Science > Sylviculture Systems Analysis

Silviculture Systems Analysis

Study Leader: Doug Pitt
dpitt@NRCan.gc.ca

Study Description:

This study applies advanced statistical modeling and inference to a broad range of silvicultural investigations. Goals include quantifying the impacts of silvicultural treatments on the quantity and quality of wood produced; assessing new technologies for stand tending and vegetation management; examining spatial and temporal interactions between site, management practices, and vegetation succession; developing silvicultural options to mitigate pest impacts, and developing sampling methodologies for forest assessment and monitoring. While this study largely addresses themes within the Forestry Practices and Pest Management Methods Network, some efforts are relevant to themes within other networks, including Synthesis of Knowledge and Information and Forest Health and Biodiversity.

Study Highlights:
Crop growth and quality impacts: Approximately 14 experiments installed in the 1980s and early 1990s are currently yielding valuable data that are allowing us to compare silvicultural strategies and tactics and quantify early-rotation effects on forest growth and quality. Several of these studies are identifying the value and importance of minimum site disturbance during and after harvesting, as well as early control of competing vegetation. Tradeoffs in stand structure and volume production resulting from individual-tree release vs. broadcast conifer release are being quantified and have implications in mixedwood management.

Vegetation succession, biodiversity:
Results of several comparative investigations have produced objective data needed to evaluate the ecological integrity of silvicultural practices and support forest certification. Studies of vegetation structure and succession following a range of vegetation management treatments have demonstrated that, even after rigorous vegetation control, post-treatment vegetation recovery is rapid and the elimination of vegetation groups or individual species is rare. Evidence suggests that conventional herbicide application does not create single-species, single canopied forests, and may be the only means of maintaining conifer dominance on some sites.

Vegetation management alternatives:
Collaborative work with research personnel from the provinces has been instrumental in providing forestry and rights-of-way managers with non-herbicide alternatives to woody vegetation control. Chondrostereum purpureum (Cp), a naturally occurring fungus that infects woody plants, was demonstrated in a nation-wide efficacy trial to provide measurable control of the prolific resprouting that typically occurs following manual brushing. Cp is now Canada's first registered biological vegetation management tool. Additionally, mid summer cutting, at a stem height just below live crown, proved to be the optimum strategy for minimizing coppice growth of aspen following manual cutting. Several investigations compare the efficacy of manual cutting to other vegetation management alternatives.

Options to mitigate pests:
Juvenile aspen may be thinned to increase piece size and reduce technical rotation length without concern for increased losses due to Hypoxylon canker. Models constructed from long-term data collected from several thinning trials allow managers to predict future losses due to Hypoxylon and adjust early stand density to grow desired products. In another investigation, a small pill containing a systemic fungicide (Bayleton) has demonstrated 6 growing seasons of control against white pine blister rust when placed in the hole at the time of planting.

Analysis and sampling tools:
Participants at a workshop on Remote Sensing in Forest Vegetation Management concluded that aerial photography still offers the most suitable combination of characteristics needed for forest vegetation assessment and measurement. Building on workshop recommendations, a sequence of medium- and large-scale aerial photographs were used to map and quantify a range of early seral vegetation conditions following several operational conifer release treatments. Digital maps depicting and quantifying areas of uniform vegetation composition and structure were constructed to support GIS queries such as treatment success, crop or habitat status, or need for treatment. Also pursuant to workshop recommendations, digital frame camera imagery is being tested for use in automated conifer regeneration assessments. Accurate crop tree counts and stocking estimates are possible from leaf-off digital images.