City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: http://read.dmtmag.com/i/46119
Tree Species Presumed to be Fall Hazards Common Fall Hazard Traits Minimize Moisture Loss Acer rubrum Betula sp. Carpinus sp. Celtis sp. Cercis sp. This B&B tree was shipped so dry that sandy soil poured out of the rootball when the burlap sustained a small tear. have the time or capability to dig the trees before it becomes too cold or the growing fields become inaccessible to machinery. A perfect example of this can be seen with the genus Quercus, which goes dormant extremely late in the fall. A possible solu- tion is to strategically procure trees from distinctly different climates. For example, if Quercus were on a planting plan in the fall, it would be wise to obtain trees from a reasonable northern source where there is an earlier digging season, thus making the trees available weeks ahead of locally grown trees. Regardless, it is absolutely critical to ensure that trees are har- vested in a dormant state. 2. Root Prune Coarse-Rooted Trees Some trees that have been labeled fall hazards have coarse root systems that regenerate more slowly. The genus Nyssa has a tap-root-like root architecture when compared to Metasequoia, which has a much more fibrous root system. Research indicates that the roots of Quercus coccinea require approximately three to four times longer to regenerate than those of Q. palustris. Also, if a tree with coarse roots is harvested in the fall and a harsh winter comes along, freezing the soil early and consistently, the tree becomes more easily desiccated due to an inability to replenish water. Therefore, any coarsely rooted tree should be prepared for digging in the fall by root pruning the previous spring. Careful root pruning in the beginning of the growing season forces a more fibrous root system by fall harvest time. For example, a 2.0- to 2.25- inch (51-57 mm) caliper tree could be prepared in spring by spading two or three sides of the root system as if it were going to be placed in a 28-inch (71 cm) root ball. It would be left in ground and allowed to grow until fall harvest, at which time the tree would be spaded and placed in a 32- inch (81 cm) root ball. 3. Harvest Thin-Barked Trees with Abundant Twigs with Special Care Deciduous trees desiccate during dormancy due to cold, wind, or sun, especially when the ground is frozen. This problem is compounded in trees that have thinner bark because there is more cambial activity on sunny days for thin-barked trees. Desiccation is also more likely on trees with abundant twigs www.urban-forestry.com Cercidiphyllum japonicum Cornus sp. Crataegus sp. Fagus sp. Halesia sp. Liquidambar styraciflua Liriodendron tulipifera Malus sp. Nyssa sylvatica Ostrya virginiana Platanus sp. Pyrus sp. Quercus sp. Taxodium distichum Tilia tomentosa Zelkova serrata X X X X X X X X X X X X X X X X X X X X X Thin Barked Trees X X X X X X X X X X X X X X X X X because there is an increased surface area exposed to potential inclement conditions. Ensure that vulnerable tree types get harvested in the right size root ball or one size larger in an effort to retain as large a root mass as possible. A larger root mass translates to a larger amount of available moisture contained within a tree. Additionally, trees with thin bark and abundant twigs should be watered during the winter season when there are extreme cold, windy, or sunny conditions. 4. Minimize Water Loss to Root Balls After harvesting, trees need a constant source of water, espe- cially when they are stored above ground. The outer layer of burlap around the root ball will wick water out of the encased soil during dry, windy, or sunny days. Make sure that trees are well watered until they are planted in the ground. Letting the root ball dry significantly even one time can cause tree mortality or make it virtually impossible to restore moisture to the core of the root mass. Depending on the weather conditions, it might be necessary to water an aboveground tree with a slow soaking for at least five minutes per day. Additional precaution could be taken by heeling the trees in mulch. 37 X X X X X X X X Harvest Time X X Trees with Coarse Roots X X X