Forest Investment Account (FIA) - Forest Science Program
FIA Project Y092130

    Distribution and impacts of Phellinus root disease in the southern interior of British Columbia
Project lead: Cleary, Michelle (Ministry of Forests and Range)
Author: Cleary, Michelle R.
Subject: Forest Investment Account (FIA), British Columbia
Series: Forest Investment Account (FIA) - Forest Science Program
Phellinus sulphurascens Pilat (syn. P. weirii), the cause of Laminated root disease (DRL), occurs across a variety of biogeoclimatic ecological classification (BEC) zones in the southern interior (SI) of British Columbia (BC) (Lim et al. 2005). The disease causes mortality and growth loss in natural and planted stands of Douglas-fir (Thies and Sturrock 1995). DRL-caused mortality usually begins on infested sites five to seven years after stand establishment and may continue throughout a rotation. Chronic (non-lethal) infections on roots of older trees can result in growth loss. Some research has been conducted in coastal BC, Oregon and Washington to determine the distribution and impact of P. sulphurascens in second-growth stands of Douglas-fir. The disease has been estimated to occur in more than 80% of such stands in the Vancouver Forest Region of BC (Paul Wood as cited in Bloomberg and Reynolds 1985) and substantial reductions in timber volume and growth have been demonstrated in several stands on Vancouver Island (Bloomberg and Wallis 1979, Bloomberg and Reynolds 1985). The disease is estimated to occur on eight percent of the commercial forest land base in Washington and Oregon and cause a 40 to 70 percent reduction in wood volume on affected areas (Goheen and Hansen 1993).

Much less is known about the distribution and impact of DRL in BC’s SI, due in some part to research being focused on Armillaria root disease (DRA), another serious pest occurring in many zones in southern BC. Phellinus sulphurascens is known to occur in the IDF, ICH, MS and SBS biogeoclimatic zones of the SI and its distribution appears to be quite patchy, with patch sizes ranging from 1 ha to more than 10 ha. Phellinus root disease often occurs in stands together with Armillaria root disease (DRA) caused by the fungus, Amillaria ostoyae and Douglas-fir bark beetle (Dendroctonus pseudotsugae). Just how these disturbance agents interact and influence individual tree and stand susceptibility to fungal infection and/or insect attack is not well understood.

In general, the presence of pathogens in BC’s forests and their impact on productivity are greatly underestimated. This is perhaps especially true for root disease and decay pathogens. For example, the 2005 Summary of Forest Health Conditions in BC (BCMoFR 2006) report lists only four diseases (none of them root diseases) as causing any damage that was detectable from aerial overview surveys. Although the report acknowledges that “some forest health concerns, particularly diseases…, are not usually discernable” from such overview surveys, it does not state where to find damage information for diseases. One of the end results of this situation is that there is little quantitative information on root disease incidence in the province. In a survey of client needs conducted by a Research Partnership in the province (Gregory and Satterfield 1999), more information about root disease, as it pertains to timber harvesting and management, was identified as a priority by a number of Partnership clients including licensees, provincial operations/policy, private consultants and other research groups. Finally, recent communications with staff in the Okanagan and Kamloops Forest Districts and with foresters working in Industry reveal that DRL and the paucity of information about its incidence and impact are of significant concern to them. Thus, the goal of this project is to begin the research needed to accurately determine the incidence and impact of DRL in the SI of BC. This will require a step wise research approach that starts from a landscape level view of DRL occurrence and/or incidence and moves to a stand level view of DRL incidence and impacts.

Phellinus root disease poses a long-term threat to the productivity of managed stands in BC’s SI. This is partly because current silvicultural practices increase the amount and potential of fungal inoculum on affected sites putting regeneration or residual trees at greater risk of becoming infected. Forest productivity is also impacted where P. sulphurascens overlaps with other disturbance agents and suitable multiple disturbance agent management practices are not properly implemented. Unfortunately, DRL is not being adequately detected in immature stands in free-to-grow surveys because the disease may not be fully expressed at the time of free-growing assessments. Nor is its presence in mature, harvestable timber being properly acknowledged due to the lack of information about its long-term impacts. These current inadequacies regarding DRL have serious implications on the accuracy of future yield predictions for managed stands and timber supply analyses in BC’s SI.

Forest managers, including those providing stewardship on forested lands owned or managed by First Nations, need to make informed decisions about best management practices for DRL. Growth and yield analysts also need to accurately assign losses to this disturbance agent in determining Operational Adjustment Factors (OAFs) for Provincial Timber Supply Reviews. The first thing required to implement best management practices and make loss estimates is information on the occurrence and incidence of DRL in Douglas-fir-leading stands of different ages. This information can then be used to guide on-the-ground growth loss and mortality measurements in representative DRL-affected stands, and then generate management and impact scenarios with existing root disease models such as the Root Rot Tracker or ROTSIM.

Results from this project will enhance and refine the research conducted in the past on the effects of root diseases on growth and yield in BC’s forests (Bloomberg and Wallis 1979, Bloomberg and Reynolds 1985, Cruickshank 2001, Lewis 1997). Overall, these results will increase the Province’s body of knowledge on the incidence and behaviour of an important disturbance agent.

This study will (1) determine the occurrence and/or incidence of Phellinus root disease using a matrix of inventory type groups, age classes and BEC zones, and (2) estimate losses due to Phellinus root disease in Douglas-fir obtained from a network of growth and yield permanent sample plots (PSPs) in the southern interior. Results of this study will permit the development of an interim OAF2 factor specific to DRL.
Related projects:  FSP_Y081130FSP_Y103130

Executive summary (0.4Mb)

Updated August 16, 2010 

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