EUCALYPTUS 

                  Eucalyptus changes in different conditions, as trees age, and with different environments. It tends to grow straight and tall when in a forest setting with branches only at the top.  Growing alone in an open area the tree is shorter with more branches.  In temperate climates, the apical dominant forest trees are often evergreens with tier branches.  In the tropics, the apical dominant forest trees tend to have arch branches.  Eucalyptus are native to Australia and have been extensively planted in Hawaii.  It is a good example and even old trees have relatively few branches.  

EucalyptusSilvacultureHonokaa.jpg (27694 bytes)
         Eucalyptus are extremely fast growing trees and as the sugar companies go out of business,  many acres are being planted in the Hamakua district which has deep soil and a good amount of rain.  They are planted as seedlings and the ones in the photo are only 2-3 years old and already more than 25' tall with 4" to 6" diameter trunks.  They are planted closely together and such trees grow straight and have no branching. 
EucalyptusIntermediateHonokaa.jpg (22868 bytes)          These Hamakua trees are near the town of Honokaa and part of a naturalized forest. New seedlings continue to germinate and the seedlings streak upwards seeking light. When an old tree dies, there's a hole in the natural canopy and all seedlings below it start stretching and elongating towards that light. Because there's very little side lighting, there are no branches. 
EucalyptusInFogHonokaa.jpg (13060 bytes)          It was a foggy day when I took this photo and the one above. The highway cut through an older forest of trees 60' to 80' tall with the largest having trunks 12" to 16" in diameter.  Notice that the trees have very few strong branches except at the top.  Branches on the lower part of the trees are weak and will likely die out.
EuclyptusHiloOlderGroup.jpg (20941 bytes)           Eucalyptus are not shade tolerant. When growing in tight forests, lower branches quickly die out and foliage remains only at the top.  In more open clusters like these in Hilo's Waiakea Village, there are more side branches, but only facing towards the outside of a group. Branches facing towards the center of a cluster would be in the shade and die out.  If two trees are growing close together, it is very unlikely for branches to develop between the two trunks.

          This suggests a basic bonsai pruning guide.  Remove branches facing into another tree.  Conversely, if you have two slender trees with branches mainly on one side of each tree, try placing the two bare trunks together with all branches facing outwards. Skimpy trees are suitable for group plantings. They would require extensive and lengthy training for them to be suitable for single tree bonsai.

EuclyptusOldLiliukalani.jpg (18091 bytes)           A tall older Eucalyptus growing out and up along a slope in Hilo's Liliuokalani Gardens.  The couple picnicking and the car giving a sense of scale. The tree is well over 100' tall. The lower part of the trunk has rough bark, but the top half of the tree has shed its outer bark to reveal a smooth light colored trunk.

          Notice that there are no branches until the tree emerges from the shade of the other trees. Even then, there are relatively few branches.  The number of low branches is an indication of a plant's shade tolerance.   Trees that are shade tolerant can be made into dense forest or landscape arrangements and are easier to maintain. 

         

 

EuclyptusOldLiliukalaniDetail.jpg (13237 bytes)           Looking up into the crown of the tree above, you'll notice that there are strong branches where there's a lot of light, and that a fairly large branch died when a nearby tree shaded out the branch. 
EucalyptusFBCLookingUp.jpg (24085 bytes)           When trees are growing close together in a grove or clump,  branches develop only on the outer edges where there's a lot of light.  In bonsai,  trees that have good branches only on one side are ideal for group planting.  Conversely, when planting trees close together, remove branches that grow into other trees or towards the center of a group. These are part of the windbreaks at Fuku-bonsai in Kurtistown on the Big Island of Hawaii. 

                These photos show Eucalyptus which has very strong apical dominance growth characteristics with limited shade tolerance.  Translated into bonsai terms,  thin trees with few branches are most suitable for multiple tree groupings to create the desirable mass.  Each slender tree would require an extensive amount of skill and many years before they become suitable for individual tree bonsai.

              At Fuku-Bonsai we grow forest arrangements mostly for our exhibit collection and utilize choice pre-trained trees of different heights and trunk thickness. While we need variety for interest, all trees are of the same plant variety.  We do not create mixed forests of two or more major trees as all plant varieties grow at different rates and as a practical matter care would be more difficult.

               Understanding the role of light is important.  If branches are too close or if one is directly above another, branches may die.  If the crown of the bonsai is allowed to be too luxurious, the most valuable bottom branches will die. The general rule is to prune the part of the tree that is growing strongly.  It's easy to create nice top growth but more difficult to create strong lower branches.  To create strong middle branches, the top of the bonsai must be pruned often. To create strong lower branches,  prune the top very often, prune the middle branches a little less often, and prune the lowest branches sparingly. 

EucalyptusNamakani1.jpg (23556 bytes)         Namakani Paio is part of Hawaii Volcanoes National Park and a lesser known but nice camp site in the summer.  It's about 5,000' elevation and it's usually about 30F cooler than at the Hilo or Kona beaches. In winter, temperatures can drop close to freezing and the cabins have fireplaces. 

        Some of the oldest Eucalyptus trees in Hawaii were planted here many years ago. This tree was planted in an open area and with a lot of light from all sides, its developed multiple trunks and a more strong lower branches.   Even so, the trees are tall and relatively narrow.

 

EucalyptusNamakani2.jpg (28133 bytes)         Eucalyptus are classical apical dominant trees that generally are found only as straight-trunked trees. As in the above photo, there's some branching with an abundance of light from all sides.  But where trees are growing closer together, there usually are no lower branches. Notice the varying trunk sizes. The ones at the left are medium size with a very heavy trunked tree in the middle (with photos below) and thinner clumps beyond.
EucalyptusNamakani3.jpg (24876 bytes)         A close-up shows trunks growing into each other and fusing as trunks expand with age.   Within the very limited space in a tight forest arrangement, it is necessary to be able to create very tight groups to be able to have the option of open areas to provide the variety of spacing needed in attractive forest plantings.
EucalyptusNamakani4.jpg (31063 bytes)         This tree may be the oldest original tree and is over 200' tall.  The trunk is covered with rough bark and there are no branches on the bottom portion of the trunk with the lowest branch about 125' above the ground!
EucalyptusNamakani5.jpg (33406 bytes)         The lower trunk and trunk base.  Older trees have a lot of character even when the trunk is straight.  There are vertical creases known as furrowing and there's buttressing as the trunk enters the ground.  Bonsai that do not have this strong trunk connection with the ground lack visual stability and such a bonsai  resembles a telephone or electrical pole rising out of the ground.

        When measuring one foot about the ground, the trunk of this tree is about 9' across. If you were to cut through the trunk, it would have a cross-section resembling a daisy pattern. In contrast, if you cut through a younger tree, the cross-section would more likely be a circle. 

EucalyptusNamakani6.jpg (29349 bytes)         Even when looking up into the crown of a patriarch tree, you'll sense the grandeur of age.  While there are bonsai techniques that can suggest age,  there's really no short cuts and a bonsai needs about 30 years of training to develop the bark, furrowing, buttressing and taper of an aged tree.
EucalyptusNamakani7.jpg (32806 bytes)         With the old tree on the left, the trees on the right appear to be comparatively young.  In a forest arrangement, having trunks of various trunk thickness and heights is desirable.  To create harmonious arrangements,   the tree with the thickest trunk should also be the tallest.  In creating Peace Forest, there were no thick trunked trees available.  Kato visually placed trees behind each other so two trees appeared to be a heavier-trunked tree.  The focus is to now thicken the large trees while preventing shorter trees from thickening.   
EucalyptusNamakani8.jpg (34992 bytes)         Looking up in the midst of the grove of younger trees, there are again no branches on the lower part of the trunks and all branches face the outer part of the grouping. No branches face into the trunks of other trees.
EucalyptusNamakani9.jpg (32352 bytes)       Another two trunked tree nearby grows apart from the other trees and has more branches. But note that the lower branches are weak while the crown is vigorous.  When training bonsai that are like this, it is necessary to drastically prune the top growth to encourage stronger growth in the lower branches.  Too often a bonsai has a beautiful crown by weak lower branches.  It's better to focus on creating strong lower branches as its relatively easier  to create a nice crown later.

                In 1980 after extensive search Saburo Kato selected Weeping Banyan (Ficus benjamina) for his demonstration at the International Bonsai Congress in Waikiki.  He wanted to create a tall tight forest in a style that he had mastered utilizing straight-trunked collected Ezo Spruce.  However, Weeping Banyans do not naturally grow in this tall forest tree form.  In maintaining and improving the form, it was necessary to study other tropical trees and Eucalyptus was the best model to guide the training.  The story is part of Restyling "Peace Forest".

EucalyptusNamakani10.jpg (45568 bytes)

                CONCLUSION.   I've always had a love of trees and especially enjoyed lying down and marveling at the complex branching patterns of old trees.  That's also what distinguishes an outstanding bonsai.  Each tree has a validity and excitement while mediocre trees may appear to have a nice profile only.  There's seems to be little glory once the initial styling is accomplished. Those with limited bonsai knowledge or appreciation don't even bother bending over to look up into the branches of an exhibited bonsai.  But that's the key to learning the lessons of nature!

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