There are probably as many different definitions for an urban forest as there are people you ask. One definition on the internet stated simply it was a densely wooded area located in a city. Hmmmm, well. Do they mean a remnant of an original forest? Or are they talking about a planted park? Do these two features alone define an urban forest? What about those cities without remnant forests that claim to have an urban forest? I am picturing the cities that have grown out of the Great Plains which was prairie with barely a tree in sight.
Another definition I came across comes from Wikipedia: “An urban forest is a forest or a collection of trees that grow within a city, town or a suburb. In a wider sense it may include any kind of woody plant vegetation growing in and around human settlements.” (I like this a bit more.)
Then a quote from the forest service website: “Over 130 million acres of America’s forests are located right in our cities and towns. Urban forests come in many different shapes and sizes. They include urban parks, street trees, landscaped boulevards, gardens, river and costal promenades, greenways, river corridors, wetlands, nature preserves, shelter belts of trees and working trees at former industrial sites.” Alright! Now, we’re talkin’!
I did find it interesting they specifically included “working trees at former industrial sites”. Actually, you could say all trees “work”. They are cleaning our air, replenishing oxygen into the atmosphere, taking in carbon dioxide, sequestering carbon, cooling our homes and streets, providing wildlife habitat, providing shade for those picnics and summer time festivals. They are mitigating storm runoff, reducing the heat island effect, and attenuating noise. They offer shelter and protection against wind. They provide recreational venues and the opportunity to find peace and tranquility in a hike.
If there are any of the above attributes you feel are undeserved, consider that not all trees perform the same functions in a like manner. Some trees have been misplaced (by us) which could minimize their abilities. Some are so mismanaged by us, they can offer only a mere shadow of their full potential. None of these circumstances are their fault but more often stem from our errors.
An urban forest is not comprised merely of the street and park trees owned or controlled by a municipality. But, in my opinion, encompasses every plant in any built environment ranging from residential, semi-rural, exurban, suburban to the hardcore urban centers. And it doesn’t matter where they are planted. They might be located in a park, in boulevards, a private garden, downtown shopping malls, rooftop gardens, potted plants. They all count.
Notice I said “every plant”. If I were writing the definition, I would enlarge it to include every photosynthesizing organism. So we would include turf grass, annual and perennial flowers, herbaceous and woody shrubs as well as our long-lived, perennial trees. If managed properly, they all contribute to a healthier environment….because they ALL photosynthesize.
Photosynthesis is one of the two most important energy-related processes in the world, the other being cellular respiration. (See my blog Understanding Photosynthesis, which actually should be retitled to Understanding the Importance of Photosynthesis.)
If you live in a city that has an Urban Forest Management Plan, you may have seen or read the information on species inventory and the benefits these trees give back to the community. These inventories generally only tally the municipally-controlled trees and do not include those in the private sector which could easily double the number of trees and, therefore, the benefits provided.