FRST 305
Photosynthesis, Respiration,
Crown development and Wood formation
Photosynthesis
• Chlorophyl in the foliage
• Chloroplasts
• Sun foliage/shade foliage
Photosynthesis
6 CO2 + 6 H2O
C6H12O6 + 6 O2
SUNLIGHT
Photosynthate
“Stuff”
C6H12O6
Energy
Respiration
C6H12O6
+
O2
CO2 + H2O
ENERGY
(Not balanced)
Priorities for Photosynthate
1.
2.
3.
4.
5.
Respiration
Foliage – Fine Roots
{Reproduction}
Primary Growth
Secondary Growth – Secondary
Compounds
• Photosynthesis > Respiration ?
–GROW
• Photosynthesis < Respiration ?
–DIE
• Photosynthesis = Respiration ?
–NOT A LONG TERM
CHOICE
Volume
• Wood formation (total volume) is:
 [ (Photosynthesis-Respiration)]
- Allocation
Where Does It Go?
Respiration Increment
Dominant Tree
26%
42%
Co-dominant Tree
29%
41%
Suppressed Tree
50%
8%
[ash stand in Denmark]
Crown Form
• Excurrent
• Decurrent
Mechanisms
• Branch angle
• Geotropism
• Weight (gravity)
Apical Growth
• Apical meristem = bud
– Primary growth
• Preformed
• Indeterminant
Epinasty
• Epinastic control
– angle and length of side branches
– genetics and environment
Shade
• Side shade
– Trees do not lose form
• Shade from above
– high shade – low shade
– becomes more diffuse
– trees can lose epinastic control
Cross section
Secondary Growth
•
•
•
•
Wood
Phloem
Stem and branches
Cambium
Cambium
• Cambial meristem
• Xylem
– To the inside
• Phloem
– To the outside
Xylem and Phloem
• Xylem
– Wood
– Water transport
• Phloem
– Chemical transport
Xylem
• Tracheids
– gymnosperms
• Vessels
– angiosperms
Early wood – Late wood
• Early wood
– Laid down first
– Lighter
– Less dense
• Late wood
– Laid down later
– darker in color
– denser
Ring Widths
•
•
•
•
Crossectional area
Matter of geometry
Distance from crown
Mechanical stimulation
Stem Form
Ring Area
Stem Form
Ring Width
Priorities for Photosynthate
1.
2.
3.
4.
5.
Respiration
Foliage – Fine Roots
{Reproduction}
Primary Growth
Secondary Growth – Secondary
Compounds
•
Which are better?
A. Cylindrical trees
B. Tapered trees
Taper
Reaction wood
• Hardwoods
– Tension wood
• Conifers
– Compression wood
Compression Wood
Compression wood
Knots
• Live knots
• Dead knots
Live Knots – Dead Knots
Stem Quality
•
•
•
•
Straightness
Ring characteristics
Density
Knots