How we use and abuse our greatest natural resource Leading question What methods do we use to manage our forests? Objectives: To identify and discuss forestry practices the Provincial Government and private industry use to manage the forests in New Brunswick Harvesting Wood There are essentially two different methods to harvest wood. These are: Selective cutting and Clear-cutting. Selective cutting — Forest harvesting in which only certain species or sizes of trees are removed from an area, often for use as timber or to make pulp for paper. Under the heading of selective cutting there are also two sub-categories. Shelterwood cutting is a method of forest harvesting in which up to 70 percent of trees are cut, leaving small patches of old growth standing to provide seeds for regeneration. Strip cutting is when only a long narrow strip of a selected block is harvested, leaving many older trees to continue to grow and reproduce on the land. Harvesting Wood Clear-cutting — Forest harvesting in which all of the trees in the area are cut for use as timber or to make pulp for paper. This is the most common method of harvesting wood. Approximately 90% of wood harvesting is done in this manner. Large scale logging operations often utilize this method of harvest. Clear cutting As mentioned above clear cutting has been, and continues to be the number one method of harvesting wood in Canada, meaning that this is not an uncommon view at most large scale harvesting operations across Canada. In most cases after a clear cutting operation occurs the ground is either left to re-grow on its own, or it is replanted. Selective cutting This is a selective cut in it’s least destructive form. Notice that only a few mature trees have been removed, and much of the canopy remains, providing shade for much of the forest floor. Selective cutting Notice that not all the trees have been removed from this cut. Most of what has been left is hardwood, and these are left in small clumps. This is a take on shelterwood cutting. Selective cutting This is an example of a strip cut. The cuts are made in narrow, long paths. The areas left fully treed on either side of the swath help to provide partial shade and new seeds to the recently cleared area. Regeneration of a forest Forest Succession: The gradual supplanting of one community of plants by another, usually as a result of differences in shade tolerance. Regeneration of a forest Each tree species has a particular tolerance to the environment factors around it. For example, some trees do well in full sun, while others require only indirect light to grow well. Some trees do well in wet area, some thrive in dry conditions. Soil composition may even determine which trees are successful in a particular area. When trees are removed from the forest, even in relatively small numbers, the growth of new, smaller trees of different varieties is greatly affected, and the overall make-up of the forest and its inhabitants is changed over time. A look at succession The following slides help to describe the process of forest succession in the average clear cut situation. Try to think of clear cuts that you have seen in your own experiences in the woods of New Brunswick. Do the animations make sense? Imagine this as a recently clear cut forest. Pioneer species are those that begin to grow rapidly following a clear cut operation occurs. Pioneer species quickly occupy a site following clearing. They grow rapidly to compete with grasses and shrubs. As the crowns of pioneer species close, seedlings from these trees are unable to survive in the resulting shade. Different species then begin to grow beneath the pioneers. The resulting undergrowth, or understory, is often dense. As the short-lived pioneers near the end of their life spans, understory begin to take over the site. The result is a major change in plant and animal species. Softwood begins to take over a hardwood dominated site as the short- lived pioneer crowns thin with aging. Beneath the second successional stage species, that often form thicker crowns than pioneers, new species that are even more shade tolerant become established. The process of succession continues until the most shade-tolerant species suitable for the site (climax species) become established. Seedlings of highly shade tolerant climax species thrive in the shade of their parents. Because of this, climax species will persist until disturbance sets back the succession process to the pioneer or some other stage. Disturbances can include a number of events such as clear cutting, pest infestation, or forest fires. The results of a forest fire in a previously heavily shaded forest. The results of the Pine Beetle infestation in British Columbia. The beetle attacks the pines, killing them off leaving a dry and dangerous landscape The clearcut site looks barren immediately following harvest. Similar area, two years following harvest, showing that grass has covered the site. Young pine seedlings are barely visible in the foreground. At ten years following harvest young pine trees, that have sprouted from seeds present in the soil and spread by wind and wildlife, are well established. In early summer 1988, as today, much of Yellowstone park was covered by aging stands of lodgepole pine. Many trees had been killed by frequent outbreaks of the endemic Mountain Pine Beetle. This condition led to the Great Yellowstone fire, 1988 Vast areas of lodgepole pine and other forest types were killed. Eleven years later showed a landscape again dominated by lodgepole pine that had sprouted from seeds present in the soil. Aspen harvest site one year following clear cut harvest. A good site several years following harvest. 50,000 to 100,000 stems per acre from stump sprouting. Mature aspen stand. 65-70 years old. Approximately 200 stems/acre. When reproduction of species with medium to high shade tolerance is desired following logging, selective harvest or thinning methods can be used. Pros and cons of forest management practices Clear cutting Selective Cutting Shelterwood Logging Pros Pros Pros – less disruptive to the forest – clear cutting only part of an old – less expensive as the entire area is environment than others growth forest cut down all at once – harvesting only mature trees of – small groups of seed-bearing trees – provide wood at a more competitive desired size/type/quality are left standing so that their seeds price – less soil erosion and runoff into local will regenerate the logged area – safer for workers streams – less disruptive to the natural – company can choose which type of – no disruption of fish spawning areas, environment than clear cutting the tree to replant nesting areas and other wildlife habitat entire area – less surge of nitrates entering the – protection from soil erosion and water, increasing the growth of algae runoff materials – no ground exposed to sun, increasing the warming of the area in the summer and cooling in the winter – less water loss from soil Cons Cons Cons – all trees are cut regardless of their – costly because extra care / time – specific areas of the forest age, size or maturity taken to cut down trees ecosystem are disturbed – damage the entire forest ecosystem, – costly to replace the trees – microclimates will now vary in the changing it to farm like conditions – prices for the consumer would not be forest changing a variety of animal and rather than a forest as competitive plant species habitats – greater warming and cooling of the area because there is no ground cover changing the microclimate – soil erosion and runoff of materials into local streams and lakes Silviculture – Re-growing the forest Growing Canada's forests Companies that harvest trees on Canada's public forests must also ensure they are properly regenerated. Silvicultural practices often address ecological issues as well as timber production. Natural regeneration is the most common silviculture system in Canada where most of the forests are even aged. Planting is also commonly used, but the results are very different than what one would see in a natural regeneration site. Silviculture – Re-growing the forest The most common trees planted in New Brunswick are: Black Spruce, White Spruce, Red Spruce, Norway Spruce, Jack Pine, White Pine, and Red Pine. Virtually no Cedar or Larch are being grown and planted after harvesting occurs. Silviculture – Re-growing our forest When natural regeneration occurs, the results are often similar to what was demonstrated above in the animation. That is if the former cut is not managed. If it is managed actions like thinning, or herbicide spraying may occur to eliminate certain undesirable species. When planting occurs the results are often a monoculture, or an area with only one dominant species present. This is often the desired outcome from the point of view of pulp and paper companies, for example. A clear-cut operation near Doaktown. Questions 1. Why do you believe clear cutting the most common form of harvesting in Canada? Support you answer. 2. 70% of the trees are removed in most cases of shelterwood cuts. Why would a harvester leave such a seemingly random bunch of trees standing? 3. The pioneer species (like seen on slide 13) are not shade tolerant, and thrive in full sun. They grow quite rapidly. What species are these most likely to be? Use the Trees of Knowledge book and your own previous knowledge to find the answer. Questions 4. The new species that begin to grow in stage two of the succession (slide 15) are more tolerant to shade. What species are these likely to be? Find your answers as you did for the previous question. 5. Why would there be a change in animal species throughout the process of succession? 6. Which species are the third stage of succession likely to be? 7. Assuming that 50,000 stems occupied each acre of the harvested site several years following stand establishment, what happened to the other 49,800 trees? Questions 8. Which practice makes the most sense for: a) J.D. Irving, b) UPM-Kymmene, c)Philip Plume, d) Larry Gibbons. Explain why you figure each answer? 9. Why would these species be the most commonly grown/planted? 10. What are the drawbacks of a monoculture? 11. This was a J.D. Irving harvesting operation. What do you think will happen to this clear cut? Will it be allowed to naturally regenerate, or will it become a monoculture, growing only one specific species? Explain your thinking.
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