Diversity and suitability (fitness) are the main components of a healthy urban forest. Different species are susceptible to different pests and different kinds of damage, while also flourishing in different environments. The more different kinds of trees are planted in a community, the less vulnerable the overall community forest will be to invasive species, climate change, or severe weather.
- Follow the 5:10:15 rule. In any community:
- no more than 5 percent of trees should be of the same species
- no more than 10 percent should be from the same genus
- no more than 15 percent should be from the same family
- When choosing a tree to plant, make sure it is suitable for the growing conditions. The Northern Illinois Tree Selector is an online tool that suggests good selections based on location, site conditions, and preferences. Request a printed version.
- Selecting and Planting Trees is a handbook of step-by-step, nuts-and-bolts instructions and advice.
- Tree Planting offers guidance on the best way to plant a new tree.