Silviculture

Silvics: The branch of forestry that provides the scientific basis for the cultural treatment of forest stands.

Silviculture:  The art of producing and tending forest stands, or the application of the knowledge of silvics; bringing together biological and economic concepts to prescribe and apply treatments to help us reach our land management objectives.

• The Control Functions of Silviculture

  With proper silvicultural techniques we can control forest establishment, composition, and growth and density.

  Controlling Establishment

  We can influence the time and place when regeneration occurs.  Regeneration can take place naturally or, as is more common in the southeast, artificially by seeding or planting.

  Controlling Composition

  Forest composition can be controlled by restricting species to ones biologically and or economically suited to the site. This can be done by: 

  • regulating intensity of cutting
  • influencing the character of the seedbed
  • scheduling the time and placement of cuttings
  • seeding or planting

  During subsequent tending, we can restrict forest composition to the most valuable trees by keeping:

  • the best-formed trees
  • fastest growing trees
  • most valuable species

  Controlling Growth and Density

  We can control growth by regulating stand density (or number of trees per unit area).  There are 2 ways this can be done.

  1. Seek optimum stocking: to achieve complete site utilization and capture mortality before it occurs.
  2. Channel growth to selected trees: concentrate growth onto selected species and individual trees, and channel the full productive capacity of the site onto fewer trees per acre.
• The Silvicultural System

  In forestry, we think of forests at 2 distinct levels: the stand level and the forest level.

  Stand Management

  In stand management we are working with a community of trees that are sufficiently uniform in composition, age, spatial arrangement, or other condition to distinguish it from adjacent communities.

  There are 2 broad groups of stands:

  1. Even-Aged: a group of trees having no or a small difference in ages; by convention, with a spread of ages not exceeding 20% of the rotation* length.
  2. Uneven-Aged: a group of trees that differ significantly in ages; by convention, with a spread of ages exceeding 25% of the planned life span for an age class.
     
     * Rotation: the planned number of years between stand formation and cutting.

  Note:  Even-aged stands never have regeneration, tending, and harvest occurring simultaneously.  Uneven-aged stands alwaysdo.

  Reproduction Methods

  Many methods of reproduction have been developed.  The details of applying the same method vary widely because they are altered for each species, forest region, and management objective. The following are broad categories of reproduction methods, in order of a decreasing percentage of the canopy removed during the cut:

  Even-Aged Stands:

  high percentage of canopy removed:

  Clearcutting - removal of entire stand in one cutting

  Seed tree method - removal of mature timber in one cutting, except for a small number of seed trees left singly or in small groups in order to provide a seed source

  Shelterwood method - removal of mature timber in a series of cuttings which extend over a relatively short portion of the rotation, that is, even-aged reproduction under the partial shelter of seed trees.

  Uneven-Aged Stands:

  low percentage of canopy removed:

  Selection method - removal of mature timber, usually the oldest or largest trees, either as single scattered individuals or in small groups at relatively short intervals, so that an uneven-aged stand is maintained.

  To see the advantages and disadvantages associated with using these reproduction methods, visit our Even- vs. Uneven-Aged Reproduction Methods page.

  Forest Management

  In forest management we are working with the collection of stands that make up the forest ownership.  Through forest management, we are integrating plans for stands into a well-organized program for the entire ownership. See the below diagram of the Silvicultural System for more information.

  Component	Treatments
  Regeneration	Natural Artificial (seeding or planting)
  Tending	Release cuttings Pruning Thinning Intermediate cuts
  Harvest (regeneration method)	Clearcutting Shelterwood Seed tree Selection system

• What Trees Should You Grow?

  One of the first decisions to make in the process of making plans for your land is the selection of tree species to grow. This will depend on your objectives and the site conditions on your land. For more information, see our Guide to Soils and Tree Species page.

  The market for pines is strong in most of Florida and pines are suited to sandy soils that are either too wet or too dry for agricultural purposes. Pine timber can be used for many products such as posts, pulpwood, lumber, plywood, and poles. For these reasons, pines are often the species of choice for planting here when timber products are the objective.

  For more information on southern pines, see our Common Pines of Florida.

• Florida's Silviculture Best Management Practices

  Florida's Best Management Practices (BMPs) for silviculture operations are the minimum standards necessary for protecting and maintaining the State's water quality as well as some wildlife habitat values while conducting forestry activities. They represent a balance between overall natural resource protection and use.

  BMPs were developed by the Florida Forest Service (FFS) specifically for silviculture and are intended to be applied on all such operations. These practices are not intended for use during tree removal or land clearing operations associated with residential or commercial development, or other activities with non-forestry objectives.

  The BMPs were first established in the mid 1970s in response to the Federal Clean Water Act of 1972. The original BMPs were designed exclusively to protect Florida's streams and lakes from potential sources of pollution associated with forestry activities.

  The latest version of Florida's BMPs is available on-line on the FFS Forest Hydrology Web page:

  Florida's Silviculture Best Management Practices