Biodiversity and the Mountain Pine Beetle

The Forest Investment Account Forest Sciences Program (FIA-FSP) has results

By Carolyn Whittaker, MSc.
Consultant.

We know that the mountain pine beetle (MPB) has had a dramatic impact on forests in British Columbia, but we know little about how MPB-related forest management affects biodiversity. Since 2004/05, British Columbia’s provincial forestry research program, the Forest Investment Account-Forest Science Program (FIA-FSP), has funded thirty-four
projects focused on the biodiversity implications of the MPB outbreak; many of these projects have been jointly funded by FIA-FSP and the Canadian Forest Service Mountain Pine Beetle Research Initiative.

Within the sustainability subprogram, research on the conservation of biodiversity in relation to the MPB outbreak has been of particular interest in recent years. The topic has also been a focus with respect to extension by the provincial forestry extension provider, FORREX. A recent FORREX workshop in Prince George, “Mountain Pine Beetle: From lessons learned to community based solutions,” highlighted much of the current knowledge on MPB management and biodiversity. The proceedings have been published in the Winter 2009 issue of the Journal of Ecosystem Management 9(3) (http://www.forrex.org/JEM/jem.asp).

For this article we have chosen to highlight several areas where FIA-FSP researchers are on the leading edge of new science: the role of wildlife tree patches and stand structure in conserving biodiversity (Rachel Botting and Craig Delong, BC Ministry of Forests and Range); the utility of timber cruise statistics to inform stand-level biodiversity assessments (John Innes and Alyson McHugh, University of British Columbia); and predicting biodiversity after MPB management (Kathy Martin, University of British Columbia).

Clearly, biodiversity is enhanced by creating and maintaining structure in managed stands, but what is the role of stand structure in large mountain pine beetle cutblocks? Botting and DeLong focused on species of lichens, liverworts, and mosses that are particularly sensitive to edge effects in order to better understand the role that wildlife tree patches play in maintaining biodiversity. They found that if the patch had been isolated from the surrounding mature forest for more than 6 years, in the smaller patches particular species of mosses and liverworts declined. Botting and Delong found a significant loss of species richness in patches of less than 1 ha compared to patches larger than 5 ha. According to Delong, “the study shows that microclimate is not maintained in smaller patches; so we need to retain a larger proportion of large patches.” Their research also found a decline in species richness with increasing amounts of dead lodgepole pine in the patches. DeLong suggests that managers doing salvage logging for MPB “leave larger wildlife tree patches
containing at most 33% lodgepole pine if they want to maintain species richness.”

DeLong states that “we should be looking at longer term studies, at least six years but ideally ten years, if we want to actually see the effects of management on species decline.” Botting and Delong are currently developing two papers: one on the relationship between species diversity and log characteristics and one on the relationship between species
richness and patch characteristics; they hope to publish these papers in Forest Ecology and Management.

One challenge with understanding the role wildlife tree patches play in maintaining biodiversity is the lack of baseline data. Under the Forest and Range Evaluation Program
(FREP), Innes and McHugh explored the potential for using timber cruise data as a baseline to inform stand-level biodiversity in MPB forests. Their study in the Arrow Boundary Forest District (all blocks >40 ha and retention areas >2 ha) completed surveys before and after harvesting and looked at biodiversity characteristics such as snags and coarse woody debris. Their main finding was that a lot of information is available in B.C., particularly in the timber cruise data sets, that could be used for biodiversity assessments. McHugh states, “We just need to collate these data into accessible useable databases and fill in gaps such as coarse woody debris.” Innes and McHugh’s study highlights the
opportunity to augment existing data sources to tackle such questions as the interactions and cumulative effects of disturbances such as epidemic, salvage, grazing, and invasive
species. Innes and McHugh plan to publish their results in Environmental Monitoring and Assessment.

Wildlife population dynamics is another critical concern related to changes in the landscape caused by large-scale harvesting of MPB forests. Martin has evaluated the role of insect and beetle management activities on wildlife at peak and post-epidemic conditions in mature mixed-conifer forests. Martin found that overall and within many guilds, there has been a boom and bust response to the MPB outbreak in forest bird and squirrel populations: first an increase during the pre-outbreak and peak, then a rapid decline during the post-epidemic phase. In particular, chickadees and nuthatches declined earliest and crashed to levels lower than pre-outbreak, whereas woodpeckers remained high longer than other guilds. Wildlife population dynamics are significant because at least 26 species of forest vertebrates eat or kill beetles, which may have delayed the increase in MPB somewhat; however, ultimately the extent of the outbreak resulted in a large and strong pulse of extra food in the forest, particularly food for winter and early spring conditions.

Martin suggests that a mix of forest management silvicultural activities (hazard reduction, cutting, retention of a range of patches of mature trees with aspen trees) is likely to mitigate the peak of the MPB outbreak by staggering the timing and perhaps the amplitude of the peak. Thus, given the habitat changes caused by MPB and other forest insects (fir budworm, spruce beetle) and beetle management activities (especially salvage logging), Martin suggests that we need to think about what habitats remain for forest wildlife in the post-epidemic forest stand conditions.

Martin’s work has recently been published in several peer-reviewed journals. For a more detailed overview of her research, see the following paper in the FORREX Mountain Pine Beetle workshop summary document: Martin, K., M. Drever, and A.R. Norris. 2008. Biodiversity maintenance and conservation in post-epidemic MPB forests in interior British Columbia. http://www.forrex.org/program/con_bio/PDF/Workshops/Pine_Beetle_Workshop/Martin_Biodiversity.pdf.

FIA-FSP supports and funds initiatives and activities that address the critical knowledge required to enable sciencebased sustainable management of BC’s forest resources. A 14-member Forest Science Board (FSB) guides the funding program along with several advisory committees comprised of operational foresters and scientists from industry, government, universities, and First Nations, as well as extension professionals. Three program advisory committees (PACs) support the FSB in shaping the FIA-FSP by providing
strategic advice and recommending funding priorities for the different programs. The PACs are the Sustainability PAC (SPAC), the Forest Growth and Value PAC (FPAC), and the Extension PAC (EPAC). Research on MPB has been a top priority since 2005 with a total of 99 projects funded from 2004/05 to 2008/09. To date FIA-FSP has funded 34 projects of relevance to impacts of the mountain pine beetle outbreak on biodiversity. For more information on the research program, see http://www.fia-fsp.ca. Completed project reports are found at
http://www.for.gov.bc.ca/hcp/fia/searchreports.htm.

BIONews, Volume 19, Number 2