Tree Growth Unit 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 ROOTS COVER 4 TO 7x THE CROWN AREA 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) Mycorrhizal association root fungus structures Mycorrhizae to increase absorptive area, especially for potassium, 2500 known From the Iowa State University Forestry Extension http://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

*Sapwood Heartwood Outer Bark Phloem Cambium Xylem From the MSU AGRSCIENCE WEB PAGE

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)