November 3, 2019, by Bea Heissler
Now that the market season is over, it’s time to put the potted trees and shrubs away for the winter. We set the trees tightly together into trenches that are about the depth of the pots. Then, use leaf litter to cover the edges of the trenches and around the tree and shrub stems to insulate the roots from severe cold.
We are also planting the many trees and shrubs that can’t be sold into an area that we are slowly reforesting. The dormant stock is good to go into the ground just before freeze up. Some mulch around the base of the trees will help to keep the frost from getting under the root ball and heaving it out. Snow will later provide additional insulation and the trees and shrubs can enjoy an early start next Spring when the ground is saturated and rains are usually plentiful.
We have many different species which we mix up when we plant. Monocultures are vulnerable to diseases and insects.
Before we moved to the farm, we lived on a reforested hill that was planted with Red Pine. The pines were fairly mature and created a continuous cover. Then, one year, a large swath died off. We cut out the dead trees and planted the area with a variety of deciduous trees as one would expect to see in a natural forest in our area. Different trees and shrubs attract different animals. The more species in an area, the greater the stability as there are many checks and balances that have naturally developed over thousands of years. Monocultures lack many of the natural controls present in a biodiverse community.
Winter Tree Protection:
When we plant deciduous trees like Maples, Oaks, Cherries, Birch and Aspen we put tree wraps around the lower main stem to provide them some protection from rodents who will chew off the young bark over the winter months when other food may be in short supply. A girdled stem kills the trees as the food produced by the leaves next Spring cannot reach the roots via the tender inner bark. If animals browse on the upper branches, the tree will put out new branches as would happen when we prune trees. There’s no real harm done with this kind of browsing.
Changing Ranges of Species:
Here, in Southeastern Ontario, we live north of the Carolinian zone which includes southwestern Ontario. In the past, winter temperatures would dip too low for many Carolinian species of trees and shrubs. With climate change, however, temperatures are rising. So, we planted American Sycamore, Tulip Tree, Kentucky Coffee Tree, and Redbud several years ago. All are doing well without extra protection.
The ranges of many plant and animal species are moving northward. As gardeners and land stewards, it only makes sense that we work with the changes that are happening. Rather than trying to restore what was, be aware of the changes and work with the evolution happening in natural communities.
When I first started the native plant nursery, I created demonstration gardens with a diversity of wildflowers and grasses. Insect activity was phenomenal with most species familiar to me. But there was one very large swallowtail butterfly that I had never seen before. Upon checking my books, I realized the Giant Swallowtail was completely out of its range. Its larval host plant was the citrus family. In the Carolinian zone, this would be the Hop Tree, Ptelea trifoliata. In this area, the caterpillars would have been feeding on the foliage of Prickly Ash, our only member of the citrus family.
Last year, I started some Hop Trees from seed. Late this summer, the saplings were covered with Giant Swallowtail caterpillars. They look like fresh bird droppings. When they feel threatened, they stick out what looks like a red forked tongue that would send small birds flying off in fear of being devoured by the “snake”.
The caterpillars appeared late in the season just before the leaves would be shed. The trees saplings were almost ready to go into dormancy and will likely have no problems putting on new leaves in the Spring.
Though insects can appear to do so much damage, it is clearly not in their best interest to kill the host plant. We just need to remind ourselves that the two species have evolved together and inherently “know their limits”. It’s only when natural controls don’t exist anymore, that a species can truly be ravaged by its pests.
We need to do everything we can to protect biodiversity as the current global environmental crisis involves the extinction of many species that have been around for millions of years. Every loss is a loss to the rest of the natural community, including us. Human activity has so seriously impacted the environment, climate and biodiversity that scientists have given this geological era its own special name, Anthropocene. Perhaps, we can turn this around and make the Anthropocene an era that turned out to be positive because collective human vision, will, and action made it so.
With or without human activity, change is a constant. Life and interrelationships in the natural environment are always evolving to adapt to changes in the many variables. We need to adapt as well. With changing weather patterns and more extremes, it would be foolish to try to maintain the status quo. Ten thousand years ago, this area looked like the tundra with massive sheets of ice retreating northward as they slowly melted away. Natural communities of today evolved as the temperatures rose and climate changed. No one knows for sure where we are heading. Nature is full of surprises.`