The Saint Mary?s project is a single tree selection silvicultural systems trial located near Cranbrook, B.C. in the IDFdm biogeoclimatic subzone. The stand is a mixture of Douglas-fir, lodgepole pine, ponderosa pine and larch with a variety of age classes due to fire and selective logging history. The purpose of the trial is to develop uneven-aged stand structure (J-shaped curves) and continuous establishment and growth of natural regeneration to produce a range of timber products. To achieve this goal, three residual basal area prescriptions with species selection criteria were harvested in 1994. The resulting treatments included: 8 m2, 16 m2 and 24 mē residual basal area, and a no-harvest treatment (basal area =38mē). The trial was set up as a completely randomized design. The four basal area treatments were randomly assigned to 4 ? 1 ha treatment units for a total of 16 units. Preferred leave trees (Douglas-fir then larch) were marked before harvesting then pine, followed by other species, were preferentially removed. Sixteen plots were established within each treatment unit to follow ingress and growth of advanced tree regeneration, and the growth response of the overstory residuals. An assessment was completed post-harvest in 1995 but was not re-measured due to lack of staffing. In 2006, the research team from the Southern Interior Region determined the integrity of the trial was still intact and that with some trial maintenance, 14 year (regeneration) and 15 year (growth and yield data) could be obtained.
This data is especially in demand given the recent mountain pine beetle (MPB) outbreak. Due to the preferential removal of pine (and a smaller component of other species) the resultant stand structures are similar to stands left after salvage logging of mountain pine beetle infested stands in the Southern Rocky Mountain trench. Burton (2006) identified the response of complex stands to selective removal or gradual loss of pine trees as a knowledge gap in a recent discussion paper on MPB attacked stands. This trial will provide valuable insight into how stands develop and provide estimates on timber growth in these treatments. It will provide a site where the growing environment within these partially harvested stands can be quantified and survey methodology can be tested. Data on the post logging stand structure compared to the present stand conditions will assist in making decisions regarding partially harvested stands and will provide data for modelling programs such as TASS and PrognosisBC. It is important to ensure these sites after partial harvesting are fully occupied and contributing to future timber supplies. However, it is often difficult to determine the level of site utilization in selectively logged mixed species stands.
The study will also explore measures of site utilization such as Reinecke?s Stand Density Index (SDI) and Leaf Area Index (LAI). These estimates of stand occupancy can be used to make operational decisions for management of single tree selection harvesting silvicultural systems. The SDI is closely related to the -3/2 power law (Long 1985) and to light capture (Vales and Bunnell 1988). It can be applied in mixed-species and multi-storied stands Long (1996). Waring (1983) found LAI is strongly related to stand volume increment. O?Hara and Gersonde (2004) demonstrate the use of LAI as a measure of growing stock and space utilization in pure and mixed conifer stands. A knowledge of LAI and its distribution among stand components (i.e. species and size classes), the influence of stocking and light environments on growth efficiency, and the relationships between SDI (or other density measurements), LAI, and productivity are potentially useful in understanding factors which influence understory development under different levels of overstory retention.
The trial site is located on ungulate (elk, mule deer) winter range. The types of prescriptions tested could be used to create desired c ...
Waterhouse, Michaela J., Newsome, Teresa A.; Armleder, Harold M.; Comeau, Phillip G.. 2008. St. Mary?s Residual Basal Area Study in a Mixed Conifer Stand. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2008MR062
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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