MODULE FIVE

Growing Trees

Topics Covered

Basic Forestry Concepts

​

Silvicultural Systems

​

Natural and Artificial Regeneration

​

Site Preparation

​

Planting

Basic Forestry Concepts

The art and science of controlling the establishment, growth, composition, health and quality of forests and woodlands to meet diverse needs and values of landowners and society on a sustainable basis.

​

Based on the science of silvics - the study of life history and general characteristics of forest trees and stands such as how trees reproduce, establish, and grow.

​

Silviculture

Forest Succession

• The orderly replacement of species through time in a given location, leading eventually to a generally stable plant community called a “climax community”
• Forest community development is complex (under natural conditions):
• Establishment of young individual pioneer species
• Growth and replacement by other species
• Eventually a forest may dominate the site
• Note: forest succession implies much more than just the establishment of trees it includes:
• Understory plants (shrubs, ferns, grasses)
• Insects and fungi (consuming, pollinating, infecting vascular plants)
• Animals (food, shelter and other resources from the plants)
• Soil organisms (bacteria and fungi contribute to nutrient cycling)

​

Growing Trees & Succession

• Foresters affect tree growth and succession by every treatment they prescribe
• Planting may speed up succession; harvesting may set back succession
• Selective forest harvesting can maintain or hold succession to a particular stage
• Nature can also affect succession – any time there is a disturbance (ex. Large tree comes down in the forest or a flood removes streambanks and trees in a forest) the forest responds
• Foresters must base their decisions for management regimes/treatments on the knowledge and understanding of the ecosystem such as how it will respond to various disturbances – it helps us predict probable outcomes and to work with Mother Nature!

​

• Silvicultural System – encompasses everything that is done throughout a rotation. System selection should be based on the following considerations: Landowner objectives; Stand character and condition; Site quality; Species silvics; Range of treatments available for use; Accessibility and terrain; Type of and proximity to forest products markets.
• There are three parts to a silvicultural system:
• Regeneration – establishment of the future forest
• Tending – intermediate treatments to improve the forest
• Harvesting – removal of trees ready to harvest

Forest Management Terms

• Shade Tolerance – indicates a tree’s capacity to develop and grow in competition with other trees in various light conditions.
• Site Quality – productive capacity of site; influenced by soil nutrients and moisture, climate and topography; measured as site index.
• Stand – portions of a forest with similar characteristics delineated by easily identifiable boundaries that are managed as units. Silvicultural systems are implemented at the stand level.

​

Forest Management Terms

Shade Tolerance

Site Quality

Forests are divided into management units with each unit called a “Stand”

Size (area) is a practical way to define a stand.

Silvicultural Systems

Silvicultural Systems

• Even-aged management
• Uneven-aged management
• Each silvicultural system should:
• Sustain ecosystem health and productivity
• Improve tree growth and quality
• “Optimize” market and non-market benefits
• Shorten investment period and contain costs

​

Forest Management Terms

In Kentucky, forest stands develop naturally as trees grow, reproduce and die.

• Natural Regeneration occurs when seeds or nuts germinate to produce seedlings or when stumps or roots sprout (coppice) following removal of the tree.
• Even-Aged Stands – occur after stand disturbance removes most or all of overstory; usually one age class as most of the seedlings are established at same time
• Uneven-Aged Stands – three or more well-defined age classes differing in height, age & diameter; develops as disturbances affect parts of stand but not whole stand.

​

Even-Aged Silvicultural Methods

Clearcut

• Removal of stand overstory in one harvest.
• Regeneration occurs after harvesting.
• System used to replace old stands with new, vigorous stands.

Seed Tree

• Depends on natural regeneration.
• Entire cutting unit is managed as with clearcut method.
• For designated time period, seed trees are left.

Clearcuts

Seed Tree Cuts

Seed Tree Cuts are a variation of clearcutting in which scattered trees

are left to provide a seed source for the next generation of trees.

Seed Tree Considerations

• The number of seed trees depends on the species.
• Can be used to “lifeboat” species.
• Some species may have a good crop of seed every year, while others may not have a good seed production for several years.

Even-Aged Silvicultural Methods

Shelterwood

• Uses several harvesting steps, each with specific objectives and characteristics. Steps include:
• Preparatory cut: improves seed trees so they can produce healthy seeds and be more wind resistant
• Establishment cut: provide growing space for regeneration and shelter for young growing seedlings
• Removal cut: leave trees are harvested

Uneven-Aged Silvicultural Methods

• Mature timber is harvested/removed at relatively short intervals
• Method can allow open growing space for regeneration
• Process depends on establishing reproduction and providing space for it to grow. Uneven-aged management may be done by single-tree selection or group-selection.

Uneven-Aged Silvicultural Methods: Single Tree Selection

Advantages of the system:

• Fewer intermediate treatments may be necessary.
• Usually no site prep is needed. Natural regeneration is usually sufficient.
• Selection is the only system that can supply sustained yield from a single stand.
• Erosion and site disturbance minimal.
• Good system for small landowners and multiple use forestry if implemented properly.

Disadvantages of the system:

• Only works for shade tolerant species.
• Small canopy openings do not favor some game species.
• Must be careful when harvesting not to damage the trees you are leaving.
• Harvests are more expensive.
• Can lead to high-grading.

High Grading

• Harvesting only the best trees in the stand and leaving the malformed, defective and diseased trees.
• Results in stand deterioration over time.
• Time does not typically improve the trees that are left.

​

Decades from now, these trees will still have low value – they will just be bigger.

When implemented incorrectly, selective harvesting often results in high grading and poor quality stands

Uneven-Aged Silvicultural Methods: Group Selection

• Groups of trees are harvested to create larger openings.
• The size of the cut can be adjusted to favor shade intermediate species.
• Natural regeneration is often reliable so there is not need for expensive site preparation or plantings.
• The edges created by a series of small openings may be more favorable for some wildlife.

​

Comparison of Silvicultural Systems

Intermediate Treatments

• These are silvicultural treatments applied between the time of stand establishment and harvest.
• Generally, they speed up succession but also serve other purposes as well.
• Possible Goals:
• Favor certain species over others
• Favor a particular wildlife species
• Regulate tree spacing and density
• Improve wood quality
• Salvage dead and dying trees
• Increase growth rates
• Examples:
• Improvement Cuts (also known as Timber Stand Improvement)
• Invasive Species Control
• Thinning
• Mid-story Removal
• Crop-tree Release
• Prescribed Fire

​

Regeneration Techniques

• Regeneration plan is critical!
• Consider soil type, site drainage, potential compaction, fertility issues, harvest timing, competition and weed control treatments
• Natural regeneration
• Takes advantage of existing trees growing on site to use as seed source for next crop of trees
• Seed source determined based on even-aged or uneven-aged management of stand

Natural Regeneration

• Direct seeding: planting of seed on site prepared area
• Planting: young seedlings transplanted from nursery to site prepared area; may be planted by hand or machine planted

Artificial Regeneration

Tree Planting

Site Preparation

Site Preparation

​

• Conducted prior to regeneration
• May remove logging debris and slash
• Reduces competing vegetation including invasives
• Improves soil characteristics
• Provides better site access for proper planting
• Ranges in cost
• May include one technique or several

Site Preparation

• Prescribed Fire
• Exposes seedbed
• Control competing vegetation
• Effective in combination with mechanical or chemical treatments
• Mechanical Site Preparation (Pine mostly)
• Chopping
• Shearing
• Piling

Mechanical Site Preparation

Common on mined lands in Kentucky

Site Preparation

• Soil
• Ripping
• Disking
• Chemical site preparation: eradicate competing plants to reduce competition
• Foliar treatment
• Soil-active treatment
• Single stem treatment

Chemical Site Preparation

Planting

Planting Considerations:

​

• Species selection
• Timing
• Transportation
• Technique
• Monitoring

Regeneration Comparison

​

  Natural Artificial

• Stocking Control limited optimal with seedlings
• Genetics good or bad seedlings produced for traits
• Growth usually slow competition controlled
• Cost low initial can be high, depending
• Rotation Age longer shorter

​

THANK YOU!

​

If you have questions about the Growing Trees module please see the ForestryWorks website or the UK Department of Forestry and Natural Resources (ukforestry.org).