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This article explores the processes of photosynthesis and respiration in trees, their impact on crown development and wood formation, and the allocation of resources within the tree. It also discusses the importance of factors such as foliage, growth priorities, and stem quality in tree health and productivity.
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FRST 305 Photosynthesis, Respiration, Crown development and Wood formation
Photosynthesis • Chlorophyl in the foliage • Chloroplasts • Sun foliage/shade foliage
SUNLIGHT Photosynthesis 6 CO2 + 6 H2O C6H12O6 + 6 O2
“Stuff” Energy Photosynthate C6H12O6
ENERGY Respiration C6H12O6 CO2 + H2O + O2 (Not balanced)
Priorities for Photosynthate • 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
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 • Respiration • Foliage – Fine Roots • {Reproduction} • Primary Growth • Secondary Growth – Secondary Compounds
Which are better? • Cylindrical trees • Tapered trees
Reaction wood • Hardwoods • Tension wood • Conifers • Compression wood
Knots • Live knots • Dead knots
Stem Quality • Straightness • Ring characteristics • Density • Knots