Friday, June 6, 2014

“Not another tree?”


Eric Berg


            On my wall, handwritten on the back of an old envelope in a script that only landscape architects and designers seem to master, are the following letters: OPPORTUNITYISNOWHERE.  There are two ways to read and approach this statement – opportunity is nowhere or opportunity is now here. I believe spring is a reminder for all of us that opportunity is now here, this spring, to plant a tree for future generations and to the benefit for those that will follow after us.

            Now if you live at the Berg household, you know the typical response would be “there is no more room for any more trees in this yard – end of subject.” I agree, 30 plus trees on a typical home landscape does seem a bit excessive, but opportunity is now here, it’s spring, there is surely room for one more. The opportunity falls under the category of what I like to refer to as anticipatory planting. This type of planting investment is based on the reality that trees do not live forever and not all species are created equal. Anticipatory planting is the act of planting a tree years, or even decades, before the anticipated removal of an over mature or disease prone specimen.

            For example, if you have a large silver maple, Siberian elm or linden in your yard you may be dealing with a tree that is mature or over mature with a defined and limited lifespan.  These species also have a tendency to be fairly intolerant to the extremes of Nebraska’s weather with excessive of limb breakage with ice, snow and wind events. A better example are the ash species in our landscape. Based on urban plot analysis completed in 2011 by the US Forest Service and Nebraska Forest Service, Lincoln has approximately 1,511,000 trees within the city limits. Of this total tree population ash represents approximately 7.2 % which equates to more than 108,000 trees planted along our streets, parks and landscapes.

            At this point hopefully most of you have heard about this little green invasive menace called emerald ash borer (EAB) which will soon threaten or kill all of the 108,000 ash trees in our community. Treatment will be a good option for many high value and generally younger landscape trees when the insect is detected locally. But not all trees will be saved as many trees will be too costly to economically or effectively treat – thus the anticipatory planting opportunity is now here!

            If you find yourself the owner of large mature ash on or adjacent to your property the probability is foreseeable that the tree will not be there within in the next 5 to 10 years due to EAB. Now is the time to anticipate that loss and prepare another planting site to replace the canopy and tree benefits you are currently enjoying.

            Not all landscapes and planting opportunities are created equal and space, rooting area, above and below ground utilities all will define limitations that must be considered. Shade tolerance, the plants ability to tolerate and grow in lower light levels, will also be a limiting factor in species selection and placement. In general, most large maturing trees, including my favorite the oaks, are considered shade-intolerant and do best with 6 hours a day or more of direct sunlight during the growing season.

Examine your landscape and look for planting opportunities at or near the tree canopy edge and located to the east, south or west of the tree your are replacing. In my own home landscape the large mature green ash planted along the street right-of-way created an opportunity to plant a large maturing bur oak directly to the south approximately 20 feet. While slightly in the shadow of the ash, the oak still receives plenty of direct sunlight and when in the next five or ten years this ash is lost to EAB this oak will be well on its way to fill in the gap and provide on-going generational benefits for those who might enjoy this landscape well after I am gone. 

The potential species list for ash alternatives and replacements is a virtual who’s who for diversity and dependability. Some of my favorites for eastern Nebraska include: Kentucky coffee tree, ginkgo, northern catalpa, Osage orange, hickory and many of the oaks such as bur, white, shingle, chestnut, Shumard to name but a few. On a side note, do not let some of the above species scare you away from planting when you view them in the nursery. To say that catalpa, ginkgo and Kentucky coffee trees are unimpressive looking when young would be an understatement. But trust me, properly plant and care for any of these species and you will be most impressed with the results. Follow guidelines for planting success from ReTree Nebraska and our friends at the Nebraska Statewide Arboretum by visiting http://retreenebraska.unl.edu/ and http://arboretum.unl.edu/. Opportunity is now here, consider your landscape, anticipate the trees that you will lose and plant accordingly.

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