Effective understorey management planning requires more than improved mixedwood inventory. Avoidance of damage to the understorey will always be a desideratum. Sauder's  paper on mixedwood harvesting describes studies designed to evaluate methods of reducing non-trivial damage to understorey residuals that would compromise their chance of becoming a future crop tree. Sauder concluded that: 1 operational measures that protected residual stems may not unduly increase costs, 2 all felling, conifers and hardwoods, needs to be done in one operation to minimize the entry of the feller-buncher into the residual stand, 3 several operational procedures can reduce understorey damage, some of them without incurring extra costs, and 4 successful harvesting of treatment blocks depends primarily on the intelligent location of skid trails and landings.
In summary, the key to protecting the white spruce understorey without sacrificing logging efficiency is a combination of good planning, good supervision, the use of appropriate equipment, and having conscientious, well-trained operators. Even the best plan will not reduce understorey damage unless its implementation is supervised.
New stands need to be established to provide for future supply of commercial white spruce from ha of boreal mixedwoods in 4 of Rowe's  regional Forest Sections straddling Alberta, Saskatchewan, and Manitoba, roughly from Peace River AB to Brandon MB.enter
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Formerly, white spruce in the understories had developed to commercial size through natural succession under the protection of the hardwoods. Brace articulated a widespread concern: "The need for protection of spruce as a component of boreal mixedwoods goes beyond concern for the future commercial softwood timber supply. Concerns also include fisheries and wildlife habitat, aesthetics and recreation, a general dissatisfaction with cleacutting in mixedwoods and a strong interest in mixedwood perpetuation, as expressed recently in 41 public meetings on forestry development in northern Alberta On the basis of tests of 3 logging systems in Alberta, Brace  affirmed that significant amounts of understorey can be retained using any of those systems provided that sufficient effort is directed towards protection.
Potential benefits would include increased short-term softwood timber supply, improved wildlife habitat and cutblock aesthetics, as well as reduced public criticism of previous logging practices. Stewart et al.
Exposed mineral soil covered only 0. Advance growth management , i. The age of advance growth is difficult to estimate from its size,  as white that appears to be 2- to 3-year-old may well be more than 20 years old. Nor is there a clear relationship between the size of advance growth and its growth rate when released.
Where advance growth consists of both spruce and fir , the latter is apt to respond to release more quickly than the former, whereas spruce does respond. Even temporary relief from shrub competition has increased height growth rates of white spruce in northwestern New Brunswick, enabling the spruce to overtop the shrubs. Site preparation is any of various treatments applied to a site in order to ready it for seeding or planting.
The purpose is to facilitate the regeneration of that site by the chosen method. Site preparation may be designed to achieve, singly or in any combination: improved access, by reducing or rearranging slash, and amelioration of adverse forest floor, soil, vegetation, or other biotic factors. Site preparation is undertaken to ameliorate one or more constraints that would otherwise be likely to thwart the objectives of management. A valuable bibliography on the effects of soil temperature and site preparation on subalpine and boreal tree species has been prepared by McKinnon et al.
Site preparation is the work that is done before a forest area is regenerated.
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Some types of site preparation are burning. Broadcast burning is commonly used to prepare clearcut sites for planting, e. Prescribed burning is carried out primarily for slash hazard reduction and to improve site conditions for regeneration; all or some of the following benefits may accrue:. Prescribed burning for preparing sites for direct seeding was tried on a few occasions in Ontario, but none of the burns was hot enough to produce a seedbed that was adequate without supplementary mechanical site preparation.
Changes in soil chemical properties associated with burning include significantly increased pH, which Macadam  in the Sub-boreal Spruce Zone of central British Columbia found persisting more than a year after the burn. The change in pH depends on the severity of the burn and the amount consumed; the increase can be as much as 2 units, a fold change.
Even a broadcast slash fire in a clearcut does not give a uniform burn over the whole area. Burning after windrowing obviously accentuates the subsequent heterogeneity. However, in another study  in the same Sub-boreal Spruce Zone found that although it increased immediately after the burn, phosphorus availability had dropped to below pre-burn levels within 9 months. Nitrogen will be lost from the site by burning,    though concentrations in remaining forest floor were found by Macadam  to have increased in 2 of 6 plots, the others showing decreases.
Nutrient losses may be outweighed, at least in the short term, by improved soil microclimate through the reduced thickness of forest floor where low soil temperatures are a limiting factor. Results showed that, in general, prescribed burning did not reduce organic layers satisfactorily, nor did it increase soil temperature, on the sites tested.
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Increases in seedling establishment, survival, and growth on the burned sites were probably the result of slight reductions in the depth of the organic layer, minor increases in soil temperature, and marked improvements in the efficiency of the planting crews. Results also suggested that the process of site deterioration has not been reversed by the burning treatments applied.
When the diameter distribution of a stand is unknown, an estimate of slash weight and size distribution can be obtained from average stand diameter, number of trees per unit area, and merchantable cubic foot volume.
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The sample trees in Kiil's study had full symmetrical crowns. Densely growing trees with short and often irregular crowns would probably be overestimated; open-grown trees with long crowns would probably be underestimated. The need to provide shade for young outplants of Engelmann spruce in the high Rocky Mountains is emphasized by the U.
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Forest Service. Acceptable planting spots are defined as microsites on the north and east sides of down logs, stumps, or slash, and lying in the shadow cast by such material. Site preparation on some sites might be done simply to facilitate access by planters, or to improve access and increase the number or distribution of microsites suitable for planting or seeding. Wang et al. Donaren trenching slightly reduced the mortality of black spruce but significantly increased the mortality of white spruce.
Significant difference in height was found between open and sheltered plantations for black spruce but not for white spruce, and root collar diameter in sheltered plantations was significantly larger than in open plantations for black spruce but not for white spruce. White spruce open plantations also had smaller volume than white spruce sheltered plantations.
Up to , no "sophisticated" site preparation equipment had become operational in Ontario,  but the need for more efficacious and versatile equipment was increasingly recognized. By this time, improvements were being made to equipment originally developed by field staff, and field testing of equipment from other sources was increasing. According to J. Hall ,  in Ontario at least, the most widely used site preparation technique was post-harvest mechanical scarification by equipment front-mounted on a bulldozer blade, rake, V-plow, or teeth , or dragged behind a tractor Imsett or S.
Drag type units designed and constructed by Ontario's Department of Lands and Forests used anchor chain or tractor pads separately or in combination, or were finned steel drums or barrels of various sizes and used in sets alone or combined with tractor pad or anchor chain units. Hall's  report on the state of site preparation in Ontario noted that blades and rakes were found to be well suited to post-cut scarification in tolerant hardwood stands for natural regeneration of yellow birch.
Plows were most effective for treating dense brush prior to planting, often in conjunction with a planting machine. Scarifying teeth, e. Rolling choppers found application in treating heavy brush but could be used only on stone-free soils. Finned drums were commonly used on jack pine—spruce cutovers on fresh brushy sites with a deep duff layer and heavy slash, and they needed to be teamed with a tractor pad unit to secure good distribution of the slash.
The S. Recognition of the need to become more effective and efficient in site preparation led the Ontario Department of Lands and Forests to adopt the policy of seeking and obtaining for field testing new equipment from Scandinavia and elsewhere that seemed to hold promise for Ontario conditions, primarily in the north. Thus, testing was begun of the Brackekultivator from Sweden and the Vako-Visko rotary furrower from Finland. Site preparation treatments that create raised planting spots have commonly improved outplant performance on sites subject to low soil temperature and excess soil moisture.
Mounding can certainly have a big influence on soil temperature. Draper et al.
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The mounds warmed up quickest, and at soil depths of 0. By November, fall frosts had reduced shading, eliminating the differential. Quite apart from its effect on temperature, incident radiation is also important photosynthetically. The average control microsite was exposed to levels of light above the compensation point for only 3 hours, i. With linear site preparation, orientation is sometimes dictated by topography or other considerations, but where the orientation can be chosen, it can make a significant difference.
A disk-trenching experiment in the Sub-boreal Spruce Zone in interior British Columbia investigated the effect on growth of young outplants lodgepole pine in 13 microsite planting positions: berm, hinge, and trench; in north, south, east, and west aspects, as well as in untreated locations between the furrows. However, planting spot selection was seen to be more important overall than trench orientation.