Tree Architecture and Growth Part 2

Secondary Growth Cambium Wood (Xylem) Phloem Stem and branches

Cambium Cambial meristem Xylem –To the inside Phloem –To the outside

Xylem and Phloem Xylem –Wood –Water transport –Mass transport Phloem –Chemical transport –Source – sink –Active loading

Xylem Tracheids –Gymnosperms Vessels –angiosperms

Conifer Wood Piece of conifer wood with four annual rings. Meaning of the letters: TR = transverse section R = radial section TA = tangential section B = bark AR = annual ring E = early wood L = late wood c = cambium r = ray rd = resin duct After Strasburger (1967): Lehrbuch der Botanik

Conifer wood After T.L. Rost et al (1979): Botany, a brief introduction to plant biology.

Black walnut (Fred Sutherland)

Early wood – Late wood Early wood –Laid down first –Lighter –Less dense Late wood –Laid down later –darker in color –denser

Juvenile wood –Wood formed under the influence of the apical meristem in the live crown Mature Wood –Wood formed lower down the stem where the influence of the live crown is much less Juvenile-mature wood distinction is completely different from heartwood- sapwood distinction. Juvenile wood is formed throughout the life of the tree not just in young trees.

BC Ministry of Forests - Research Branch - Forest Productivity Section

Reaction wood Hardwoods –Tension wood Conifers –Compression wood

Compression wood

Compression Wood

Callous Wood Formed after an injury –Fire scars

Ring Widths Crossectional area Matter of geometry Distance from crown Mechanical stimulation

R R’ Area of old tree (radius=A) =  A 2 Area of new tree (radius=R) =  (A+B) 2 Ring (new growth) =  (A+B) 2 -  A 2 A B A’ B’ If new wood = 75 If tree had diameter of 5 then ring width = 5 If tree had diameter of 11 then ring width = 3

Stem Form Ring Area

Stem Form Ring Width

Priorities for Photosynthate 1.Respiration 2.Foliage – Fine Roots 3.{Reproduction} 4.Primary Growth 5.Secondary Growth – Secondary Compounds

Incomplete rings Cambial mortality False rings

Taper

Knots Live knots Dead knots

Live Knots – Dead Knots

Stem Quality Considerations Straightness Ring characteristics Density Knots