As a part of Lignum Ltd.'s 2002 FIA Program, a literature review was undertaken by DWB Forestry Services to gather information around managing spruce (and Douglas-fir) in combination with aspen. In general, the intent of this literature review was to gather and summarize information on conifer/aspen relationships. With this information, it was hoped that parallels could be drawn to help aid in silvicultural decision-making in the Cariboo Forest Region, and move toward a new stocking standards framework. Under current management practices, the general goal following harvesting is to re-establish a coniferous forest that meets the current legislated free growing standards. This generally must be done within 15 years from the start of harvesting (sometimes 20 years). There is very little tolerance around free growing requirements in regards to conifer to non-crop vegetation ratio. If a new stand does not meet the requirements, either a planting or brushing treatment (or both) is required. There have been numerous instances in young stands where aspen is growing along with a shade tolerant coniferous component (often spruce). Such stands cannot be declared free growing under the current guidelines. Many of these stands (or portions of), if left to develop naturally, would never meet the current free growing definition, even though it is expected that the shade tolerant conifer component of the stand will at some time develop into valuable, mature crop trees. In other cases, a portion of the regenerating stand has naturally developed into pure deciduous. In these cases, fill planting of shade tolerant species underneath the deciduous may allow a healthy, productive, mixed species stand to develop. Backlog sites exist that have a deciduous overstory with an established understory of shade tolerant conifers (primarily spruce, sometimes Douglas-fir), that are growing well but are not considered free growing. These sites may never meet the current free growing definition without a brushing treatment. There are also sites that do not have an adequate conifer stocking in the understory, where it is felt that a fill plant with spruce or Douglas-fir would be a more appropriate option than brushing. However, decision-making is again hindered by the current free growing definition. That being said, the government can be more flexible in their application of the free growing definition on backlog sites since there is no legal requirement on the these blocks. Some of the flexibility that exists on backlog sites is as follows (often due to economics): - On pre-'82 blocks, you can use the 'Backlog rule' to declare sites stocked or free growing provided that a minimum of 60% of the required stocking is present. - In certain circumstances, up to 20% deciduous can be accepted. It is felt that there may be an opportunity to apply some of this flexibility to industry appraisal blocks, but only if management standards are based on solid evidence gathered from scientific research. This literature review is the starting point. Shane Schofield, Neal Gooding and Mike Peterson.
Harmeny Systems Ltd., Schofield, Shane; Gooding, Neal; Peterson, Mike; DWB Forestry Services Ltd.. 2003. Options for managing Spruce and Douglas-fir in combination with Aspen (deciduous) and measuring success: a literature review. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2003MR137