Cities are growing as our populations continue to grow and our demand for houses. As we clear urban forests or neglect to allocate consistent funds to manage and maintain healthy urban forests, we lose. The current practice of clearing forests for large track-house, mini-mansion, or apartment developments is fast and easy and causes irreparable damage. Those trees are 70 - 100 years old; have a diversity of species not easily replaced and were the home to birds we love like the red-tailed hawk and vireos. Replacing sourwood, blackgum, hickories and others is expensive because of the way they root.
Studies looking at the role of cities and their urban forests as conservation sites for the biodiversity losses in adjacent once-wild or still-wild habitats is interesting and hopeful!!!
There are caveats which I will address last.
Several plants of rare or endangered status have been found in urban settings, people's gardens. The preservation of ash and hemlock trees by individual homeowners provides future seed and pollen reserves that could help natural populations start again once we've eliminated the borer or adelgid. These are a kind of genetic banking.
17% of the ~ 800 North American bird species are in decline and 20 species of once "common" birds have declined by 50%! This has led to more than just planting more trees but a movement to plant habitat for the birds-and-bees. The US Forest Service, who not too long ago thought an urban wildlife movement laughable, has signed on. Cities like Phoenix, Oslo, and Singapore have joined a movement called the Biophilic Cities Network - I want Baltimore and Knoxville to join that movement. Heck - I want every city to join that movement.
So, why should we support the native tree diversity we find around our cities by caring about what is in our cities? Because the areas we live in are unique and to be celebrated and a lot of us hike, bike, kayak these areas because of the nature and what it gives us. We can create a little piggy-bank with the possibility of serious ROI simply by changing what we are growing along our streets, outside our stores, in our gardens. Through selected urban forestry planning and funding, through our garden habitats and yard choices, we can create a habitat friendly to the creatures we love and many we don't see, don't know. In this way, by preserving say, our oak tree diversity, we can ensure the 6K - 9K caterpillars a single pair of chickadees need to feed their offspring, are available.
Another major consideration is the impact of invasive plants on the biodiversity in our urban forest habitats. Between 17% and 50% of plants in urban green-ways are non-indigenous. They are weedy because they can grow faster and throughout the year thereby literally covering the indigenous plants with blankets of leaves. We still sell a lot of these from our local greenhouses and horticultural big box stores. They don't feed the native birds and they can change the soil making it less healthy for the indigenous plants. Part of what we need to provide funds for is managing these forest habitats. It's a daunting prospect if we think of it as having to be done this year or next year. Instead - making a 10 year plan to address the areas bit by bit is probably more manageable mentally and economically.
A great set of projects by my favorite landscape design/installation company can be found at (see their projects menu) https://www.gardnermonaco.com/
Does your city have a urban forestry office or a sustainability office? If so, you are lucky! Now, how man people are employed in those offices and what is their annual budget? Do they have oversight of the green-ways in your city? Who do they contact with to manage those green-ways? Are those people trained in landscape ecology or plant ecology? Answering these questions may take about an hour of your time and could help you to help your city and your experience of the forests you call home.
Better Nature is dedicated to helping preserve our mature trees and ensure those saplings become mature. We are also dedicated to using plant health care approaches that protect the food need by chickadees and pollinators and even the beloved non-venomous snakes that keep mole/vole populations low.
Citations for above include:
research papers by Dr. Douglas Tallamy
Royal Horticultural Society