Management Objectives for Mature Coniferous Forests
Before writing a prescription for a harvest area, the general management objectives must be outlined. In coniferous forests of the North East, we include for discussion the following five broad management goals.
We have produced this decision key to act as a tool to identify stands that are suitable for non clear-cut harvesting. This requires defining some simple objectives and identifying stand structural data for inputs to the key. Depending on management objectives and stand conditions, the cutting cycle is either a form of reproduction cutting, including planting and thinning if required, or an intermediate cutting.
Each management objective is discussed in terms of the stand information required to achieve the objective. An assessment of this stand information will evaluate the suitability of the stand to accomplish the desired management objectives. Specific objectives of individual managers or particular stand combinations, features or opportunities, can with some integrity be incorporated into specific prescriptions. The management objectives for mature conifer forests include:
1. Capture of Imminent Mortality / Conservation of Growing Stock
In naturally overdense immature to mature forests, volume often dies and is lost before harvesting operations can take place. This objective is accomplished by using partial cutting operations as a method of entering more stands at an earlier date, thus capturing this volume that would be missed at later periods. Data inputs includes species composition and a tree vigor classification that identifies it as imminent mortality. Tree class guidelines as defined by McLintock (1958) and found in the Silvicultural Guide for Spruce-Fir in the Northeast (Frank & Bjorbom, 1973) are a good starting point. For our purposes tree "stability class" should differentiate between imminent mortality, and stability rating or index. In other words tree available for cutting on the first pass and trees suitable to be left for the later fellings.
There is also the assumption in wood supply modeling that practices which minimize volume loss and maintain current growing stock, in anticipation of the new forest, will mitigate negative impacts of the wood supply shortage. ( Baskerville pers. comm.) Certainly much modeling work must be here to evaluate and quantify these relationships.
2. Promotion of Natural Regeneration Favouring Desired Species and Protection of Advanced Regeneration
Natural methods to achieve regeneration are inherent to the silvicultural systems, hence the similarly used term reproduction systems. Essentially, silvicultural goals predict post cutover response. The best place to start is with the pre-cut condition or advanced regeneration status. In some cases this may require the characterization of the development stages, if the stand contains more than simply a mature “overstory” associated with a regenerating “understory”. In the prescriptions associated with a recommended silvicultural system, cut pecking order guidelines are essential in accomplishing objectives. In addition to examples of those submitted in some of the reviewed guides, the following cut pecking order guidelines are proposed for incorporation into the prescriptions to achieve natural regeneration favouring spruce.
Cut Pecking Order Guidelines
In a mixed spruce / fir regeneration, perhaps the best stage to favour spruce over fir is during pre-commercial thinning. Pre-commercial thinning is a effective and critical step to achieve improved spruce composition.
3. Economic / Biological Feasibility
In some stands transition from mature to regenerating development stage, each cut must be economically and biologically viable. To evaluate this, information regarding initial volumes, product / species distribution, and tree vigor or stability rating is required. If the precut survey reveals minimal volumes, insufficient for economic viability for more than one cut, or unsuitable stand or site quality , then the stand should not be considered for multiple-pass harvesting. Biological considerations dictate that imminent mortality be removed in the first cut, therefore only trees that are able to fulfill their planned function(s); for example as a seed or shelter source, and are sufficiently stable to remain until the planned objective has been achieved, are to be left for the second, final felling. A typical first cutting of a two pass operation will be the removal of between 30 to 50 percent of the initial, moribund volumes. (often called the prep cut or first phase of a shelterwood cutting, followed by a final felling after natural regeneration has become established
4. Promotion of Value Added Products / Improve Low Grade Markets
Management for value added products, such as sawlogs, in the future can be done by leaving the reserves, ie. Medium sized or studwood sized, healthy spruce at the second stage of the two-pass harvesting operation. This possibility should be verified by noting the presence of suitable candidate trees during the precut survey. It would appear that the shelterwood and seed tree system could be very effective for managing sawlogs in the future. (Let us assume that any logs we are ever going to harvest are growing now) Leaving studwood sized seed trees through their primary seeding function, through pre-commercial thinning of the new stand, to the next intervention is plausible.
This process has been referred to as "banking potential sawlogs" for use at higher values at a later date. Many forms of reproduction or intermediate cutting could accomplish this. Firm expanding markets must be found for the low grade products generated in the first cut, in order to permit economic viability and obtain optimum utilization of the resource. In the right stands commercial thinning promotes sawlog growth. Significant rate differentials between products would promote good utilization practices, thus improving profitability.
5. Non-Timber Management Objectives
objectives and inventory component of prescription harvesting, focus on operational,
timber management functions at the stand level.
However, many non-timber values are influenced and manipulated with
responsible applications of silvicultural techniques, although more rigorous
data collection efforts and methods may be required for some of these values.
Many of these alternative needs are yet to be defined or worked into a precut
survey format. For example, in the
case of deer, at the stand level, the critical components that deer require
are functional winter shelter near appropriate food sources.
Other non-timber management
objectives include enhancement of special wildlife/plant habitat, promotion
of recreational opportunities, landscape aesthetics, carbon sinking, management
of water resources and riperian buffer zones.
Other non-timber management objectives include enhancement of special wildlife/plant habitat, promotion of recreational opportunities, landscape aesthetics, carbon sinking, management of water resources and riperian buffer zones.
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