Presentation on theme: "How we use and abuse our greatest natural resource."— Presentation transcript:
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?
Pioneer species quickly occupy a site following clearing. They grow rapidly to compete with grasses and shrubs. Imagine this as a recently clear cut forest. Pioneer species are those that begin to grow rapidly following a clear cut operation occurs.
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 cuttingSelective CuttingShelterwood Logging Pros – less expensive as the entire area is cut down all at once – provide wood at a more competitive price – safer for workers – company can choose which type of tree to replant Pros – less disruptive to the forest environment than others – harvesting only mature trees of desired size/type/quality – less soil erosion and runoff into local streams – no disruption of fish spawning areas, nesting areas and other wildlife habitat – less surge of nitrates entering the water, increasing the growth of algae – no ground exposed to sun, increasing the warming of the area in the summer and cooling in the winter – less water loss from soil Pros – clear cutting only part of an old growth forest – small groups of seed-bearing trees are left standing so that their seeds will regenerate the logged area – less disruptive to the natural environment than clear cutting the entire area – protection from soil erosion and runoff materials Cons – all trees are cut regardless of their age, size or maturity – damage the entire forest ecosystem, changing it to farm like conditions rather than a forest – 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 Cons – costly because extra care / time taken to cut down trees – costly to replace the trees – prices for the consumer would not be as competitive Cons – specific areas of the forest ecosystem are disturbed – microclimates will now vary in the forest changing a variety of animal and plant species habitats
Silviculture – Re-growing the forest Growing Canada's forests Companies that harvest 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.