SILVICULTURAL PRACTICES. Forestry Committee May 2007. SILVICULTURE. The application of various treatments such as; tree planting, pruning, intermediate cuttings and harvest cuts.
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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.
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: biological & economic factors that bear upon it, & then devise the silvicultural practices which will best meet their management objectives. Practices aimed at the highest return possible & still accomplish both goals in a profitable manner.
Timber production & watershed protection: biological & economic factors that bear upon it, & then devise the silvicultural practices which will best meet their management objectives. Practices used to areas adjacent to streams, ponds or lakes that require special techniques to protect the areas & still accomplish the management objectives.
Require avoiding the following practices:
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: biological & economic factors that bear upon it, & then devise the silvicultural practices which will best meet their management objectives. 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
The 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.
A 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.
Low 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: tailored to each forest stand 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.
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.
Treatments in young stands past the sapling stage to free the desired species from competition by regulating the composition of mixed stands.
Prescribed 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
Used to free young stands, up to sapling size from competition of older, overtopping, individual trees.
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
Intermediate cuts to stands larger than saplings. They are done to improve the stand competition, quality, condition or form by removing inferior trees.
Sanitation 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.
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.
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.
Removal of the mature timber.
Establishment of reproduction.
Supplementary treatments of the timber-growing site to develop favorable conditions for seedling growth.
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: too lightly. This can cause a delay in the rotation of the forest resulting in an economic loss for the landowner. 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.