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Ecosystems

ecosystems

Key idea Specification content
Ecosystems exist at a range of scales and involve the interaction between biotic and abiotic components.

 

An example of a small scale UK ecosystem to illustrate the concept of interrelationships within a natural system, an understanding of producers, consumers, decomposers, food chain, food web and nutrient cycling.

The balance between components. The impact on the ecosystem of changing one component.

An overview of the distribution and characteristics of large scale natural global ecosystems.

The word document below relates to pages 64 – 65 in the textbook

Ecosystems 1 (word doc)

Small-scale Ecosystem in the UK

An ecosystem is a natural system made up of plants, animals and the environment. There are often complex interrelationships (links) between living and non-living components of an ecosystem. Biotic components are the living features of an ecosystem such as animals and plants. Abiotic components ate non-living features of an ecosystem such as climate (rainfall and temperature), light, rocks, water and soil.

Objective: To explore the components of a small-scale ecosystem in the UK.

Success criteria:

I can describe what an ecosystem is and what it is made up of. I can define the term interdependence. I can identify ecosystems on different scales. I can explain how energy is transferred in an ecosystem.

Interdependence – Interdependence is the dependence of two or more things on to each other.

A food web is simply a number of food chains joined together. It shows how the loss of one organism has an effect of other organisms in the food web. This is called the interdependence of living things.

Because we are all part of a giant food web, changes in one part of the web can have a big impact on other parts of the web. When one food source disappears, a predator will have to find another food source in order to survive.

world-web

The nutrient cycle

A set of processes whereby organisms extract mineral necessary for growth from soil or water, before passing them on through the food chain, and ultimately back to the soil and water.

Ecosystems can be local or global

Local ecosystems are often small-scale ecosystems such as ponds, hedgerows or woodlands.

pond

pond-ecosystem-inhabitants-60024320

Global ecosystems are large-scale ecosystems such as tropical rainforests, deciduous woodlands or deserts. These are called biomes.

Desert

Read the article below – about a small scale ecosystem in the UK (Oxford)

Temperate deciduous woodlands: a Case study

Epping Forest, East London, UK

Located in East London. The remains of a much larger forest that colonised England at the end of the last Ice Age.

Epping map

 A large number of native trees found in the tree foliage include oak, elm, ash and beech. May find 20 species of dragonfly in the shrub layer. A 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 grow at Epping Forest. Mammals, amphibian and reptile species call Epping Forest their home. You may find these close to the forest floor or in the shrub layer. 38 species of birds are supported in the tree foliage. 700 species of Fungi can be found at Epping forest, most likely on the forest floor.

Epping

How Epping Forest is interdependent
The species at Epping Forest are interdependent which means that they rely on one another. As most trees are deciduous, they have adapted to the cold UK climate and lose their leaves in winter to save energy. In summer they have large leaves to maximise photosynthesis.
In autumn the forest floor is covered in a thick layer of leaves. The nutrients in this leaf layer are converted to the humus in the soil and so by spring these leaves have disappeared. These nutrients will support new growth, which will eventually produce fruits and berries that support primary consumers.People and the ecosystem at Epping Forest are also interdependent. In the past pollarding was common (cutting back trees to promote new growth)

Epping structure

Soils of temperate deciduous woodlands

The soil is deep and very fertile because there is a thick layer of leaf fall
This means that the leaves decompose and the nutrients can be used again by new vegetation

Soil

Human uses of temperate deciduous woodlands

People use deciduous woodlands as a source of timber, for recreation and conserving wildlife. Woodland managers have to maintain a balance between conservation and human activity.

Uses of deciduous woodland

Humans use woodlands in a variety of ways:

·       as a resource – wood is used for fuel (firewood) or as timber for buildings

·       for recreation – for example for deer hunting or walks

·       for conservation

Case study: Epping Forest

Epping Forest is an example of a deciduous forest. It is located in north-east London.The forest is used by visitors and looked after to help maintain the wildlife and its historic landscape. Recreational activities here include:

·       walking

·       horseriding

·       cycling

·       fishing in the larger ponds and lakes

There are also 60 football pitches and an 18-hole golf course in Epping Forest.

 The management of temperate deciduous woodland – Epping forest

The City of London Corporation has overall responsibility to manage the forest, which is a site of special scientific interest which protects the trees by law. The management has to balance conserving the land with keeping it open to the public. This is difficult to do. Traditional management techniques include pollarding (Pollarding is a pruning system in which the upper branches of a tree are removed).

Pollarding

This technique encourages new growth, and maintains the trees for future generations. It is a form of sustainable management in the woodland. Pollarding also encourages birds to nest. Dead wood is left to rot. Rotten wood is food for fungi and encourages wildlife. Some grassy areas are left uncut to encourage wildlife like butterflies. The recreational areas for biking and horse riding are marked out. This reduces damage to other areas of the forest.

Epping Forest is sustainably managed in several ways…

  1. Recreation is controlled, there are car parks, a visitor centre, waste bins and information leaflets advising people on how to treat the forest. As well as this horse riding and walking are to take place of designated paths. This is sustainable management as it ensures the forest will be left in the same way for future generations to enjoy.
  2. Vegetation (bushes) at the side of the roads has been cut back so that deer are aware of traffic and to give drivers a chance of avoiding collisions. This is to protect the deer as there are many deaths from road traffic accidents. This is sustainable management as it ensures that the deer population will be preserved.
  3. Pollarding – trees are cut to shoulder height to ensure that they regrow. This is sustainable management as it ensures there will be timber for future generations.
  4. Cattle grazing has been reintroduced to a small area of the forest, this promotes the rejuvenation of some flora.
  5. The Epping forest conservation volunteer manage the forest by clearing and maintaining footpaths.

Objective : To explore how change in components affect an ecosystem.

Success criteria:

I can identify factors influencing change to ecosystems. I can explain how change in ecosystems would cause an imbalance. I can give examples of change in Epping Forest, East London. I can explain how ecosystem restoration can support balance in Epping Forest, East London.

Periods of extreme weather or climate change can cause change and disturb the balance of ecosystems. In the years 1976 to 1977, England experienced a drought that killed many trees. A further 15 million trees were felled by a great storm in 1987.

Great storm

As a result in this change in tree species in the ecosystem, population numbers declined for many food species in the food chain. Secondary forest growth has since taken place and consumer species have migrated back. The recovery of the English woodlands is an example of ecosystem resilience.

Ecosystems are sometimes damaged in permanent ways, especially when humans forces are involved such as deforestation. The removal of the forest exposes the soil beneath to rainfall and so it can be washed away, making it impossible for the ecosystem to recover. In the long-term, climate change could have an impact on ecosystems. Temperatures and precipitation patterns in Southern England, might make it harder for ecosystems like Epping Forest to survive in their current form.

How does damage to the ecosystem affect the food web:

Oak woodlands support many species. Suppose that the population of beetles is reduced by disease, this would directly impact on the numbers of woodpeckers. With fewer beetles, comes fewer meals and their numbers may decline. However, we may see an increase in oak tree growth if fewer beetles were feeding on them.

The indirect result of a reduction in beetles.

-Owl and hawk numbers may fall because they feed on woodpeckers.

-Woodpeckers are carnivorous and have multiple food sources, they may just eat more caterpillars (but this would have problems for blue tit numbers).

Food.chain

Restoring ecosystems

Many species have been hunted to extinction without full understanding of the changes this would inflict on the ecosystem.

In Epping Forest (East London) more cattle grazing has been introduced into the ecosystem (ecosystem restoration) to encourage growth of flora (vegetation) such as veteran trees (legacy trees such as oak) as these declined from 1976-1988 this was due to extreme weather causing drought and felled trees. The oak allows fauna (animals) to consume it therefore maintaining the number of species in the forest.

Grazing allows more flowers to flourish than mowing would. Low-growing species such as Birds-foot Trefoil only thrive where the thatch of dead grass stems is regularly removed e.g. hooves of the cattle create bare ground.

epping grazing

Use the following two resources: textbook (page 63) and the YouTube clip below to answer the following: How has the reintroduction of wolves into Yellowstone national park impacted on the ecosystem?

The distribution and characteristics of the global ecosystems (biomes)

Objective: To explore the distribution and characteristics of global ecosystems.

Success criteria:

I can define the term biome. I can describe the global distribution of worlds ecosystems. I can suggest reasons why global ecosystems form latitudinal belts across the world.

A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Each biome consists of many ecosystems whose communities have adapted to the small differences in climate and the environment inside the biome.

world-biomes-map

Biomes are large-scale ecosystems defined by abiotic factors. These are:

  • climate (determined by latitude, altitude and ocean currents)
  • relief (rainfall and temperature)
  • geology
  • soils
  • vegetation

Biomes

earths-biome-3-638

Tropical forests are found near the equator in Central and South America, parts of Africa and Asia. They are hot and humid and contain a huge variety of plants and animals – around half of all the world’s species. The trees are mostly hardwood. The climate is called equatorial.

Savannah or tropical grasslands are hot and dry, dominated by grass, scruband occasional trees. They have two distinct seasons – a dry season when much of the vegetation dies back, and a rainy season when it grows rapidly. They are found in central Africa (Kenya, Zambia, Tanzania), northern Australia and central South America (Venezuela and Brazil).

Desert is the driest and hottest of areas. The world’s largest desert is the Sahara in North Africa. Areas of scrub land that border the desert are called desert scrub.

Mediterranean climates are not too hot or cold. They are found around the Mediterranean Sea, near Cape Town in South Africa and Melbourne in Australia.

Temperate grasslands are dominated by grass and trees and large bushes are scarce. They have a temperate continental climate – the weather is mild with moderate rainfall. Grasslands include the Puszta in Hungary, the Veldt in South Africa, the Pampas in Argentina and the Prairies in the USA.

Temperate deciduous forests contain trees that lose their leaves and are found across Europe and USA. The weather is mild and wet. The climate is called temperate maritime.

Coniferous forests, containing evergreen trees, are found in Scandinavia, Russia and Canada. They have a cool climate with moderate rainfall called cool temperate. Read the article below which is about this ecosystem.

CONIFEROUS WOODLAND ECOSYSTEMS

Mountain areas can be very cold at night and during winter. The growing season is short and at higher levels trees will not grow.

Tundra surrounds the North and South poles. They have an extremely cold climate, with limited numbers of plants and animals able to survive there.

The YouTube videos below deal with a range of ecosystem issues:

 

 

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