Monitoring native plant diversity in managed stands is currently used by the forest licensees within the Prince George Timber Supply Area (PGTSA) as an indicator of Sustainable Forest Management (SFM) and subsequently used to satisfy requirements of other SFM initiatives, including Canfor?s Forestry Principles of Ecosystem Management and Adaptive Management. This particular indicator originated in
2001 when a public advisory group requested that forest licensees should be able to demonstrate that their management activities were not reducing the vegetation diversity on the landbase. This concept has evolved in the literature over the past few years into assessments of ecosystem resilience to harvesting practices The PDI Program has been a part of Canfor?s Sustainable Forest Management Program since 2001. Canfor has been monitoring plant diversity across all of its operating areas in the Prince George Timber Supply Area, which includes the Prince George, Vanderhoof and Ft. St. James Forest Districts as well as TFL 30. Using three mathematically derived diversity indices known as the Shannon-Wiener, Simpson?s and Species Diversity indices, Canfor has been able to evaluate whether managed stands are as floristically diverse as naturally regenerating stands. The goal of this monitoring has been to allow forest managers to objectively monitor the effects of various management practices on ecosystem health. In 2006 and 2007, monitoring took place within nine Grouped Site Associations (GSA) and in 2008, monitoring occurred in four of the original nine GSA?s. These four were selected because previous results suggested that many of the individual plots in these GSA?s are relatively less diverse in managed stands than in naturally regenerating stands (Timberline 2008). A statistical analysis of all 2006, 2007 and 2008 plots revealed that, on a whole, managed stands in the Prince George Timber Supply Area (PGTSA) seem to be as floristically diverse as natural stands. This conclusion is based on the comparison of 691 plot samples and measured statistical analysis of nine GSA?s to naturally disturbed benchmark stands. All plant diversity indices were met except the Species Richness target for Bl rhododendron. The Species Richness target for Bl rhododendron is greater than 30 and the mean of all years combined for this GSA was 29.254.
2008 results show that, on average, about 10% of individual plots within each of the four GSA?s fail to meet the Shannon-Wiener and Simpson?s indices and over 77% of individual plots within each GSA fail to meet the Species Richness index. When taken as overall averages, results show that diversity in managed stands is similar to natural stands according to the Shannon-Wiener and Simpson?s Indices; however, plant diversity in managed stands appears much lower than naturally regenerating stands according to the Species Richness Index. Although mean diversity targets are met, many individual plots were below targets. In the previous year?s PDI report, it was recommended that Canfor should review specific management practices in those areas where diversity values are exceptionally lower than the targets (Timberline 2008). To determine whether forest management has contributed to lower species diversity on a block-by-block basis, specific forest management practices were reviewed in blocks within four GSA?s, selected for reasons discussed above.
Because 77% of individual blocks fell short of meeting the Species Richness target compared to about 10% in the other index targets, the Species Richness Index was chosen for the analysis of forest management effects on species diversity.
Results indicated that species richness appears to be sensitive to season of harvest. verall, blocks that were harvested in the winter had higher species richness than those harvested in the summer. Mean plot data for Sxw-horsetail, Sxw-huckleberry and Bl-rhododendron GSA?s indicated that plant diversity was higher for blocks har ...
Timberline Forest Inventory Consultants Ltd.. 2009. MONITORING NATIVE PLANT DIVERSITY IN THE PRINCE GEORGE TIMBER SUPPLY AREA - 2008. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2009MR302
Topic: FLNRORD Research Program
Keywords: Forest, Investment, Account, (FIA), British, Columbia
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