Family:Betulaceae, The Birch Family (1) Genus:Betula L. – birch (1) Species:Betula papyrifera Marshall – paper birch (1) Common Names:White birch, canoe birch, silver birch, western paper birch, mountain paper birch, Kenai birch, Alaska paper birch, and northwestern paper birch (2) Cultivars: ‘Prairie Dream’ is a cultivar from North Dakota and ‘Renaissance Oasis’ is from Ohio both of these have proved strong resistance against borers and climate extremes. (2) Region of Origin:The range of paper birch follows along the northern limit of tree growth across Canada and moves west into Alaska. The southwestern region is near British Columbia and the state of Washington. There are only scattered outliers to be found in Montana, and the Dakotas. The trees can be found through Minnesota, Wisconsin, Michigan and up along the east coast from North Carolina. (2)
Figure 1: North America growing region of Paper Birch
Figure 2: Paper birch forest. (10)
Form: Height at maturity: 50-75 feet (3) Girth: up to 24" in diameter but usually found with a diameter of 10-14" (3) canopy spread: canopy spread can be seen between 20-40 feet. (3)
Life Expectancy: The paper birch's deciduous leaves make this a perennial tree in the Norther region. It has a relatively short life span of 80-120 years. The paper birch is highly susceptible to Bronze Birch Borer which targets distressed birch trees. These birch trees are commonly found in urban environments where drought, construction projects, and root stress are more common. They also struggle in urban environments due to soil compaction and pH levels.
Wood: The wood structure is diffuse porous. Its is a heavy, strong, and fine grained wood with many commercial applications. It is used for boxes, baskets, toothpicks, popsicle sticks, and tongue depressors. It is also used as veneer in aircrafts and automobile applications. Birch sapwood is white and its heartwood is a reddish brown tone.
Figure 3: Paper Birch Wood cross section
Site Characteristics: Paper birch trees prefer slightly acidic soils (pH 5.0-6.5). Its optimum soil is moist, but well drained. They have a very shallow root systems so they are very susceptible to stress, even from short periods of drought. These trees should be planted in locations where the soil will remain slightly shaded, cool, and moist. The biggest challenge in site location is to also optimize sunlight for the leaves for most of the day. Paper birch prefer mostly sunny conditions for its foliage. Planting birch trees on the North and East sides of a building are ideal. Birch trees can get well above 30' so planting near overhead wires is not advised. Birch trees do not like compacted soils, with this being said there are a number of cultural practices in which you can adopt to help minimize the stress under these conditions. Mulching is one of the most important because its decomposition adds organic matter to the soil which will help reduce compaction around the roots of the tree. Watering of any birch tree is most important due to their shallow root structure. Soil should remain moist throughout ye year and decreased in late August for the trees Winter preparation. Paper birch is zone hardy from 3-6 and can survive throughout most of the northern United States.
Figure 4: Summer Foliage
Figure 5: Fall Foliage
Reproductive Details: Paper birch trees have a single, alternating leaf structure with a double serrate margin. The shape is ovate and the leaf venation is pinnate. The leaves are usually 2-4" long and are green- yellow depending on the season. Paper birch trees have imperfect flowers which mean that they only contain one gender. Perfect flowers have both genders and can self pollenate. The fruiting female catkins are deciduous. The male catkins have 1-4 per bud with male flowers in clusters of 3 with 2 stamens per flower. The growing season for the paper birch is relatively long. The fruit are numerous small single seeded nutlets, and all birches can hybridize with each other. Paper birch trees bloom from March-April. Propagation is mostly taken place from both cuttings and seeds. Cuttings should be taken in the early Spring, and the most optimum time to preform a cutting is in the morning when it has rained overnight. Seeds propagation should be planted 1/10th of an inch under the soil to optimize sun penetration for germination.
Figure 6: Paper Birch Flower
Figure 7: Leaf structure: Betula Papyrifera
Uses: As stated above, Birch wood is used for fire wood, toothpicks, carvings, and tongue depressors. Many historical nations used birch bark as material for baskets, cradles, and canoes.Birch oil extract is used to repel some insects. Birch extract and leaves have also been used historically as a laxative, and have been known to help with burn and wound treatments. The sap from birch trees can be used to make syrup, vinegar, and birch beer. Nature also uses birch trees, over 30 types of birds and mammals use birch trees for food. Within the landscape birch trees are used for many design styles. They offer a unique textured bark and offer impressive shade when found in a broad clump form. Paper birch trees can be used as foundation plantings to scale a home's curb appeal and line property borders. It can also be used as a windbreak in certain scenarios. Although paper birch trees have a shallow root system, their roots rarely protrude above the surface, making this a great tree to plant in the lawn or near sidewalks, and roadways. Paper birch can also be planted as a specimen tree in landscape beds with other smaller plantings surrounding it. (9)
Maintenance: Step by step instructions for Proper Paper Birch installation: Although paper birches can be planted at anytime of the year. If site conditions are limiting, pick a time of the year that is cool, has partial sunlight, and has an area that has moist soil. Step 1: select proper sunlight and soil conditions for your paper birch with the information listed above. Avoid overhead power and telephone lines, and compacted soils. Consider canopy spread and height at maturity to ensure there is enough distance to nearby obstacles. Step 2: Plant the birch tree using best management practices for they type of tree you are planting i.e. seedlings, potted, Balled and burlap, or dry rooted. step 3: Maintaining your tree: Water the soil consistently to attain moist soil conditions. Test soil conditions to determine if there is a need for fertilization. If there is a significant nutrient deficiency fertilization should be preformed. Fertilizers should be applied in early spring or late fall. Maintain proper tree architecture throughout the trees life. Pruning should not be done between may 1st and august 1st. This is when bronze birch bore is most likely to be seen. (4)
Limitations: diseases, pests, and general requirements Paper birch has two major pests, leaf miner and bronze birch bore. Bronze birch bore is the only one that kills the tree, but leaf miner can significantly reduce the attractiveness of the tree. The other risk of leaf miner is that it can reduce the birch trees resilience against bronze birch bore. By using an insecticide on birch trees you can help prevent trees from going into periods of stress. This insecticide spray is most effective when used as a foliar spray application. The first application is most critical and should be done in very early spring. Bronze birch bore has a separate list of preventable measures as follows: 1) Make sure your birch tree is planted in an appropriate site location. 2) maintain tree health to the best management practices through the information above. 3) If the tree does become infested follow a very heavy watering schedule, also apply insecticides to the bark to prevent further infestation. If the tree only shows dead branches on part of the canopy, prune out infested branches (see figure below). Paper birch trees require moist soils, a ph level between 5.0-6.5, and thrive in cool temperature locations. If these basic requirements are met, the chances of obtaining a healthy tree for many years is a much more likely outcome. (4)
Figure 8: Dead wood pruning: before and after (8)
*The champion Paper Birch tree has grown to a height of 93' and the spread of its crown is 65', it is located in Hartford, Maine. *For more information on the building and design of authentic birch canoes please visit: http://www.nativetech.org/brchbark/canoe.htm