October 5th, 2023

Volunteers pose in front of the first "little forest" planted in the downtown core in Peterborough. As part of a GreenUP initiative made possible due to generous donations by community members, three densely planted mini forests will grow into biodiverse pockets in the urban core, creating oxygen, controlling erosion, providing shade, purifying water, offering habitat, and more. (Photo: Lili Paradi / GreenUP)

Volunteers pose in front of the first “little forest” planted in the downtown core in Peterborough. As part of a GreenUP initiative made possible due to generous donations by community members, three densely planted mini forests will grow into biodiverse pockets in the urban core, creating oxygen, controlling erosion, providing shade, purifying water, offering habitat, and more. (Photo: Lili Paradi / GreenUP)

By: Laura Keresztesi, Program Coordinator, GreenUP

Peterborough has just planted our first three Little Forests! As part of a GreenUP initiative, these densely planted ‘mini’ forests will grow into biodiverse pockets in our urban core.

If you are like me, then you will have a lot to learn about these trees and how they succeed.

I know they create oxygen, control erosion, provide shade and purify water. I know they offer habitat, help with traffic calming and lead to higher property values. I know that walking in a treed area can help boost mood and calm anxiety.

Beyond those facts, I find myself pondering, what actually will help trees take root and grow?

The answer may be right under our toes.

Did you know that there more microbes in one teaspoon of soil than there are people on this planet? When we spend so much time walking on pavement, it is hard to connect to the vast array of life that is taking place in the soil beneath us.

Volunteer Mataeya Mintz-Stone prepares to categorize trees by species name and classification for the first “little forest” in the downtown core in Peterborough. In a little forest, the growing technique requires trees to be classified as canopy, understory, and forest floor plants. (Photo: Lili Paradi / GreenUP)

Volunteer Mataeya Mintz-Stone prepares to categorize trees by species name and classification for the first “little forest” in the downtown core in Peterborough. In a little forest, the growing technique requires trees to be classified as canopy, understory, and forest floor plants. (Photo: Lili Paradi / GreenUP)

Let’s dig into the topic of soil and healthy soil communities.

For a tree, keeping the area around the trunk and under the branches of the tree undisturbed and free from other plant competitors will help it remain in good health. It will build a strong root network that does not have to compete with other plants. We recommend using a mulch to protect the roots and create a moist environment for the tree to thrive in.

Microbial life is so important. Just as our gut flora microbiome plays an integral role in our body’s health, the microbiology of the soil around tree roots plays an essential role in the health of the tree.

Tree roots can do their job better when they are aided by mycorrhizal fungi and beneficial microbes. When these ingredients are present in the soil, they help break down organic matter, releasing essential nutrients that the tree can absorb.

In June, supporters of the first “little forest” in Peterborough, the Antrim Street location of Peterborough Child and Family Centres, came together to prepare the soil to plant the mini forest. Pictured here are volunteers acting as the trees that will grow there and provide natural play elements as well as shade for young people at the centre. (Photo: Laura Keresztesi / GreenUP)

In June, supporters of the first “little forest” in Peterborough, the Antrim Street location of Peterborough Child and Family Centres, came together to prepare the soil to plant the mini forest. Pictured here are volunteers acting as the trees that will grow there and provide natural play elements as well as shade for young people at the centre. (Photo: Laura Keresztesi / GreenUP)

Mycorrhizal fungi help trees in many ways. They help roots find water and nutrients in hard-to-access places. As they spread out, mycorrhizal fungi take up essential nutrients like phosphorus, copper, calcum, magnesium, zinc and iron – just like what we need!

Mycorrhizal fungi also protect the tree from harmful fungi, and can even act as underground ‘communication networks’ for trees. Dr. Suzanne Simard, a Canadian scientist at the University of British Columbia, is known for her research on the “wood wide web” or the underground network through which trees talk. Through this network, trees share nutrients, and warn each other about insect attacks, drought or other dangers. In exchange, the mycorrhizal absorbs some of the carbon-rich sugars made by the tree.

One way to build soil health is by gathering a sample of soil from a healthy forest environment and brewing a ‘tree tea’ with it. This soil will be rich in beneficial microbes and mycorrhizal fungi. Bundle the soil up in a piece of material, place it in a bucket of rain water, and let that ‘tree tea’ soak like your morning cup. Sprinkle some compost or molasses to feed the microbes, then water the earth you want to enrich.

Fall is a great time to plant trees. At this time of year, trees have stopped producing leaves and fruit and are putting their energy back into their roots. It is a great time to think about how we care for our trees, by starting with the soil.

Two student volunteers tease apart the root ball from the container of a native tree species at the City of Peterborough’s Trees4Ptbo event on September 23, 2023. Fall is a great time to plant trees, as trees have stopped producing leaves and fruit and are putting their energy back into their roots. It is a great time to think about how we care for our trees, by starting with the health of the soil. (Photo: Lili Paradi / GreenUP)

Two student volunteers tease apart the root ball from the container of a native tree species at the City of Peterborough’s Trees4Ptbo event on September 23, 2023. Fall is a great time to plant trees, as trees have stopped producing leaves and fruit and are putting their energy back into their roots. It is a great time to think about how we care for our trees, by starting with the health of the soil. (Photo: Lili Paradi / GreenUP)

The Little Forests planted in Peterborough this fall will need to have their soil networks kick-started with care. To do this, GreenUP will enhance the fungal networks by inoculating them with our own ‘tree tea’.

GreenUP is extending an invite to community members on October 11th to join Junaid Khan from Trecology for an urban forest hike to make tree tea. We will visit stands that include trees such as maple, birch, cedar, basswood and black cherry to collect healthy microbes. To find out more information, email laura.keresztesi@greenup.on.ca or follow @ptbogreenup on social media.

The Little Forest project was made possible by generous community and volunteer support.