Manitoba
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Forestry Branch

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Silvicultural Surveys

Hardwood Renewal Surveys

Hardwood Renewal Surveys:

Free to Grow Surveys:


Objectives

The hardwood renewal survey is carried out on hardwood dominated blocks, typically 3 to 5 years after harvest. The overall purpose is to document the existence of regeneration and provide a comprehensive assessment of tree quantity, quality, health and spatial distribution.

The objectives of hardwood renewal surveys in Manitoba are:

  1. To determine the extent of forest renewal in terms of stocking (ex. percentage of the area occupied) and density (ex. trees per hectare).
  2. To estimate height and provide a qualitative description of the hardwood and softwood trees 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 renewal standards to determine renewal success.
  8. To compile provincial forest renewal statistics.

Background

forest surveyor
Forest renewal survey block

Prompt reforestation of cut-over or burnt forest lands is an integral component of forest management. Forest hardwood renewal 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 forest 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 surveyors. The Manitoba Hardwood Renewal Survey Manual 2014 has been developed and is intended to provide forest renewal 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 sampling procedure throughout Manitoba.

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Methods

A systematic sampling system with a random starting point is used for renewal surveys in Manitoba. In the systematic sampling system plots are evenly distributed across the harvested area. Systematic sampling is commonly used in forest surveys as the systematic survey provides a good estimate because plots are distributed over the entire harvest block. When using a systematic sample the estimate will be more precise if survey areas are pre-stratified.

assessing a regeneration plot
Assessing a hardwood renewal survey plot

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 tree. If an acceptable tree is present then the plot is considered stocked. An acceptable tree is either a healthy hardwood tree greater than one meter tall or a healthy softwood tree greater than two years of age. A healthy tree 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 trees and is expressed in terms of stocked plots as a percentage of the total number of plots established within the survey block. Stocking is calculated by dividing the number of stocked plots by the total productive plots in the survey (ex. 25/75 = 33% stocking). In Manitoba stocking alone is used to determine if an area is sufficiently regenerated through comparison with provincial hardwood renewal standards.

At every fourth plot, in addition to determining stocking, the number of established trees present on the plot are counted. An estimate of density, the number of trees 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 (ex. 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 1000 hectares of 3 to 5 year old hardwood dominated harvest blocks.

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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 Sufficiently Regenerated (NSR) although they may develop into healthy forest stands and are periodically left to do so. Areas identified as NSR may not 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 sufficiently  regenerated by the province, based on the results of the hardwood renewal survey.

For more information contact the Forestry Branch regarding:

  • Development of Forest Renewal Standards for Forest Regeneration in Manitoba. 1995. Manitoba Department of Natural Resources, Forestry Branch, Winnipeg. 43pp.,

Manitoba Hardwood Renewal Survey Manual 2014

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Free To Grow Surveys

Objectives

The objectives of free to grow surveys in Manitoba are:

    1. To determine the success of the forest renewal on softwood dominated harvest blocks, and how well stocked the block is, by assessing the number of trees 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 blocks are free to grow.
    9. To compile provincial forest renewal statistics.

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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 conducted to ensure harvest blocks have met Manitoba’s Forest Renewal Standards.   

FTG surveyer
Free to grow survey

The Free To Grow survey is intended to assess the renewal status of softwood dominated  harvest blocks  approximately 10 years after disturbance. The majority of softwood trees on 10 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.

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Methods

Free to grow surveys should be performed in late July and August after softwood shoot growth has been completed and hardwood 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.

The free to grow survey uses circular plots with a radius of 3.57 metres comprising an area of 40 square metres. They are established systematically across the harvest area to provide sound data on the renewal of the harvest block.

Sustainable Development survey crews performs approximately 2,500 hectares of Free To Grow surveys annually.

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

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.

Manitoba Free to Grow Survey Manual 2014

Free to Grow - 10 Year Report 1994-2003

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