The ReLeaf Tree List

The heart of this plan is a new citywide tree list for Cedar Rapids that embodies the first four of the ReLeaf Rules: “Right Tree, Right Place, Right Reason,” “Citywide Diversity & Local Character,” “Locals Not Imports,” and “Big Not Small.” The new list is a modification of the City’s previous list that more fully reflects the ReLeaf Principles.

A key aspect of the ReLeaf Tree List is that it groups trees by desirability. Trees are either Superior, Allowed, or Contingent. To maximize community and ecosystem benefits, only trees from the Superior category should be planted. These trees are not only large and hearty; they also support the food web; all are either natives or native cultivars that support caterpillars. Ideally, newly planted trees would be sourced from this list alone, up to the point that any one species, genus, or family meets the 10-20-30 rule.

However, the “Right Tree, Right Place, Right Reason” rule means that the Superior list is not enough. So does the supply chain of trees: there just aren’t

that many natives to be had on short notice. For that reason, the Allowed category includes additional big, locally adapted trees that may not support the food web but are preferable to a hole in the canopy. Finally, there is the Contingent category, so named because there are certain places where a large tree truly won’t fit. Most often, that is under transmission wires. These trees are smaller, but none of them are exotics with no roots in Cedar Rapids.

The ReLeaf Tree List encourages us to plant Superior trees whenever we can and plant Contingent trees only when we have no other option. Residents are, of course, free to plant whatever they want on their private property but will be encouraged to learn about the ReLeaf Tree List and to follow its guidance.

The Tree List orders trees by their contribution to the food web, with the shape of the canopy and growth rate also shown. The Tree List shows the right place for each tree. Finally, the List identifies which trees produce flowers, fall color, or edible fruit.

> Find the ReLeaf Tree List in the Appendices section at CityofCR.com/ReLeaf.

The Importance of Natives

For many years, urban foresters have debated the importance of planting native trees in streets and yards rather than the wide variety of attractive imported species that have proliferated across the continent. What the foresters questioned, the biologists have confirmed. Non-native trees can provide many useful ecosystem services, but one thing they do not do is support the food web. In fact, they actively undermine it.

Plants and animals have evolved in tandem across the millennia. It takes hundreds of thousands of generations for insects to alter their diets. Most insects are restricted to eating just a few plants. Monarch butterflies for example, only eat milkweed. Native plants support native wildlife. A plant that supports more than 100 species in another country may support five or fewer here.

In addition, imported trees and plants may overrun native plants in natural areas. Planting an imported tree is not merely a missed opportunity to plant a native tree; rather, it often leads to a net loss in native trees overall. Fewer native trees means less food for native creatures.

City Street Tree Inventory

Enough with the Maples, Already!

The pie chart shows the diversity of Cedar Rapids’ street trees in 2014. It’s worse than it looks. The latest tree blight, emerald ash borer (EAB), means that the City stands to lose as many as a quarter of its street trees aside from the derecho. The lesson here is clear: planting so many ash trees was a mistake. Looking at the chart, does anything else trouble you? Cedar Rapids is, in a word, over-mapled. At least as far as street trees go, we have exceeded recommendations for planting one genus. This excess is mirrored on the private side, where maples are clearly the yard-tree of choice. This is understandable, given their lovely fall color, but it is not resilient or sustainable. For this reason, maples are not included in the ReLeaf Tree List. We can look forward to a time when Cedar Rapids’ canopy is so robust and diverse that the planting of maples can be encouraged once more.