Human Impact on the Environment (including succession) •Changes in complexity •Effects of intensive food production •Effects of increased energy production •Pollution

Changes in complexity Ecosystems change naturally over time.

The change is gradual, repeatable and may take years or centuries.

These processes are known as succession.

•Autogenic (primary and secondary) •Allogenic (climax disturbed) •Degradative (heterotrophic)

Autogenic Succession Changes in ecosystem species composition is brought about by the biological processes of the organisms themselves.

Primary succession Takes place on ground where no soil has formed and no organisms have been present before Secondary Succession Takes place on previously occupied ground where soil is present

Primary succession

Primary succession e.g bare rock, concrete, sand dunes •First colonisers (pioneer species) include lichens followed by mosses as the lichens break down surface.

•Decaying plant matter and rock pieces create early soil layer which annual plant seeds can germinate in •Further decaying material creates enough soil for grasses and small shrubs to grow in.

•Many years sees soil deep enough to support trees of the climax community like pines and oak.

•Climax communities are relatively stable, show many food chains and show high biodiversity.

sea buckthorn couch grass marram grass sycamore

Secondary Succession •Existing area with soil is colonised by plants like a bare field, forests destroyed by fire.

•Soil usually has organic matter.

•Pioneer species are often annual plants.

•The process is much quicker than primary succession.

•All communities make it less favourable for themselves and more favourable for other species until the climax community.

Allogenic Succession Is secondary succession in an area that has a climax community established but it is disturbed by climate change, forest fire etc.

Degradative (Heterotrophic) Succession Are the changes that take place when an organism dies and decomposes. A similar sequence of organisms will be seen and does not involve plants.

Bacteria and fungi, insects including flies and then beetles (eggs and larvae), spiders that eat the insects. Used by forensic scientists to judge decomposition

Succession progression •show an increase in the complexity of food webs.

•show an increase in the biodiversity.

•show an increase in habitats and niches.

•show an increase in stability •show an increase in productivity

Human influences on succession • Monoculture • Eutrophication (algal bloom) • Toxic pollution • Habitat destruction All these activities will reduce the complexity in ecosystems and will have a detrimental overall effect on the ecosystem.

Intensive food production (monoculture) Growing of one or two species over large areas of land Mainly to produce food or raw material Effects soil condition.

Effects field size.

Effects habitats and shelter Use of pesticides and chemical fertilisers on these monocultures further affects species diversity and stability of the ecosystem

Monoculture Advantages •reduces competition for nutrients, light, space.

•increased profit from high yields.

Disadvantages •pathogenic micro-organisms spread more easily.

•pests spread more easily and increase.

•soil can erode due to lack of root systems.

•adverse weather can destroy whole crop.

•very unstable, low biodiversity.

•increased use of fertilisers, pesticides, herbicides and fungicides

Increases in Energy Needs

Energy sources Non renewables.

Finite - coal, oil, natural gas and nuclear.

Create significant pollution.

Renewables (alternative).

Infinite - solar, wind, hydro electric, wave, tidal, geothermal, biofuels Create much less pollution.

Reality - energy requirements are increasing and present finite energy sources will not meet demand.

Oil - 50 years, Coal - 200 years

Present problems caused by energy use: Global warming and the greenhouse effect gases from burning fuels are carbon dioxide and water.

gases build up in layer around earth more reflected heat is trapped and earth warms effects on weather patterns, ice distribution, climate, distribution of organisms Other gases contributing to the greenhouse effect are methane, nitrous oxide and CFCs.

Corals are polyps (animals) that secrete calcium carbonate to create skeleton.

corals appear white (bleached).

zooxanthellae algae (symbiosis) in corals leave as result of warmer waters.

Bleaching hotspots around the world

Present problems caused by energy use: Acidic precipitation burning fossil fuels produces sulphur dioxide, nitrous oxide and carbon dioxide.

water in the atmosphere combines with these gases.

precipitation (rain) is acidified.

soil and water is acidified.

plants and aquatic organisms particularly are effected.

Areas in Europe at risk of Acid rain

Effects of acid rain

What can be done?

• Use less non renewable fuels for energy.

• Use other more renewable energy sources.

• Change the mind-set of the whole human population from being reliant on oil.

Pollution Pollution is the negative effect of a harmful substance on the natural environment.

All environments are effected by pollution.

Aquatic (fresh water and salt water) Air Land Pollution occurs as a result of human activities

Pollution Effects of pollutants on species include: • appearance/disappearance of species • community function and structure changes • behaviour and demography changes • energy flow, production and nutrient cycling changes

Pollution Tars, solvents, pesticides, domestic rubbish, lead, mercury, copper, zinc, iron, arsenic All dumped onto the land or released into the atmosphere on a daily basis.

Landfill sites are a cocktail of dangerous chemicals, many leach into ground water sources.

Fresh Water Naturally contains: •dissolved salt ions sodium, potassium, magnesium •gases oxygen, carbon dioxide, sulphur dioxide •solids soil dust, pollen Pollution added: •sewage (domestic and industrial) •farm waste •industrial waste Many are biodegradable organic pollutants but they will cause changes in the water quality.

Fresh Water Monitoring water quality for: Colour pH Odour Temperature Turbidity detergent level dissolved oxygen level suspended solid level biochemical oxygen demand (BOD) ammonia, nitrate, chloride and phosphorus levels

Fresh Water Biochemical oxygen demand (BOD) Is a measure of how much biodegradable material there is in a water sample.

Oxygen is essential for this activity.

The BOD is the mass of oxygen removed from a water sample at 20 o C in the dark in grams per cubic metre.

The oxygen level in water directly effects the living organisms found there.

High BOD = high level of organic matter and vice versa

Fresh Water Biological monitoring using indicator species.

These give an indication of the state of an ecosystem depending on their presence or absence.

Invertebrate species are often used.

Indicators of clean water caddis fly larva and may fly larva. They need high oxygen levels to flourish Indicators of water polluted with organic matter. Low oxygen levels mean sludge worms and rat tailed maggots can flourish

Biological monitoring Advantages: •detects intermittent pollution.

•provides early warning.

•accumulation of toxic chemicals mean. detection of low levels otherwise not easily detected.

Disadvantages: •natural variation exists in invertebrate communities.

•indicators may tolerate one pollutant but be susceptible to another.

•expertise in identification is essential.

Biotransformations • Chemicals once released in to the environment undergo changes.

• Leaching of ions increases with acidic conditions.

• Oligotrophic conditions in lakes is caused by changes in nitrates caused by leaching aluminium ions.

• Chemicals can be made more toxic in the environment.

Biomagnification / Bioaccumulation • Living organisms can build up chemicals in their systems.

• These quantities start small but as the food chain progresses through the trophic levels they increase in concentration.

• These higher concentrations can cause problems • Examples include chlorinated hydrocarbons such as: pesticide DDT and industrial chemical PCBs (polychlorinated biphenol)

DDT (Dichlorodiphenyltrichloroethane) • used to kill mosquitos (1940s and 50s) • stable in environment • accumulates in fats (bioaccumulation) • changes to DDE which thins egg shells • birds of prey particularly effected • resistance has been built up by mosquitos (35 species) • DDT occurance spread to areas not used e.g. Canada and Greenland • does not biodegrade

Mercury Poisoning • Japan 1969 Minimata Bay • Mercury dumped into bay by chemical plant • Bacteria converted mercury to methyl mercury • Very toxic • Biomagnified in food chain • Humans ate fish from Bay • Caused neurological disorders, organ failure and deaths (68)

Favoured and susceptible species • Species occupy different environments, some are more tolerant of pollution than others.

• Favoured species are less sensitive and can tolerate a wider range of environmental conditions.

• Susceptible species are very sensitive and cannot tolerate changes in the environment.

Indicators of clean water caddis fly larva and may fly larva. They need high oxygen levels to flourish Indicators of water polluted with organic matter. Low oxygen levels mean sludge worms and rat tailed maggots can flourish