silvicultural practices

SILVICULTURAL PRACTICES

SILVICULTURE

The application of various treatments such as; tree planting, pruning, intermediate cuttings and harvest cuts.

The forest manager must analyze each timber stand for the biological & economic factors that bear upon it, & then devise the silvicultural practices which will best meet their management objectives.

FACTORS TO BE CONSIDERED

Timber production: Practices selected to produce the highest value products as well as volume that was feasible for the site & available markets.

Timber production & wildlife habitat: Practices aimed at the highest return possible & still accomplish both goals in a profitable manner.

Timber production & watershed protection: Practices used to areas adjacent to streams, ponds or lakes that require special techniques to protect the areas & still accomplish the management objectives.

BEST MANAGEMENT PRACTICESBMP’S

Require avoiding the following practices:• Using wheeled or tracked vehicles• Leaving trees or tops in the water• Roads or trails of any kind, unless

absolutely necessary• Fire

• Any type of mechanical site preparation or machine planting

• Portable sawmills and log decks• Aerial application of any pesticides or

herbicides

STREAMSIDE MANAGEMENT ZONES (SMZ’s)

Areas near creeks & streams that are protected to prevent erosion & pollution.

Distance from the edge of the streambed

Region Primary SMZ Secondary SMZ

Lower Coastal Plain 20’ 0’Upper Coastal Plain 40’ 40’Piedmont & Mountain 80’ 80’

Timber production & recreation areas: Practices used to keep both timber production and recreation activities profitable.

Always keep in mind that the practice of silviculture is tailored to each forest stand

CUTTING OPERATIONSThe principle & most beneficial silvicultural

treatments used in the southeast.The majority of timber is managed for

maximum production.Intermediate cuttings: cuttings of the

timber at any time from reproduction stage to timber maturity or final harvest.

Rotation: the time from when the stand is established until the final harvest cut.

INTERMEDIATE CUTTING OBJECTIVES

• Improvement of the existing stand• Regulation of tree & stand growth• Early financial returns• Reduction of conditions favorable to

insects & disease• To create conditions favorable to

reproduction

THINNINGA form of intermediate cutting in young

stands to improve the yield of the stand at final harvest & to provide the owner with early financial return.

The objective is to leave better trees so future growth is concentrated on the higher value trees & to utilize all merchantable material produced by the stand during its rotation.

THINNING TECHNIQUESLow thinning: taking out overtopped &

small trees in the understory

Crown thinning: removing trees from the middle & upper levels, opening the canopy for maximum growth of dominant & co-dominant trees in the stand

Selection thinning: removes the dominant trees to concentrate growth on the lower crown classes. Not recommended unless immediate income is top priority. Considered high-grading.

Mechanical thinning: based on spacing with little or no regard for tree vigor, form or position in the canopy.

MECHANICAL THINNING

Two methods most often used are row thinning & fixed intervals.

Row thinning-taking out rows of trees at a time. (example: every 3rd or 5th row)

Fixed interval-strips cut throughout the stand.

CLEANING

Treatments in young stands past the sapling stage to free the desired species from competition by regulating the composition of mixed stands.

METHODS OF CLEANINGPrescribed burning-using fire under very

closely controlled conditions; the most economical tool used in young pine stands

Cuttings-removing the undesirable trees by cutting

Basal spraying-using chemicals sprayed at the base of trees to reduce competition; reliable but expensive

Foliage spraying-spraying hardwoods with herbicides is effective for broadcast control methods & widely used

LIBERATION CUTTINGSUsed to free young stands, up to sapling

size from competition of older, overtopping, individual trees.

Accomplished by:Girdling-cutting through the bark & cambium layer to kill the stem & leave it standing in place.Basal spraying-spraying herbicides around the stump or injected into the tree to kill it, used for large trees

IMPROVEMENT CUTS

Intermediate cuts to stands larger than saplings. They are done to improve the stand competition, quality, condition or form by removing inferior trees.

TYPES OF IMPROVENENT CUTSSanitation cut-removing trees infested with

insects or attacked by disease.

Salvage cut-removing trees that are dead, damaged by insects, disease, wind, lightning or various other factors.

Pruning-removal of side branches from standing trees to produce knot-free lumber from logs of higher quality. No more than 1/3 of the tree crown should be removed.

LIVE CROWN RATIO-generally considered the best indicator of condition of the stand in relation to the optimum growth & financial returns to the owner. Calculated by the amount of live crown divided by the overall height of the tree.

STAND CONDITION INDICATORS

Live crown ratio-sapling size to larger trees should have a live crown ration of 1/3 of their total height for proper growth ratio.

Overcrowding-causing the crown to recede to ¼ or even less of the total height. Stands should be thinned to get optimum growth.

STAND CONTITION INDICATORS

Increment boring-taking a core sample of the tree to determine the tree’s growth rate. A reduction in the width of the annual rings indicates the need for thinning.

Basal area-an excellent indicator of the degree of stocking in the stand & the need & extent of thinning required. Measured in square feet, taken with a wedge prism.

The general tendency for forest managers is to thin timber too lightly. This can cause a delay in the rotation of the forest resulting in an economic loss for the landowner.

HARVEST CUTTING OBJECTIVES

Removal of the mature timber.

Establishment of reproduction.

Supplementary treatments of the timber-growing site to develop favorable conditions for seedling growth.

HARVEST METHODS

Clear cutting: Virtually cutting all of the trees in a stand, both large & small. When clear cutting is used, artificial reforestation is the primary method of establishing a new stand.

Seed tree cutting: a form of clear cutting, except 4-10 trees are left dispersed throughout the area to provide for reproduction.

Shelterwood cutting: a harvest cutting method where 25-40 trees per acre are left to supply seed for regeneration. Sometimes as many as 3 cutting stages are used in a shelterwood cut.

Selection cutting: a complex method of cutting & removing individual trees throughout the stand based upon maturity, growth rate, diameter & vigor.