Trees have many benefits that we often do not think about. They contribute to the health of our planet and help to fight against climate change. Trees have the ability to capture and store carbon in their biomass – their roots, their branches, and even their stumps. Even more exciting is that the older a tree is, the better it can absorb carbon from the atmosphere. Research has shown that almost 70 percent of the carbon stored in trees is accumulated in the last half of their lives.
It is only a theory, but it is thought that older trees will store more carbon because they are at the top of the tree canopy and thus have consistent access to the sun. However, it is not just the height of a tree that is important, as trees will store more carbon in proportion to their size. This happens through the process of photosynthesis, where the trees will take the energy from the sun, and along with carbon dioxide from the atmosphere, will convert it into carbon-based sugars that are then stored in the tree and allow the tree to do its daily work.
Older trees are more efficient in the storing of carbon, as they are less sensitive to changing weather conditions. When you look at a tree’s rings of life by taking a cross-section of the trunk, those rings tell a story. By studying the rings, you are told a story by the tree. It tells you of years of plenty and years of famine, and it shows that almost half of the carbon stored occurred in the last quarter to half of the tree’s life. We should consider the worth of old-age trees in our battle against climate change.
The areas on Earth which are not occupied by humans are very important. Not including the oceans, which are also an important carbon storage area, forests store around 90 percent of the biomass on the surface of the Earth. In particular, tropical forests remove enormous amounts of carbon globally every single year. Plants have the ability to convert carbon dioxide from our atmosphere into a form that is difficult to release back into the air. Trees, being the most visible part of our landscape, have an extremely high value.
Green spaces in our urban areas are not only aesthetically pleasing, but they have the ability to cool off urban heat islands. This cooling effect is fact. It is cooler in the shade of a tree than in the shade of a building due to some of the processes that are occurring in the tree itself. The leaves will reflect light and heat back upwards while they are providing shade, but the process of transpiration will release water into the air which lowers the ambient temperature.
Countless studies have been done that reflect this great phenomenon. Urban forests do combat the urban heat wave. Even a reduction of 10 percent in the canopy in an urban forest can increase the mean temperatures in the urban area by up to 10 degrees. The opposite is also true: increasing the urban green cover by 10 percent can reduce the temperature increase in the concrete jungle to only one degree.
We all know that plants have the ability to improve the quality of the air around us. They have the ability to extract a wide range of air pollutants that are emitted by traffic, industry, building materials and furniture. They also release oxygen, which improves the quality of the air we breathe.
Our forested areas contribute to flood and water management. They facilitate the infiltration of rainwater into the ground so developing green spaces is essential to improving our green infrastructure. Runoff is a concern as it has a huge impact on our water management practices. We should think about ensuring that our green space development is an integral part of the overall plan for water management.
As you can see, there are both obvious and less obvious reasons to value our green spaces and especially the trees!
Patricia Hanbidge is Shawnigan Lake School's Environmental Lead and Horticulturalist. She has worked extensively around the world, helping people develop food sovereignty, enhance food security, and build more sustainable communities.