This research addresses the Forest Science Program strategic goal to improve knowledge-based science in support of sustainability. Consistent with Research Theme 1, recommended by the Sustainability Program Advisory Committee for 2004-5, we have quantified forest structure, function and processes and applied them in an experimental application of variable retention silviculture. Funded in 2004-5, the first component of this project quantified the spatial and temporal aspects of natural disturbance ecology (Topic 1.5) of the Bamfield Huu-ay-aht Community Forest (BHCF). We have measured the abundance and spatial distribution of ecosystem structures (e.g., canopy cover and coarse woody debris) and shown links to functions such as seeding establishment and tree recruitment to the canopy (see Statement of Progress, below). We are now quantifying the temporal processes that create structural variability in these forests and contribute to natural regeneration. This information is the baseline for our second research component, a variable retention (VR) experiment. The experimental component of our research is a replicated, controlled trial of VR silviculture that emulates natural canopy gaps in coastal old-growth forests. In this trial, harvesting includes high retention and low removal using small patch cuts (microgaps of 5-8 trees and 0.25 ha patches). The size and spatial distribution of natural gaps provide guidelines to ensure that the spatial dimensions of the harvested VR gaps are within the natural range of variation. Our objective is to test for differences between natural gaps and gaps created by VR silviculture. We will compare tree regeneration, understory vegetation, soil microorganisms, nutrient dynamics and resource availability (substrate and light) in natural and VR gaps and adjacent forest. Pre-harvest sampling was completed in June to September 2004. These results will be compared with post-harvest data (2005-9) to test for the impacts of VR gaps on above- and below-ground biodiversity (Topics 1.4 and 1.2). Monitoring of sites will document medium to long-term impacts of harvesting. Ultimately, these empirical data will be used to develop criteria and guidelines to predict/assess the impacts of VR silviculture on composition, structure and stand dynamics of forests in the very wet hypermaritime Coastal Western Hemlock (CWHvh) biogeoclimatic subzone. Our results will empower coastal forest managers to employ scientifically-based, practical, adaptive management that demonstrates sustainable use of BCs forests, facilitating successful certification of forest management practices.
Passmore, J., Daniels, Lori D.; Lertzman, Kenneth P.; Stan, A.B.; Prescott, Cindy E.; Grayston, Susan J.. 2007. VR emulating canopy gaps in coastal forests: an operational trial and experiment. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), Variable, retention, harvesting, British, Columbia
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