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Site 1 - A park tree in Frederiksberg Garden

DeScRiPtion

The tree is an old Acer with a height of 25 meters with a structurally relation-ship 2/3 stem and 1/3 crown. it has a considerably small width of the crown and there are large dead branches at the top. the stem has many epicomic shoots (sleeping buds (see pic. 1)). At stem basis the roots show high biomechanical adaptation (see pic. 2). That indicates that the tree does not have the stability of sinker roots but have instead compensated with cable roots. The trees age is most likely around 100 years. Looking at the age of the tree and at what time it was planted it probably originates from a forest plant. The soil consists of a mixture of clay and humus with building materials visual at surface at some places. there is an open drainage few meters from the tree, indicating it has been or is a wet area possibly with a high water table.

SuRRounDinGS

Surrounding the tree there are several younger generations of Beech and Ash (probably self seeded). There are as well remains of removed trees of the same age and at further distance there are several trees at the same age still standing. The tree is the dominating tree in the stand.

HiStoRy

Looking at the size and width of the crown in relationship with the stem it is a sign of that the tree, earlier on, grew up under competition with other individu-als. The remains of trees from same age along with other trees of same age still standing further away is also an indication. The crown architecture is a result of thinning gradually over a time (what is known as B-thinning). The consistency of the thinning created competition between the tree and the surrounding trees for light. That made the tree, through internal competition for carbohydrates, to favour branches at the top of the crown – where the light was. That has created a high and narrow shaped crown.

DiAGnoSticS

the tree has epicomic shoots and dead branched at the top of the crown, known as “top dying”. This is a result of poor water suply hence the tree does not have large enough root system to supply the crown with water. There are two obvi- Pic. 1

ous causes to that the tree has a bad water supply. Chronologically, the first cause could be that the tree was planted on a site with high water table. that meant that the tree developed a superficial root system since the sinker roots only developed down to the water table. The tree has therefore been reliable on the water existing in the upper level of the soil and not being able to seek water further down in drought period.the other cause could be that the tree has had, due to the weak thinning, a high social stability with the surrounding trees. It has therefore not developed a root system strong enough to resist the new increased windier situation that occur-ring when they removed the surrounding trees. This has led to loosening of the root plate which meant that some or all of the vertical sinker roots was damage - and with them – the fine roots. Root plate loosening in older tree is practically irreversible because of the slow adaptation to the new circumcises due to low relative growth rate. To compensate for the loss of sinker root, and poor stability, the tree developed a superficial root system of cable roots.In both cases a good and deep root system is as earlier mentioned a crucial ele-ment against drought, especially at an old age, since upper soil levels dry out faster.

Action

The tree is in the degenerating part of its lifecycle. To give the tree a better water supply is not really possible. The tree should be under observation for decaying but also because it is more sensitive against fungi attacks. If there is any risk of that the tree could harm surrounding trees or people it should be taken down.

MAnAGeMent

There is not much that we can do today for the tree, but this could have been avoided if there had been a better management where D-A thinning (very strong thinning in young stands to no thinning in older stands) been the practice. D-A thinning leads to a more flexible and biological adaptive stand. An additional ac-tion during establishment is the provide soil with possibility for deep rooting by deep ploughing. If the water table is high it is important to drain so trees can develop deeper roots. It is also important to choose a species that is suited for the specific water condition at the location and to plant it at a small size.

Pic. 2

Pic. 3

Site 2 - three-four stand trees in Frederiksberg Gar-den

DeScRiPtion

A forest tree stand with one old Ash and two old Beech. The trees height is 25-30 m. (Ash is the largest), 2/3 stem and 1/3 crown. They have a small crown due to the hight competition for the light before thinning. Old trees in the degenerat-ing part of its lifecycles.We suggest an age of over 100 years for this stand.

SuRRounDinGS

The stand is surrounded by diffrent generations of younger trees.

Soil conDitionS

The stand is situated on a slope, where the water can run off, so it has a good drainage. Clay wet soil, with decomposed organic matter, without grass, shel-tered with falling leaves. There is a lake close to the Ash tree but with a path between them, so we don´t know if the roots could reach the water because of the soil compactation of the path (see pic. 5). There are no symptoms of soil compression, as we can´t see many superficial roots, only in Ash.

RootinG DePtH Deep soil, so, if we look at the origin of the trees, we can expect a deep well developed root system. The Ash has a superficial root system, with large cable roots with a diameter of 15-20 cm (see pic. 4). Two of the roots have been cut (see pic. 6). We can´t see top dying or symptoms of waterlogging in this tree or the surrounding trees, so this superficial root system might be a biomechanical adaptation to soil compresion as well as adaptation to the position on the steep slope.

HiStoRy

At the beggining it was a dense stand of trees, with hight competition for nutri-ents and light. There was a late heavy thinning, which influenced trees architec-ture. Now, it is an stable group with less competition, only with the surrounding smaller trees, shrubs and ivy.

Pic. 4

PotentiAl lonGevity

In general we can see few dead branches and signs of degeneration. The Ash has a superficial root system with symtomps of fungal activity in one the cut roots, so we think that it can´t live for too long (see pic. 6). The other trees are in better condition.

FLexIBILITy FOR mANAgemeNT

Little flexibility for management due to the old age of the trees. We can prune the few dead branches. the Ash with fungal problems must be watched. We only recommend to fell it if it will become a danger for the people walking along the path. It is a stand with high social stability and if we remove the Ash, the two Beech trees would be more sensitive to hard wind and they might develop root plate loosening.

Pic. 5

Pic. 6

Site 3 - A group of young norway spruce trees in Frederiksberg Garden

DeScRiPtion

the stand of young norway spruce is situated on a north facing slope in Freder-iksberg Garden.The trees can be divided into two sizes. At the top of the slope is planted trees of 5-6 meter and further down the height is 2 meters. The spacing differs since the stand is thinned recently(see pic. 10). Spacing between the largest trees is around 2 meters and 1 meter between the small trees. no signs of thinning be-tween the small trees (see pic. 8). As the trees can be divided into 2 even-aged classes we assume that the trees originate from a nursery and not self-seeded. Due to root pruning at the nursery the trees will most likely not have developed sinker roots.

tHe SuRRounDinGS

To the south there is a small lake and an open plain. In the other directions the planting consists primarily of beech in which some of them are approximately 20 meters tall. A smaller beech is standing rather close to the stand(see pic. 7). the stand is wind exposed from south and sheltered from the other directions.

Soil conDitionS

Clay soil with high amount of partly decomposed organic matter. The risk of wa-terlogged soil is minimized by the fact that the step slope will make the water run off rather fast. This is only relevant at the upper part of the stand. The area further down is at risk of being waterlogged due to the heavy clay soil and prob-ably high water table.

MAnAGeMent AnD lonGevity

To secure trees with long time health and longevity, high single tree stability with fully developed crown and root system is needed. Therefore heavy thinning in the early stages is necessary, probably D or e thin-ning. later on the thinning intensity should drop to a thinning. this thinning strategy will keep the competition for light lower and provide possibility for the trees to develop deep crowns. Furthermore wind pressure at the larger crown

Pic. 7

Pic. 8

will result in biomechanical adaptation in the root systems (and stem) which in the long run will minimize the risk of root plate loosening. Deep crowns and large root system will provide the single tree with optimum water uptake and production of carbohydrates. Due to that, the tree has a great-er chance to withstand fungus attack and changes in the environment.

MAnAGinG tHe SuRRounDinGS

it is important that the surrounding is managed in a suitable way. there is one beech tree close to the stand which has to be taken down. if not the trees closest to the beech will react to the less amount of light and develop a smaller crown since Norway spruce is rather sensitive to shade. Further more the trees close to the beech trees will be sheltered by the beech and develop greater social stabil-ity. This topic is also relevant in relation to other beech trees near by. The beech stand has to be cut down at some time, leaving the northern area open and mak-ing the stand of norway spruce wind exposed.

Soil conDitionS AnD lonGevity

The soil conditions are not optimal for Norway spruce. On heavy clay soils and alternate wet soils Norway spruce is likely to decline in an early age. The trees will develop superficial root systems on clay soils and is therefore vary sensitive to wind and drought. exposed stand edges are unstable. the trees on top on top of the slop are exposed by wind from south(see pic. 9) and will therefore be at risk of windfall. As climate change is providing the Danish climate with periods of greater drought, heavier rainfall and mild winters, norway spruce will have difficulties surviving. Longevity is reduced by the soil conditions due to the superficial root system and the problems that follow. A much more flexible stand could be developed on deep grounded soils with free drainage. At such locations Norway spruce de-velop deep root systems making it more resistant to drought, wind exposure and heavy precipitation will not result in water logged soil.If longevity should be increased a drain could reduce the problems related to water logging.

Pic. 9

Pic. 10

Site 4 - Biological “design” of a stone terrace around two old trees in Frederiksberg Garden

DeScRiPtionTwo semi-solitaire old park trees a Hoarse Chestnut and a Beach, both over 100 years old, and are standing on a plain close to water canals in Frederiksberg gar-den (see pic. 11). Both the chestnut and the beech has large asymmetrically crowns due to in-ternal competitions for carbohydrates. The semi-solitary status of the trees has influenced the architecture, creating crown shapes with low branches that are rather homogenous except from where the crowns are intermingling. in the in-termingling part the branches are competing for light and as a result the braches are bending out to the sides. on the hoarse chestnut tree there are epicomic shoots (see pic. 12) and the tree is closest to the lake and leaning a bit more then the beech. the beach has a forking crown with top dying. (see pic. 11)The trees have reached their degradation face and are beginning to lose branch-es and subjective to wind damage.

Soil conDitionSThe trees are planted in at open grass area with a very wet soil and are so close to the water canals that there is an estimate water table at the depth of 50 – 70 cm. Both trees have made biomechanical adaptation to the high water table by making a superficial root system. Some of the roots are visible and shows sign of damage from lawnmowers or other machines (see pic.13).

CompetitionAt a young age the trees had no competition except from each other. They have therefore developed large crowns with low branches and large root systems. The great social stability means that they are dependent on each other.

StReSS FActoRSThe very wet conditions are the highest stress factor, but wind and fungi are also impacting the trees. The chestnut has dark bark on one side (see pic. 12), and

Pic. 11

Pic. 12

this might be indications of fungi coming from the roots. Nearby trees have fungi (Tøndersvamp). the beech “top dying” and the hoarse chestnut epicomic shoots are both sign of water insufficiency. most likely that is caused by the high water table and varia-tions in the level of the table due to changes in season. Root in roots and fungi are also affecting the trees uptake of water.

lonGevityBoth trees are around 100 years and in theirs degenerating fase. Within the next 50 years the trees will become more and more of a hazard for the park guests and will have to be heavily cut or taken down.

tHe teRRAceIf the terrace must be build (even though it is not recommended), a high empha-sise has be made not to damage the root system to ensure survival of the trees. The superficial root system makes it almost impossible to dig and to establish the foundation for the stone terrace. The risk of damaging the roots when removing the soil is big and the work to avoid cutting the root is huge. The setting for the stones has to be compressed which will make the problems about compression in the soil even worse. Wet soil is very easily compacted, so the stone terrace has to be set in a construction soil that allows drainage. The stability and longevity of the trees has be considered - if it is not just a temporary construction. A solution could be to build a tree deck raised above ground and the root system. exact estimation has be made to where the supporting foundation should be placed. Another solution would be to place the foundation on top of the roots to avoid root damage – like a platform. The compression will still be a problem and the trees might not be able to adapt to the new conditions with less water

Pic. 13

Site 5 - urban trees at vesterport

DeScRiPtion

The site is located at Vesterport train station and is a row of Tilia platyphyllos “orebro” along vester Farimagsgade. the row of trees is established in 1999 and the site can be divided into the part, the northern part, north of Kampmanns-gade and the southern part, south of Kampmannsgade.

the establishments of trees are planted in 1999. trees are around 7 - 8m high and have 1/3 stem and 2/3 crown. The crown has been pruned to a height of 3m. Crowns are well pruned and still very flexible. The circumference is 57cm in a height of 1m and 56 in a height of 1,3m.

tHe noRtHeRn PARt The trees planted north of Kampmannsgade, at Stauning plads, are planted in normal plant holes with soil replacement down to 60 – 70 cm depth.

Soil conDitionS

The large soil surface is covered with a 5 – 8 cm mulch layer. The surface area is circular with a diameter of 2, 93 m. allowing a high water infiltration (see pic. 14)

MicRocliMAte

The ground cover of mulch creates an isolating layer and limits the competition of weeds and grass. It also replenishes organic matter and nutrients in the soil. Fungi growing in the mulch are of no harm to the tree, but just a sign of high nutrients. there are 8, 5 m between trees; witch gives room for two parking lots. The parked cars com-press the soil and unavoidable cars will drive in the mulched area and compress the soil even more. Shoots from the bottom of the trees (epicomic) are an indi-cator of poor water supply

Pic. 14

Pic. 15

StReSS FActoRS

Trees are placed in an area with high traffic and therefore we have a lot of dam-age due to cars and lorries, (see pic. 15) lack of water is a major stress factor and the raised granite stone around the trees does not help. this only helps a bit to protect the trees from road salt. The human impact is noticeable and there are some bark injuries seen. It is important to keep in mulching to keep the fine roots that have developed in the top soil layer.

lonGevity

The trees have fairly good conditions for urban trees and that increases there lifespan. 60 – 80 years of age could be the longevity of these trees.

tHe SoutHeRn PARtThe trees south of Kampmannsgade are planted in planting pits (see pic. 16).

Soil conDitionS

The planting pit is build up with construction soil (gartner macadam). This load bearing soil allows root expansion and air supply. the pit has been drained to avoid water logging. Around the trees are a raised Cobblestone rings and iron grates, 1,2m diameter, this limit the water supply, but protects the compression of soil.

MicRocliMAte

the trees are on a row in a fairly open windy area. the row of trees are located in-between a bicycle path and a sidewalk. The area is a highly trafficked area with many bicycles stand. To protect the trees there have been put up iron fenc-ing around tree trunks to avoid damage. One of the trees was protected with a plastic barrier against salt damage, (see pic. 17) this trees was located near one of the iterance to the station.

tRee ARcHitectuRe

the establishments of trees are planted in 1999. the trees are approximately 7m high and have been pruned to a crown height of 2,5m. 40 % stem and 60% crown. the circumference is 47cm in a height of 1m and 46 in a height of 1,3m.

Pic. 17

Pic. 16

StReSS FActoRS

Due to the urban environment there is high level of stress. The limited soil condi-tions are a stress factor that limits nutrition and water up take. The raised Cob-blestone ring around the planting pit limits the salt impact but also limits the water supply.The wind impact is a stress factor that gives higher water transpiration and calls for biomechanical adaptation. There is a high risk of soil compression in the area, cars park close to trees and compress soil giving water logging layers (see pic. 18).Human impact and water stress are the highest stress factors.

lonGevity

many of the trees have wounds to large branches and are vulnerable to fungi (see pic. 19).the high stress of the urban scene strongly shortens the lifespan of the trees. An estimation of 50- 60years are likely to be the longevity of these trees

coMPARinG tHe tWo PARtS

The northern part is considerably better soil conditions than the southern part. Both are subject to soil compaction and stress factors, with water being the main growth limiting factor. The northern trees are estimated to have a longer lifespan than the southern trees, sue to less stress and more flexibility. If starting from the beginning again a better fencing could be done in the northern part and a higher infiltration area should be made in the southern part. Tilia platyphyllos is fairly salt resistant, but salt tolerant trees such as Robinia and Populus could also have been used.

Pic. 19

Pic. 18