Ecosystems

Ecosystem

• a natural system which links together the living and non living environment

• Distinctive

• The non living parts of an ecosystem will help to explain the living parts that exist there

distinctive

An ecosystem has particular characteristics different to another ecosystem

Biotic

living

abiotic

non living

flora

plants

Fauna

animals

in what ways can ecosystems be studied at different scales

• local (a small scale ecosystem is also called a habitat e.g. trees)

• Regional (e.g. England’s Lake District moorland)

• Global biomes (South America’s tropical rainforest)

• Earth (some scientists argue that all of the planet’s organisms are linked together)

Producers

• organisms such as green plants that use photosynthesis and take nutrients from the soil using roots

• Make their own food, don’t consume it

Primary consumers

Herbivores

secondary and tertiary consumers

• carnivores - animals that feed on herbivores

• top carnivores will hunt and eat other carnivores

decomposers

• organisms that break down dead organic matter and animal excretions over time

• scavengers (e.g. insects that eat dead wood)

• Detritivores (e.g. bacteria)

• Help return nutrients to soil in the form of an organic substance called humus

Food web

pattern showing consumers and what they eat

food chain

Interrelationship between feeding groups

nutrient cycling

• for living things to exist they need energy and this comes from eating plants/animals

• The plants themselves get their energy through the process of photosynthesis

• The energy passes through an ecosystem as part of the food chain

• Without a flow of energy an ecosystem would not function properly

• Living things also need nutrients to survive

• Many of these nutrients are found in the soil

• Vegetation takes nutrients from the soil through their roots

• The nutrients are then moved through the food chain and eventually cycled back to the soil when living things die and decompose or through animal excreta

what nutrients do living things need

• carbon

• Nitrogen

• Phosphorus

• Potassium

• All essential for plant growth

How are nutrients present in the soil

result from the weathering of rocks in the ground

Where is Epping forest

• located in NE of London and lies within the country of Essex

• On a ridge of high land between the Lea and Roding river valleys

• All that remains of a larger forest that colonised england at the end of the last ice age

What was epping forest used as

formerly used as royal hunting grounds

How is epping forest used

• over 1000 years, Epping forest has been managed in ways such as being a timber resource and also recreation (easily accessible)

• 60% is a Site of Special Scientific interest (SSSI)

Measurements of epping forest

• widest point is 4km

• Approx. 2500 hectares in total

• Around 19km from north to south

biodiversity of epping forest

• bogs and ponds have their own unique species, including 20 kinds of dragonfly

• Large number of native tree species, including oak, elm, ash and beech

• Lower shrub layer of holly and hazel at 5m, overlying a field layer of grasses, brambles, bracken, fern and flowering plants

• 177 species of moss and lichen

• 9 amphibian and reptile species

• 38 bird species

• 700 species of fungi (important decomposers)

How is epping forest’s ecosystem interdependence shown

the forest’s producers, consumers and decomposers are all interdependent, which is clearly shown by the annual life cycle of the trees

Tree life cycle

• most of the trees are deciduous - lose leaves in the winter

• Adaptation to UK’s seasonal climate. Winters are darker and cooler than summers (mean temp is 18 in July but 5 in January)

• Trees grow broad green leaves in spring so they can maximise photosynthesis during the summer

• Shed leaves in autumn so can conserve energy in winter - leaf litter

• By spring, leaf litter has disappeared due to decomposers and detritivores

What happens to leaf litter

• nutrients stored in the leaves are converted to humus in the soil, ready to support the new season’s plant growth

• This will ultimately include the fruits and berries that in turn support many primary consumers

How does nutrient cycling demonstrate interdependence of plants, animals and soil

• people and ecosystem components are interdependent too

• In the past, coppicing (cutting back trees to encourage new growth of wood) was common

• Today, visitors pick berries and flowers

• In turn, this helps spread seeds, which stick to their clothing

characteristics of nutrient cycle

• biomass store is large because of the great height of the trees and dense undergrowth beneath them

• Soil store is also large because there is always plenty of humus

• High flow rates between the litter, soil and biomass stores reflect the vigorous cycle of new growth that takes place each year

• Forest also loses a lot of nutrients each year via leaching, during episodes of heavy rainfall

Leaching

• natural process where water, usually rainwater, seeps through the soil and dissolves nutrients and minerals, carrying them away

• Often occurs in areas of high rainfall

• Can lead to the loss of important nutrients that plants need to grow

• When these nutrients are washed away, they can end up in rivers and lakes, potentially causing pollution

• Can affect soil fertility, making it more challenging for plants to thrive

physical factors that affect the balance of an ecosystem

• periods of extreme weather or climate change e.g. in 1976-77, England experienced an 18 month drought, killing many trees

• A further 15 million trees felled by a great storm in 1987

• Population numbers declined for consumer species in the food chain

• Secondary forest growth has taken place

• Consumer species

• Wildfires

• Disease

Human factors that affect the balance of an ecosystem

• deforestation - removal of forest exposes soil beneath to rainfall, so it can be washed away, making it impossible for the ecosystem to recover

• Especially true in tropical rainforests (lots of heavy rainfall)

• Removal of hedgerows

• Human induced climate change

• Use of agricultural fertilisers

• Draining ponds

how does the removal of hedgerows disturb ecosystem balance

• removed to increase size of fields

• Offer food and shelter for many species, especially from extreme weather, which can improve animal health by reducing stress and cold and can protect crops

• Species include nesting birds, pollinating insects, bats and hedgehogs

• Habitats provided for beneficial insects can help control pests

• Source of wood, capture CO2 from atmosphere, natural windbreaks

• Habitats will be destroyed, altering the plant/animal balance

How does the use of agricultural fertilisers disturb ecosystem balance

• cause algae to grow over a pond/river, leading to eutrophication

• This blocks sunlight and prevents it from entering the water, meaning that photosynthesis cannot occur, reducing the growth of plants that fish eat

deforestation

• destroys habitats for birds

• Affects nutrient cycle (more leaching)

Draining ponds

• drained to use for farming

• Aquatic plants will die, as will fish and other pond life

Using the example of a food web specifically, outline how ecosystem balance can be disturbed

If the population of beetles is reduced by disease, this would have an impact on the number of woodpeckers, as they would have less food

It could cause their numbers to decline. In turn, this may affect owl and hawk numbers because they eat woodpeckers.

Woodpeckers also eat caterpillars, so they would have to eat more of these if beetle numbers reduced.

However, blue tits also eat caterpillars, so their numbers could reduce as well

what are some of the ways of managing ecosystems to restore balance

• ecological restoration

• Where an ecosystem has been damaged by humans, the process of succession (plants and wildlife returning to the area) must be facilitated by human intervention

ecological restoration

• The process of assisting the recovery of an ecosystem that has been degraded, damaged or destroyed

• it is about sustaining the diversity of life on Earth and re-establishing an ecologically healthy relationship between nature and culture

example of succession

• reintroduction of grey wolves to the Yellowstone ecosystem

• Coyotes had become larger and more dangerous due to the lack of predators that could eat them

• Grey wolves decreased coyote numbers

• Reduction in predation from coyotes lead to an increase in rodents such as voles and mice

• More kills made by wolves, providing more food for scavengers e.g. ravens, eagles, grizzly bears, cougars, etc.

Distribution of global ecosystems/biomes

• biomes are not evenly distributed across the globe

• Coniferous and broad leaved evergreens are mainly restricted in the northern hemisphere

• Tropical grasslands and savanna are only in the southern hemisphere

• Monsoon forest and tropical rainforests are mainly in South East Asia, but there are some of these regions in south America and Africa

• Tundra is also mainly in the northern hemisphere, but there is some in south America

mediterranean

• located at around 40-45 degrees north of the equator

• Some regions outside of this area e.g. South Africa and Western Australia

• Summers are hot and dry

• Winters are mild

• This is because pressure belts migrate slightly north and south during the year, so areas of high and low pressure change slightly

Polar

• in the Arctic or Antarctic

• Polar air cells

• Cold air sinks at a high pressure, leading to low temperatures and dry conditions

• Main regions are Antarctica and Greenland

• Temperatures can fall below -50