Trees and how they grow
Three main processes Respiration Transpiration Photosynthesis Breathing & using energy Drinking water Making their own food
Respiration
Tree Structure
The trunk
Phloem zone
Longitudinal view of Vascular Cambium Xylem tubes Vascular rays
A Ray initiating at the Cambium/ Phloem interface and extending inwards
Annual Rings
Porous wood
Aporous wood - note the denser appearance and the larger vessels
Growth Ring structure with xylem vessels
Archie the Bobcat operator
Doug the arborist
Archie removes his old girlfirend’s initials from the trunk of a tree with his Bobcat
What the #*^% do you think you are doing?
Doug talks CODIT – Archie learns
Compartmentalisation of Decay in Trees CODIT
Figure 17 In a sense, a tree is a multiple perennial plant. Every growth ring can be thought of as an individual tree. Every new "tree" envelopes all the older trees. (fig.17)
When a tree is wounded, the outer tissues are removed. Fungal spores float in the atmosphere and land on the wound colonising the exposed tissue
Fungal strands dissolve woody tissue and grow into the wood, starting the process of decay. The tree responds with the development of several WALLS
Fungal attack of cells through cell walls where the contents of the cell are consumed by the fungi
Wall 1 Tyloses in the xylem vessels expand and block the vessels resisting vertical spread of decay
Xylem vessels Tyloses
Wall 2 - The growth rings The rings resist the inward spread of fungus. The deeper into the wood the fungus goes, the denser the wood, the more lignified the cells and the more resistant to the fungus the wood becomes
Wall 3 – The Rays The Rays contain high levels of starch. These react with Oxygen to form Phenolic Acids. The acids are highly toxic to fungus and the fungus finds it difficult to spread in a radial direction.
Another close look at Walls 2 and 3 gives the impression of subdivided three dimensional wheels.(fig.20)
There is great variation in the dimension of Walls 3 Rays Annual Rings There is great variation in the dimension of Walls 3
The formation of Wall 4 The cells in the Vascular Cambium differentiate and do not produce new xylem and phloem cells. At the edges of the wound new wood forms called Callus tissue
Wall 4 Callus tissue is a new layer of cells that grows over the damaged section in a 3d pattern. At the point where the wound occurred a physical and chemical barrier is formed – Wall 4
Wall 3 Wall 4 Wall 2 Wall 1
What it looks like… A wound with advanced fungal activity. The fruiting body present shows extensive decay
Progressive wall 4 collapses and extensions of decay
Callus tissue closing over the wound Wall 4 formed at the Vascular Cambium just after wounding, with only slight internal decay An old wound
A completely compartmentalised wound – the callus tissue has met and joined.
A serious cavity in a Newcastle park A serious cavity in a Newcastle park. A grown man can easily stand in this cavity
Home Sweet Home Cavities provide habitat
Phytophthora in fruit trees
Tree Injection A last resort for treating insect pests on leaves and some diseases in trees
t/R 0.3 If the ratio of the thickness (t) over the Radius (R) is less than 0.3 then the tree is considered unsafe K. Mattheck 1999 t R
The tree is unsafe as the ratio is less than 0.3 t = 200 mm R = 700 mm t/R = 200/700 = 0.286 The tree is unsafe as the ratio is less than 0.3 An example t R
Some Facts… Painting wounds does not prevent decay in most situations Water does not cause decay Climbing using climbing spikes can lead to decay and should only be used for removal of trees Any injury to the tree will lead to the process of compartmentalisation Installing cables and rods can cause decay Installing swings, bolts, nails, signs, wire etc can lead to decay.
A low t/R ratio here!!
Roots and mycorrhizae The root, plus another organism can increase the roots’ effectiveness. Ecto and Endo mycorrhizae Vasicular arbiscular mycorrhizae (VAM) Understanding the changes in the root zone cause a negative vortex which then gradually causes the death of the tree.