FRST 305 Photosynthesis, Respiration, Crown development and Wood formation

Photosynthesis Chlorophyl in the foliage Chloroplasts Sun foliage/shade foliage

Photosynthesis 6 CO H 2 O C 6 H 12 O O 2 SUNLIGHT

Photosynthate C 6 H 12 O 6 “Stuff” Energy

Respiration C 6 H 12 O 6 CO 2 + H 2 O + O 2 (Not balanced) ENERGY

Priorities for Photosynthate 1.Respiration 2.Foliage – Fine Roots 3.{Reproduction} 4.Primary Growth 5.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 Tree26% 42% Co-dominant Tree29% 41% Suppressed Tree50% 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

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.Respiration 2.Foliage – Fine Roots 3.{Reproduction} 4.Primary Growth 5.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