Background research is important for developing an understanding of a problem and identifying any solutions that have already been developed or implemented. 

This research then informs the correct action to take to combat the problem.

Working through this step students will:

• learn what ecosystem services are and why they are important to humans

• understand the role plants play in managing urban heat

• compare native plants, weeds, native forests and plantations

• explore some plant adaptations that plants have developed to survive.

Trees do so many things for us! The services that trees provide to humans and animals are called ecosystem services.

Two of the important ecosystem services provided by trees are: 

• food 

• shelter.

The leaves, nectar, pollen, flowers, berries, seeds and nuts that trees produce provide a great source of food for animals. Hollows, bark and large branches in old trees can provide many different animals such as insects, birds, possums and bats with a safe place to live. Animals who rely on other animals as a source of food also have plenty of options. The interactions between all these animals and their environment creates a food web.

All the different types of plants and animals together that can be found in the natural environment is called biodiversity. Generally, around the world and in Australia, biodiversity is being lost due to an increase in human activities such as urbanisation. 

Loss of biodiversity impacts the health of our natural environment and the survival of plants, animals and even people!

Trees also provide shelter for humans. One of the really important ways they do this is by providing shade on hot days. Their leaves evaporate water which has a cooling effect on the atmosphere around them. This ecosystem service is particularly valuable in a place like Sydney that experiences extremely hot and dry summers. 

Trees provide humans with wood for building houses and furniture. We also use wood fibres to make paper. Many people around the world rely on wood for fires to keep warm and cook their meals. Wood is a vital resource and the best thing is, it is renewable! We can grow more wood as we need it.

One of the best things trees do is reduce air pollution by absorbing carbon from the atmosphere and storing it as wood. This helps to limit the amount of carbon dioxide in the atmosphere, which has increased considerably in the last 100 years from burning fossil fuels. Scientists say this is one of the main causes of climate change. By planting trees, you can help carbon out of the atmosphere.

On top of all of these things, trees and other plants look nice. They can soften the look of concrete, buildings, roads and signs and also help people to feel calm and connected with nature. Studies show that people who regularly spend time in nature are less stressed and feel happier.

Native trees and other plants have been in Australia for many thousands of years and are adapted to the local conditions. 

Adaptations are the features or behaviours of plants and animals that have developed, changed or evolved over time as a strategy for survival and reproduction.

Across Australia there are many different environmental conditions that plants grow in. Everything from alpine environments, (high, cold mountain regions), to lush subtropical forests or dry, desert environments. The locally native plants, in each of these, have evolved, over time, to deal with the specific environmental conditions of the area.

An example of plants adapting to their environments can be seen in rainforest plants. These often have huge dark green leaves, to try to capture as much light as possible in a dark, closed forest environment.

In the Sydney area, locally native trees have adapted to the Sydney conditions, which means they survive well in poor soils, hot, long summers and areas of low rainfall. This makes them a good choice for planting in the local area. 

For example, gum trees (which include Eucalyptus trees) have adaptations to survive in hot, dry and sunny conditions. Gum trees have greyish leaves that hang downwards so that the intensely hot midday sun doesn't hit them directly from above. Instead they catch the gentler morning and afternoon sun. 

As well as trees adapting to survive different environmental conditions, local animals are also adapted to using native plants for their food and shelter. This is another good reason to choose native plants for tree planting.

By replacing native plant species in the local area we are supporting the local ecosystem and improving biodiversity.

We have seen the advantages trees can bring to the local environment. It is important, however, that we plant the right trees in the right places. Different species of trees grow in different ways – some get very big and some will always be small and compact. Choosing the right tree species depends on the place, the local situation and how the place is used.

One type of tree that is native and used a lot by wildlife is the gum tree (including Eucalyptus). However, these trees get very big, and they have thin leaves that hang downwards and don’t make thick shade. They also have a habit of suddenly dropping big branches. This means they are not very suitable for schools or small spaces, however they are great in parks where there is lots of space. 

In schools and gardens there are many other sorts of native Australian trees that are suitable. Some of them you might have heard of: what about wattle trees (our national floral symbol)? Or bottlebrushes that the rainbow lorikeets love? There are also paperbarks, tea trees, grevilleas and many more.

Urban places gain many benefits from trees, such as shade, cooling and wildlife habitat. Buffering noise on roads and reducing air pollution are also important services that trees provide to city residents.

Planting in corridors that link up green spaces and along creek lines can create the maximum benefits of trees in the urban environment.