Special Management Zones

The Special Management Zone (SMZ) is a BMP which consists of a specific area associated with a stream, lake, wetland or other water body that is designated and maintained during silviculture operations.  The purpose of the SMZ is to protect water quality by reducing or eliminating inputs of sediment, nutrients, debris, chemicals, and water temperature changes that can adversely affect aquatic communities.

SMZs provide shade, stream bank stability, and erosion control.  SMZs are designed to maintain certain forest attributes that will provide specific wildlife habitat values.  Mast producing trees as well as den and cavity trees are left in SMZs in order to meet habitat requirements for certain wildlife species.

Site Sensitivity Classes (SSC)

SMZs are subject to specific criteria that define operational restrictions and special management objectives. The Site Sensitivity Class (SSC) is based on the local soil type and the slope of the land, which indicate the general potential for erosion and sedimentation. For determining the SSC, Florida soils have been classified as A, B, or C. Soils of class A are stable and those of class C are highly erodible. Percent ground slope has been classified as 1 through 6, 1 being relatively flat and 6 being very steep.

SSCs are expressed as A1 through C6.  For example, an A1 site would have stable soils and flat topography, whereas a C6 site would have highly erodible soils and steep slopes.  As such the SMZ width associated with an A1 site would be relatively narrow when compared to that associated with a C6 site.

Special Management Zones have 3 principle components.  One or more of these parts may apply on a given forestry operation, depending on the Site Sensitivity Class and on the type and size of water bodies on the site.  Click on the links below for important information on these zones:

Primary Zone

The primary zone applies to perennial streams*, Outstanding National Resource Waters (ONRW)*, Class I Waters*, Outstanding Florida Waters (OFW)*, and in some cases, wetlands.

  • Perennial Streams: flow in a well-defined channel throughout most of the year under normal climatic conditions)
  • NRW (Outstanding Natural Resource Waters): water bodies which exhibit characteristics that meet specific water quality standards for national designation for protection from pollution and degradation.
  • Class I Waters: water bodies that serve as sources of potable water, designated by the State for additional water quality protection.
  • OFW (Outstanding Florida Waters): water bodies which exhibit unique characteristics in terms of quality and value designated by the State for additional protection from pollution or degradation.

Although forestry activities are allowed in the Primary Zone, this zone has significant timber harvesting restrictions, and varies in width from 35 to 200 feet per side, depending on the size of the water body.  See our Site Managment Recommendations to view tables illustrating these guidelines.

The Primary Zone provides water quality protection to adjacent water bodies by maintaining shade and reducing the disturbance to ground cover vegetation and leaf litter.  In addition, this Zone also provides important wildlife habitat values, particularly for those species that require snags, cavities, tall trees, and other characteristics associated with less disturbed forest conditions (illustration by Florida DOF).

Selective timber harvesting and other forestry operations are allowed in the Primary Zone, subject to the specific management criteria below:

  • A - Clearcut harvesting is prohibited in the Primary Zone, except for under special conditions.
  • B - Clearcut harvesting is always prohibited within 35 feet of all perennial waters and within 50 feet of all water bodies designated as OFW, ONRW, or Class I Waters (see above).
  • C - Selective harvesting may be conducted to the extent that 50% of a fully stocked stand is maintained.  The residual stand should conform to the following:
    • 1. Trees are left to maintain the approximate proportion of diameter classes and species present prior to harvesting, except oaks (other than water oaks) may be favored.
    • 2. Repeated entry into harvested Primary Zone in short time intervals for additional harvesting is prohibited.
    • 3. No trees are harvested in stream channels or on the immediate stream bank
  • D - Special emphasis should given to the following within the Primary Zone:
    • 1. Protection of very large and/or old trees
    • 2. Protection of snags (dead trees) and cavity trees
    • 3. Protection of trees where any part of the canopy overhangs the water
  • E - The following forestry activities are prohibited within the Primary Zone of the SMZ:
    • 1. mechanical site preparation
    • 2. fertilization
    • 3. aerial application or mist blowing of pesticides (herbicide, fungicide, insecticide)
    • 4. loading decks or landings and log bunching points
    • 5. road construction except when crossing a water body
    • 6. site preparation burning on slopes greater than 18%

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Secondary Zone

The Secondary Zone applies to all intermittent streams (streams which maintain seasonal flow), intermittent lakes and sinkholes with intermittent water.  Also, the Secondary Zone may apply as an "add-on" for perennial water bodies, OFWs, ONRWs, and Class I Waters.

  • ONRW (Outstanding Natural Resource Waters): water bodies which exhibit characteristics that meet specific water quality standards for national designation for protection from pollution and degradation.
  • Class I Waters: water bodies that serve as sources of potable water, designated by the State for additional water quality protection.
  • OFW (Outstanding Florida Waters): water bodies which exhibit unique characteristics in terms of quality and value designated by the State for additional protection from pollution or degradation.

For intermittent water bodies, the Secondary Zone is always at least 35 feet wide on each side of a stream or around the circumference of lakes and sinkholes. Depending on the Site Sensitivity Class (SSC), the width of the Secondary Zone for intermittent water bodies may be as much as 300 feet (illustration by Florida DOF).  See our Site Managment Recommendations to view tables illustrating these guidelines.

In the case of intermittent waters, perennial water bodies, OFWs, ONRWs, and Class I waters, the SSC is used to determine the necessity for and the width of the Secondary Zone.  Generally, the more erodible the soil and the steeper the slope, the wider the Secondary Zone and the SMZ. Read the Site Sensitivity Classes (SSC) section of this page for more information.

The Secondary Zone has no timber harvesting restrictions.  However, the following operational restrictions apply:

  1. no mechanical site preparation
  2. no operational fertilization
  3. no aerial application or mist blowing of pesticides (herbicide, fungicide, insecticide)
  4. no loading decks or landings
  5. no site prep burning on slopes exceeding 18%
  6. no roads except for crossings

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Stringer

The Stringer applies only to intermittent streams (streams which maintain seasonal flow), intermittent lakes, and sinkholes with intermittent water, and is composed of trees left on or near the bank along both sides of these water bodies.  The stringer can provide limited food, cover, nesting, and travel corridors for a number of animals, especially birds (illustration by Florida DOF).

Stringers are most beneficial when connected to larger SMZs where they provide benefits to water quality by reducing the risk of sedimentation and bank damage.  The presence of a Stringer provides a physical barrier, which will help to ensure that heavy equipment operation in and around the water is minimal.  Stringers also foster the use of designated crossings, and help equipment operators locate streams and other water bodies during site preparation and skidding.

There are no specific requirement in terms of species, size or spatial distribution of trees left in the Stringer.  However, trees in the Stringer should be hardwood species, potential den trees and snags, and provide continuous canopy except designated stream crossings.  All trees that occupy the immediate stream bank should be included in the Stringer.  See our Site Managment Recommendations to view tables illustrating these guidelines.

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