The Hamburg Tree Pruning System

- Proper Pruning for Urban Trees

Prof. Dr. Dirk Dujesiefken Institute of Arboriculture, Hamburg / Germany

Institute of Arboriculture

Phase III Phase IV Institute of Arboriculture Investigations:  115 roadside trees were pruned  almost 750 branches were cut  trees reactions to wounding were investigated, especially - callus growth at the wound edges - compartmentalization in the wood

Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Results  The results of Shigo were confirmed with these investigations, that means branch collar or so called “Shigo cut” should be preferred to flush cuts because - it leads to smaller wounds, - the wounds close faster, - discoloration and decay is smaller and - stem tissue is not wounded.

Institute of Arboriculture wrong! correct! flush cut branch collar cut

Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Branch without branch collar

 cut must be straight, but outside the branch bark ridge  no stem tissue is wounded  no dieback at the lower margin of the wound

Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Pruning of dead branches

 cut only the dead branch tissue  distinctive swelling at the base of the branch must remain at the stem

Institute of Arboriculture Institute of Arboriculture Branches with included bark

 cut outside the lip-like rib or branch bark ridge  cut must be straight  bigger branches with included bark and with a crack in the fork should only be reduced or anchored

Institute of Arboriculture Institute of Arboriculture Codominant stems

 cut must be made outside the branch bark ridge  bigger branches with a crack in the fork should be reduced or anchored  codominant stems should be cut when the tree is young

Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Reducing cut

 cut must be made outside the branch bark ridge  diameter of branches should not be bigger than 5 resp. 10 cm (2 resp. 4 inch)

Institute of Arboriculture The Hamburg Tree Pruning System

Compartmentalization and wound size - effective compartmentalizing tree species - e.g. beech, elm, hornbeam, and sycamore - maximum wound diameter: 10 cm / 4 inches - weak compartmentalizing tree species - e.g. birch, horse chestnut, poplar, and willow - maximum wound diameter: 5 cm / 2 inches

Institute of Arboriculture Institute of Arboriculture Institute of Arboriculture Area of discoloration

[cm²] 600

500 horsechestnut 400

300

200 lime 100

0 0 20 40 60 80 100 120 140 Branch diameter [mm]

Institute of Arboriculture book

New method to prune young trees

- Find the temporary and permanent crown

- Find problems in the upper crown

- Are there other problematic branches?

- What is the next step for clearence? Permanent Crown

Temporary Crown 1

2

3 Book „Trees – a Lifespan Approach“

Editors: Piotr Tyszko-Chmielowiec and Kamil Witkos-Gnach

Authors: Dirk Dujesiefken, Neville Fay, Jan-Willem de Groot and Nigel de Berker

Download for free! http://www.aleje.org.pl/pl/publikacje/podreczniki/618-trees- lifespan-approach

Institute of Arboriculture

Institute of Arboriculture