Friday, October 12, 2012

Thinking about Our Trees II

As a follow-up to the last post regarding the benefits of trees, here are some thoughts and suggestions as we go forward in what will likely be a hotter and drier climate. The potential impact on trees is not completely understood, but I hope we're committed to keeping our community forests green and vibrant.

Lincoln's street trees are vital to community health and vibrancy.

One thing that the drought has helped make abundantly clear is that we can no longer take our trees for granted. For several decades, relatively abundant rain in our area has made it fairly easy to grow trees in including many marginal species that would otherwise not grow here. But there is a reason that prairie dominated this part of the world before settlement: the rain often goes away for long stretches at a time. Water is the limiting resource in this equation and for us to succeed in developing and maintaining a vibrant community forest we need to make that forest more resilient to the impacts of drought. A few suggestions:

1.       We need to be more thoughtful in picking the right tree for the right place. This is especially true for trees that will be expected to survive without any supplemental moisture. We’ve gotten a bit complacent in recent years and have selected many of our trees for ornamental appeal. Red maple, with its brilliant red fall color, is a classic example of a very popular tree that is not nearly as drought-tolerant as species like bur oak, red oak, coffeetree, hackberry, buckeye, Osage orange, pecan, walnut, etc.  

2.       Let’s think canopy! The community forest works best when there are lots of wide spreading shade trees coming together in a leafy embrace! Too many of our shade trees have been replaced by shorter-growing ornamentals.

3.       Plant trees close together and with other landscape plants to help separate them from the areas we mow. Trees that are grouped share a healthier soil (rooting zone) and are more drought tolerant than scattered individuals.

4.       Be smart with irrigation. In a typical summer (let alone a hot/dry summer), more than 3 billion gallons of water is sprayed on Lincoln’s landscape—primarily its lawns. Is this water being used efficiently and to aid in the best survival of our trees? It’s certain that there will be watering restrictions imposed during future droughts. Instead of designing irrigation systems primarily to keep large swaths of naked lawns green, we need to start thinking about irrigation as a tool primarily used to carry our landscapes through drought. One of the great things about trees is that most are actually quite drought-tolerant and just an occasional watering around them might be all they need to survive a severe drought.

5.       Speaking of irrigation, it’s probably time for a little tough love with more of our green space. Too many landscapes are now babied along with irrigation throughout the growing season. Unfortunately, when drought comes and watering bans are implemented, such landscapes are not able to survive on their own. Trees and other landscape plants that are forced to endure dry periods are better able to survive a severe drought. The trick is for us to find that happy medium.

Lincoln’s community forest is literally worth hundreds of millions of dollars (if not more). As with our built infrastructure—utilities, buildings, roads, etc.—our green infrastructure, especially trees, requires significant and ongoing attention, work and investment. And nearly anyone can help in their planting and care. To me it is abundantly clear that by helping to plant and care for trees, we are helping to make our communities much more livable. It starts in our own backyards and on the blocks that we live. The simple act of planting a tree—and then caring for those trees, is one of the best ways anyone can help make their community a more beautiful and prosperous place.  

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