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Silviculture

Belongs to subject Sylviculture

Seed-tree method Uneven-aged forestry Regeneration can take place through self-sown seed ("natural regeneration"), by artificially sown seed, or by planted seedlings. Natural regeneration is a "human-assisted natural regeneration" means of establishing a forest age class from natural seeding or sprouting in an area after harvesting in that area through selection cutting, shelter (or seed-tree) harvest, soil preparation, or restricting the size of a clear-cut stand to secure natural regeneration from the surrounding trees. In natural forests, conifers rely almost entirely on regeneration through seed. At least seven variable factors may influence seed germination: seed characteristics, light, oxygen, soil reaction (pH), temperature, moisture, and seed enemies. Black spruce responded similarly. Tree provenance is important in artificial regeneration. Good provenance takes into account suitable tree genetics and a good environmental fit for planted / seeded trees in a forest stand. The movement of general-collection seed and stock across seed zone boundaries is prohibited, but the use of stand-collection seed and stock in another seed zone is acceptable when the Ontario Climate Model shows that the planting site and place of seed origin are climatically similar. Seed quality varies with source. Seed orchards produce seed of the highest quality, then, in order of decreasing seed quality produced, seed production areas and seed collection areas follow, with controlled general collections and uncontrolled general collections producing the least characterized seed.

Wings of white and Norway spruce seed can be removed by dampening the seed slightly before it is run through a fanning mill for the last time. A 1915 inspection reported 97% viability for white spruce seed.

During extraction and processing, white spruce seeds gradually lost moisture, and total germination increased. Cone collection earlier than one week before seed maturity would reduce seed germination and viability during storage. White spruce seeds require a 6-week post-harvest ripening period in the cones to obtain maximum germinability, however, based on cumulative degree-days, seed from the same trees and stand showed 2-week cone storage was sufficient.

A treatment that releases tree seedling or saplings by removing older overtopping trees.

Volume growth of individual trees and the merchantable growth of stands are increased. By altering stand density, foresters can influence the growth, quality, and health of residual trees. In the early development of forest stand, density of trees remain high and there is competition among trees for nutrients.An even-aged regeneration method that can employ either natural or artificial regeneration. A regeneration method which depends on the sprouting of cut trees. Prochnau (1963), 4 years after sowing, found that 14% of viable white spruce seed sown on mineral soil had produced surviving seedlings, at a seed:seedling ratio of 7.1:1. Row and spot seeding confer greater ability to control seed placement than does broadcast seeding. An even-aged regeneration method that retains widely spaced residual trees in order to provide uniform seed dispersal across a harvested area. In the seed-tree method, 2-12 seed trees per acre (5-30/ha) are left standing in order to regenerate the forest. The method's objective is to establish new forest reproduction under the shelter of the retained trees. Unlike the seed-tree method, residual trees alter understory environmental conditions (i.e. sunlight, temperature, and moisture) that influence tree seedling growth. The single-tree selection method is an uneven-aged regeneration method most suitable when shade tolerant species regeneration is desired. Single-tree selection can be very difficult to implement in dense or sensitive stands and residual stand damage can occur. In the Chippewa National Forest (Lake States), seed-spot sowing of 10 seeds each of white spruce and white pine under 40-year aspen after different degrees of cutting on gave second-season results clearly indicating the need to remove or disturb the forest floor to obtain germination of seeded white spruce and white pine. The greater seed source from uncut trees between the cut strips, and the disturbance to the forest floor within the cut strips could be expected to increase the amount of natural regeneration. White spruce plantations on mixedwood sites proved expensive, risky, and generally unsuccessful. This prompted efforts to see what might be done about growing aspen and white spruce on the same landbase by protecting existing white spruce advance growth, leaving a range of viable crop trees during the first cut, then harvesting both hardwoods and spruce in the final cut. 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. Site preparation treatments that create raised planting spots have commonly improved outplant performance on sites subject to low soil temperature and excess soil moisture.

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