Tree GrowthUnit 10

Objectives

• Learn how woody plants grow

• Know where growth occurs in a tree

• Understand the relationship of tree ring growth and environmental conditions

• Describe limiting factors for tree GROWTH

Question

• If I were to hammer a nail into a tree 3 feet off the ground and the tree grows 1foot per year. In 25years how far off the ground will the nail be?

How Does A Tree Grow• MERISTEM tissue in the • Bud--crown• Root tips--roots• Cambium--trunk

From the MSU AGRSCIENCE WEB PAGE

Roots

• Apical MERISTEM protected by a root cap (cells divide and differentiate)

• Permanent roots—anchorage

• Feeder roots

• Root hairs—water and nutrient absorption

Roots• Absorbing roots are concentrated in the top 6-18 inches of soil (water,

nutrients and oxygen)

• Roots cover 4 to 7 times the area of the crown

From the MSU AGRSCIENCE WEB PAGE

Tree Root Classes

• Heart root (red oak, honey locust, basswood, pines)

• Tap root (hickory, walnut, butternut, white oak and hornbeam)

• Flat root (birch, fir, spruce, sugar maple, cottonwood and silver maple)

From the Iowa State University Forestry Extensionhttp://www.ag.iastate.edu/departments/forestry/ext/pubs/F-308.pdf

Trunk

• Growth in diameter of plants is due to cell division in the cambium

• Located just under the bark• Inside—xylem –conducts water and

nutrients• Outside—phloem—transports sugars,

amino acids, vitamins, hormones and stored food

Heartwood

XylemCambium

PhloemOuter Bark

From the MSU AGRSCIENCE WEB PAGE

*Sapwood

From the MSU AGRSCIENCE WEB PAGE

From the University of Georgia School of Forestry http://www.forestry.uga.edu/warnell/service/library/index.php3?docID+172

From the MSU AGRSCIENCE WEB PAGE

Wood Types

• Spring wood (early wood)• Summer wood (late wood)• Heart wood—old xylem tissue (provides

structure and infection resistance)• Sapwood—living xylem active in fluid

transport• Phloem—inner bark nutrient transport,

outer bark—dead phloem

Factors Affecting Ring Growth

From the University of Georgia School of Forestry http://www.forestry.uga.edu/warnell/service/library/index.php3?docID+172

Crown• Buds—apical MERISTEM 3 types

• Mixed—shoots—leaves and or flowers

• Leaf buds

• Shoot buds

• Terminal buds--apex of MERISTEM (trunk)

• Lateral buds—branches and flowers

From: Iowa State University Forestry Extension Notes F-308 www.ag.iastate.edu/departments/forestry/ext/pubs/F-308.pdf

Types Of Buds

• Fixed growth—the number of leaves and nodes for next year is fixed by this years resource availability (length of nodes is dependent on next years conditions (pine, oaks hickory)

• Free growth—buds containing leaves are preformed but additional leaves can be added depending on that years CONDITONS (cottonwood, willow, and silver maple)

Tree Form

• EXCURRENT—strong apical dominance (conical—pines)

• DECURRENT—lack of strong apical dominance—deliquescent (large

spreading crowns)

From: Iowa State University Forestry Extension Notes F-308 www.ag.iastate.edu/departments/forestry/ext/pubs/F-308.pdf

What Have We Learned Today

• Learned tree growth occurs in Meristem tissue of Roots (tip), trunk (cambium) and crown (buds) (Down, Out and Up)

• Water is the most restrictive factor affecting tree growth (Light, Temperature and Relative humidity)