Living World

An ecosystem is a community of plants and animals that interact with each other and the physical environment.

• Abiotic - Relating to non living things in the ecosystem e.g. the soil.
• Biotic - Relating to living things in the ecysystem e.g. the plants and animals.
• Producer - An organism or plant that converts energy from the sun into glucose.
• Consumer - These get energy from the glucose made by the producer when they eat them.
• Herbivores - This is a primary consumer - a plant eating animal e.g. a cow
• Carnivores - This is a secondary consumer- these animals feed on herbivores e.g. fox.
• Decomposer - An organism that breaks down dead plants and animals and return the nutrients to the soil. Examples are bactertia and fungi.
• Food chain - The connections between different organisms that rely on one another as their food source.
• Food web - A complex hierachy of plants and animals relying on each other for food.
• Nutrient cycling - A set of processes whereby organisms extract minerals necessary for growth from soil and water before passing them on through the food chain.
• Global ecosystem - Large biomes with flora and fauna adapting to their environment.

1) Leaves die and fall to the forest floor

2) Fungi and bacteria break down the leaves

3) Nutrients are added to the soil as the leaves decompose.

4) The nutrients are absorbed by the tree roots

5) Trees use sunlight and nutrients to grow and produce leaves.

There are many interrelationships (links) between the living (biotic) and non-living (abiotic) components of an ecosystem.

If the climate changed by getting warmer, how would this affect the ecosystem?

1) Vegetation - it may become too hot/dry for the current vegetation meaning different vegetation may begin to grow.

2) Different vegetation would mean different living creatures would be found.

3) With current plants and animals the soil composition may change as the nutrient cycle may be affected.

I need to be able to explain the impact on the ecosystem of changing one component e.g. the vegetation by deforestation. 

Global-scale changes:

• Climate change

Local-scale changes:

• Drought
• Deforestation 
• Hedgerows removed to increase the size of fields
• Fertilisers
• Lakes, rivers drained for irrigation
• Hunting
• Pollution e.g. oil spills
• Parasite kills off/ reduces number of a species in food web.

Epping Forest is in the south east of England, north-east of London. It is a deciduous forest - meaning the trees lose their leaves in the autumn. 

Nutrient cycle in Epping Forest

1) The trees are deciduous nso they loose their leaves in the autumn to conserve their energy during the winter.

2) The forest floor is therefore covered in a thick layer of leaves.

3) Through the winter the decomposers break down the leaf litter adding humus to the soil. 

4) The soil is then more fertile and ready for the new growth in the spring.

5) Leaves appear again on trees in the spring as temperatures increase allowing for photosynthesis in the summer.

Tropical rainforests :

• Along/close to the Equator.
  
• Hot all year, between 27-30 degrees celcius.
• Wet all year. Average 2000-3000mm per year.

Deserts

• Close to the tropics of cancer and capricorn - roughly 30 degrees North and South of the equator.
  
• Very hot all year round, above 30 degrees celcius.
• Very low rainfall,less than 250mm annually.

Tropical grasslands (savanna)

• Between tropicl rainforests and deserts - between 15 and 30 degrees North of the equator. 
  
• Very hot all year, between 25-35 degrees celcius.
• 500-1000mm per year but always with a dry season.

Temperate grasslands:

• Between 40 and 60 degrees North of the equator but only in the centre of continents.
  
• Hot summers (25 degrees C)  and very cold winters, as low as -40n degrees C.
• 500-900mm per year with most in late spring and summer.

Tundra (cold)

• From the Arctic circle to about 60-70 degrees North.
  
• Below 0 degrees C for most of the year.Up to 10 degrees C in summer.
• Less than 250mm of rainfall per year.

There are three main physical characteristics of a tropical rainforest.These are:

1) The Climate: The temperature is high throughout the year.This is because they are on the equator. The rainfall is high because the global atmospheric circulation causes low pressure on the equator causing rising air, creating clouds and heavy rainfall.

2) The Soil: The soil in tropical rainforests is suprisingly infirtile. Without the vegetation, heavy rainfall can dissolve and remove nutrients in a process called LEACHING. Trees shed their leaves all year. These leaves are quickly broken down adding the nutrients to the soil.These nutrients are quickly taken up by the vegetation. Only the top layer of soil is rich in nutrients.

3) The vegetation: There are several layers ina tropical rainforest;

• EMERGENTS - These trees grow to over 50 meters tall! They out-compete their neighbouring trees to gain the maximum sunlight. They can withstand high winds and temperatures.
• CANOPY - These trees grow to heights of 20-40 meters. They compete for the sunlight overhead.Strong light levels mean there is an abundance of life.

• UNDER CANOPY - This layer still receives very little sunlight, although more than the shrub layer. It is hot and damp and shaded from the wind.
• SHRUB LAYER - Only receives 2% of sunlight meaning less plants and animals are found here. Plants which love damp,shady conditions thrive here.

Buttress roots: 

• Large wide roots that are shallow.
  
• The trees need to grow tall to reach the canopy to obtain sunlight. The roots need to be wide to support the trees. Due to the poor soils the nutrients are only found in the top layer meaning trees need to spread roots out accross the forest floor to get the nutrients.

Drip tips

• Allow excess water to drip off the leap. 
  
• In a rainforest there is a lot of rain (obviously!) and so the leaves need to remove excess water to prevent algae growing which could block sunlight and stop photosynthesis. It also stops leaves from breaking during heavy rain.

Tree frog:

• Sticky pads on its fingers and toes. Vibrant green colour.
  
• The sticky pads allow the frog to climb high into the canopy layer which means he can access rainwater, either as it falls or where it has gathered on leaves. The vibrant green colour means he is camouflaged in the green vegetation which means he is less obvious to predators and less likely to be eaten.

Sloths:

• Strong claws allows it to hang from branches. It's hair is filled with green algae.
  
• Strong claws mean it has a stronger grip to hang from branches high in the canopy so he does not fall. The canopy is where more food and water is to survive. Algae means the sloth can can camouflage so it's less likely to be attacked/eaten.

Spider monkey:

• Has incredibly strong, long arms and hands. It also has sharp nails.
  
• Long arms help them to move around the canopy layer to reach different food sources in order to survive and to quickly move away from predators. Sharp nails are needed to tear off bark to eat the insects and sap beneath to get nutrients from other animals to survive.

What is biodiversity?

Biodiversity is the range of plants and animals found in an area. The hot, wet conditions of tropical rainforests create a unique environment which is ideal for plant growth.

Approximately 50% of all the planet's land based animals are found in tropical rainforesrs!

There is a greater density of species within rainforests than found in any orther ecosystem.

Most animals are found in the canopy where there is maximum light (monkeys are well adapted to living in trees). Animals such as wild boars live on the forest floor eating seeds and berries.

In a 10km x 10km piece of land in the rain forest, you would find: ambphibians, flowering plants, trees, birds, butterflies, reptiles and ants.

Deforestation is the chopping down and removal of trees to clear an area of forest.

There are 62 countries with tropical rainforest within their borders. It is estimated that about half of the worlds tropical rainforest have been cleared. The scale and accelerating rate of deforestation is truely worrying.

The FASTEST RATES of deforestation are in BRAZIL and INDONESIA which total 40% of global deforestation

BUT

Rates of deforestation in BRAZIL are actually DECREASING.

The rates of deforestation in Indonesia and Peru are particually alarming. The rate of deforestation in these countries has DOUBLED from 2000-2005 to 2005-2010.

Causes of deforestation

• Cattle ranching: Large areas of the Amazon have been cleared to make way for livestock rearing. The rearing of cattle accounts for 80% of tropical deforestation in Brazil. Once the cows have grazed one piece of land the soil quickly declines. The land only lasts a few years as the heavy rain turns the soil infertile and acidic meaning the cattle farmers have to move on and destroy even more rainforest.