical Savanna Grasslands: African Savanna
Location
5-15deg N+S Equator
Occupy 65% Africa
Savanna
areas of tropical; grasslands that can occur with/without trees + shrub
Tropical Savanna Grasslands: African Savanna
Climate
- high temps throughout yr (>20C highs:36C, 11-13hrs daylight)
- seasonal climate - sun migration
- precipitation 600-2000mm (near rainforests enough rain for tree growth/ near deserts grasses sparse, drought)
Tropical Savanna Grasslands: African Savanna
Seasons
- Dry/cool season: low sun period but still high temps = high evapotranspiration = soil moisture deficit.
- Wet season: excess rain, less reliable seasonal pattern, convectional intense electric storms = bush fires (key sust. biodiversity) = clear dead+ageing veg. + leave ash = adds nutrients to soil = rapid plant regen.
Inter-tropical convergence zone
forms intense solar heating:
- warm air holds more water vapour = air at surface heated - holds moisture from surface/plants
- air rises + cools = holds less water vapour = rain
air moving in convection currents = convectional rain
Inter-tropical convergence zone
Location info
- 30deg N+S equator = hot, high pressure (air lost moisture = heated faster back into ITCZ by surface winds
- sun migrates = so does ITCZ
e. g. Kano, Nigeria: one season: sun overhead = ITCZ dominates + bring intense rain? rest of yr = tropical high pressure + dry air mass - closer to equator = long wet season + higher rainfall totals = tropical climate
- towards poles = shorter wet, less rain = hot desert climate
Tropical Savanna Grasslands: African Savanna
Soil
- leached, ferralitic
- wet season: excess precip. / potential evapotransipiration = leaching of soluble minerals, deposited in deep soil
- dry season: evaoptrans. < precip. = silica+iron carried up soil close to surface
- local variations of soil = diff types of veg. = asedaphic soil e.g. thick, clay based = woodland / leached, sandy = grassland
- savannas on tectonically stable geological shields = weathered + lacking nutrients
Tropical Savanna Grasslands: African Savanna
Vegetation Adaptations
All grasses, trees, scrub = xerophytic(drought)/pyrophytic (fire)
adaptations to drought:
- deep roots to reach water table
-partial/total loss of leaves
- sunken stomata to reduce water loss
adaptations to fire:
- thick fire resistant bark
- most biomass below ground - aid rapid regen after fire
- growth tissue at base of shoot = burning encourages growth
Tropical Savanna Grasslands: African Savanna
Vegetation Adaptations
warm, wet summers: large net primary productivity = much photosynthesis
e.g. Africa - acacia, palm, baobab trees+elephant grasses (grow >5m / trees- 12m)
Biomass = less than TRF = shorter growing season
Litter: small due to fire
Soil: large - nutrients won’t burn here
: Tropical Savanna Grasslands: African Savanna
Animal Adaptations
- largest variety of herbivores - giraffes, zebras, gazelles
- large herds (protection from top predators -lions, cheetahs, hyenas)
- short food chains (usually stop 2nd consumer)
herbivores in E Africa: - highly specialised eating patterns = browsers (nibble twigs + leaves = white rhino), grazers (eat grass+herbs - black rhino)
- selective grazing: categorisation of height they eat + eat at diff times day/night/yr = minimises interspecies competition
dry season: - compete for water intense: small animals hibernate/modify diet to dormant seeds or birds/large animals migrate to search for water/food (herds) = support top predators
Threats to savanna posed by human activity
- overgrazing (50m ppl Asia+Africa raise livestock = soil erosion, dec soil fertility, desertification 46,000km^2 African savanna = desert/yr)
- salinisation (inc salt content in soils due to: irrigation as pumps too much water it evaporates quickly and leaves salt + can take away nutrients so soil infertile), nomadism -> settled patterns farming
- hunting (fires attract game animals + valuble body parts)
- burning - releases CO2
- deforestation - Brazil, Cerrado: wood fuel, cash crops
- inc pop growth + urbanisation: Kenya pop 48m (x4 since 1970 / traditional wildlife restricted/ scattered pockets of isolated natural veg
(- international tourism: parklands threatened / game reserves safe access = Masai Mara, Kenya)
Value of maintaining biodiversity
locals use for: medicine, food, building materials, clothes
savanna provides: med, timber, ornaments
Indigenous ppl rely on biodiversity
pressure: agri, pop growth, urbanisation, industrial growth (all dec biodiversity)
Ways to develop savanna sustainably
- nature based tourism
- beauty + wildlife attract large no.s = income raised = preserve health + diversiy of ecosystem (protect animal species)
- nature preserves
e.g. Serengeti + Ngorongoro Conservation Area, Tanzania, Kenya (world heritage sites)
Serengeti: one of most famous parks, had most grazing animals + predators in Africa, saved plant and animals that wouldn’t exist today without preserves
Urbanisation
Growth in proportion of a country’s population that lives in towns/cities
Derelict
Land in poor condition from disguise/neglect
Urban niche
Position of a species in an ecosystem. Describing range of conditions necessary for persistence of species + ecological role in system.
Micro habitat
A small scale area within a town/city, providing a specialised environment which certain species of plant can develop and thrive
Deinstitutionalisation
The decline of industrial activity (due to mechanisation)
Oxford Ragwort
Wind bourne seeds
Yellow flower
Herbaceous plant
Japanese Knotweed
Large herbaceous plant used in urban areas, migrated to unwanted places = invasive
London Plane Tree
Large resilient trees that can cope woth urban environment
Rural/urban fringe
Transition area immediately surrounding towns and cities
Greenbelt land
Land protected by las from development (surrounding cities)
Desertification of farmland
Pressure from tourists = paint balling, pressure from walkers, dog walkers, cyclists, pollution damage land
Wildlife/green corridors
Ways of linking wildlife habitat - allow species to move between isolated areas, replenish isolated pops. Provide shelter, protection, food and breeding sites
Ecological conservation areas
Succession influenced deliberately by humans
Brownfield sites
Derelict areas in an urban setting
Conservation groups
Create environments where traditional species can redevelop.
Secondary Plant Succession Occurs in:
- industrial sites
- transport routes
- residential gardens + allotments
- parks + green spaces
- landfill sites
- water bodies
- urban woodland
Urban Climate : Rural Climate
Urban:
- dirtier: 10-25x more pollution
- hotter: mean temp 0.5-1.5C higher
- less humid: winter: 2% less / summer: 8-10% less
- more rain: 5-10% more
- more cloud: 5-10% more
Deindustrialisation on urban areas
wasteland: old factory sites, docklands, railway sidings
= transformation of land cover: good for rapid colonising species, more tolerant to people
Ecological niches on deindustrialised wasteland
- bare tarmac
- brick walls
- piles of rubble
- wall tops
- water pools + damp patches
- sheltered corners
- empty buildings
Succession on urban wasteland
- human disturbance creates new habitats = recolonize = new ecosystem
- secondary succession un disturbed urban site
Succession on Urban Wasteland
- Pioneer Community - Oxford Ragwort
- Changes in habitat
- Vascular plants colonise - Japanese Knotweed
- Shrubs and trees arrive
- Climax community
Example: UK
Where succession managed and encouraged by people
London Wildlife Trust: The Ripple
- set: industrial landscape of Barking Reach (once dumping area for pulverised ash)
- 10 hectare
- orchids + southern marsh = major attraction (woodland floor May-June)
- silver birches next to meadow = native wildflowers, grasses attract bees + butterflies
Routeway Ecologies
- Railway lines - allow movement of animals, windbourne seeds sucked along, lack human disturbance
- Road traffic - same distribution as rail, nitrogen fumes = boost growth wildflowers, embankments well managed
- Motorway verges
- soil: excavated from road and put on sides
- geology: hard (granite) = steep sides, slow soil formation / soft (clay): high weather rates, low gradient, root plants hold structures = stable
- construction: prepared good seed bed, grass/flower seed mix, DEFRA choose suitable sites for planting, most common trees: oak, ash, silver birch
- after seeding: new species, rate + extent invasion depends on: nature terrain, no. dormant seeds in top soil, management methods
- c’s major roads: 60 sites special scientific interests + rare plants e.g. green-winged orchids + white admiral butterflies, mice, red kites M40
Changes in Rural/urban fringe:
Land Use
- agri land
- space for new housing, businesses + industrial parks
- transport including roads + airports
- recreation: parks, sports stadia, golf courses
- waste disposal: landfill sites + sewage works
Changes in Rural/urban fringe:
Rural Ecosystems
- intensive agri
- hedgerows
- small woods
- nature reserves
- market gardening for nearby urban markets
- wasteland
Changes in Rural/urban fringe:
Urban Ecosystems
- new gardens
- established gardens
- parks + playing fields
- roadside + railway verges
- allotments
Changes in Rural/urban fringe:
Greenbelts
hard to obtain planning permission
Changes in Rural/urban fringe:
Negative Influences on R/U Fringe
Agri land risk of urban blight due to:
- vandalism
- pressure of tourists + leisure (diversification from trad farming to paintballing)
- pressure of (dog) walkers, off road cyclists
- pollution: traffic, housing, litter
Changes in Rural/urban fringe:
Positive Influences on R/U Fringe
- sustainable development
- listed buildings
- scheduled ancient monuments
- special assets = distinctive landscape (river valleys + areas rich in biodiversity)
- reservoirs, canals: all of value to comm’s + contribute to quality of life
- recycling of derelict land - plant woodland to improve local landscape
Changes in Rural/urban fringe:
Opportunities
- recreation demand >1/2 countryside visits <5 miles home
- 267 country parks + 73m visits/yr = improved to contribute wider R/U fringe amenity + sust needs
Changes in Rural/urban fringe:
Threats
- agri problems + additional (crime + fly-tipping)
- urban deprivation: opportunity = involve comm’s in urban edge to manage area offers comm renewal, social inclusion + health problems
Changes in Rural/urban fringe:
Green Corridors
- link wildlife: allow species move between isolated areas = replenish isolated pop’s
- corridor provides shelter, protection, breeding sites, food
e. g. Milton Keynes
Changes in Rural/urban fringe:
Gardens
- paved areas = ecosystems destroyed, inc runoff, inc flood risk
- lawns = monocultures, well-managed, no weeds, chemicals limit biodiversity (worms)
- large exotic plants introduced = escape into surrounding areas (oxford ragwort)
- ‘wildlife gardens’ planting patterns encourage species (butterflies, insects, birds, small mammals)
e. g. ponds managed attract species (frogs, amphibians), areas hedgehogs hibernate, birds to nest + feed, limit chemical use encourage widest variety
Ecological Conservation Areas
Why develop on abandoned urban land?
- provide amenity space
- dec maintenance costs in area
- improve visually: hide eyesores, encourage businesses to move in
- encourage wildlife back in
- schools: study areas
- act as noise + pollution inhibitors
Ecological Conservation Areas
Management Techniques
- reduction in acidity in old, industrial, coal-spilled sites: add lime
- deliberate clearing areas = variety habitats for smaller, light-demanding species
- mow once/year after meadow wildflowers flowered
Ecological Conservation Areas
Groups and Organisations
Local Authorities:
- planning needs
- balance desire to make use derelict land against potential cost taxpayers
Conservation Groups:
- create environments traditional species re-establish
Local People:
- safe environ for leisure pursuits
- establish sports field through Fields in Trust
Urban Wildlife Groups:
- areas provide cover for wildlife
Oxford Ragwort
- Unplanned
- Introduced: 1700
- Origin: Sicily on volcanic ash
- Place first intro: Duchess of Beaufort’s garden
- Migration/spread: Oxford, railway lines clinker beds, other parts of country (accelerated by train movement and limestone ballast which provides a similar medium to lava-soils of native home Sicily)
- Benefits:
- Problems: all of plant contains alkaloid poison which causes irreversible liver damage + with a bitter taste most animals avoid eating it, if grazing becomes scarce = no choice to eat it (esp if cut and left on ground as becomes more palatable)
Japanese Knotweed
- Unplanned
- Introduced: 19th Century
- Origin: Japan
- Place first intro: Urban areas
- Migration/spread: easily via rhizomes and cut stems/crowns
- Benefits: can prevent/treat cognitive disorders, impr heart health, lower risk cancer, lower bp, maintain proper insulin levels
- Problems: damage to paving/tarmac, damage archaeological sites, reduction biodiversity by out-shading native vegetation, restriction access riverbanks, inc flood risk by damage flood defence structures and through dead stems blocking streams, reduction land values, unsightly appearance
London Plane Tree
- Planned
- Introduced: 1550 them 18/19th Century
- Origin: Spain
- Place first intro: London
- Migration/spread: urban areas as resilient, cope well with hot, dry, wet, cold and poor compact soil
- Benefits: provide green corridors, used to line roads and avenues to create a more pleasant living environ for city dwellers
- Problems: deciduous leave need picking up in autumn or slip hazard caused, some killed by fungus from USA, some evidence that airborne trachiomes from the backs of leaves (spiky hairs) may be causing respiratory symptoms on some people (like hay fever)
Ecosystem issues on a global scale
The relationship between human activity, biodiversity and sustainability.
Inc population = stress on resources and environmental systems
Population growth and economic development = inc demand for natural resources and reduction in biodiversity.
Management of fragile ecosystems
Conservation vs exploitation
Fragile ecosystem
One which is easily disturbed and lacks resilience to change in conditions.
Evidence and impact of loss of diversity
Red list: est that up to 1/3 plant species are threatened globally and that climate change could result in the extinction of 1 million of the worlds species by 2050.
WWF: global footprint has exceeded the earths biocapacity by 25% in 2003.
Evidence and impact of deforestation
Worlds rainforests could completely disappear in a hundred years at the current rate.
Deforestation for:
- money
- provide for families
- agriculture (small farmers ‘slash and burn’ trees)
Evidence and impact of climate change
- increased concentration of atmospheric gases = inc surface warming (if continued=modify earths climate and biome distributions, inc sea levels and inc occurrence of extreme weather events)
- evidence: mass-melting of permafrost layers, inc storms and floods, inc coral bleaching, rapid retreat glaciers, warming oceanic waters, greenhouse emission data
- extinctions of plants inevitable as do not adapt as quick as rate of accelerating global warming
- animals more adaptable but if major sources pf habitation and food decline, they will die out in large numbers
Evidence pollution
Inevitable result of industrialised development. Example: burn fossil fuels = acid rain = affects land+water based environments
- destroys waxy coating on leaves of confer leafs
- dissolve and leaching of nutrients in upper soil
- decline in many species of lichen
- higher levels of acidity in streams, rivers, lakes
Reduces biodiversity.
Moving towards sustainability
UN and WWF
Kyoto conference: more industrialised c’s agreeing to cut carbon emissions by 30% by 2010.
Uk Biodiversity Action Plan
BAP
1994
20 year period
- 10% UK designated Site/Area of Special Scientific Interest (S/A SSI)
- list 1149 priority species, 65 habitats focus on conservation over next decade
- encourage people to change their behaviour in relation to environmental issues
International agreements of ecosystem issues on a global scale
COP21
Meeting of parties of kyoto protocol: agreement legally binding if joined by 55 countries which together represent 55% global greenhouse emissions
Involves:
- achieve a balance between sources and sinks of greenhouse gases
- keep global temp inc under 2 degreesC
- review progress every 5 years
A group that is skeptical about the threat to the environment causes by human activity?
Lavoisier group
