FRST 557 Midterm Quiz 1
September 23, 2014
Answer all questions in the booklet provided.
This quiz is 50 minutes long. There are 4 questions, each worth 12.5 points.
Point form answers are acceptable, but use sentences where needed for clarity.
1.
Stand dynamics (Bruce) - After a disturbance, an even-aged cohort will progress through a series of developmental stages. Describe the 'understory reinitiation' stage. Describe what is occurring at this developmental stage, explain why it is occurring, and describe what happens next.
Answer: The understory re-initiation stage occurs following the stem exclusion stage. During understory
re-initiation, the overstory loses its grip on the site. Crown shyness results in gaps between crowns, self- thinning continues, but slows, some overstory trees die due to disturbance agents. Growing space becomes available to shade-tolerant tree regeneration in the understory because the crowns of the remaining overstory trees are unable to expand laterally enough to fill the gaps (as would happen during the stem-exclusion stage). As regeneration establishes, the stand develops a two layered stand structure.
This process continues, and as members of the original overstory die of competition, and increasingly of old-age and biotic/abiotic disturbances, there is continuous release of growing space, establishment and release of understory regeneration, and accumulation of large organic debris. This leads to the next stage of stand development, an old-growth stand with complex, multi-aged structure and lots of coarse woody debris. Whether stands progress to this later stages depends on the disturbance regime of the site.
2.
Species Choices (Steve) - What factors should you consider when deciding which species to use for reforestation? What are the advantages and disadvantages of growing mixed-species stands?
Answer: Ecological factors such as potential productivity and health, management factors such as whether particular species will provide the goods and services that the owners/stakeholders desire.
Ecological and management considerations are integrated and candidate species are ranked based on potential productivity, reliability and feasibility. Productivity refers to species-specific growth rates
(singly, or in mixed-species stands). Reliability refers to susceptibility to forest health factors/disturbance.
Feasibility refers to the cost and effort needed to establish and maintain the species until maturity (to rotation age), and whether sufficient light/growing space is available for shade intolerant species (e.g. which silviculture system is planned). Ecological conditions and management objectives are integrated via designing the target stand, of which species choice is a key consideration.

Advantages - Ecologically, growing mixed species stands promotes biological diversity, by providing more food and habitat sources to other organisms, and typically leads to more complex structure since species grow at different rates and the canopy stratifies. Mixed species stands may be more resistant to biotic and abiotic disturbance if species differ in their susceptibility, or presence of one species limits spread of disease/insects/fire to the other. Different species may have different niches and make better use of heterogeneous sites. From a management perspective, even if one species is damaged, the remaining species may provide the desired goods and services, reducing risk of complete prescription failure.
Having two species also provides a broader range of goods and services which spreads risk by reducing dependence on a single product or service. A slower growing, more tolerant species may promote selfpruning and improve the form and wood quality of a faster growing overstory species (e.g. European beech overstory with Norway spruce understory).
Disadvantages – Ecologically, in some cases, one tree species acts as an alternate host for an insect or disease that affects another, increasing the susceptibility of the mixed species stand (e.g. Adelges cooleyi on spruce and Douglas-fir). From a management standpoint, having two species grow at different rates complicates treatment timing, including harvest timing, and reduces the uniformity of logs and grades which can make logging, shipping and marketing less efficient.
3.
Project Management (Deb) – What is ‘project management’? There are several indicators of a successful project. Describe three of these indicators.
4.
Thinning (Bruce) - Discuss and contrast two different thinning methods. List the pros and cons of each of these two methods. Describe a situation (consider site and management factors) where the first of your two methods would be the most suitable.
Answer: Thinning is the removal of some trees to provide more growing space for the remaining trees. It maintains the vigour of a stand and shifts growth onto a smaller number of trees. There are 5 methods of thinning (Pick 2) – low, crown, selection, geometric and free. Low thinning mimics natural self-thinning by removing trees from the lowest crown classes, it has little effect on relative stand density, and it is easy to select trees. Crown thinning removes low quality trees from the upper crown classes, favors development of high quality trees from the intermediate and upper crown classes, gives a better financial return from low thinning and has a greater effect on relative stand density. Selection thinning removes dominants and if the best trees are removed represents high-grading and loss of potential growth, but higher financial return in the short term. Geometric thinning is usually the removal of strips

or rows, and trees of all size and quality classes are systematically removed along the rows, reducing harvesting costs, but also the potential to remove low quality or damaged trees. Free thinning is a mixture of all thinning types and may be used in irregular single cohort stands as a first quality improvement entry and to set up corridors/trails for future thins.
[d=avg diameter of trees marked for thinning. D= avg diameter of all trees before thinning
Low =d/D well below 1 (usually neighborhood of .7-.8)
Crown = right around 1 (usually .9 to 1.05)
Selection =well over 1 (usually greater than 1.2)
Geometric = 1
Application (one example needed, two given for illustrative purposes)
Crown thinning could be used in a naturally regenerated stand with some coarse dominants on a site with low-slope and well drained soils using ground based equipment (e.g. hand faller, line skidder) with the objective of improving the quality of the stand and recovering some value from the logs removed.
Geometric thinning could be done in a plantation where trees were planted in rows and every 4 th row is to be removed for pulp logs via mechanical harvesting (feller-processor and forwarder). This would provide additional growing space to the adjacent rows, some portion of which could grow to sawlog size.
On steeper ground, the same result could be achieved with hand-falling and cable-yarding. The trails or corridors created by removing every 4 th row could be used for subsequent thinning entries.
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