FRST 305 Final Exam
December 13, 2011
- This exam is closed book.
- Answer all questions in the exam booklet provided.
- You may use lists of points, but use full sentences where this is necessary for clarity or discussion of issues.
- There are 6 questions, each is worth 20 marks. This is a 2.5 hour exam.
- GOOD LUCK!
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1. What are the properties of high quality seed? How should seed collections be designed to produce high quality seed?
High quality seed is sound, healthy, stores well, will produce trees with desire features, and at seedlot level will have a high % germination and high genetic diversity
A-class (orchard) seed – minimize pollen contamination by orchard siting and management, remove all old cones from orchard after each collection
B-class (wild seed) – collect from at least 20 high quality parents during medium+ seed years
For A and B class seed – monitor crop and collect just before maturity, inspect cones for insects, disease, seed maturity, bag cones loosely in burlap sack with seedlot number inside and outside bag, keep cone sacks in a cooled shaded location with good airflow, protected from rodents and birds during interim storage, rotate sacks weekly to promote seed maturation and drying. Avoid conditions which lead to mould.
2. What are the benefits of having non-crop vegetation in a regenerating stand? What are the three alternative strategies for vegetation management? Give an example of a situation (a site and management context) where you would use one of these strategies and explain why this would be the best strategy for this situation.
Benefits – diversity of habitat and food sources for animals, food and medicine for humans, erosion control, visual cover, nitrogen fixing (e.g. alder, legumes), nutrient cycling and addition of organic matter to soil, thermal cover for regenerating trees.
3 vegetation management strategies: prevention, outcompetition, suppression
In choosing vegetation management strategy and methods consider management and biological/ecological objectives (e.g. reduced competition with crop trees while maintaining benefits of non-crop vegetation), operational factors (efficient, safe) and administrative factors (minimal environmental damage or impacts on neighbours). For example, you could use mechanical cutting with a brush saw to cut 1 m radii around Douglas-fir seedlings that were being overtopped by salmonberry and salal on a gently sloping, not too slashy, CWHxm 07 site series clearcut near an urban area with a stream flowing through it. This is the suppression strategy and would be efficient and minimize potential injury to workers, avoid contamination of the stream with herbicides and leave some non-crop vegetation cover for visual screening, wildlife habitat and berry picking.
3. If your management objectives for a given site were to harvest some timber about every 20 years while retaining continuous forest cover on the site, what silviculture system would be the most appropriate? What age class structure would this create? What else would you want to know before confirming this decision?
Single tree or small group selection system.
Either of these silviculture systems would create an uneven-aged age class structure, a similar amount of ground area in each tree age and size class, and a reverse-j diameter class distribution across the stand.
I would want to know the management objectives for the site and the desire products and features, the existing species composition by tree size class, the operability of the site (this system requires high levels of tree retention and repeated harvest/thinning entries, so works best on gentle easy to access sites with trees that are not too tall), ability of desired (target) tree species to abundantly self-regenerate, stand health (minimal potential for disease/insect transmission between canopy layers/successive tree generations), regional level fire hazard and fuel management requirements.
4. When thinning a stand, what factors should you consider when deciding how many trees to cut? What factors should you consider when deciding which kinds of trees to cut? If you are marking the stand and you have two similar trees (next to each other) to choose from, how do you decide which one to cut?
Thinning re-allocates growing space and creates the potential for extraction of trees during each thinning entry. I would want to know the management objectives for the site, short and long term desired products and features, current composition, density and tree size distribution, target composition, density and tree size distribution, site quality and tree growth rate, relationship between tree size/quality and value, stand health and risk factors including potential for wind and snow damage, fuel management concerns, operability.
In choosing between two trees, I would consider the form, health, growth rate, value and contribution to target stand conditions of each tree. I would consider the operational feasibility of cutting either one, and how cutting it would affect the remaining tree and operational efficiency of future thinning/harvest entries.
5. What is growing stock? How do the following factors or treatments affect the quality of growing stock: tree breeding; inter-tree spacing at time of planting; geometric (strip) thinning; pruning?
Growing stock is the collective term for the trees on your site that are contributing towards your management objectives; these trees make up your target stand.
Tree breeding improves the genetic quality of your growing stock; parents are selected for their ability to transmit genes to their offspring that will enable them to perform well on the target planting sites and produce the desired products and features while resisting biotic and abiotic disturbance agents; well designed breeding programs and seed orchards maintain high genetic diversity
Inter-tree spacing at the time of planting affects the growing space available to your trees as they establish and begin to compete. Sites planted at higher densities will arrive at crown closure more quickly, with earlier onset of inter-tree competition. Trees with more growing space will hold their branches longer and therefore grow deeper crowns, have larger basal branch sizes (and therefore knots), have more conical (more tapered) stems, and more crown/juvenile wood. They will increase in diameter faster than trees with less growing space.
Geometric/strip thinning reduces the amount of growing stock proportional to the percentage of strips removed, this is a systematic thinning process that leaves the post-thinning tree size distribution the same, rows of trees with strips removed on just one-side may develop lop-sided crowns.
Pruning removes dead and live branches from the lower stem, allowing for creation of clear (knot free), mature wood in subsequent growth rings in this portion of the trunk. Pruning may slow tree growth if too many live branches are removed at once. Pruning also improves visibility through the stand, and may reduce the potential for laddering of fires into the canopy.
6. What are the benefits of growing mixed species stands? What are the challenges in managing mixed species stands? How can you predict how a mixed species stand will develop over time?
Mixed species stands have higher genetic and (usually) structural diversity, greater resistance to biotic and abiotic disturbances, wider range of potential products and opportunities.
Mixed species stands will stratify into height/size classes if different species grow at different rates, leading to variable product sizes and maturation dates (rotation ages). If two or more species act as alternate hosts, diseases/insects issues may worsen (e.g. Adelgescooleyi).
To predict future stand conditions you can take a diagnostic approach – know the height over age curves (growth rates), shade tolerance, response to competition and lifespan of the different tree species, and how these vary with site quality. You can observe how mixed-species stands develop on ecologically similar sites. You can also develop or use mixed species stand growth models to forecast future conditions.
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