Just as a garden cannot be planted and ignored, a managed forest cannot be abandoned after establishment. A process of periodic monitoring and tending is necessary to achieve the manager’s objectives and expectations.
Silvicultural effectiveness monitoring focuses on the quality and quantity of silvicultural treatments that are carried out each year. The objective of this program is to ensure that the necessary silvicultural work is being carried out as specified in the forest management plans and that these treatments are effective.
Aside from the regeneration phase and its associated treatments (site preparation), much of the silviculture practised in Ontario is centred on managing the amount and type of vegetation growing in a given area i.e. managing competition. This can be between individuals of the same species (intra-specific) or between species (inter-specific).
In order for trees of one species to develop to maturity in good health, it is important to manage their densities (the number of stems per unit of area). This can be controlled during regeneration by planting seedlings at fixed distances from each other, and later by a process known as thinning or spacing. Individual stems in poorer health or form are cut from the stand. This permits the rest of the stems to develop with little interference.
 |
| Forestry worker using brush saw to thin trees. |
When the cutting is done with no expectation of selling the wood felled, it is called pre-commercial thinning. When the material being cut is large enough to transport to a processing facility, such as a pulp mill, the procedure is called commercial thinning.
In pre-commercial thinning, the technique involves the use of a brush saw, a gas-powered rotary saw blade mounted on the end of a long shaft. Commercial thinning is carried out by an chainsaw or a small feller-buncher.
 |
|
Small feller-bunch used for commercial thinning. |
Most vegetation management is carried out with chemical herbicides. These herbicides, registered by the federal government and approved for use in Ontario by the Ministry of the Environment, are applied from the ground or from the air. They are used under very strict controls with no-spray buffer zones to maximize their effectiveness and minimize drift into non-target areas.
From the ground, herbicides can be applied manually by means of individual back-pack sprayers or by heavy “air-blast” sprayers mounted on large skidders. These techniques are faster and less expensive than mechanical vegetation management but can be applied only under optimum weather conditions, typically during the absence of rain. Ground application of herbicides is one of the best techniques for managing vegetation in small and fragmented stands or in stands where concerns from adjacent property owners prevent aerial application.
The most effective, uniform, and fastest means of applying chemicals is by air. Most often the chemical is applied by helicopters from a relatively low height (50 to 100 feet or 15 to 30 metres). In this way, several hundred hectares can be treated each day by a single aircraft.
Pruning is another tending treatment with the potential to enhance the quality of logs. Applied on an experimental basis only, pruning can:
- diminish the size and number of knots
- improve stem form
- reduce the “branchiness” of stems
- concentrate the growth of clear (knot-free) wood on the stems of crop trees
Although pruning is not yet used in Crown land operations anywhere in the province, some small woodlot owners use this practice.
