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Emulating Natural Forest Patterns
Emulating -match or surpass (a person or achievement), typically by imitation. What would cause different patterns in the forest?
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Wildfire Wind Insects Flood Natural Disturbance
The forest in Saskatchewan has been shaped by a number of different forces. As a result, it is highly diverse, but also highly resilient. These forces are generally referred to as natural disturbances. In Saskatchewan, natural disturbances include wildfire, wind, insects and floods. Less of a concern is disease for Saskatchewan. Photos Courtesy of Ministry of Environment
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Wildfire Wildfire is the most prevalent natural disturbance
Wind damage is becoming a close second Wildfire has had the greatest impact on the forest landscape. The map here shows wildfire activity over the last seven decades. Wind damage is becoming a close second in terms of disturbance. This may be due to the impacts of climate change.
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Wildfires create a mosaic of forest types
The different colours on this map represent different forest types and their distribution. Although species have different ecological requirements, the distribution reflects the results of natural disturbances. Forest Mosaic Wildfires create a mosaic of forest types
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Fire Characteristics Patches Residual Trees Fire Event Boundary Matrix
Disturbance Event - typically wildfire in Saskatchewan Disturbance Patches - separated from other parts (Patches) of the disturbance event by intervening areas of forest Insular Residuals – Trees are left as single trees while others are left in bunches of various sizes Matrix - undisturbed land that falls within the boundaries of an event and is connected to the undisturbed surrounding area Residual Trees Fire Event Boundary Matrix Photo Courtesy Wildfire Management Branch
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Planning scales Event Scale – Harvest over 5 Years
Photo Credit: P. Lee The Natural Forest Patterns (NFP) approach is applied at 3 different scales: Landscape scale: e.g. Forest Management Area – Prince Albert Forest Management Area – green area in the middle of the provincial forest – location of events over a 10 year period Event Scale: location of harvest blocks for the next 5 years Patch Scale: Area harvested over 1 year – individual harvest blocks This approach is designed to emulate the impacts of natural disturbances. By doing this, the implication is that the activities will produce a more ecological – like impact which will result in an more natural disturbance. Further this should produce a more sustainable approach to maintaining the ecology of the forest over time. Harvest blocks beyond 500 m from each other are considered to be in separate events. An harvest event occurs over a 5 year time frame. The maximum size is restricted to 8,000 hectares in size (including insular residuals and matrix). On average, 24,000 ha are harvested in Saskatchewan per year which means there would only be about 4 of these events per year. Since many of the events will be smaller than 8,000 ha there will be more events. Landscape Scale – FMA Area Picture Credit: Ministry of Environment Patch Scale - Harvest Block Photo Credit: Ministry of Environment
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Insular Residuals Clump Island Single Trees Matrix
Insular Residual - Singles From one to four trees Insular Residual – Clump An area <2 ha that includes more than four trees Insular Residual – Island An area ≥ 2 ha in size Each grouping is premised on the requirement that the trees are close enough that there is an interactive effect between tree crowns. The total area of insular residuals based on natural disturbances and allowance for an economic harvest is between 3 and 15% with an overall weighted average of 9% of the event area. This means for a 8,000 ha event, there would still be from between 240 ha and 1,200 ha left with trees on them. Matrix Photo Courtesy of Al Baliski of Mistik Management
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The New look NFP Pre- NFP Photo Curtesy P. Lee
Pre-Natural Forest Pattern approach illustrates the past approach to harvesting. The harvested area is a rectangle shape with straight edges with no residuals i.e. earlier types of clearcut. The Natural Forest Pattern approach produces an area of irregular shape with insular residuals resulting in a more natural disturbance and a variety of habitats and biodiversity. NFP Pre- NFP Photo Curtesy P. Lee
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Old growth Stands generally older than 90 years
More structurally diverse A portion of the landscape is left in older age classes Old growth (91 – 110 years) and very old growth (>110 years old) are important habitats on the landscape. They offer a unique habitat for a multitude of life forms not found in other age classes of the forest. Forest stands retained on or within steep slopes, riparian reserves, isolated patches and islands in waterbodies and/or within harvest blocks within the FMA may contribute to achieving old and very old forest targets. Photo Credit Ministry of Environment
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Interior Forest Forest beyond the forest edge
Edge width (Buffer) is based on age & condition of adjacent areas Interior Forest Interior Forest Road & Buffer Interior forest is defined as the that forest area which is beyond the forest edge and is defined by a specific distance (edge) from the adjacent disturbed area. It is far enough away from the edge so that any effects due to the edge (e.g. windthrow, increased predation, etc) are minimized or are eliminated altogether. Interior forest is important as it offers a safe haven / habitat for forest species. Edge Effect Buffer Zone: 60 m where adjacent area is non-forested OR less than 40 years old; 30 m where adjacent forest stand is > 40 years old and younger than mature forest; 0 m where adjacent stand is mature forest. Interior Forest Photo Credit: R. Wright / Bob Wynes Ministry of Environment
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Maintaining Mixedwoods
Photo Credit Ministry of Forests BC Approach: Protect of understory Leave seed trees Plant softwoods=conifers on reclaimed areas (e.g. roads) The intent is to maintain or increase softwood volumes in harvested stands to meet future demands. With respect to white spruce, it generally starts out in the understory and will dominate as the overstory trees (usually aspen or balsam poplar) die off. Photo Credit: Forestry Branch Province of Manitoba
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Salvage harvest Harvesting has a different impact than wildfire
Logging is allowed in burnt forests But only a small portion of the burnt area is allowed to be harvested Salvage harvest refers to the harvesting of areas which have been burnt. Because this is already a disturbed area, it is treated differently. The same rules for green stands applies here (i.e. residuals, interior forest etc.) but a greater un-harvested area (≥20% as opposed to the average of 9% in green harvests). The undisturbed area is contiguous and does not include roads, trails, skid trails etc. within it. The undisturbed areas will include merchantable size timber. Photo Credit: J. Duval Ministère des Ressources naturelles et de la Faune Gouvernement of Québec
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The Boreal Forest which covers half of Saskatchewan is a dynamic environment that is always changing. The more we learn about how things work the better we will know how to harvest what we need and always have the forest with us. End
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