Forestry Branch

Regeneration Surveys

Regeneration Surveys: objectives background methods results Free to Grow Surveys: objectives background methods results

Objectives

The regeneration survey is the initial inventory carried out on an area following disturbance, typically after 5 to 7 years. The overall purpose is to document the existence of regeneration and provide a comprehensive assessment of seedling quantity, quality, health and spatial distribution.

The objectives of regeneration surveys in Manitoba are:

 

1. To determine the extent of forest renewal in terms of stocking (i.e. percentage of the area occupied) and density (i.e. seedlings per hectare).
2. To estimate height and provide a qualitative description of the conifer and hardwood seedlings present.
3. To determine potential plot productivity and provide a qualitative description of micro site.
4. To provide a measure of potential health problems as well as identify stands requiring additional forest health assessments and or follow up treatment.
5. To produce a map of the survey block that shows the physical features, location and stocking status of the plots. Dwarf mistletoe infections along edges or on residuals are also mapped.
6. To provide a process by which survey crew members can convey other observations regarding the block to forest managers.
7. To provide a measure of forest regeneration that can be compared to provincial forest regeneration standards to determine regeneration success.
8. To compile provincial forest renewal statistics.

Background

Prompt reforestation of cut-over or burnt forest lands is an integral component of forest management. Forest regeneration surveys are essential for measuring forest renewal success and developing sound forest management strategies. Data collection procedures must employ sampling and evaluation techniques which measure forest regeneration and precisely describe field conditions.

All regeneration surveyors in Manitoba must be licensed by the Manitoba Forestry Branch. The Manitoba Forestry Branch offers a training program that provides classroom and field instruction as well as tests that lead to the licensing of forest regeneration surveyors. A manual has been developed and is intended to provide forest regeneration surveyors in Manitoba with instructions for collecting forest regeneration quantitative and qualitative data. All survey and data recording methods outlined in the manual should be strictly followed to ensure a consistent regeneration sampling procedure throughout Manitoba.

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Methods

A systematic sampling system with a random starting point is used for regeneration surveys in Manitoba. In the systematic sampling system plots are evenly distributed across an area. Systematic sampling is more commonly used by foresters than random sampling because it is more cost efficient and perceived to provide better estimates because plots are spread over the entire population (Freese, 1962). When using a systematic sample the estimate will be more precise if survey areas are pre-stratified (Corbett and McCulligh, 1989).

Circular fixed area plots of 10 metres² in size with a radius of 1.78 metres are laid out in a systematic grid, normally by two-person crews. Plots are checked to see if they contain at least one acceptable seedling. If an acceptable seedling is present then the plot is considered stocked. An acceptable seedling is either a healthy conifer seedling greater than two years of age or a healthy hardwood sapling greater than one metre tall. A healthy seedling cannot have any apparent damage from the following list: Dead, Galls, Dwarf Mistletoe, Lean, Chlorosis, Poor Vigour, and Browse.

Stocking is defined as a measure of the proportion of the area actually occupied by the seedlings and is expressed in terms of stocked plots as a percentage of the total number of plots established within the survey block (Ford-Robertson, 1971). Stocking is calculated by dividing the number of stocked plots by the total productive plots in the survey (eg. 25/75 = 33% stocking). In Manitoba stocking alone is used to determine if an area is satisfactorily regenerated through comparison with provincial regeneration standards.

At every fourth plot, in addition to determining stocking, the number of established seedlings present on the plot are counted. An estimate of density, the number of seedlings per hectare can then be calculated. Each species found within the plot area is tallied independent of the other. A precise count of each species is required up to ten seedlings. When more than ten seedlings are found their number is estimated in multiples of ten (ie 10, 20, 30...90).

Average seedling height is also determined at every fourth plot. Height estimates are averaged to determine the height of each species within the block and are estimated to the nearest ten centimetres.

The status of each plot is mapped onto a survey map along with site and topographical information.

Manitoba Conservation survey crews annually survey approximately 4200 hectares of 5 to 7 year old plantations and natural regeneration.

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Results

When the detailed survey information have been entered into a computer program and calculations performed, the results (including which renewal standard has been achieved) are summarized into a report, which is then provided to forest managers. (See also: Forest Renewal Standards)

Under the system, areas that do not achieve the forest renewal standards are classified as Not Satisfactorily Regenerated (NSR) although they may develop into healthy forest stands and are periodically left to do so. Areas identified as NSR should be sites that are not expected to develop into a healthy forest stand without additional silvicultural activity.

Reforestation activities should not be assumed to be completed on an area until the area has been certified as satisfactorily regenerated by the province, based on the results of the regeneration survey.

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For a more complete review please see:

 

• Delaney, Jeffery R. 1995. DEVELOPMENT OF FOREST RENEWAL STANDARDS FOR FOREST REGENERATION IN MANITOBA. Manitoba Department of Natural Resources, Forestry Branch, Winnipeg. 43pp., and
• Delaney, Jeff, T. Ringash and D. Auer, 2000. MANITOBA FOREST REGENERATION SURVEY MANUAL. Manitoba Conservation, Forestry Branch, Forest Health and Ecology, Winnipeg. 39 pp.

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Free To Grow Surveys

Objectives

The other objectives of free to grow surveys in Manitoba are:

 

1. To determine the success of forest renewal, and how well stocked a block is, by assessing the number of seedlings per hectare.
2. To determine the number of well spaced trees per hectare.
3. To determine the number of free to grow softwood trees per hectare. By definition, well established softwoods that are well spaced from one another and growing free from hardwood and shrub competition.
4. To provide information regarding the health of the regenerating forest.
5. To provide an estimate of competition on a site that can be used when considering stand tending activities.
6. To record the species and number of residual trees in a block for possible harvesting or stand tending considerations.
7. To provide a process by which survey crew members can convey other observations regarding the block to field staff.
8. To provide a measure of forest regeneration that can be compared to provincial standards to determine if blockss are free to grow.
9. To compile provincial forest renewal statistics.

Background

The goal of reforestation in Manitoba is to replace harvested lands with a forest similar to the original forest covertype. Free to grow surveys are the second survey regenerating softwood forests in Manitoba receive in order to ensure this goal is being achieved.

The Free To Grow survey is intended to assess the status of S and M regenerating sites approximately 14 years after disturbance. The majority of softwood trees on 14 year old softwood sites should be free to grow. Softwood trees that are more than 10 years old grow best and have a better chance of survival when they are free from competition and grow in full sunlight. Sites which are less than 10 years of age should receive a regeneration survey before free to grow surveys are considered.

 

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Methods

Free to grow surveys should be performed in late July and August after conifer shoot growth has been completed and deciduous leaves have fully developed. This timing coincides with the full seasonal development of most plants and makes the identification of competitor species and free to grow status easier. Sites tended with mechanical or chemical release must be allowed two full seasons of growth before free to grow surveys are performed.

Free to grow plots are a circular shape with a radius of 3.57 metres comprising an area of 40 square metres. They are established along a survey line at predetermined distances from one another in an effort to observe the status of forest regeneration in representative portions of the site.

Manitoba Conservation survey crews performs approximately 2500 hectares of Free To Grow surveys annually.

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Results

There are six separate assessments conducted during each free to grow survey:

 

1. stocking assessment
   • all softwood trees > .20 metres tall and hardwood trees > 1.0 metres tall are counted
2. well spaced tree assessment
   • well established trees (eg. black spruce > 1.0 m) that are well spaced from one another are counted
3. free to grow determination
   • well established softwoods that are growing free from hardwood tree or shrub competition are counted
4. assessment of forest health
   • damage occurring on trees within each plot are recorded and pockets of damage observed between plots are mapped
5. competition assessment
   • tree and shrub competition is estimated
6. assessment of residual trees
   • the species and size of residual trees within each plot are recorded

The status of each plot is mapped onto a survey map along with site and topographical information.

When the detailed survey information have been entered into a computer program and calculations performed, the results (including which Free To Grow standard has been achieved) are summarized into a report which is then provided to forest managers. (See also: Forest Renewal Standards)

Under the system, areas that do not achieve the Free To Grow standards are classified as Not Free To Grow (NFTG) although they may develop into healthy forest stands and are periodically left to do so.

Reforestation activities should not be assumed to be completed on an area until the area has been certified as Free To Grow by the province, based on the results of the survey, and subsequent treatments should be prescribed.

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For a more complete review please see:

 

• Delaney, Jeffery R, T. Ringash and D. Auer. 2000. MANITOBA FREE TO GROW SURVEY MANUAL. Manitoba Conservation, Forestry Branch, Winnipeg. 35 pp. and
• Delaney, Jeff. 1998. MANITOBA FREE TO GROW HANDBOOK, Province of Manitoba, Department of Natural Resources, Forestry Branch, Forest Resources Management, Winnipeg. 19 pp.