UNCE, Reno, Nev.

How Woody Vegetation Grows

With special thanks to all our contributors including:

Topics to be covered:

How woody plants photosynthesize How woody plants grow Shoots and roots Aspect and elevation considerations Additional Resources

◦ this is just the tip of the iceberg!

Tree growth begins with photosynthesis to produce new wood when the growing season begins.

Bark Cambium

Heartwood

Sapwood

Latewood

Earlywood

How a Tree Grows

Seed - reproduction Leaves - photosynthesis

(carbon capture)

Roots - water & nutrient uptake

Bark - protection Cambium/buds - growth Xylem - water transport (up)

[dead] Phloem - carbohydrate

transport (down)

Outer BarkPhloem

Cambium

Sapwood

Heartwood

Woody Stem Structure Shoot Growth

Meristems: annual growth can also be seen in the branching patterns of many tree species (esp. conifers)

6th year

5th year4th year

3rd year

2nd year1st year

Terminal leader

One year’s growth

Roots Two main types

◦ Taproot ◦ Fibrous root (pines)

Most roots are found in top 18” of soil◦ Up to 50% in the top 6”

Root systems can occupy an area 4-7 times the surface area occupied by the crown

AVOID DAMAGE! Healthy trees have a healthy, expanding root system, injured roots may lead to dead branches above

NC State Ext.

Graft unions can form on roots◦ Can move disease from one tree to

another (Armillaria root disease –most important in Rocky Mtn. Region) Armillaria Sign: Mycelial

fans under the bark. USDA Forest Service

Rate of root grow varies at different times of the year

How a Tree Grows Increase size by growing regions or meristems

◦ Terminal buds - height◦ Cambium – width (diameter)

Most forests are regenerated sexually ◦ Seed dispersal is required ◦ Exceptions: aspen (and others)

Environmental factors:◦ amount of light (forest gap)◦ available moisture (mineral soil)◦ temperature (dormancy & germination)

Trees have a natural defense response to wounds and pruning cuts.

Trees can compartmentalize the wound thus preventing the spread of decay organisms

Wound Response

NC State Ext.

Trees are Tough!

Pine life cycle

Lodgepole pine forests usually end with a stand replacing fire every 200-350 years (USFS-RMRS)

Cool MoistDense regeneration and high competition for sunlight and nutrients

Warm DryWidely spaced trees lack moisture for growth and germination is hindered

Wetter side

“Rain Shadow”

W

S

N

E

Aspect Influence

Elevation and Aspect Influence Forest Cover Types

Resources (there are too many to list) CSFS

◦ http://csfs.colostate.edu/ CSU Ext. Trees and Woodlands

◦ http://www.ext.colostate.edu/sam/trees.html

Now what? Identify all of the trees and shrubs on

your property (and nearly adjacent areas should also be looked at, elms).

Select your key species and cover type.

Consider your objectives for this resource.