September is National Arbor Month. It is the perfect time to acknowledge the great work trees do for the environment, and how we can take part in building more sustainable environments by planting even more! During Arbor Month, public awareness on indigenous trees is also encouraged and two indigenous tree species are highlighted. 2020’s common tree of the year is the Cape ash – commonly used as a street tree - while the rare tree of the year is the Adansonia digitate or African baobab.

One of the objectives of Goal 15 of the Sustainable Development Goals is to “sustainably manage forests”. Many countries, including South Africa, have set strategies for increasing and maintaining tree populations. For example, in 2017 South Africa joined other African countries in a “forest landscape restoration” initiative to plant 100 million hectares of trees in Africa by 2030. South Africa aims to plant 3.6 million hectares of trees as part of the project.

So, why are trees so important?

Trees and their role in the environment

Carbon dioxide absorption and Oxygen production

Through a process called photosynthesis, trees produce oxygen and chemical energy in the form of carbohydrates. They use light energy from the sun, water, and carbon dioxide to achieve this. Researchers estimate that one tree can absorb up to 21 kilograms of carbon dioxide per year. It has also been reported that a single tree can produce enough oxygen supply for two people for a whole year.

Air quality

In addition to taking up carbon dioxide, trees can remove other pollutants – like nitrogen oxides, ammonia, and sulphur dioxide – from the air. This ‘filters’ the air and improves air quality.

Providing habitats and maintaining biodiversity

Biodiversity refers to the ‘variety of plant and animal life’. Another important role that trees play is that of providing a habitat for animals and ensuring biodiversity. For example, many different species of reptiles and insects live within the interiors of the baobab tree.

Prevention of soil erosion

One of the biggest environmental challenges is soil erosion. This is the process where the top layer of soil is removed or lost due to the activity of physical elements such as wind and water. It has significant effects on soil fertility and soil structure. Using their root systems and leaves, trees can keep soil intact. When tree roots are embedded and anchor into the ground, they are able to hold soil in place. The leaves act as a ‘screen’ against wind forces and rain that can cause soil to runoff and deposit into rivers.

Why we need more trees

As industrial activity continues to rise, so too does the level of carbon dioxide and other greenhouse gases. Furthermore, plant and animal habitats remain threatened by deforestation. Experts estimate that an individual produces 6 tons of carbon dioxide every year and would need to plant six trees every month to make up for their carbon footprint! Although trees alone cannot take on the full task of tackling climate change, they are certainly a starting point for developing greener environments, fighting pollution, and maintaining biodiversity in ecosystems.

Cities like Johannesburg are aiming to become ‘smart cities’ that are environmentally sustainable. Johannesburg has roughly 10 million trees - one of the largest ‘city-tree’ populations in the world.

Do your part

Sci-Enza celebrated National Science Week from the 27^th of July to the 03^rd of August 2019. We honoured the theme “facing the harsh realities of climate change” through a variety of activities that included the planting of trees at two schools in Pretoria.

Agriculture and Rural Development Republic of South Africa donated 20 trees to plant at 2 pre-schools in Mabopane to celebrate National Science Week. We planted 8 trees at Modisabana/Nomanini Day care centre. We planted another bunch of ten trees at Kiddies Ark Day care centre. The event is depicted below. The kids got involved in the activity and really enjoyed taking part. We started with an introductory engagement about trees where we taught the kids about the importance of the trees and they even sang a few songs for us.

You can also play your part wherever you are. Why not start today! Take time to learn about the indigenous tree species of South Africa – which sustain natural biodiversity within our ecosystems – and help builder a greener environment by planting a tree (or two!) this Arbor month.